Flow bench Head Porting collected work by NOSIGMA

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Re: Flow bench Head Porting collected work by NOSIGMA

Post by 1bolt »

Interesting I replied to that before I realized it was from last year. Somehow I always end up posting to old threads. I'll post my thoughts here too, less abrieviated (oh great I'm going to drone on longer than usual!). I think I'll convert Dino's numbers and see how they compare to yours and mine. I honestly like to think I'm finding some things out about the 0331 head (the last major casting, that tended to crack in its early runs) that will surprise some people.

The numbers on Dino's site are at 25" of pressure drop, not 28" also the person who got them (on the Strokers Yahoo list originally maybe on here now as well, not sure); Said he may have obtained them with an intake manifold on, but I doubt that. They were flowed in like 2002. Crazy enough I asked Dino about those numbers just a couple weeks ago myself.

(The numbers I'm talking about are at: http://www.jeep4.0performance.4mg.com/tech_specs.html for anyone not knowing)

Elevation + temp are air density right? and I think most flow bench software simply plugs these numbers in when you are calibrating the bench. Just like a Dyno all numbers are corrected for temp, density and barometric pressure.
I wont pretend to be an expert but that's what I understand anyway.

For what its worth my numbers for the 0331 head using NOSIGMA's flow bench are very close to yours. Also all flow benches will show some variation. But mine are also above the ones on Dino's site for an unmodified 0331 head at the same valve lifts, the number that matters is pressure drop. I'd have to look at John's flow spreadsheet but CFM numbers at 25" of drop are lower than 28".

One thing I don't want to step out on a limb for (but I can't seem to avoid) is that the 0331 head is not a bad flowing head. Until I get more numbers I wont make any bold statements though. It does have the cracking problem and that's all most Jeepers need to know.

But as far as Porting goes... well... let me just say it has a lot of potential due to the smaller better shaped Exhaust ports. Better short turn radius, much higher floor, and slightly higher roof... The intake port ceiling also appears to be slightly higher than previous head castings.

For an example of flow bench variation: as an experiment the home made flow bench crazy dudes at
http://www.tractorsport.com/cgi-bin/...gi?;act=SF;f=1
passed around a set of orifice plates (look for "pass it around plates") that got flowed on a bunch of benches, including home made, do it yourself and big dollar Super flow benches, and EVEN the multi million dollar Ford flow bench... There were variations but they were all shockingly close. A few CFM give or take across many of them, I didn't see a one that was really far off (like more than 10 CFM either direction)... The reporting was blind, no one saw numbers until the end of the experiment.

CFM at a given pressure drop is CFM, the thing to wrap your head around (and I don't fully have mine wrapped around it I admit, as I'm still learning) is that a LOT of the "correction" is done for you by the manometers. You're measuring the pressure drop in one manometer compared to another. corrected for temp and barometric pressure, it's all very neat and self correcting assuming the bench doesn't have defects, or leaks, which so far appear to be easy to spot (they show up as fluctuating readings, and as spikes or dips, or sharp curves in the calibration curve you plot out using orifice plates (known sized holes that should always pass X amount of air at X amount of pressure drop).
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by Alex22 »

The correction factor from 25 inches to 28 inches (of water) is Flow @25 x 1.06 and the correction from 28 inches to 25 inches is Flow @28 x .95
I couldn't find a nice formula so I just wrote this out using paint.
Image
To calibrate the Superflow benches they give you a test plate with a given flow at 10inches and they allow a small percentage variation.
The flowcom we have connected to the SF-600 reads the test pressure, manometer value, temp and barometric pressure, then the program records the data for us. In the column "corr CFM" it is correcting for the small difference in test pressure, correcting 27.98 inches to 28 inches.
The small leaks in a flowbench can be hard to notice and difficult to find.
Another trick is to flow a head at 2 or 3 different test pressures then convert the numbers to each other and compare, this can help you find turbulence.
I'm still going to use the 0631 casting on my stroker because I would prefer the reliability/durability of a better head over one that might make a little more power. I have not confirmed this myself, but I have heard that the 0721's 0631's and 0331's have the same intake port, but the 0331's have different (smaller) exhaust port to heat the catalytic converter up faster.

What flowbench are you using?

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Re: Flow bench Head Porting collected work by NOSIGMA

Post by 1bolt »

A home made one, considering an aeronautical engineer home made it, its not too shaby :) I am flowing some heads now to see if there's any sort of error factor or correction factor I'll need to know. I have several pieces with known flow numbers, including some SBF intake manifolds that have published flow numbers, carbs, heads and jeep heads. By the time I'm done I should have an accurate picture. More importantly I'll have another rundown of what 4.0 heads flow what, to add to the data Dino has. As well as porting numbers from both good (0630 and 7120) and crack prone heads, to see if there's any redeeming value to the 0331.
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by Alex22 »

Once I get my flow numbers on my 0721 head we can see the difference in the intake and exhaust flow since both of the heads will be flowed on the same bench there won't be the variable of 2 different benches.

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Re: Flow bench Head Porting collected work by NOSIGMA

Post by nosigma »

1bolt,

Wow.
No doubt you were by far the best person that could have ended up with that flow bench. Its been sitting idle for almost 5 years and you've given it quite a work out in the last month. I really look forward to following this. If I ever pull my Rambler head mind if I bring it by to see where it ended up with the bigger valves and shifted guides?

A couple comments on the posts....

Pinging:
I run 10:1:1 compression on my Rambler 6, 258 with a 4.0 head. My quench is around .015 with rod stretch. Piston is way up out of the hole at TDC. I had to deck the block to get it. When I get home I will find my notes for exact dimensions. With 12 deg inital and 32 deg total, all in by 2600 rpm (mechanical advance only) I dont ping on 93 or 89 octane. If I back out 4 degrees initial I can run 87 octane but I have to use just a little care, but not much on steep hills. I attribute this to the swirl I got by cutting the trough in the intake combined with shaping the valve guide boss. Combined with the turbulence generated by the quench and I seem to get away with a lot of compression on an iron head.

Nice work, keep the discoveries coming.

John
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by Flash »

first of i would like to say thanks for all the Info, that was only a good guess before all of your hard and dedicated work! :cheers: :cheers: :cheers:

So you motor has a actual quench of .015" or the piston is proud by .015"?
I have suggested many a times, the the .040" quench was probably high, considering these 6's don't rev that high!

Welcome aboard, nosigma!



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Re: Flow bench Head Porting collected work by NOSIGMA

Post by 1bolt »

John I appreciate the bench and the comments. I'm glad you joined us here, I can't tell you how much fun I'm having with it. Today I started a 4.0 sized bore adapter that is 98mm inside diameter acrylic tubing I found on Ebay, 98mm = 3.85" probably as close as I'll find to 3.87". I've read that anything within give or take 2mm for a bore adapter will give accurate readings, so that covers stock 4.0 bore size up to .060 overbore and I'm also converting the giant 4.25" adapter from your 401 work into a Carb and intake adapter. To make switching between them easy I'm working on a quick change setup where the adapter meets the stack using a gasket and bolts instead of the permanent sealed setup.

Any time you need to use your bench just say the word. I'd love to see how your finished head flows, especially with the valves moved closer together. Of course if you ever have it that far apart you should stroke it man! Something about squaring the bore/stroke ratio really turns the 4.0 into a beast, beyond just the extra .6 or .7 liters of displacement...

BTW John's Rambler has by far the most V8 like idle I've ever heard from a I6, he has a big old lumpy cam in their and the idle is really sweet.
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by heartlandoffroad »

what kind of a intake radius plate are you using or are you using clay? another thing I have found is that these heads LOVE a header on them have you done any testing with a header attached? I know when I was doing mine I was able to get WAY over 200 with a header on it.
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Re: Flow bench Head Porting collected work by NOSIGMA

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I use clay, But I'm making one out of plexiglass. The bench has undergone some serious reworking lately to make it easier to use and more productive. I'm planing on going to digital manometers and computer data acquisition hopefully this month (still researching products like, PTS, Audie and Performance Trends stuff). Which should help me maximize the time I have to work with the bench (this is not my day job unfortunately).

I haven't flowed exhausts with a flow pipe extention yet, but I haven't done any serious exhaust work yet either. The only exhaust flows I've done where comparative stock and stage I port cleanup flows of the 7120, 0630 and 0331 heads just to see how they baseline.
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by Alex22 »

x2 on the clay radius. We have also cut the rough shape out of wood and port matched it with bondo or epoxy. Once in a while we will bolt the intake and carb onto the head and then flow it. Every head we flow gets an exhaust adapter, they do make huge differences.
The clay on the intake should be half the port width wide and at least that tall. You will want to try to save the same piece of clay for all of your tests because they can have a big impact on flow over .400 valve lift. To see how much of an effect it has put your finger on top of the radius when flowing it at full lift and watch the manometer drop. (decrease flow)

The performance trends program is nice for the flow bench, no more writing or calculations. The data and graphs in my project thread are from performance trends "port flow analyzer." but the program isn't perfect, at times I find myself working around the program instead of with it. It might be because we don't have all the bells and whistles on the program or maybe its just the bugs in the program.

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Re: Flow bench Head Porting collected work by NOSIGMA

Post by 5-90 »

Hm. Where are ya? I've been collecting heads so I can get them all run on the same bench, same day, same operator so I can come up with a good comparison of flow numbers (so far I've got #2685, #2686, and #0630. Still need #0331 and #7120 - anyone got any they're replacing? I don't care if they're cracked or warped, since I'm going to saw them up anyhow...)

If'n ya don't mind, I may take the information at the beginning of this thread and make a .pdf of it, so it can be preserved bloody /somewhere/. It should not be lost!

Ultimately, I want to have a valid, controlled comparo of as many of the AMC six heads as possible - at least the 1975-up 258 & 242 heads that we're likely to be playing about with.

Part of this is as research for a _Power_ _Manual_ update, part of it for reference, and part of it is due to my own irrational curiousity. I want to saw the heads up to make them easier to handle, and because I want to section a cylinder or two to check out the casting from the inside as well.
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by Plechtan »

I just got my head back from Hesco, Intake flow @ 25" and .6 lift is 249 cfm Exhaust flow is 151cfm at the same conditions. I am going to do a little more work to the head, trying to get to around 200 exhaust and 300 intake @ 28"
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Re: Flow bench Head Porting collected work by NOSIGMA

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5-90 wrote:Hm. Where are ya? I've been collecting heads so I can get them all run on the same bench, same day, same operator so I can come up with a good comparison of flow numbers (so far I've got #2685, #2686, and #0630. Still need #0331 and #7120 - anyone got any they're replacing? I don't care if they're cracked or warped, since I'm going to saw them up anyhow...)

If'n ya don't mind, I may take the information at the beginning of this thread and make a .pdf of it, so it can be preserved bloody /somewhere/. It should not be lost!

Ultimately, I want to have a valid, controlled comparo of as many of the AMC six heads as possible - at least the 1975-up 258 & 242 heads that we're likely to be playing about with.

Part of this is as research for a _Power_ _Manual_ update, part of it for reference, and part of it is due to my own irrational curiousity. I want to saw the heads up to make them easier to handle, and because I want to section a cylinder or two to check out the casting from the inside as well.
I must not have noticed this, 5-90 John had compared a good many of those heads already the heads "in play" so to speak that are worth bothering with are the three HO castings, not much point in looking at those older ones.

Not to step on your toes but this IS "bloody somewhere" and while I'm absolutely sure John would have no objection and I know for a fact he's already pretty much given you permission on NAXJA a few years back, I personally consider this stickied thread to be that "preservation" so to speak. Feel free to PDF it if my input makes a difference.

I will be Using John's old bench with several improvements including digital data acquisition manometers to compare the HO heads side by side at a later date, there's just too much on my plate at the moment. Mostly having to do with getting the family through this shitty economy. Some of the academic pursuits have been back burnered.
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A conversation with Rick Mudge

Post by Plechtan »

I thought this would be the best place to post this, I Talked to a guy named Rick Mudge the other night, he worked for 20 years at JTE ( Jeep and truck engineering) in the Flow lab. He knows everything about the Jeep head. He did the head work on the Garth Hill Dragster. He is retired now, but was more than willing to give me some advise. Out conversation lasted about 2 hours and covered many subjects, I will post here the main points he made about the Jeep head.

1. Do not bother putting in an exhaust valve bigger than 1.550, the port will not be able to handle flow from a valve bigger than that.
2. if you want to get into the 300 cfm range on the intake side, you will need at least a 2.050 intake valve.
3. The port match on the top of the intake port ( intake to the head) is critical. Any lip in the area will cause major turbulence ruin the flow. ( trim those injector bosses down) ( maybe somebody could verify this on a flow bench, check with a stock manifold, then port match)
4. a dual header is a wonderful thing, two separate exhausts is better than an x pipe
5. The combustion chamber should be as small as possible, on the Hill dragster the head was so thin that the only way the could get the head to seal to the block was to use a graphite gasket. use a deeper dish in the piston to adjust the compression ratio. The combustion chamber on the jeep head is not the best.

The conversation covered many other things, but the main point was, the head is only a piece of the puzzle, you must also consider the intake and exhaust as when looking at the head, it is a complete system. Once you get the head, intake , and exhaust flowing well, then you need to look at a Cam that will take advantage of that. once that is decided, then the Valve train would have to match as well. These are topics for other threads, so please do not go off topic here. We should stay focused on the cylinder head
Last edited by Plechtan on May 2nd, 2009, 2:41 pm, edited 1 time in total.
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Re: Flow bench Head Porting collected work by NOSIGMA

Post by 5-90 »

1bolt wrote:
5-90 wrote:I must not have noticed this, 5-90 John had compared a good many of those heads already the heads "in play" so to speak that are worth bothering with are the three HO castings, not much point in looking at those older ones.

Not to step on your toes but this IS "bloody somewhere" and while I'm absolutely sure John would have no objection and I know for a fact he's already pretty much given you permission on NAXJA a few years back, I personally consider this stickied thread to be that "preservation" so to speak. Feel free to PDF it if my input makes a difference.

I will be Using John's old bench with several improvements including digital data acquisition manometers to compare the HO heads side by side at a later date, there's just too much on my plate at the moment. Mostly having to do with getting the family through this shitty economy. Some of the academic pursuits have been back burnered.
OK - you've got me! And, it's a pity you're on the other coast, or we could (between us) just about come up with a full set of heads, I think. I've so far gotten a 2685, 2686, and 0630 head - still looking for a 7120 and 0331 (Ideally, two of each - but the only head I have two of is the 2686 - RENIX - head.)

As far as having been told to go ahead before, I've found that keeping things in my hat doesn't work very well anymore - my hat leaks. Bugger.

Let me know what you've got as far as heads go - I haven't gotten a chance to saw the ones I have up yet, but I would still like to see at least one cylinder on each head in common use (2685 through 0331) flowed on the same bench, with the same operator, and under the same (roughly) atmospheric conditions for an actual "apples to apples" comparison.

I wonder when I'll be heading out toward VA again - my kid sister lives out that way...
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