I am going to the track tomorrow and had a quick question. I will be mixing to 100 oct. what is a reasonable amount of boost to run? i have a full turboback, ecu reflash, drop in filter, walboro 255, and hallman MBC. any help would be greatly appreciated. Thanks. Brett

 

mixing 100 with what? Are you using 91 oct mixed with 100, 93 mixed with 100 or just stright 100? I run stright 101 oct and i boost to 24 safely.

 

The sweet spot is 22-23 on an 03, If you have the same turbo, than that number! I did have it set to 25, put I had less problems at 22-23. I believe that is the MAXIMUM EFFICENCY

 

I think if you run 21 psi on 91 or 22 psi on 93, it would be safe to increase boost by .5 psi for every extra point of octane. someone on here listed a conversion chart link not too long ago. I believe people are running 26 psi on straight 100.

 

boost it to 25 with a good tune

 

Just shoot for 23-24psi. You can't tune for it, so it won't be optimal.

 

I will be mixing 110 with 91 to get 100 or maybe a little more. i was also thinking 24-25 psi. i will probably set it at 22 to start then increase it by .5 or 1.0 until i hit 25 psi just to see what kind of MPH i gain. thanks for the replys

 

Just wanted to make sure you are catless, since you'll be using leaded 110...

 

Yes i am catless.

 

We have found that on straight 100 octane (with just a couple gallons of 93 mixed in), we are able to run 28 psi spikes with no problem. We verified this on a Mustang dyno, with no loss in power up to 28 psi. This was however almost all 100 octane, not a 1/2 and 1/2 mix. This is on the TME turbo, cams, intake, upgraded FMIC, and a ECU flash. The timing plays a critical part into how much boost you can run. The timing is adjusted in the ECU flash, and that makes this possible. If running stock timing map, this is something that would need to be verified on the dyno. When you reach a boost level spike that is TOO high for the octane, you will see the peak torque number drop off and/or the torque and HP curve get jagged (unsmooth) around the high boost spike.

The stock turbo is going to drop back to 22 psi at the least anyhow on the top end even with the 28 psi peak. 28 psi sustained would probably not be a good bet on 100 octane, but 28 psi peaks were okay. At least on this car that we tuned.

My $02.

Brian

 

23 is a safe bet!

 

23 is safe, 24 is optimal

 

I have seen up to 30 psi on straight 100 with no knock, but don't expect things to last too long like that (i.e. the turbo). Personally, I think 26 is fine with a proper tune and headstuds (for cheap insurance) on straight 100. If you're just turning up boost with no tuning, I don't know what a good answer for that is.

 

I have used VP 99 OCT from the race track shop and also I have used 100OCT from a local gas station here in Tucson.

My experience with both gas(99 and 100oct) was always the same, my car is tuned to 91OCT so when I used the 99-100 I just added 2-4 gallons to the existing 4 gallons of 91oct on my tank. I am assuming I was getting a 94OCT mixed.

I use a Hallman MBC and I crancked the boost significantly, I have never had detonation in my car. I think I maxed out the MBC all the way to the max setting but still did not get detonation.

As far is the improvement on the track, it normally gives me an additional 1.5-2.0 MPH higher trap speed and average of .2 sec on the 1/4 mile.

It is not much, I guess, but I know that I rather need a tunning for higher gas.


I hope that helps.