<http://herbstmail.com/v-web/gallery/Cars/Dyno>

Since I have no basis for comparison I don't know if this looks right or not. I'm a little surprised at how torque falls off above 6k. Sorry the line is so faint on the image.

Street Port
Blueprinted stock sequential twins
Open Intake/Downpipe/Cat-Back with stock cat
ASP Medium
Pettit Unlimited ECU
12 PSI 101 Octane
(peak RWHP reported as 281 @ 10 PSI in 3rd and 4th gear but I don't have the curves)

Any comments?

 

why u running 101 octane?

 

Uh, because I can?

Seriously, I've never hooked up an O2 sensor to know how good my A/F ratios are with the Pettit maps and figured I'd rather be conservative in case of a boost spike. Sometimes I put in 91 octane but mostly run race fuel which these days is only twice as expensive. I'm thinking I may push a little above 12 PSI soon, too.

 

u make less power with more octane. only run hi octane when u want to run some serious boost. Not to mention u are wasting your money.
---only trying to help.

 

Really? Something to do with the rate it burns?

 

if you know then why do u run it? thats expensive

 

I don't know what my A/F is. If I knew it was always ok or rich I might be less conservative on octane. Since I fill the tank less than once a month the money doesn't matter much, and a grenaded motor would overwhelm the difference for sure.

Does high octane really produce less power?

 

yes.

 

Hmm. Could you point me to an explanation of why? Is it a rotary thing?

 

I'ts kind of like retarding your timimg. You will be safer (less chance of detonation) but you will make less power because of the later ignition which is similar to higher octane in the sence that your complete combustion will occur later. I hope this helps.

 

put a midpipe on and you'll break 300

hey, it's a disposable planet

 

Your avatar is insane. What is that?

 

Picture of a model Weta Productions made in their design for the balrog in Peter Jackson's Lord of the Rings films. Very cool bit of work.

 

So, if I understand this correctly, I could expect a faster burn with lower octane, with an effect sorta like more spark advance. Might that prevent the torque rolloff I'm seeing at high RPM?

I'm guessing spark issues wouldn't give such a smooth rolloff...

 

You're still sequential right? If so your transistion is happening about 1000-1500rpms late.

 

About 4800. Isn't normal about 4500?

 

My transition is around 3800.

 

why is that?

 

Because that's where it is supposed to be?