What boost, timing and fuel to run this weekend at the track?

[baller760]

This weekend I will be running my Buick at the track. It's the first time in 4 years and I will be doing it with a basically stock car with a fully restored stock suspension, poly body bushings, and stock turbo. The only mods I have are 42.5lb/hr injectors, 340 fuel pump w/hotwire, Cold air intake, adjustable FPR, 3'' single shot exhaust, ported elbow, gutted cat, Turbo Tweak 91 Octane adjustable chip, and BFG Drag Radials.

First, I plan on adjusting the timing 4.5 degrees like Turbo Tweak states in the instructions using my scanmaster. This should put the timing somewhere around 21-22 degrees. Next, I need to decide whether to run 100 octane unleaded for a mix of about 97 octane, or run 116 leaded for a mix of about 107 octane. Both the 100 and 116 cost the same price. Finally, I figure with 97 octane I should be able to run about 20 psi of boost, and with 107 I could probably push the turbo to 23-24 psi of boost.

What should I expect to run in the 1/4 with the following:

14 psi boost, BFG Drag Radials:

20 psi boost w/ drag radials:

23-24 psi boost w/ drag radials:

Also, would 4-5 gallons of leaded gas for one night at the track be harmful to my engine? I would prefer to run more boost rather than limit myself to 20 psi because of octane issues. The track is only open once a month for the street legal event so I wouldn't be doing this weekly.

 

[gnxtc2]

Drain the fuel and add straight race fuel, 116 octane. You'll never get all the fuel out of the tank.

2 gal x 91 octane = 118
5 gal x 116 octane = 580
Total = 698

698 / 7 = 99.7 octane.

2 gal x 100 octane = 200
5 gal x 116 octane = 580
Total = 780

780 / 7 = 111.4 octane

You are going to need more race fuel in the mix to bring the octane level up.

There will be no deterimental effects to your motor with leaded fuel unless you blow the motor up with a bad tune. Your O2 sensor won't like it.

Billy T.
gnxtc2@aol.com

 

[fubar2.5]

If you still have your cat converter on do NOT use leaded gas.

 

[baller760]

That's interesting how you came up with those numbers. According to this page on Turbo Regal Web Site the octane levels would be a little different.

Octane Mixing

Either way, what should I be looking to run at the different psi levels and should I add a can of toulene just to be safe if I'm so worried about the octane?

Oh, and the first calculation you made with 91X2 = 182, not 118, so the effective octane level would be 108.

And the cat will be gutted.

 

[UNGN]

Stock turbo at 24 psi won't be much faster than stock turbo at 21 psi.

The stock turbo likes timing more than it likes boost. You may want to see if someone has a cheap race chip for 42.5 injectors w/TC lockup, because it will likely be significantly faster than your street chip at the track.

Go with the leaded race gas mix. You should be fine if you keep an eye on the knock on the 2-3 shift.

With race gas and traction, I wouldn't be happy if I ran slower than 12.40's @ 109 with your mods.

Leaded race gas will only hurt the cat and the O2 sensor. Since your cat is gone, the O2 sensor will probably recover after a tank or two of 93.

 

[gnxtc2]

Yea, I F**cked up on the first cal And it didn't look right when I first posted also

Billy T.
gnxtc2@aol.com

 

[baller760]

It's alright man, I was yankin your chain. :wink:

As far as locking up the converter I was planning on using the paperclip trick and just trying to advance the timing as far as I could using the TurboTweak method. It might be too late for a race chip at the moment. I don't know if I could get one ordered and have it arrive at my doorstep by Friday afternoon without paying ridiculous shipping costs.

Also, are my BFG's too sticky to burn out? haha. I was trying to do a burnout today on an abandoned street as a little practice and I couldn't get them to start firing up like my street tires. I would just launch at 7psi real hard with no tire squeal. I think it may be that my powermaster accumulator bowl is dying so I can't hold the boost I want to. I'm assuming the waterbox really helps get the burnout going though.