In topic:  the 0331 head thread (help out if you have one!),  1bolt wrote:

Ouch if I was you I would definitely check the mains while the engine is down...

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In topic:  4.5 Stroker I love it but want more power....,  1bolt wrote:

I'm going to go a completely different direction than anyone else...

What power do you want?

Do you want to leave riced up hondas 4 car lengths back at stop lights and chirp big off-road tires on dry pavement?

Do you want big peak HP numbers on a dyno sheet, Or want to pull on turbo'ed hondas doing 80mph on a lonely freeway, or zip around an off road dirt course at 4000-5000 RPM's for hours on end?

Do you want to "mile an hour" at the drag strip or "60 foot"?

You can't really do both under a small budget. If you can afford a cam, then you can improve power up high or down low (depending on what you already have), they both have there own set of unique design choices. Without making the engine larger or fundamentally more efficient (lower internal friction and higher breathing efficiency) you have to tune for one or the other. You can emphasize torque later in the RPM's or earlier in the RPM's (or somewhere in the middle where most mild cams will fall).

Horse power (AKA higher RPM torque)
bigger ports (larger cross sectional area), shorter intake runners, bigger throttle body, long tube headers with larger primaries, 2.25" or bigger exhaust, more cam "valve overlap" and duration and lift (less trapping efficiency to gain more CFM air flow at higher RPM's) low dynamic compression

Low/mid Torque
smaller ports, longer intake runners, bigger throttle body, long tube headers with smaller primaries, 2" or smaller exhaust, tight cam with little to no "overlap" period and moderate duration (air velocity and trapping efficiency more important than large CFM flow) high dynamic compression

Higher compression will benefit both, but you need to tear down, machine and re-gasket for that, same with better quench (allowing more timing advance and more compression before ping creeps in on the same fuel). Aftermarket fuel and spark control tuned on a dyno will probably improve both simply because the factory stuff has lots of built in "safety margin"and emissions oriented tuning choices, which a performance oriented tune will improve on. But that's expensive.

I would say you're not getting the most out of your combo, if you truly have near factory static compression somehow (as Cheromaniac figures) while having such bad quench, from the stock deck with 4.2 rods and 4.0 pistons. I'm terrible with numbers, but the last time I looked at that combo I seem to recall a 4.0 piston on a 4.2 rod and crank leaving the piston ENTIRELY too deep in the hole for effective quench... something like .090 or .100 quench distance... I'm not sure where that puts your static compression ratio but just off the top of my head I think it would have to be pretty bad... maybe I'm mis remembering. Dino did you take into account the pin hieght of his stock 4.0 pistons on 4.2 rods? I seem to recall this combo being an OKAY low budget choice with a block decking to get near factory quench, but without decking I recall it being pretty much unusable... I'm probably not remembering correctly.

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In topic:  the 0331 head thread (help out if you have one!),  1bolt wrote:

Labor is indeed cheap in brazil but to stay on point, so far I don't even think we need to decipher casting dates or foundry codes, the big obvious "TUPY" would seem to be unmistakable.. Unless we see A) a later head that doesn't have TUPY cast on it or B) a cracked head in the usual spot, that has TUPY cast on it: I think this is pretty much case closed... I never suspected this thread would be concluded so easily. Then again maybe it's not; As some of those later 2004 to 2006 0331 heads starts coming off we may find out something new, like a third casting revision that muddies the waters. Also possibly the Alabama Cylinder heads head might not have TUPY on it. but until something like that filters in:

If it doesn't say TUPY then it's poopy (LOL sorry)

I'm going to sticky this thread, I'd like to see further posts in this thread restricted to more example heads or any other new info. Especially later mid 2000 model year and I'd still like to see some pics of the Alabama cylinder heads 0331 bet it says TUPY on it, and they are importing it.

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In topic:  Head porting-for SilverXJ,  1bolt wrote:

The abbreviated version is: don't gasket match, all of the gaskets on 4.0 are less accurate than the factory castings, in my experience, and matching to them is more likely to cause worse mismatch than to solve any mismatch...

If you want an extremely accurate port/manifold match use tracing paper,and carefully map out all the aligning dowel locations along with the stock port openings, then overlay it on the manifolds (carefully making sure the aligning dowel marks match up to the holes in the intake)... Chances are you will be pleasantly surprised at just how well matched they already are, and even if one or two are slightly off I think you'll see that just the slop in the dowel pins could cause all the perfect port matching in the world to end up misaligned and mismatched after install... This is probably why the factory leaves the intake manifold side slightly smaller than the port on the head.

Also intakes revert just like exhausts do, worse sometimes, that's why there's always a coating of black greasy gunk (unburnt hydrocarbons) in the first couple inches of intake manifold... the "step" created by the intake manifold being slightly smaller in cross section to the port in the head, can actually mitigate some of this.

The truth is most people like us want to trick out and optimize our stuff, it makes putting it back together and fixing stuff more fun, but when you dig deep into performance you realize a few key things. A) most "high performance" is aimed at drag racing (they don't care about torque below 3000-4000 RPM's, or throttle response) B) most OEM's know full well why they put smaller restrictive ports and manifolding on their cars... It's not because they're stupid and want to throw away power, it's because they know their non-performance vehicles will operate more efficiently and perform better on the street and under load with more torque and less horsepower. C) Both OEM's and Aftermarket know that most people mistakenly think that peak horse power is important. They sell cars (and aftermarket parts) with peak hp numbers. At some point in the 60's we were all duped into thinking that peak hp is the important number even for street cars and trucks.

The truth is If you do nothing but move the same EXACT amount of torque 500 RPM's higher you will get more horsepower on a dyno sheet. You will lose throttle response, you'll have less torque in the lower RPM's where you use it more, poorer idle quality, worse fuel efficiency (unless you change your rear end gears to match the new torque curve) you will lose towing power, and your car will feel slightly less powerful... but you'll have a bigger number on a piece of paper.

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In topic:  the 0331 head thread (help out if you have one!),  1bolt wrote:

The first couple years were cracking and coming in as warranty calls... So yeah they changed the casting to save money. In this case it required improving the quality. The early heads all crack in the same place and nowhere else (so far anyway). No other Jeep I6 head is known for cracking. We know for a fact that they revised the 0331 and the revised casting has never showed up cracked. So it's safe to say they revised the casting to improve the quality.

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In topic:  the 0331 head thread (help out if you have one!),  1bolt wrote:

Awesome,who would have guessed it would be so obvious... Great detective work there Wild One. Now I guess the next question is do all 0331's after 2002 have Tupy there or did they revise the casting further in later years... I would love to see a 2005 or 2006 4.0 head... If they have Tupy cast on them as well then it will be elementary to discern a flawed 0331 from a good one, and those of us after best torque (or max effort porting of a factory head) can be confident we're not wasting time and money on something that will crack.

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In topic:  the 0331 head thread (help out if you have one!),  1bolt wrote:

Great post wildone unfortunately no one as yet knows which mark is the date code, and how to decipher it. This should be easy to figure out once we have enough heads that are a KNOWN year. that we can compare them and find out which numbers are the same for the same years... then we'll know what marks are the date codes. Basically this thread is just getting off the ground, I think we need another half dozen or so before we have a large enough sampling to get some answers.

Your situation along with wanting to be able to spot later castings of the 0331 heads are exactly why we're doing this thread. Basically no ones going to feel comfortable with an 0331 until we can tell for certain that it's not an early casting with the flaw.

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In topic:  ways to boost torque,  1bolt wrote:

nothing will compensate for a poor gear/tire ratio like swaping to a numerically higher gear, speaking from years of experience myself and with friends rigs. Seems to be commonplace around where I live, people I've known always seem to try to upgrade their engines after a lift. One of my strokers ended up in just such a vehicle, an undergeared weekend warrior rig. The stroker by itself will just not compensate for the gears. And even if it could you'd lose mileage.

4.56 and 33's on my stroker XJ and I can chirp those 33's, with 31's you want AT LEAST 4.10's

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In topic:  kb944's and 954's $352.95,  1bolt wrote:

If they sent me the wrong one, wouldn't accept a return and refused to send the correct one out 100% free I would file a BBB complaint and stop payment with my credit card company...

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In topic:  Carburated Stroker, intake and Cam question,  1bolt wrote:

The primary function of a dual plane intake is to increase the air velocity through the carb venturi, AKA "carb signal" this can be done by dividing the intake so each cylinder sees only half the intake manifold (in any combination), to it has half the plenum volume to draw on thus increasing the air speed through the carb.

Increasing carb signal gets you much better throttle response, idle quality and off idle power (low and lower mid range torque is improved substantially) this is because the higher air speed means better atomization of the fuel, and also more accurate metering of the fuel. There's also a small "secondary" inertial ramming effect (tuning effect) just like there is when you lengthen the intake runner or make it smaller...


That is the famous Edelbrock RPM Airgap (for one of my Ford small blocks in this case) it is a dual plane, the air gap lets you more clearly see the runners coming off the split plenums. The two inner runners go across to the opposite bank than the end runners, so the banks are not actually split. Cross talk or reflected waves are so chaotic and unpredictable IN PRACTICE for a street application that they are rarely a major part of manifold design in V8's... The RPM Airgap is hands down the best dyno'd dual plane intake for almost every V8 out there and it achieves this by lengthening the inner runners by crossing them over allowing them to be longer than they would be if the manifold just split each bank from the other. Basically wave tuning took a back seat to inertia tuning, which is the norm for most intakes. Excepting F1 and other ultra high dollar racing where they run in very predictable and steady RPM ranges ... Wave tuning is too hard to get right for very small power gains, while inertia tuning (think siphon effect) is very easy to get right and offers more power over a much broader RPM range.

That edelbrock is a so called 180* you can also split a single plane intake (a so called 90* intake) or divide the secondaries from the primaries for each cylinder by dividing the plenums and the runners all the way to the port, which is a so called 360* intake (you can also reduce the size of the intake runners or the total volume of the intake manifold in any combination to achieve the same goals with varying effects on upper RPM horse power)...

Offenhauser makes a "360*" intake for AMC 6's


this is one I have laying around, the entire manifold is split so that when the primaries are open only about half of the intakes total volume has air and fuel rushing through it, which means the air speed at low engine RPM's is dramatically increased. I mean DRAMATICALLY, I've never found good dyno comparisons of this intake but I would bet that it's worth 30-40 lb-ft of torque off idle and probably kills 20hp at the upper end of the RPM range. In other words it should be a great intake for a Jeep...

A few notes: making your intake runners bigger (matching the 4.0 ports) will improve UPPER RPM HORSE POWER while reducing lower RPM power... If you make a port flow more CFM by increasing cross section, air speed at lower RPM's will be reduced (which gets you less inertial ramming) while airspeed at higher RPM's will be increased. Also You really only need to pay attention to dual plane intakes for a 4bbl carb, a 2100 Autolite/motorcraft (I'm a classic mustang guy so that carb will always be an Autolite 2100) is a 2 bbl so the stock 258 manifold will be fine.

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In topic:  Mopar 4.7 Stroker,  1bolt wrote:

For that money I'd rather have HESCO build me a stroker at least I'd know they'll stand behind it.

Mopar's Marked up the ATK by $1800 dollars (comparing retail prices) if you adjust this for the large wholesale volume discount Mopar gets from ATK then it's probably about a 60% markup... Talk about bending people over...

$1800 dollars is a steep price to pay for an extended warranty. Another $900 and you could have two strokers with 1 year 12,000 mile warranties.

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In topic:  Custom Header Specs / Design,  1bolt wrote:

One thing to keep in mind on "wave tuning" is that doing it properly and actually GETTING the wave you're shooting for requires actual track testing and will only be effective in a narrow RPM range even with it dialed in. In the end basic inertia (scavenging) seems to be both more significant and easier to tune for.... I base this on in-depth reading over at speedtalk, not any expertise on my own part. Basically it's for racing where getting an extra 2 ft-lbs of torque over a 300 RPM niche might mean faster laps.

So with that in mind, you want the longest primaries you can fit, or reasonably afford to have custom built... Tube size on most 4.0 headers is 1.5" OD Effectively 58" inches of primary length is the most you'll want to go. Somewhere around 38" is fairly optimal, longer than that adds power still but starts getting into diminishing returns. In other words at some point after 38" you're playing a game of weighing the cost of an increasingly complicated snake nest of tubes, and the half point of torque you might gain by adding a couple more inches to the primaries...

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In topic:  High Energy Ignition (TFI) for the 4.0 ?,  1bolt wrote:

Plechtan wrote:
So it looks like a good upgrade if you have a MSD ignition or other High output ignition.

I did it on my 4.0 headed YJ 258 long long ago, and it was very straight forward and worked with a MSD TFI blaster coil just fine. IMO if you're doing non-computer controlled ignition for your LSR MJ you should look for a Mallory Unilite for AMC inline 6's... the Mallory is the original "billet" dizzy and with your application over 6000 RPM's the Mallory is the only thing I would trust. MSD makes a pro billet AMC 6 dizzy too but Turbo Tom doesn't like them and he clearly knows what he's talking about and that's good enough for me. Not that I've known small block ford dizzys to have any problem with 6000 RPM's...

Only catch is... that Mallory is rare as hens teeth

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In topic:  7120 vs 0331 head,  1bolt wrote:

SilverXJ wrote:
How did the 0331 head fair with an aftermarket header for the earlier head and the new manifold vs. the same but with a 0630 head? Besides the cracking in the earlier 0331 heads, are there any draw backs seen in EAP to using the 0331 head?

Well I didn't run that permutation, but I would expect that a longer tube aftermarket header (the long tube Borla averages something like 26 or 28 inches from memory), to improve hp (peak) and maybe bump mid range torque while giving up a little off idle torque (wheel chirping torque I like to think of it)... One problem about using EAP for Jeeps is it doesn't do the best job of predicting below 2000 RPM's because it does not model bogging, swirl/tumble (fuel vaporization effects) etc. which play a large role in how well an engine makes torque at low speeds (but which make no real difference higher in the RPM's).

Besides cracking I don't see any draw backs to using the 0331, but cracking is a biggie. It does seem that past 2001 those heads no longer crack. There's no detrimental effect to having an exhaust port that flows a little less, when it creates much more velocity and thus does a better job of scavenging... Gear heads get worried when they hear the exhausts are smaller; but for any street use (and especially for JEEPS and off-road) smaller exhausts with longer primaries are a very good deal... It's also IMO the best head to start porting on... the exhaust on the earlier ones can't be raised without making it even more lazy at the floor. That port starts out too big and porting it just makes it worse. The 0331 exhaust could be raised probably a 1/4 inch and it would still be smaller than the old overly large ones (IMO).

Man I wish I had more time this makes me want to do some porting, I've started a "max effort" experiment on an 0331 to see how much CFM I can squeeze out with an eye to feeding the new re-worked port volumes and CFM flows to EAP and simulate the results. but I've got a new kid on the way so time is hard to make, and progress is slow. I'm a frustrated David Vizard wannabe

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In topic:  7120 vs 0331 head,  1bolt wrote:

In brief, the 0331 head and manifolds, were redesigned by Rick Mudge (who ported Garth Hill's NHRA 4.0 drag racer) to do a better job in the RPM range that Jeep 4.0's are intended to operate. The intake manifold is longer (11.5" long runners compared to about 9"), more equal runners and feeds the slightly higher, and slightly larger intake ports of the 0331 head. The cast iron exhaust manifold has longer primaries (10" on average compared to 6" average on the header style factory exhausts) and matches up to the 0331's exhaust ports much more closely than previous tube headers (which means better scavenging).

IMO you can't talk about the 0331 head without also talking about the manifolds which are both better than previous factory pieces.

The 0331 intake ports flow better than any other HO head in my experience, Both I and Alex22 have flowed the 7120 (or 0630, they are the same) and 0331 and both of us found the 0331 to have higher CFM on the intakes. There's some numbers here if you do a search.

The exhaust ports are MUCH smaller but flow only a little less than older HO heads, this is because the area that was "filled in" so to speak to make them smaller was a "lazy" area (the floor of the port after the short side radius) NOSIGMA's velocity maps show this area on 7120 heads plain as day. And he also talked about how he'd love to be able to fill in the floor of the port raising it and increasing exhaust gas velocity... Looks like Rick Mudge did this, raising the floor makes the port smaller, but it also makes the short side radius much more gradual. He also gave the new exhaust port a trapazoidal crossection where the roof is smaller than the floor which has also been found to be a more ideal shape for the 4.0 heads, even the intakes have a small amount of trapezoidal narrowing towards the roof.

I used EA pro to sim the 99+ intake, the exhaust and the 0331 head as single mods (retrofitted to an older HO) and as a full system (in other words like a 99+(WJ) or 2000+ (XJ and TJ) factory engine without the factory emissions/MPG camshaft, and the emissions tuning (and without the pre-cats)...

I've never posted the numbers up here because I think no one will believe they are realistic... And even if Engine Analyzer Pro is a great engine simulator used by race engine builders, it might be wrong, and I might be wrong to believe it.... I'll just say this... I believe the SYSTEM (not only the head) without the factory emissions tuning and fuel economy cam is good for a LOT of torque over an earlier HO.

A lot of this info can be pieced together by reading the sticky thread on head porting (collected work of NOSIGMA).

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In topic:  How to Remove Harmonic Balancer / Vibration Damper,  1bolt wrote:

dude I did that once,.. that washer doesn't look like a washer I also broke the puller and took it back and got a replacement... "must have been a flaw in the casting or something"
I also once got a puller that the main bolt was crooked, like they tapped it at an angle off center, man that thing was the hardest bolt I've ever cussed at. it's amazing how hard a HB is to pull off a press fit with a bolt that's trying to pull slightly off center... I gave up got a replacement that checked out okay and went back and pulled the thing like it was butter... the old one required all my weight baring down to even turn a half turn.

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In topic:  JP manifold swap article,  1bolt wrote:

It's the perfect compliment to an RV cam

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In topic:  JP manifold swap article,  1bolt wrote:

Dino's findings are very close to what Engine Analyzer Pro predicted, maybe damn near idenitcal when you realize that Dino's numbers are from a chassis dyno which includes drivetrain losses. there's a thread about it here, if the earlier HO heads like the 7120 and 0630 heads intake ports and exhaust ports were as good as the 0331 head the intake would make more power than is does. The main benefit of that intake is improved low end torque. and better average horse power (not peak hp). Still on a dollars per power scale $50-100 is a smokin' deal.

And hey because we're talking about JEEPS here not Drag Race cars; Throttle response and improved low torque are WAY more useful in a Jeep than a "mythical" 10 horse power at 4800 RPM's would be. I mean is it a "MYTH" because it doesn't give the amount of horsepower that some people pulled out their asses a few years ago and plastered all over the web? Yeah, sure. On the other hand is it a "myth" that JP magazine has uncovered as being a useless mod? No I haven't seen the article but it sounds like JP is steering their users wrong and creating their own myth...

If the factory had wanted it to improve peak HORSE POWER (AKA improved Torque higher in the RPM range) with that intake they would have made the runners shorter not longer. The 2000+ has 11.5" runners, somewhere around 6" would be ideal for peak hp numbers on a 4.0+ sized engine and factory cam, the older manifolds were 8 to 9.5" (Renix to HO).

As always, making power is about how SYSTEMS interact with each other, the 0331 system (head and both manifolds) has better intake ports, smaller more efficient exhaust ports that actually improve power in the useable RPM range, longer intake runners (more inertia ramming at lower RPM's) longer and smaller exhaust runners (better scavenging at lower RPM's)... If the first couple years of them weren't crack prone we'd all be taking this for granted by now.

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In topic:  Dollars per HP,  1bolt wrote:

Spam bot, I just banned it, No wonder it looked on topic it just quoted Dino (Cheromaniac) from page 3 looked like a link to some French Identity theft protection service.

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In topic:  Fitch Fuel Catalyst,  1bolt wrote:

Horsepower TV did a dyno test of one, and claimed there was an improvement... In gallons per hour used, anyone familar with the dyno process has Got to ask why they showed results in gallons per hour instead of brake specific fuel consumption. BSFC is a exact and unequivocal measurement of fuel efficiency on a dyno... GPH is very much NOT. All sorts of things can cause GHP to change (like starting the first run with an empty just installed Carburetor which they did) If you look hard enough there are several dyno tests of the fitch, using Brake Specific Fuel Consumption, and none have shown an improvement in fuel efficiency, one even showed slightly worse. BTW Horsepower TV pimps the Fitch during just about every show; AND I know for a fact that they can measure BSFC, in fact they have used BSFC in other unrelated tests.

The Fitch is the slickest most intelligently marketed snake oil... but It is snake oil, refining gas more even if a couple small pellets could do that, would lead to WORSE GAS MILEAGE.... as higher octane (more refined) fuel has LESS ENERGY CONTENT.

Forget about the fact the more refined fuel will get worse gas mileage in a normal car. The claim that it even refines gas at all is ludicrous, refining is a lossy chemical process and petroleum engineers have already examined the fitch and determined that there's not enough "material" in the pellets to refine even a few gallons of fuel before being completely spent, and this is assuming the pellets were actually in a refinery system capable of actual chemical refinement, instead of inside a metal filter housing re purposed to look like something. Exxon would spluge all over itself if it could refine gasoline by dropping metal pellets in a big tank...

Sorry to say but the placebo effects is responsible for any and all "improvements" just like Acetone and Hurricane intake widgets etc.

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In topic:  Can't figure it out,  1bolt wrote:

That cranking compression is so high it makes me wonder if he's got too little pre-load on the lifters or something... even a performance stroker shouldn't have much over 160-180psi should it?

IIRC The 901 Crane is not an RV cam, it's a a warmed over factory profile if I remember correctly (I could be misremembering but I do have one lying around somewhere and I recall it being a street grind) so if its a street oriented cam it should have some overlap that should bleed cylinder pressure...

Over 200 PSI sounds like something wasn't done right either with the machining/piston dish or the valve train specs.

As everyone has already pointed out you need control over your timing and richer fuel mixture for sure. If you have E85 near by run it until you can get something programmable and have it dyno tuned. I would not run the factory ECU with that much compression going on with even 93 octane. With the lean condition and factory timing you're running a real risk of hammering a piston land or valve into submission.

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In topic:  Titan suggestions,  1bolt wrote:

Can't tell anything about towing capability without more cam specs, the duration and lift don't tell us if it's a high overlap cam or when the valves open up (cam timing) but based on 212 seat duration I'm guessing its not a radical horse power Cam

I suspect that a 500 CFM carb is quite a bit too much for RV/Towing style useage... you'll get your best low end and mid range torque from a smaller carb, that 500 will only really be in its sweet spot at higher RPM's. It's not losing a ton of power or anything but it's not optimal for towing for sure.

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In topic:  are tj 4.0 block and 95 4.0 blocks the same?,  1bolt wrote:

Moved to basics; Yes they are the same. Most years of 4.0 blocks from the first (or even going back to 258 and 232 blocks) to around 2001 are functionally identical. Only the last few years have any real differences, and even these in my view are basically the same, only the later grand Cherokee blocks require significant adaptation to put in a TJ YJ or XJ. Different accessory placement (Alt and AC compressor) or serpentine belt lengths do not incompatible make (like my Yoda impression? Different motor mount brackets just barely qualifies in my book.

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In topic:  exhaust size,  1bolt wrote:

honestly if I could answer with certainty I'd probably be making a living in the racing industry and not here offering opinions. I do remember reading somewhere that a configuration like you describe (Banks makes a header like this) may have benefits different from typical high RPM horse power that most aftermarket manufacturers are trying for. So that setup may be to enhance low end torque or mid range power at the expense of higher RPM horse power.

There's a considerable amount of in depth details about things like asymmetrical headers, 180* headers, balance tubes etc. in David Vizards books on How to build Horsepower, which is probably where I read about the configuration you mention. Only problem is he's nearly always talking about V8's and although he spreads things around and often applies principles to other engines to illustrate points I don't recall him ever touching on the ideal exhaust setup for a typical I6 firing order... Now that I think if it though I seem to recall him talking about Jaguar I6's in one of his books. Should be the same firing order so the same principles would apply. I'll try to track it down and see if there's any nuggets.

It's important to realize that most people view power as something that is added to by engine mods. When it really should be looked at as something that is MOVED around (tuned for specific uses) On an engine that is well built It's very difficult to add low end torque without losing higher RPM (peak) hp... And it's very easy to lose lower RPM torque by doing things that increase that peak hp.

On the other hand lots of header designs have no regard for wave tuning, and do things for reasons like fitting the primaries under intakes, how it looks etc. In addition to other practical matters of fitting things, they might also configure things to fit the longest primaries into the smallest area etc.

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In topic:  exhaust size,  1bolt wrote:

Well we have it on good authority (see the sticky thread in Performance toward the end) that an I6 will perform best with a split dual exhaust that should be 123 into one and 456 into the other; split all the way to the tail pipes. No H or X pipe. The reason as best I can determine is that an I6 does not have a complimentary firing order like a V8 does. Basically you get no help from the opposing banks exhaust just the oposite you get reversion (one exhaust fighting another). Because the firing order leads to having an exhaust pulse right as another exhaust valve is closing during "overlap". The spent cylinders exhaust valve is nearly closed as that same cylinders intake valve cracks open, leading to exhaust pulse from 1, 2 or 3, being pushed into the closing exhaust and out the opening intake valve of 4, 5 or 6).

This is probably one reason why there's always built up gunk in the first couple inches of a 4.0 intake manifold. Also might explain why Renix intakes always seem to be more caked than HO intakes, (in my experience having torn down dozens of them) the renix exhaust has all 6 primaries (most of them less than 6" long) merging into a single log.

I am too lazy to actually figure out which cylinders would interfere with which just for this example, but I hope you get the idea (maybe someone else will wrap their brain around it and work it out for us) but the gist is that most V8's will benefit from a cross over pipe of some sort, while a straight 6 wont. You can see how the factory headers have evolved and seem to try and keep the front three isolated from the back three further and further as the years progressed, from Renix log, to HO with two smaller logs that only merge at the down pipe, ending in the cast iron 99+ exhaust manifold that keeps them split past the pre-cats.

So keep it split, as for size... IMO 2" is fine all the way back, and may lead to better scavenging in the low and mid RPM's while 2-1/4" will probably breath a little more freely at upper RPM's neither will have a big difference over the other. a couple footpounds given up for a couple hp or vice versa.

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In topic:  When to stop Porting,  1bolt wrote:

Very good reading, another resource would be speedtalk.com forums, there's more know how over there than anywhere else on the entire net.

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In topic:  When to stop Porting,  1bolt wrote:

there's a sticky thread at the top that has all sorts of great info.

If everyone thought of power as something that is "tuned" like a musical instrument, or a Sub woofer enclosure instead of thinking about it as "adding" power it would be easy to explain why you don't want to hog out an intake or exhaust port. You're not linearly increasing power by making mods... you're moving it around!

In very general terms if you Increase the size of the pipe (exhaust or intake tract) or shorten it, the engine breaths easier at higher RPM's (less restriction naturally but also complex inertial "siphoning" effects) but LOOSES power at lower RPM because air has momentum, and longer (and smaller) pipes create a stronger siphon effect at low RPMs that makes air flow very efficient. This is why the rounded runner intake makes more torque through the RPM range, it has longer runners.

It is also why they made the 0331 head with smaller exhaust ports, and smaller exhaust manifold runners... better siphon effect (as everyone knows in exhaust terms this is called scavenging) than the older larger exhaust ports and exhaust header which are much larger, but don't make as much torque.

You are mostly just "moving" power around, once the engines displacement and build qualities (Cam choice, compression, internal friction, oil pressure losses etc.) are set in stone then you have X amount of potential power, and mods for the most part move the peak power around, or "free up" whats already potentially there, but is being reduced by something (like a restrictive air filter or intake plumbing).

Some general advice... If you want low torque don't increase the size of the ports cross section OR the intake runner; and this includes not "gasket matching". You want to PORT MATCH. Gasket matching is a term coined back when casting technology was so bad that the gaskets were often more consistent than either the intake or the head ports, so the gasket was used as the template to get both pieces to line up. Modern head porters do a PORT MATCH which effectively ignores the gasket unless it needs trimmed to fit the ports. Modern castings are very much improved and often line up with so little misalignment between port and runner, that very little material needs to be removed. A gasket match under those circumstances especially with a old crappy non MLS gasket like this:

Can result in removing so much material that you create a pocket that will hurt low torque AND high horse power, this illustration I did a while ago will help visualize why:

By increasing the cross section of the port and then decreasing it again you make a pocket where air will expand which slows it down, the air behind it will slow down as well, the air IN FRONT will be "pulled" by this pocket, in other words slowing the air down. Loss of velocity is always bad for torque (assuming the port was nominally efficient to begin with) I would guesstimate you could drop 10 or even 20 foot pounds conceivably if you make a pocket in such a crucial area.

On the exhaust side... I hate to say it but I think most people make their worst mistakes here, DO NOT bell out, "radius" or "round" the exit of the exhaust port!

This is the worst exhaust I've ever seen, the guy who was building this stroker and put so much time and effort and money into it (including a meticulous writeup on JeepForum -- then he basically went deafeningly silent after he finished, and eventually he quietly sold the engine... I bet it makes less torque than a budget stroker

For the reason why I think that; First go google "exhaust reversion" don't take my word for it. Leave the transition from exhaust port to gasket to exhaust header a SHARP EDGE. Because exhaust flows BOTH WAYS (I know hard to believe but 100% true), and you only want it to flow out well, you don't want it to flow BACKWARD well. You want to make any reversion as difficult as possible and gas flowing backward from the header back into the port will have an EASY time with a radius, but a sharp edge is almost the best possible shape short of an inverted cone (reversion cone).

Also go with smaller exhaust ports if possible (such as an Alabama Cylinder heads 0331 head), and a smaller diameter header primary size with VERY long (longer the better over 2 feet with somewhere around 48 inches being ideal) primaries. The header part is not easy because the aftermarket is just like the OEM's they know that most people ignorantly key on peak horse power numbers, so they are quite willing to move your torque peak higher in the RPM range to get higher peak horse power numbers to feed you. You might very well never rev your engine to this new higher peak, which means you'll have actually LOST USEABLE POWER because the aftermarket part moved it further up into territory you seldom use.. You can also lose fuel efficiency in this deal

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In topic:  232 crank vs 258 crank,  1bolt wrote:

YJason wrote:
I think by using the 232 crank your only getting .087 more stroke and defeating the purpose of building a stroker. For fast revving I'd go with the 4 counterweight 258 crank. Mine revs really quick and has excellent throttle response. Well it did until I broke the timing chain but thats a whole nutter story.

The basic reason a 232 might be interesting really doesn't have anything to do with increasing the displacement of the engine. The 232 crank puts a stock sized 4.0 rod and replacement piston into super tight quench territory and elevates the compression ratio. Doing this any other way probably requires custom pistons and more machine work. I say probably because you never know what oddball combo might pop up, the 232 crank stroker is just such an "oddball" and is a product of the "imagineering" that goes on here.

IMO the 232 is an "elegant" performance build but not something that going to be interesting to the average Jeeper. It is extremely interesting to someone who is considering high octane pump gas or E85. With a deeply dished forged piston (or race gas) it is also a very interesting build for forced induction.

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In topic:  Synthetic oil change intervals,  1bolt wrote:

I don't think it's unrealistic to try and get over 5 or 6k but I wouldn't do 10k on the recommendation of any small scale test. If they took 100 jeeps and 99 of them showed good used oil analysis' all the way to 10k on the same synthetic oil, and one jeep had a poor UOA (Used Oil Analysis)I would wonder if my Jeep was a 1-100 or a 99 out of 100... So I would only go over 6,000 miles with a UOA around 5,500 or 6,000 if it looked good I would check at 10k and if that looked okay I would change the oil and repeat the process once more, to confirm and then I'd feel save.

In other words even if the "test" involved several hundred or thousand Jeeps and all showed good UOA's at an extended change intervals like 10k miles you STILL don't know if you have a leaky injector, or a coolant leak getting into the oil slowly... If you are a little high on wear metals or gasoline in the oil or coolant in the oil at 5,000 miles you might be damaging your mains by 8,000 miles... So without testing your oil at least a few times and occasionally thereafter you could be doing serious harm without knowing it.

So If you go long intervals test... if you don't want to spend 25 bucks occasionally to double your oil change interval (OCI) then go more conservative (6k is fine in my book without testing) I still do the odd UOA just to check.

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In topic:  4.5 or 4.7?,  1bolt wrote:

I can't remember what the quench is for this style build but it's not good at all. The 4.5 is known as a "junk yard stroker" or Ultra low budget stroker. So called due to the fact that no overboring/machine work and stock 4.0 pistons on 258 rods is usually assumed to be a money saving choice, such as re-ringing a junk yard 4.0 that has decent bore wear -- unlike your scenario where it's just not necessarily needed.

If machine work is free and your budget is reasonable... you'd be missing out not to overbore, and go with a well matched piston and deck the block for "zero deck" (piston flush with deck at TDC) for sake of brevity I've been trying to get the term "GC" (Gasket Quench) to catch on around here so we can stop typing that long involved sentence... basically GC means zero deck and your head gasket thickness then determines your quench spec, a .043 gasket = .043 quench which is excellent, and will allow more compression before onset of ping, more power or lower octane fuel use for the same power (or more power with higher octane and a aftermarket engine management setup).

If you only deck the block to improve quench you'll put your compression ratio through the roof which will require deeply dishing the stock piston (which can take a fair bit of dishing it appears they are very thick in the crown) and/or enlarging the 4.0's combustion chambers which we have on good authority are too big already and not ideal for performance.

If money and machine work permit you'll be much happier with a more engineered thoughtful build... Just ask all the budget stroker owners (myself included) that have ping issues.

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In topic:  Flogging the wee wee out of a Jeep 4.0 I6,  1bolt wrote:

great stuff Tom, looks like 10's are going to be a piece of cake!

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In topic:  4.6L with no power???,  1bolt wrote:

index the distributor/cam sensor with the toothpick method... your problem will go away... 100% sure that's the problem it almost always is on fresh startups.

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In topic:  My new stroker..check it out,  1bolt wrote:

My Borla long tube (not actually that long it's a tri-Y but longer than most headers made for the 4.0) has seen 65k stroker miles and no cracks (knock on wood) I suspect part of the reason their Tri-y's last so long is all the primaries go into the secondaries at very little angle then the secondaries come together the same way. I have another identical one that has seen plenty of use and has no cracks either... in fact i bought it because of how good the first one has been.

IMHO the last place to skimp on any more ambitious build is with the header.... though I would seriously consider not using a renix intake as well.

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In topic:  DLC coated lifters, dry lub film bearings,  1bolt wrote:

just guessing but the kind of specialty house that could teflon coat the inside of an intake, is going to take nearly a hundred similar donations to pay for not that I don't appreciate the offer, just don't think it'll happen, I'm pretty sure the results wont make it worth the trouble...

Anyone think of anything that is inexpensive, tubular, slightly convoluted (a 90* smooth bend would be ideal), and is teflon coated on the inside? that would make a good test subject? I realize there are different teflons/processes as well so that would have to be considered... It wopuld have to be cheap enough that I could destroy the coating after I measured the flow, so I could measure the flow without teflon.

With something like that I could very easily come up with a Flow coefficient that I could plug into Engine Analyzer Pro to get an estimate of the effect on performance. It would be fairly accurate and not cost much.

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In topic:  DLC coated lifters, dry lub film bearings,  1bolt wrote:

well yes and no, OEM's coat the TB blades to keep them from sticking sometimes, but as far as coatings for ports and runners pretty much nadda on the domestic front, at least none that I've heard about, maybe the Japanese do? Basically coatings on a port only reduce the Reynolds number (the friction) of the wall, this supposedly has very little effect on the bulk of the air flowing through, it basically just acts like increasing the cross section of the port or runner a tiny amount. Appearently (from my understanding of the subject anyway) cast Aluminum already has a pretty good texture for a fast moving boundary layer.

(that's one of the reasons Teflon non stick surfaces are usually textured similarly)

I wasn't entirely joking, I'm just geek enough to want to test teflon versus cast texture on my flow bench, and easily poor enough not to want to spend hundreds to get an intake coated without knowing the results before spending the cash.

As I noted I have seen a few discussions about this but never any testing. So I could be entirely wrong. I've litterally spent hours searching speedtalk to find racers talking about air flow oriented coatings, there's surprisingly little.

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In topic:  DLC coated lifters, dry lub film bearings,  1bolt wrote:

Very interesting Tirod you got any links for the teflon intake runners? I read some SAE stuff a couple years back where GM teflon coated a throttle body and got 25% more airflow at part throttle, but I've done a lot of research and found a lot of info that suggests a teflon coated surface wont really do anything significant for air in a port or runner, only to areas where high friction exists such as in the boundary layer (on the wall of the runner, or at the throttle blade,) so in practice no substantial CFM increase is found...

Guess it would be easy enough to test.... just take the wifes teflon cookie sheet cut it up and roll it up on a piece of tubing and run it on a flow bench against a plain piece of metal sheet with the exact same diameter, or maybe sand blast a piece of aluminum sheet with black beauty (really coarse) to get a cast texture and roll that into the same diameter... ... Hmmm man my Wife would be pissed if my flow bench wasn't in pieces... hahah

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In topic:  Damaged cam,  1bolt wrote:

Yeah if the nose was a little soft that would explain the wear... heck maybe the noise as well... maybe the odd angle on the nose was tossing the lifters up a little.

One long shot but I've actually seen it happen, check and make sure the push rod tip is actually completely seated into the bottom of the rocker. I've seen aftermarket pushrods that didn't quite seat into some aftermarket RR's on a 5.0. in effect the pushrod acted like a longer one.

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In topic:  Damaged cam,  1bolt wrote:

thanks hatem thats a good nugget there. Since Chris says he installed the springs at a higher height I think coil bind or just close enough to bind to cause the extra pressure on the noce of the cam... maybe the cam is a little soft too and the two conspired (so to speak) to cause the damage... I'm stumped otherwise.

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In topic:  Damaged cam,  1bolt wrote:

no offense taken as I said I'm not exactly batting a thousand on internet diagnostics, I just can't see how turning an engine over with starter bumps could possibly cause your problem. Think about it, engines dry start all the time probably 10's of thousands of times in their life span.

Anyway if everything checks out, the only thing left to do is stab another one in cross your fingers and hope it doesn't make noise when you try to break in the next cam... Hope your luck changes man.

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In topic:  Damaged cam,  1bolt wrote:

Just from thinking about it, I seriously doubt it's a failure, or broken component like 6 mysteriously damaged lifters. With all six lobes having that problem I would tend to think the Cam was soft, or not heat treated properly or just didn't get work hardened on the nose during break in for some strange reason, but because you had valve train noise and I can't think how the worn noses would cause any noise... I think there's some geometry issue with the rockers, length of the push rods or something that would explain all six lobes having the same damage, done presumably from the added stress of the binding which also caused the noise.

Unless the lifter bores aren't aligned right and somehow this was causing the lifters to "toss" off the cam and smacking back down on it... but that it not a "valve trainy" (to coin a phrase ) noise. Every time I've heard lifters slapping down on a cam it sounded like solid lifters or Rhodes lifters on startup... sort of a clipity clopity old school cold engine noise. Maybe the edge of the lifter is climbing up the ramp and when it gets steep enough the actual edge was digging into the nose of the lobe.

I don't know just kinda wild ass guessing here. Is there any rounding or polishing on the edges of the lifter foot? If it does turn out to be the lifter bores, I've got another block you can have.

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In topic:  Damaged cam,  1bolt wrote:

Man I hope it's not the block I sold you, but I doubt it is, I think it's more likely whatever was causing the noise... maybe the lifters, but all 6 at the same time? that seems unlikely. I think there's got to be some binding, and I would double check Mopars work, and also make double sure that are seated all the way and not up on some raised machining lip... you never know with a big company like that if some mix up or error caused the wrong springs to be in the package, or the label to be wrong. I wouldn't know how to check the lifter bores or if that's likely enough to bother checking, but I'm sure the specs exist somewhere... If you have a hard time finding the correct specs let me know and I will put a straight edge down the tunnel of one of my spare blocks and another down the lifter bore wall and see if I can find an angle... Maybe it's a bad block from the factory that wiped the factory cam that you found on tear down...

I think it's binding somewhere but I'm like 1 or 2 for 100 in Internet long distance text based diagnostics so what do I know

dwg86 wrote:
Although there shouldn't be any camshaft wear after 100 miles, I wouldn't think .007 would be enough to make valve train noise. I am curious to see what Comp has to say.

I agree its not wear, and obviously not ZDDP related that oil is good.

Damn Chris whats with you and Cams anyway?

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In topic:  how fast are yall's strokers?,  1bolt wrote:

So you would have cracked into the 11's if you had tweaked the gas a little after the 8th mile....

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In topic:  Damaged cam,  1bolt wrote:

doh I see now that you have aftermarket pushrods and adjustable roller rockers... I definitely think it's a valve train geometry thing now, you've got binding somewhere when there's actual oil pressure pumping the lifter... so what you need is to substitute in a solid lifter or take a used lifter that's not too worn and alter it so its spring wont compress, and use that to see where the bind is occurring. I bet the roller tip is coming off the valve at full lift, or close enough to it that side loading is causing the valve stem to bind... How do the valve stems look BTW?

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In topic:  Damaged cam,  1bolt wrote:

Man you have the worst luck, I thought mine was bad. IMO your culprit has to be tied in with what was making the noise. You either have springs binding, rockers binding on their saddles, rocker noses coming slightly off the valve tip, causing side loading of the stem (and thus binding everywhere else), push rods that are too long, or lifter pre load that is too high. Or (gulp) maybe the machinist line bored your cam tunnel off center closer to the deck of the block accidentally, causing stock push rods to be too long...

Wear only on the nose of the lifter seems like a binding issue, measure everything in your valve train, including push rods and even the lifters themselves confirm that everything is actually what its supposed to be and not some slip up like someone sent you lifters that are taller by mistake or longer pushrods, or taller springs would be easy to mix up. Also who makes the cam?

I know you've gone through some serious stuff and although I've read a whole lot of it; I'm kinda lost now. Can you give us a little recap on whats going on post titan debacle? Is this a third stroker build or the "post titan" one you did yourself that you had running and were tweaking A/F ratios last I saw? How many miles are on the engine as assembled? Did you have the cam out (and measured) before the 100 miles with noisy valve train?

How much ZDDP does VR1 have? Maybe the odd wear is just the beginning of failure, and once the nose of the lobe was rounded the lifter face would have been headed for dishing? Still I think somethings binding at full lift.

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In topic:  how fast are yall's strokers?,  1bolt wrote:

My XJ which is cammed for low torque did a low 15 second quarter, without burnout (wouldn't have helped anyway) neutral dropping at only 2000 RPM's. with an Auto (which coincidentally or not needs replacing now), LSD's front and rear, 3.5" lift 33/12.5/R15 tires (BFG AT KO's) 4.56 gears, 3900lbs with me and a tank of gas... It falls on its face around 4500 RPM's due to the cam being a total RV and towing grind from Clifford. I pretty much did it on a lark, but I'd done previous runs with a G-tech RR with similar numbers (mid to low 15's)

low 15 seconds in a heavy lifted XJ is pretty good IMO and I'm 100% positive I'm making 15 or 20 hp less than Dino because he has a factory Cam and I have the RV cam and his manual trans to my AW4. I'd probably leave on him due to the lower RPM torque peak, and the steep gears and tall tires, he would catch me and blow past on the other end.

To put it in perspective a perfectly bone stock fox body Mustang GT will run in the 14's a little faster than Dino. Which IMO says a lot for how much fun our Strokers are... I am a fan of Mustangs as well (I'm on my 5th)

Tom didn't you say you coasted to a sub 13 second quarter mile on those initial runs because you were shooting for 8th mile times? I guess "turd" is in the eye of the beholder, 12 second quarters without even trying with a hurt engine is impressive to me... That means you have one of the quickest I6's known around these parts and you had your foot off the gas doing it heheh.

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In topic:  the 0331 head thread (help out if you have one!),  1bolt wrote:

Thanks Alex I never even saw this addition!

I'd like to extend an even better offer, anyone who posts pics (taken as I detailed in the first post please) of:
an 03 or later factory head
an Alabama Cylinder Head casting (or other known to be revised factory replacement casting)
Or autopsy's a cracked or uncracked 0331 (band saw through the head where the crack is in such a way as to show how much iron is there)

Will get donator beni's (I'll donate on your behalf) which includes jeepstroker.com stickers, donator status and access to donator areas.

Alex keep um coming if you get any more that come through!

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In topic:  Flow bench Head Porting collected work by NOSIGMA,  1bolt wrote:

Nope sadly we still don't know, we have a thread on the 0331 with pics of the casting marks from various heads trying to find some commonality (a date code or other identifying marks) on heads that crack versus newer heads that don't. All we do know is that a 0331 from Alabama cylinder heads has the "flaw" fixed and is known to be a revised OEM casting stock replacement...

Maybe someone should call them and see if they can track someone down who can tell us what year they revised the head to not be crack prone... It seems like cracking heads on 02's are rarer than 01's, and 03's have few reports of cracks that I recall (like maybe one or two on the big JeepForum thread Dino started a while back?).

If I was going to port an 0331 I would find a local yard that has a wrecked 04-06 WJ or TJ and go pull the head for $50 bucks. Don't forget the exhaust manifolds and the intake while you're there, the manifolds are a big part (maybe the biggest part) of the system, and unless you're going to replace the iron exhaust manifold with a long tube header then the iron one is the best part for the job for a off road/street Jeep build... Lower underhood temps and better scavenging (if you omit the pre cats) and run the dual outlet pipes all the way back to some hi flow cats and a set of good mufflers.

You wont want either manifold if you're going drag racing (not many of us doing that though)... well maybe you do if you have a Turbo in mind as the iron manifold is very desirable in a turbo application

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In topic:  Multipart question, 4.2/4.0 hybrid, dyno numbers...,  1bolt wrote:

I think someone on the eagles nest should post that to their FAQ section

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In topic:  Multipart question, 4.2/4.0 hybrid, dyno numbers...,  1bolt wrote:

I've seen lots of butt dyno claims for that head swap including my own, no I'm talking about an actual dyno comparison before and after and It may have been posted here, or at least linked to. I remember making the comment: I thought so!

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In topic:  Multipart question, 4.2/4.0 hybrid, dyno numbers...,  1bolt wrote:

It's all good, stroke it next time you'll be shocked how much difference doubling the hp will make

Did you know there was a year when the 2.5L fuel injected AMC 4 banger made more power than the 4.2? Honest 100% true. Jeep factory ratings!

I know all about having to do what you have to do. Still I am having a hard time with 30 MPG I'm not trying to kill the messenger though if that was the factory rating I'll take your word ... I'd have a hard time believing 25, I never got out of the teens with either of my 4.2 experiences, and that includes fresh builds, BBD (properly working if you can believe that! granted it didn't work properly for more than the usual year or two before it needed another rebuild... A 2100 carb with 1.08 venturi , Weber, Holley TBI injection, and factory 4.0 fuel injection... and a 4.0 HO head swap in there...

Amcinstaller, the only before/after dyno numbers I remember of a 4.0 head swap onto a 4.2 was about a year back and it was something like 20hp... My own experience seems to jibe with that... Now if a lumpy cam is installed I can see any 4.2 gaining some significant hp numbers, because the factory 4.2 cam is so far upside down on torque versus hp.

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