Boost vs Real World Performance

SlowE93

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Jul 2, 2017
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Does anyone have any data regarding boost and trap / 1/4 mile E.T
OR 1/2 mile, 60 to 100, 60 to 130, etc ?
I bumped into an old thread on another forum a few weeks ago.
The O.P. posted 1/4 mile times and said that his fastest pass was on a little bit lower boost vs max tune.
I know this will vary from different turbos being used across the platform.
On a dyno his stock turbo 24 psi (in midrange) showed highest whp.
At the track IIRC around 21 psi peak yielded him his best time / trap. I know efficiency range, IATs, Timing corrections, etc all play a part.
Curious to see how many people get same results, (track or highway pulls)or better with a couple psi LESS than their max effort tune/boost/psi.
Many will run whatever made the most power on a dyno (while racing), BUT thats only a 1 gear pull. Real world multiple gear runs will encounter higher IATs, timing corrections, flatline post shift timing (A.T.), Boost dropping out between shift, etc
Share your experiences if you are faster with less boost.
 

SLOWESTN54

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Feb 9, 2021
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If you had two runs which only differentiated in boost level, wouldn't your car make more power?
 

SlowE93

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If you had two runs which only differentiated in boost level, wouldn't your car make more power?
Generally speaking, more boost = more power. On a dyno with a single gear pull, you see more power on paper.
Now if you run that same configuration in say a 1/4 or 1/2 mile event, it does not mean you will be fastest or quickest. Iats will climb with higher boost, DME will pull timing once IATs reach a certain point. Then there is knock detection that will also add to timing corrections. All these things will actually slow you down.
 

SLOWESTN54

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Feb 9, 2021
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Generally speaking, more boost = more power. On a dyno with a single gear pull, you see more power on paper.
Now if you run that same configuration in say a 1/4 or 1/2 mile event, it does not mean you will be fastest or quickest. Iats will climb with higher boost, DME will pull timing once IATs reach a certain point. Then there is knock detection that will also add to timing corrections. All these things will actually slow you down.
Very true, my best 100-200 was ran on lower boost, as iat's stayed cooler. Generally speaking As you up the boost you'd also have to up cooling whether it's via a bigger/ more dense intercooler, or a bigger meth nozzle.
 

SlowE93

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Very true, my best 100-200 was ran on lower boost, as iat's stayed cooler. Generally speaking As you up the boost you'd also have to up cooling whether it's via a bigger/ more dense intercooler, or a bigger meth nozzle.
Correct. Thats why I was asking for input to see how many people run what they made on dyno pull vs others that found less = more so to speak.
Now people running meth should have no problems with IATs , of course turbos, tuning, etc still play a part in all this.
But this is why I am curious to see the responses.
Maybe If a Doc tuned car responded in here we could get more feedback 🤷🏾‍♂️
 
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SLOWESTN54

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Correct. Thats why I was asking for input to see how many people run what they made on dyno pull vs others that found less = more so to speak.
Now people running meth should have no problems with IATs , of course turbos, tuning, etc still play a part in all this.
But this is why I am curious to see the responses.
Maybe If a Doc tuned car responded in here we could get more feedback 🤷🏾‍♂️
LOL! I mean you'd get 18 responses from 18 accounts but in reality it'd be one person.
 

rac

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I think your overthinking it. A dyno is not a heat friendly environment being stationary. People may well be posting the best dyno pull they possibly can but in the situation you describe if they ran back to back to back dyno runs the average power of three runs might be slightly lower than more consistent boost pressure under the same multi dyno run situation. Notwithstanding all the variables that aren't related to heat, like traction control or some idiosyncrasies of the dme logic and shifting.
 

rac

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Really depends on how honest your dyno work is to the end goal of repeatable performance versus internet post glory
 

SlowE93

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I think your overthinking it. A dyno is not a heat friendly environment being stationary. People may well be posting the best dyno pull they possibly can but in the situation you describe if they ran back to back to back dyno runs the average power of three runs might be slightly lower than more consistent boost pressure under the same multi dyno run situation. Notwithstanding all the variables that aren't related to heat, like traction control or some idiosyncrasies of the dme logic and shifting.
Not over thinking anything.
I read a post of a guy running quicker /faster on less boost than he made on a dyno (same tune and fuel).
Just curious to see others who share the same experience as he did.
 

SLOWESTN54

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Not over thinking anything.
I read a post of a guy running quicker /faster on less boost than he made on a dyno (same tune and fuel).
Just curious to see others who share the same experience as he did.
I might be very wrong here, don't our factory ECU's compensate for hotter air by increasing boost. Is the op sure his car didn't make less boost as air temps were cooler the day of the pass.
 

SlowE93

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I might be very wrong here, don't our factory ECU's compensate for hotter air by increasing boost. Is the op sure his car didn't make less boost as air temps were cooler the day of the pass.
He runs a Jb4 and sets his boost on the fly.
 

SlowE93

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If I can find the thread, I will link it here. Was from a few years back. Found it on N54Tech but didnt bother to bookmark it.