Dollars per HP

[Plechtan]

For a long time I have been wondering if the parts purchased for a stroker were cost justified? People build strokers for $1,000 and some people build strokers for $5,000.00. Does the $3,000.00 4.6 stroker really out perform a $1,200.00 4.6 stroker? Are we spending money on Pistons and head porting, when it may be better spent on tuning?

The thread from Comanche91 http://www.jeepstrokers.com/forum/viewt ... it=unichip Illustrates the point. He takes a Hesco 4.5 stroker (which i do not believe has a ported head), puts a 99+ intake on it and picks up 12 RWHP ( good investment) Then adds a unichip and tuning ( $600?) ans picks up another 42 RWHP. Since the drivetrain was involved it was probably more like 50 hp at the motor.

I would assume that the motor was running the stock ECU with oversize injectors and maybe an adjustable FPR to start, very similar to most stroker installations. So if the 4.5 was able to see an additional 50 hp with a little tuning, then what buried horsepower might there be in a 4.7? or an engine with oversize valves and ported heads?

50hp for $600 seem like a pretty good deal, but is the unichip the best solution?

[gradon]

I just picked up a unichip for $407 shipped, and will have to pay a Unichip custom tuner $300-400 to custom dyno tune it. It's expensive, and yes I could've bought it from hesco for $575+shipping and then another $150+ for a download cable(or shipping back and forth until I "thought" it was good) to receive adjusted tunes and still not have been on a dyno to see my actual numbers nor areas that needed/could use more/less timing or more/less fuel. Who knows beforehand the exact tune of my 96, with a 10:1scr, 8.5:1 dcr 4.6(comanche's is a 4.6 too--it's been bored .030", so I still dunno where the 4.5l came from--he's got 4.6 badges, right? ) with an Amsoil 3090 filter on a k&n fipk, on a 62mm tb, on a ported and smoothed 99+ intake, on a ported and polished head, with a mopar 30ab cam, with 25.5# LT1s, with a borla header and cat-back, with various sensors and their tolerances. . . you get the pic--a lot of variables. I've spent hours tuning the psc1(before I soaked it) and got the afrs where I "thought" they should be: zero'd the fuel trims in closed loop and had my wot at 12.5:1, but no timing adjustments(you need the ftc for that). I figure mine will get at least what comanche got out of his and the nice thing about the obd2 unis is that they have the sockets for the 3 stock harnesses to plug into and 3 harnesses out to plug into the pcm--truly a piggyback and plug and play(and easily removed if need be). Mine needs 2.5K-3K in closed loop to be richer and possibly take some timing out--something that usually requires a stand-a-lone(but I did find that unplugging the cts keeps it in open loop, should any of you wish to leave it in OL and completely tune your own maps(might have a constant CEL, but who cares if it's exactly how you want it or even get Kolak to remove that code out of the pcm). Anyhow it might be a month out before it gets tuned by Altered Atmosphere Motorsports(they were the first shop in the US to get an AWD dynojet and they specialize in Nissans), but for now it's coming "loaded with the k&n fipk, header, and cat-back tune". I agree that custom engines need custom tuning to get the most out of them.

[Plechtan]

I just picked up a unichip for $407 shipped, and will have to pay a Unichip custom tuner $300-400 to custom dyno tune it.

SO about $800 to tune your truck, be interisting to see the HP gains and /or fuel economy gains.

The thing i don't like about the Unichip is that you can't tune it yourself. If you change somthing, you have to go back to the tuner.

[1bolt]

The low hanging fruit is always the best to go after, in terms of cost per horsepower anything you can do while rebuilding that doesn't significantly add to the cost should be seen as low hanging fruit... easy pickings... Getting good quench and spending the money for 93 octane every tank is "low hanign fruit" because you probably will deck the block anyway... so deck it enough for GQ (gasket quench) and purposefully build for a high 9's low 10's compression ratio... Smooth the chambers, plane the head for smaller chambers (and larger quench pads as a side benefit) while dishing pistons to keep it in pump gas range... those are low hanging fruit... Overboring is as well, slim head gasket, 99+ intake, moding a larger throttle body (see Dino's Mustang TB) to fit.

[Plechtan]

The Mustang throttle body seems like a good upgrade, and Dino does specify it on most of his recipes. Most people seem to go with A bored out throttle body. I see two issues with the Mustang TB, 1. It has a IAC solenoid, not a stepper motor. 2. If you are running a Renix with a automatic you will need a way to make the Jeep TPS work on the Mustang TB.

The IAC issue can be addressed by using an external IAC block. this is an aluminum block with 2 fittings and a place to bolt the Jeep IAC motor. They are used for Megasquirt and other aftermarket EFI system. You run a hose from the block to a vacuum port on the intake. You would then block off the IAC location on the throttle body.

[Plechtan]

The low hanging fruit is always the best to go after, in terms of cost per horsepower anything you can do while rebuilding that doesn't significantly add to the cost should be seen as low hanging fruit... easy pickings... Getting good quench and spending the money for 93 octane every tank is "low hanign fruit" because you probably will deck the block anyway... so deck it enough for GQ (gasket quench) and purposefully build for a high 9's low 10's compression ratio... Smooth the chambers, plane the head for smaller chambers (and larger quench pads as a side benefit) while dishing pistons to keep it in pump gas range... those are low hanging fruit... Overboring is as well, slim head gasket, 99+ intake, moding a larger throttle body (see Dino's Mustang TB) to fit.

I aggree, i think that the tuning issue will be more important if the head has allot of work done to it. A stock head would have stock flow and just adding some oversize injectors to compensate for the larger engine volume is probably ok. So if the engine is not going to get tuned, maybe it is a waste of money to do a bunch of head work.

[Flash]

I aggree, i think that the tuning issue will be more important if the head has allot of work done to it. A stock head would have stock flow and just adding some oversize injectors to compensate for the larger engine volume is probably ok. So if the engine is not going to get tuned, maybe it is a waste of money to do a bunch of head work.

I agree, as well but TOO late

Flash

[gradon]

So I sent the psc to split second a few weeks ago and today I got a reply: "We tested the unit and found that we were unable to read data from the unit. We wrote to the unit which cleared it and now it works fine. We did a complete final test and the pressure calibration and RPM accuracy are well within specifications. We also did several read and write cycles without difficulty. I would say it is good to go." Cool I didn't blow it, but I could've fixed it myself if I would've tried to write to it. My main issue was only being able to zero the fuel trims in closed loop and having light pinging b/t 2.5K-3K CL under part throttle accel. I'm tempted to write another map while keeping the cts unplugged, which keeps the pcm in OL, cause then I can make the light-ping area richer(probably needs 13.5-14.0:1). The only issue with keeping it in OL is the idle can't be 14.7 cause it'll need it to be richer for the cold start warm-up. The Uni is on the way. . .

[Cheromaniac]

The Mustang throttle body seems like a good upgrade, and Dino does specify it on most of his recipes. Most people seem to go with A bored out throttle body. I see two issues with the Mustang TB, 1. It has a IAC solenoid, not a stepper motor. 2. If you are running a Renix with a automatic you will need a way to make the Jeep TPS work on the Mustang TB.

I actually specify a bored 62mm Jeep TB on most of my stroker "recipes". The Mustang TB is a one off that I have on my own stroker engine and it's overkill on a mild stroker (including mine).

1. I used my Jeep idle stepper motor on the Mustang TB. All I had to do was put some epoxy in the idle bypass holes of the Mustang TB to make them smaller and match the Jeep idle stepper motor.
2. Making the Renix TPS work on the Mustang TB is no more difficult than trying to make it work on a 4.0 HO TB. My HO TPS was a direct fit on the Mustang TB with no modification required.

[1bolt]

One thing to keep in the back of your mind about tuning results (and this is no reflection on Comanche91) but it's HESCO, their Dyno always seems a little happy... In fact if I'm not mistaken someone (maybe it was Comanche91=Hornbrod?) had his bone stock 4.0 dyno'ed before it was even stroked on Hurley's Dyno and IIRC it was "happy" to the tune of something like 30 horses. I may very well be misremembering and it was someone elses stock 4.0 that I'm thinking of, but it was HESCO and the numbers looked fairly inflated.

Is there REALLY 50 horses to be had with a 99+ intake upgrade and a Q-chip? Don't know however I will say this, while I'm skeptical, I have played with spark curve using Engine Analyzer Pro while simulating the 4.0 and going from a nominal setting to "optimized (or what EAP calls optimized) simulated spark does show a fairly dramatic difference... Problem being, that I don't know which is closer to the 4.0 factory ECU's tuning... Nominal or optimized? I don't have an actual breakdown of the factory ignition curve.

If the factory left a lot of "room for improvement" as a safety margin against ping, then dyno tuning a programmable fuel/spark system will have a greater impact. And it's pretty fair to suppose that the factory DID leave a fair amount of room, due to the fact that the 4.0 is speed density, and has no knock sensor after the Renix years, and thus no way of sensing if it's too close to the bleeding edge. It pretty much has to be fairly conservative tune... But all that said I still don't know if I buy 50 horses...Also part of the improvements in torque with the 99+ are the iron exhaust manifold that has longer smoother runners and the smaller exhaust ports and larger intake ports of the 0331 head... they all work together.

[Plechtan]

IBOLT: Didnt you already model the 99+ intake? I think it showed 10 engine HP gain, on a stock 4.0. But the Heso dyno is showing a 12RWHP gain on a 4.6 which woudld be about 15 hp at the engine. If you get a chance, try running a basic 4.6 with the 99+ intake. Be interisting to see how the numbers compare.

[1bolt]

The 99+ intake gains about 3-4hp by itself in EAP, the significant gain is the torque 10 to 20 foot pounds which gets moved lower in the RPM range, due to the longer runners providing more inertial filling. As I've said before to gain a couple horses AND make more (a lot more) low/mid RPM torque that intake must be a LOT better than the older ones. Because those two things are often counter to each other (making more peak hp while adding low RPM torque that is)

If people would think of horse power as simply a mathmatical abstraction of the amount of work that the engines torque output is doing at any given RPM, the whole mess would be easier to understand (I know I struggle with this stuff a lot myself) and a lot of people could avoid spending dollars on horse power at RPM's they might not ever rev to. (IMO for the most part people who WANT to rev up there know what they're doing).

We could sum the whole mess up like this:

Move torque peak to right for more horses
Move torque peak to the left for more balls
Increase the amount of average torque for more power everywhere.

(right = higher RPM, left = lower RPM)

If you want your engine to pull like a scalded dog from 3500 RPM's to 5000 RPM's move the torque right.
If you want your engine to break tires loose with a sudden throttle application at a stop light... move torque left

Naturally if torque and hp "cross" (become the same number) at 5250 RPM's then the further to the "right" you move the torque peak the more horses you will get... The inverse is true... Diesels (and the Jeep 4.2 for example) have an almost inverted torque/horsepower relationship, the emphasis (the optimization of what torque the engine has) is on low pulling power.

Move torque right by shortening the length of intake runners, AND/OR widening the whole intake tract so it flows more air (porting), increasing Cam duration, and lift, and overlap.
Move torque left by lengthening the intake tract, and lowering the amount of valve overlap.
(among other things like advancing and retarding the cam etc.)

Add to the total torque output by building a bigger/better engine (stroke, bore size, quench, compression, lowering frictional losses (bearings sizes))...

For the most part "bolt ons" (cam not = bolt on here) only change where things are optimal.... "tuning" the length of the intake runner/port or the exhaust. You can obviously get some improvements in total torque output by putting more efficient parts on or by carefully optimizing parts (porting without significantly widening the cross sectional area of the port)... But again for the most part... what you build into the engine is what's available.

[gradon]

The expectations I have from the custom tuned unichip are an optimized fuel and timing map for my rig. I'd also bump the redline up to 5500, remove governor, enable aux fan earlier, and see what other options are available. If I see 225hp and 275lb-ft to the wheels, I'll be happy. Building it is 90% of the work--the other 10 is fine tuning and perfecting. It's still 100% jeep and has the same issues that have to be tackled when they arise.

[Plechtan]

Be interisting to see your final numbers. be sure to do a stock run and one with the PSC1 so we can all see if the additional tuning is worth the dollars spent.

[Plechtan]

So I sent the psc to split second a few weeks ago and today I got a reply: "We tested the unit and found that we were unable to read data from the unit. We wrote to the unit which cleared it and now it works fine. We did a complete final test and the pressure calibration and RPM accuracy are well within specifications. We also did several read and write cycles without difficulty. I would say it is good to go." Cool I didn't blow it, but I could've fixed it myself if I would've tried to write to it. My main issue was only being able to zero the fuel trims in closed loop and having light pinging b/t 2.5K-3K CL under part throttle accel. I'm tempted to write another map while keeping the cts unplugged, which keeps the pcm in OL, cause then I can make the light-ping area richer(probably needs 13.5-14.0:1). The only issue with keeping it in OL is the idle can't be 14.7 cause it'll need it to be richer for the cold start warm-up. The Uni is on the way. . .

Why did you choose to to go with the Unichip over the Split Second Ignition and fuel unit? Since you already had experience with the split second product and you can tune it your self, why the choice to go with the unichip?