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Hemituner

On The Dyno, A Study Of The Effect Of Boost On The 6.4 Intake

88 posts in this topic

That's what I thought tuning was for. Hell 6.1's aren't calibrated for turbulences either. They are just short runners. So why can't the 6.4 be tuned as a long runner to 0-4600 then short from 4600+.

 

Right now my tune AFR doesn't drop a bit when short runners kick in. Smooth carry over. Didn't always work that way, but Dave Katz @EFI got it to smooth out to where you don't even see the dip on the dyno anymore. I believe he added a little timing and good to go.

Yeah I know go 6.1, but shyt if you could have more TQ down low isn't it worth it the help on the big end???

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One thing you guys are forgetting is this is a bank to bank issue, not an intake to intake. It has nothing to do with turbulence. It's how the air enters the manifold. You would never know there was an issue if you didn't monitor both left and right banks independently. You might even find its a cylinder to cylinder issue if you instrumented each port. It has nothing to do with the flapper itself or the short vs long runner design.

 

J

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So on a 5.7 you can just tune out for the two sets of RPMs 0-4600 | 4600-top since that's the only difference. The only reason we are saying intake issue is because the 6.4 PCM is being told to do something(add fuel/add, take timing/SOMETHING) because it KNOWS it has a SRV switching at designed RPM. Which could give the different dynamics of the bank to bank issue. I'm trying to pick brains to see how the 5.7 might do since it's has NO SUCH change something (add fuel/add, take timing/SOMETHING) during selected RPM switch over.

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So on a 5.7 you can just tune out for the two sets of RPMs 0-4600 | 4600-top since that's the only difference. The only reason we are saying intake issue is because the 6.4 PCM is being told to do something(add fuel/add, take timing/SOMETHING) because it KNOWS it has a SRV switching at designed RPM. Which could give the different dynamics of the bank to bank issue. I'm trying to pick brains to see how the 5.7 might do since it's has NO SUCH change something (add fuel/add, take timing/SOMETHING) during selected RPM switch over.

The bank to bank fueling issue is happening because of one bank flows better than the other, not because of long or short runner. Intake is ok NA, but PD Boost exposes the issue which more than likely aided in piston failures. Correct me if I am wrong AJ, but that is what I read into it.

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SauveRT; it's becoming clear that the SRV manifold while being pressurized only is causing a change is air distribution between the intake port entries. It is most likely caused by the angled entry to the main plenum.

The angled entry is a marked improvement over previous HEMI manifolds. Because air has mass, and therefore momentum, any reductions in bends and redirection of air flow equals a measurable reduction in drag forces. As air is being drawn into the main plenum under vacuum forces (as opposed to pressurized), it disperses across most of that internal plenum area.

 

Again - because air has mass and wants to continue on a given vector (resists changing direction), high-pressure air generated by forced induction that enters the main plenum at an angle will definitely want to remain on that heading - straight towards the right bank. It's likely some port entries are starved - while others see a marked increase in head pressure. The resulting imbalance will be difficult to counteract - even with bank-to-bank tuning changes as the imbalance will not be consistent in behavior across the rpm range at differing throttle positions and resulting boost levels.

Note that the 6.1 aluminum manifold exhibits an imbalance from forced induction of a different nature and to a much lesser degree - that being from front to back as opposed to one side (bank) imbalance to the other side (bank).

 

Note none of the OEM manifolds were designed for FI. Depending on psi, those running boost through an SRV manifold might wish to re-assess...  
 

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I'm sure the 6.4 intake has a lot to do with it, but 392s are breaking pistons with PD blowers as well, which replace that manifold altogether.

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I'm sure the 6.4 intake has a lot to do with it, but 392s are breaking pistons with PD blowers as well, which replace that manifold altogether.

 

Yup  I seen it with 3 magnusons, 2 Prochargers .And various different tuners.  I have also been told by the local dealer that pistons are breaking with NO mods at all  ..

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Soooo , this is NOT a fuel issue but an air issue ?

correct, air distribution issue , more so when boosted and because the ecu doesn't see or counter for the difference some holes are rich and some lean... When you have a piston as vulnerable as the 6.4 piston bad things happen... My take is ,what AJ has done is found a way to tune the fuel for each cylinder as to keep the proper a/f per hole...

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correct, air distribution issue , more so when boosted and because the ecu doesn't see or counter for the difference some holes are rich and some lean... When you have a piston as vulnerable as the 6.4 piston bad things happen... My take is ,what AJ has done is found a way to tune the fuel for each cylinder as to keep the proper a/f per hole...

Under boost I find it somewhat hard to believe given all the different intakes involved.

AJ, usually if there is a uneven dist of air it's normally front to back, so why on the 6.4 intake if it's a mirror design side to side ?

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correct, air distribution issue , more so when boosted and because the ecu doesn't see or counter for the difference some holes are rich and some lean... When you have a piston as vulnerable as the 6.4 piston bad things happen... My take is ,what AJ has done is found a way to tune the fuel for each cylinder as to keep the proper a/f per hole...

 

And this will negate the need for forged pistons at moderate 7-8 lbs of boost, or is that still the recommended route.

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Don't even think about it Jon.

If you're going the forced induction route, GET FORGED!

 

AJ, you guys are really pushing the HEMI farther and farther into the mod world...thank you.

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correct, air distribution issue , more so when boosted and because the ecu doesn't see or counter for the difference some holes are rich and some lean... When you have a piston as vulnerable as the 6.4 piston bad things happen... My take is ,what AJ has done is found a way to tune the fuel for each cylinder as to keep the proper a/f per hole...

Good guess, those special headers you welded up with 8 widebands have been getting a lot of use ;)

AJ

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Good guess, those special headers you welded up with 8 widebands have been getting a lot of use ;)

AJ

I was going to ask how you were measuring Aj, does this mean you need to do the same to tune for this ?

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buahhahahah

 

 

is this that retard from lx forums ? 

Yup - that's me :^)

 

You must be that little fat boy who picks his nose and eats it...

Yup  I seen it with 3 magnusons, 2 Prochargers .And various different tuners.  I have also been told by the local dealer that pistons are breaking with NO mods at all  ..

Interesting - is there any consistency as to which cylinders fail?

Under boost I find it somewhat hard to believe given all the different intakes involved.

AJ, usually if there is a uneven dist of air it's normally front to back, so why on the 6.4 intake if it's a mirror design side to side ?

Air entry prior to the main plenum...is at an angle...

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