Car makes less power with more boost ?

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TomWright
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Car makes less power with more boost ?

Post by TomWright »

Hello guys,

As the title states car was making good power on 2.5 psi made 320 rwkw but we added more and more boost we could not make any more power in fact we ended up making less power with around 9-10lbs of boost from memory.

The power ling on 2.5 psi was smooth and on 9-10 it was shaky and dippy etc, I should add the power would go flat at about 4800-5000 rpm it should be making power well up to 6500 rpm,
Mixtures are good, timing is reasonable, no boost cut.

In my logs I was getting a lost sync error #68 so a re sync error,

We are thinking it might be a cam timing issue ? either dialed in wrong or ground wrong.

The car is a 408ci LS1 with a pte turbo, powerglide using a ms3 gold ecu from efi source, fuel is e85.

Please let me know any thoughts you may have I also do have data logs if anyone is interested.

Tom
billr
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Re: Car makes less power with more boost ?

Post by billr »

Sure,
:msq:
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

Here is the latest tune file.

Tom
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

This was the last data log.

Tom
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

I also just did a composite log and it appears my crank timing would be back not at all what the standard crank signal should look like ? 24x ls1

Tom
billr
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Re: Car makes less power with more boost ?

Post by billr »

No data in that CSV file, try again.
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

This one should work.
CRSTune
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Re: Car makes less power with more boost ?

Post by CRSTune »

Are you sure you're in the right efficiency range of that turbo? Do you have any boost leaks? Is your intercooler sized for the application and have proper air flow? Your air temp skyrockets (peak of 155.1F). That's enough to start triggering MAT ignition retard (granted not much). I wouldn't expect you to make power blowing hot air.
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TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

The car is non intercooled but running e85 so that rules that out yes everything is matched the turbo is rated to 1700 hp,spools good I don't think that's the problem, and no boost leaks (map is reading 10 lbs). I have seen a guy with a ls 440ci and a 116mm turbo make 2000hp to the tyres with no intercooler. This should be making easily upwards of 700hp to the tyre and not breaking a sweat.

I'd agree it'd make more with an I/C and I have plans to add one in the future but feel there is an issue here and I am pretty sure it is not tune (seems no one has been able to spot anything) related more mechanical.

Thanks for your response.

Tom
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

Something I don't understand and someone might be able to straighten me out, the injector is at 56% duty cycle (1700 cc) going off a calculator that is around 800hp to the crank on e85 so if it's burning that fuel where is the hp ?

Tom
billr
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Re: Car makes less power with more boost ?

Post by billr »

Are you measuring actual fuel consumption? Maybe it isn't flowing as much fuel as you think. If any hp is really "missing", it is most likely going out the exhaust as wasted heat. Do you have EGT probes?
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

Yes I do have EGT probes Bill was around 1000 deg F at each collector and the Inj PW is about 12-13ms which would be around the 50-60% DC mark and the PW on the 4~psi was 8 ms 35% DC and that was showing more hp . I am hoping someone can look at the composite log and tell me what they think of the cam / crank signal I am thinking if the cam timing is out, the HP is getting blown out the exhaust maybe.

Thanks for your response again.

Tom
Yves
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Re: Car makes less power with more boost ?

Post by Yves »

Detonation ?
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

nope, I was thinking maybe timing drift but probably not ?
R100RT
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Re: Car makes less power with more boost ?

Post by R100RT »

Can't look at your msq on my phone - are you running wasted spark?
One of my favourite "induction conspiracy" theories relates to fuel charge burning on the wasted stroke when valve overlap, boost, and ignition timing all converge. If you have evidence of carbon tracts back up your inlet then could be a factor. If not wasted spark then ignore this comment. (For naysayers, it is a known issue and I witnessed it on a system I had done.)
Also, haven't noted any mention of spark blow out - what plug gap are you running. Just some thoughts.
Last edited by R100RT on Sun Feb 05, 2017 4:23 pm, edited 1 time in total.
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Re: Car makes less power with more boost ?

Post by turbo conversion »

Have you pulled the plugs and looked at them after pulls at the two different boost levels?

This will tell you if you are lean or rich or the same comparing one to the other.

Plugs will always tell the truth, o2 sensors will lie to you.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

we ran 2 x o2's at the same time and they read the same o2.
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Re: Car makes less power with more boost ?

Post by turbo conversion »

TomWright wrote:we ran 2 x o2's at the same time and they read the same o2.
Okay, but they can still be reading incorrectly that is why I would look at the plugs.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
TomWright
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Re: Car makes less power with more boost ?

Post by TomWright »

So I think I have it narrowed down to - either a bad crank sensor OR the reluctor wheel has been installed back to front.

Tom
billr
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Re: Car makes less power with more boost ?

Post by billr »

I have the perception you are testing this on a dyno. If so, just check the spark timing with a strobe.
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