408 s484 missing power over 15# boost
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Teching In
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408 s484 missing power over 15# boost i have a 317 headed 408 with a s484 turbo that quits making power past 15#.
at 15# i made 819 whp and at 24# i made 864.
this is on e85 with 210lb injectors and a MF 4303 fuel pump.
as i turn up the boost injector pulse width follows and afr stays where i want it around 10.5 at that point. it acts though by the 23-24 psi boost mark, i am out of pump because i am no longer able to stay on top of afr with added injector.
i have good control on boost and am not out of wastgate spring as i can still easily go up or down from there.
i am baffled why power wont come up with boost.
the turbo is a billet s484 with a 96mm turbine and 1.32 ar
heads are stock 317 with btr spring kit
9.3 compression
truck intake
air to air intercooled sub 100 degree iat while in the dyno
manual trans
we had traction problems early on so we several tie downs going all over trying to hold this thing down. it is a sandrail that weighs roughly 2000lbs
by my estimates i should have been tickling 1000 wheel with this thing by 24 psi. once i get to 15 psi power per pound of boost dissapears.
any ideas?
thank you
barry
at 15# i made 819 whp and at 24# i made 864.
this is on e85 with 210lb injectors and a MF 4303 fuel pump.
as i turn up the boost injector pulse width follows and afr stays where i want it around 10.5 at that point. it acts though by the 23-24 psi boost mark, i am out of pump because i am no longer able to stay on top of afr with added injector.
i have good control on boost and am not out of wastgate spring as i can still easily go up or down from there.
i am baffled why power wont come up with boost.
the turbo is a billet s484 with a 96mm turbine and 1.32 ar
heads are stock 317 with btr spring kit
9.3 compression
truck intake
air to air intercooled sub 100 degree iat while in the dyno
manual trans
we had traction problems early on so we several tie downs going all over trying to hold this thing down. it is a sandrail that weighs roughly 2000lbs
by my estimates i should have been tickling 1000 wheel with this thing by 24 psi. once i get to 15 psi power per pound of boost dissapears.
any ideas?
thank you
barry
As mentioned, its in your fuel capacity... add another pump and watch your duty cycle on your injectors, remember your flowing 30% more fuel on E85, compared to Race fuel or pump gas, so that fuel pump isn't going to stretch as far....also even though it has a rating of 2K HP, that's probably based on low pressure system, not a 60psi EFi system as pressure goes up, flow is reduced hence less HP compared to a Carb for same pump...
Thread Starter
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at 15# i am low 11's. at 23 psi i am low 11s targeting 10.5. i target 10.5 by 20 psi. i know i am out of pump at that point because i cant hit the target .
i know i need a bigger pump but, i am not going lean enough to be killing power.
i just went through the valve train when i had the motor out a couple months ago.
from 15 to 24 psi i only pick 45 hp. there is simply not 200 hp in the tuneup that i coupld find. i made 30 pulls on saturday, 20 of them were over 20 psi and no combination of fuel and timing would find the power.
maybe its just me and i am missing something but...
i know i need a bigger pump but, i am not going lean enough to be killing power.
i just went through the valve train when i had the motor out a couple months ago.
from 15 to 24 psi i only pick 45 hp. there is simply not 200 hp in the tuneup that i coupld find. i made 30 pulls on saturday, 20 of them were over 20 psi and no combination of fuel and timing would find the power.
maybe its just me and i am missing something but...
Thread Starter
Teching In
Joined: Aug 2013
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Thread Starter
Teching In
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Good post. Thanks.
I tune a 408 with that pump. We have been 8.7@158.
It also won't hold AFR........it rises to 12:1, and lives.
We have voltage issues that I just can't figure out.
So check that, that pump, which doesn't impress me, needs 14+ volts to deliver.
Ron
I tune a 408 with that pump. We have been 8.7@158.
It also won't hold AFR........it rises to 12:1, and lives.
We have voltage issues that I just can't figure out.
So check that, that pump, which doesn't impress me, needs 14+ volts to deliver.
Ron
What ecu? Sure your not getting spark blow out? Maybe tighten the gaps up and retry. You need to make sure you’re not losing voltage up top. I would also pull and extra ground wire to each coil bank to a good ground.
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it is a megasquirt ms3pro. coils are the round heat sink version with br7efs plugs at .027" gap.
"br7efs plugs at .027" gap. ". Maybe too much at 25psi?
.022, and see what you have.
What do the plugs look like, after the 25# pull[s]?
What do you have for coil dwell time? That heat sink coil may not be happy, over about 4ms.
.022, and see what you have.
What do the plugs look like, after the 25# pull[s]?
What do you have for coil dwell time? That heat sink coil may not be happy, over about 4ms.
I am having a similar issue with mine above 20 psi and my shop told me it is spark blowout. They told me they switch all of the older LS1 cars to the newer LS3 type coil because it has more spark and to find a used set somewhere and switch them out so we can turn the boost up.
Barry,
we have similar setups and having the exact same problem. https://ls1tech.com/forums/forced-in...need-help.html
I can get to 17psi then it hits a wall. I am suspecting back pressure but I checked it last night and worse case it was 1.6:1 at 18+psi. Planning to speak with Forced Inductions and PTC to see what they say.
we have similar setups and having the exact same problem. https://ls1tech.com/forums/forced-in...need-help.html
I can get to 17psi then it hits a wall. I am suspecting back pressure but I checked it last night and worse case it was 1.6:1 at 18+psi. Planning to speak with Forced Inductions and PTC to see what they say.