91 or 87

[ToXSicK RoCKeT]

hey fella's, this goes out mainly to some of the motor head 08 busa dragracers, but PLEASE, anyone feel free to chime in

OK, i know with the GEN1 busa's there was alot of guy's making more HP and running better ET's with 87 octane fuel than with 91/92. NOW, have any of you found this to be true with the 08's(GEN2)? i was thinking with the bump in compression that it would need and run better on the higher octane? your thoughts please.

 

[BA BUSA]

Gen 2 is tuned for minimum 90 octane...12.5 CR

 

[jefro]

Brock's recommends using 87 octane with their Street map on the 2008's, at least at the strip. I don't feel safe running it around town where at times I'm lugging the motor down to 2500 rpm or so. Also, the motor is more heat soaked on the street sitting at stoplights or stuck in traffic on a hot day.

 

[shawnski]

i use premium 91-93 octane, if you use 87 octane and hearing unusual noises and knocking, you need to go back to over 90 octane.

 

[Loki08]

For the extra $1.20 per tank, is it really worth it not to run the specified octane?

Those of you in the heat soaked south, the extra 4 points of flashpoint resistance can make a difference between detonation and not.

 

[ToXSicK RoCKeT]

For the extra $1.20 per tank, is it really worth it not to run the specified octane?

Those of you in the heat soaked south, the extra 4 points of flashpoint resistance can make a difference between detonation and not.

+1 its not the $$$ im concerned about, its squeezing every bit of hp out of this thing

........... i just remember hereing on the gen1's 87 was good for as much as 2 tenths

 

[BA BUSA]

........... i just remember hereing on the gen1's 87 was good for as much as 2 tenths

That's because the Gen1's are tuned for 87...people who thought that 91+ or race gas would be better, actually run slower.

Gen2's minimum 90 please

 

[BA BUSA]

I had my '03 tuned for 91...but that is just because at the track (road course) I run a litre bike too and it runs on 91...I only have to bring one type of fuel for both bikes.

 

[ToXSicK RoCKeT]

........... i just remember hereing on the gen1's 87 was good for as much as 2 tenths

That's because the Gen1's are tuned for 87...people who thought that 91+ or race gas would be better, actually run slower.

Gen2's minimum 90 please  

GOT-CHA, THANKS FOR THE REPLYS AND INFO EVERYONE

 

[roadthing]

The higher the octane rating the slower the burn. High compression engines REQUIRE higher octane ratings for a more complete, and efficient burn during the power stroke.

As higher octane fuels burn more slowly, the fuel/air mix will continue combustion for a longer duration. Since duration of the burn is longer, the continued expansion of gases in the cylinder exert a more smooth and linear amount of pressure on the piston. Part of the beauty of having high compression ratios.

If you have a high compression motor, and it were equipped with an anti-knock sensor, you could run 87 octane. You would need to be able to adjust your spark curve, not just the AF ratio. BUT, if you elected to not feed such a beast what it NEEDS, then why even bother with higher compression ratios?