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Boost in Mid range Questions on Pump gas and quarter mile

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Hi Andre I know I asked you about this question in the webinar but I didn't really fully understand your explanation,

Does Boost in mid range effects how much timing I can use on top end like 5k to7k rpm on pump gas on the same turbo?

If we are knock limited on pump gas will using less boost in mid range allow up to push more timing safely on top end ?

What i am trying to say is by using more boost in mid range we increased the combustion temperature therefore if we are knock limited

we will be force to run less timing at higher RPM, but if my goal is to run fastest quarter mile on this setup and quarter mile usually only uses 5k to 7k RPM will less boost in mid range allow for more timing on high rpm ?

And does turning Coolant Fan on earlier lets say 190 degrees help combat knock too I dont mind reducing fan life if it can help me achieve more power safely.

Andre will most likely tell you the safer way to go is to run few more psi than few more degrees of timing as timing near the threshold of knock is dangerous. You should not be looking at maximizing timing based on rpm. The area that is more prone to knock is your peak combustion pressure, "torque peak" as the torque tapers off and rpm rises is when you bring the timing back in. Give the motor what it wants, if more timing doesnt make power than theres no need to increase timing.

On the stock turbo my Boost is pretty maxed out on top end so i can only increase timing to gain power and it is still far from MBT timing on pump gas, my goal really is to maximize power and have fastest quarter mile trap speed run on pump gas.

I am trying to understand if this can be done with different tuning strategy, even if it means having no boost in mid range and just tune from 5k to 7k that's what it will use on the quarter mile track only.

Reason why i have this question was because I noticed when i was tracking my evo on 93 pump gas same setup with other people just different tune, and we have totally different trap speed and got me really thinking how they achieve the higher trap speed with a lot more timing same boost on pump gas without triggering knock.

What are your afrs? whats the setup you are running, its hard to tell you what to do without knowing what the platform is.

AFR was 11 on 93 pump gas in NY, Intake exhuast and test pipe 3 port on EVO X platforum running 28 PSI at 3500 rpm taper to 19 20 psi redline with 7 degrees peak torque timing ramping up to 14 15 degrees redline.

I have used e85 to verify the MBT timing on this engine is like 10 degrees peak torque up to 24 25 redline, so as you can see it is still far away from MBT but when using 93 octane it is very knock limited.

I was wondering if i start tuning only 5k to 7k on dyno , will I be able to use a lot more timing vs doing a tune tune from 2k to 7k RPM on 93 pump gas.

I understand your question, however it isn't a situation I've personally seen pan out on the dyno or the track. Particularly if take a wider view of combustion temperature as we go down the drag strip or around a race track, the temp will climb to a point and then plateau. It's unlikely when we consider where the temp may plateau, to make much of a measurable effect by dropping the midrange boost to aid combustion temperature when your looking at a 1st - 4th acceleration run for example. In any case to see a potential improvement in the high rpm area you would need to drop the boost so far in the midrange that the net result would be a slower car.

You may be able to see the ability to add more timing if you only do a dyno pull from say 5000-7000 rpm rather than starting at a more realistic rpm of perhaps 2000. This isn't real or reliable though. You can confirm this by immediately doing another pull from 5000-7000 and if you have advanced the timing to the very edge of knock, the second pull will almost certainly result in detonation.

yea i definitely don't think this is a reliable way of tuning for daily driving, I was just curious if that's how other tuner achieved higher trap speed but if the car can make the 12 11 second 1/4 mile pass with no knock running higher timing on pump gas maybe this can be used as an edge for competition only.

We usually reply within 12hrs (often sooner)

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