Wide open throttle for 20 seconds... Airport runway fun

[Gnx6]

So I am going to do the airstrip thing again. It is going to be hotter than in in Sacramento so based on opinions from last time I took 1 extra safety measure. Normally I run 91 octane and Alky Control kit at 25 psi but since it is going to be very hot I bought a fresh load of Sunoco 100 octane fuel. I am going to drive until she is really low on fuel and refill with 100..

So the question is, at 104 degrees outside am I pushing my luck even with the 100 octane?

Link for event:
http://www.aerospaceca.org/wings&wheels/

My old runs last year:
http://www.youtube.com/user/californiazedder

 

[Gnx6]

Yes I plan to use a gopro for video and use powerlogger for the runs. Hopefully I don't screw it up tis time. Missed out on tons of good video last year and forgot to use laptop. Also had gopro on wrong settings for most of the event and did not notice... DOH DOH DOH.. hit record button but was on picture mode...

 

[Ttype6]

So I am going to do the airstrip thing again. It is going to be hotter than in in Sacramento so based on opinions from last time I took 1 extra safety measure. Normally I run 91 octane and Alky Control kit at 25 psi but since it is going to be very hot I bought a fresh load of Sunoco 100 octane fuel. I am going to drive until she is really low on fuel and refill with 100..

So the question is, at 104 degrees outside am I pushing my luck even with the 100 octane?

Link for event:
http://www.aerospaceca.org/wings&wheels/

My old runs last year:
http://www.youtube.com/user/californiazedder

You'll be ok if you also use the alcohol.

 

[Gnx6]

Ya, not going to change any settings, just using 100 octane and Alky as opposed to the usual 91 & alky.

 

[earlbrown]

So you're just going to change the fuel without tuning for the different fuel and then go WOT for 20 seconds?


That's ballsy. I dig it.

 

[Gnx6]

I figured if the car was tuned on 91 and Alky changing to 100 octane would be a little safer for the heat.. Was too farking hot for any kind of real performance. Car did well considering the temps. The also made a last minute change to the runway length we could use so was barely wot for a 1/4 mile.. It was 108 degrees and track temp was around 118... Too hot..

 

[Buick Mark]

That sounds like fun!!

 

[turbofrank]

Changing octane and not turning up boost = wasting money. The alky allows cooler engine temp

 

[Joeld]

Can you run too much octane at a given boost? I know you can run too little. I think his thought is, more octane is better than less.
Is that the case?
Joel

 

[we4Mateo]

You may need to bump the timing a bit to get the same power out of the 100. That's what Earl was referring to. Yes, the car will run, and probably have zero knock, but you may actually be down on power without the extra timing needed to light off the 100 oct. I personally wouldn't change anything either as you probably won't get all the old gas out anyway so it'll be blended and it's not like you are putting in 110 or C16. The point is if it's tuned with one type of fuel combo, it should be retuned for the new fuel combo. You are just running a little extra safety though, which I get, so you should be ok if you want the KISS approach. Watch that knock gauge closely though; 20secs is a long run @ WOT in a boosted 6.

 

[Ttype6]

Can you run too much octane at a given boost?

Higher octane fuel burns at a slower rate. We need this as we increase compression ratio or boost. The extra pressure speeds up the burn rate. If it speeds up too fast,it can create to much force before the piston gets to TDC. Then you have pressure trying to move the piston in the opposite direction of the one it is moving. This will also increase the pressure. Then you have an out of control burn or an explosion. We don't want it to explode. We want it to burn at a certain controlled rate. If we have a situation where the flame front advances too fast we can retard the timing,lower the boost,cool down the intake charge,or use a fuel that burns at a slower rate/has a higher octane rating.

Conversely,if we are making good power with no detonation and we do any of these things and nothing else,the motor can or will produce less power. If we have a good running motor and we switch to a slower burning fuel,we need to do something to speed up the flame. We could advance the spark timing or increase boost or both.

The short answer to your question is Yes.

 

[Gnx6]

I should have leaned it out... oh well... Runs great with 91 and alky most of the time.. Though I will say it went like a raped ape last night in the cool weather around 9pm...

 

[Ttype6]

I should have leaned it out... oh well... Runs great with 91 and alky most of the time.. Though I will say it went like a raped ape last night in the cool weather around 9pm...

Cooler always works better.