Why do people dyno their car with higher octane?
12-07-2002, 09:34 AM
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Why do people dyno their car with higher octane?
Just curious, as Josh's post reminded me. It seems to me that all the cars that use a dyno always add higher octane fuel to their car and THEN tune it. Is it just me or does this make no sense at all? Yes adding the higher octane will resist knock, but if you are tuning to the threshold anyway like I would hope you are doing, then it wouldnt make any difference whether it was on 100 or 93 octane, since you were teetering on the borderline anyway. I just find it funny that all these people always dyno their car with slightly higher octane and tune it that way, because the moment they get off that dyno and get regular gas in their car, they will begin to knock like a bitch and power will decrease significantly. Anyone here have any thoughts? Sorry this wasnt an attack against you josh, I dont want to make it out to be like that. This thought was actually brought about by my friend with his supra going to tune it on the dyno, but the owners of the shop that were going to tune it said for him to put some 100octane in the tank for the dyno day, and I argued with my friend saying hell no dont do it. Your comment just reminded me thats all.
If you are going to make power claims for a daily driver, then tune and dyno on just plain 93oct. That's my thought for the day.
If you are going to make power claims for a daily driver, then tune and dyno on just plain 93oct. That's my thought for the day.
12-07-2002, 11:56 AM
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because they are gay..
actually the other guy was right when he said so they can get extra hp to brag about.. race gas makes pussy cars look like monsters.. i will never put race gas in my car for a serious matter. my car will be built and tuned for the pump, and everyday drivable power.
actually the other guy was right when he said so they can get extra hp to brag about.. race gas makes pussy cars look like monsters.. i will never put race gas in my car for a serious matter. my car will be built and tuned for the pump, and everyday drivable power.
12-07-2002, 12:39 PM
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i tune mine using pump gas....... and run pump gas on the street. When i'm on the track however, i run 14 gallons of 93oct and about 6 gallons of 110 oct. (it gets hot during 30 minute run @ 16-17 psi) This will be changing soon with the new fuel system allowing me to run hard w/ low amount of fuel in the tank.
12-07-2002, 01:48 PM
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Originally posted by GreyGT-C
i tune mine using pump gas....... and run pump gas on the street. When i'm on the track however, i run 14 gallons of 93oct and about 6 gallons of 110 oct. (it gets hot during 30 minute run @ 16-17 psi) This will be changing soon with the new fuel system allowing me to run hard w/ low amount of fuel in the tank.
i tune mine using pump gas....... and run pump gas on the street. When i'm on the track however, i run 14 gallons of 93oct and about 6 gallons of 110 oct. (it gets hot during 30 minute run @ 16-17 psi) This will be changing soon with the new fuel system allowing me to run hard w/ low amount of fuel in the tank.
Nick
12-07-2002, 01:59 PM
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i'm talking about roadcourses..not drag racing. and yeah, i run between 15 anfd 20 gallons in the car and finish a session w/ about 10-15 gallons left. Next session is 10-15 gallons ending w/ 5-10 gallons.I NEVER run below 10 gallons at the start of a session because of possible fuel starvation in the curves .I do this because i run pre-mix and it's a pain to leave, haul ass to the gas station and come back, just in time for your next session. Running the car for 11-12 seconds is one thing to do when you tune for it. Run your car wide open for 30 minutes and your intake temps are gonna be high, especially in a turbo car.
PS. i drive a rotary, one ping of detonation means its rebuild time.
But with the new surge tank.....this will no longer be a concern 
PS. i drive a rotary, one ping of detonation means its rebuild time.
But with the new surge tank.....this will no longer be a concern
12-07-2002, 02:01 PM
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Originally posted by marshall
or maybe they use higher octane because it's an extra safety measure while rough tuning.
or maybe they use higher octane because it's an extra safety measure while rough tuning.
About the 20 gallons of gas, seriously why do you do that? A gallon of gas weighs at least 3lbs if not more, times that by 20 and you have 60-100lbs of extra weight. May not sound like much, by why even run that much extra?
About the higher octane not burning as hot etc, all youd have to do is turn that boost controller up just a HAIR and it would far outshadow any downside from your original tuning. From my experience with race gas (115oct) I felt a noticable difference throughout the entire RPM range. My car was nicely tuned at that point as well, without any timing dips or plateaus, and maxing around 18*. So although at this point I dont have any hard proof to show you since I cant remember everything I have read, I would have to say that higher octane gas would most likely not hurt you even on 93octane-like tuning.