Two Dyno days one winner

[Vegas69]

We'll just have to agree to disagree. A leaded racing fuel and an unleaded street fuel will effect tuning. Sure you can run both on the same tune up but how do you find the sweet spot on your intended fuel by using a band aid on the dyno? Alot can be learned from exhaust temperature, air/fuel ratio, and ultimately loss and gains in power making changes.

I do agree that using the higher octane fuel doesn't mean more power unless pump gas is insufficient. It's probably a safer bet to break in an engine for the less experienced. I specifically remember Pettis shutting mine down and leaning out the carb to reduce exhaust temperature at start up.

At the end of the day, we found max power on 91 octane with safe exhaust temps, safe air/fuel, and 34 degrees of timing. That was my intended application. Seemed to work out alright.

I'm no expert but I know enough to disagree with you.

[GregWeld]

Originally Posted by Vegas69

I'm no expert but I know enough to disagree with you.

I think you'll need some more research before you can really make that statement.

I don't think you really paid attention to what I was saying. That he wouldn't necessarily make more power using 100 than he would have running 91 -- but he can tune the motor without fearing the dreaded detonation while he's fooling with timing etc. The motor was built to be run using pump gas... therefore the compression etc doesn't demand 100 octane fuel... and 100 octane fuel doesn't "make" more power - they just protect against detonation. The higher compression motors demand higher octane fuels - but that's a different situation. We're talking about a street motor with normal compression.


I should add that VP makes Streetblaze that is a 100 octane unleaded OXYGENATED fuel that will make more power... so I guess we really should know what fuel he tuned on. My guess is leaded 100 octane non oxygenated for the safety factor.

And it's okay if we disagree... I just like being right.

[GregWeld]

By the way -- this is a great discussion because there's a lot of thinking out there by people that don't know that might learn something from it.

I know plenty of guys that think they should toss in some 100 octane because they're going "racin'".... On a hot day - pushing to the max - it might help protect their motor - but they're NOT making more power.

[intocarss]

Originally Posted by GregWeld

By the way -- this is a great discussion because there's a lot of thinking out there by people that don't know that might learn something from it.

I know plenty of guys that think they should toss in some 100 octane because they're going "racin'".... On a hot day - pushing to the max - it might help protect their motor - but they're NOT making more power.

I know those guys

[GregWeld]

Originally Posted by intocarss

I know those guys

Don't we all!!

Gasoline and A/F ratios are really misunderstood. Can't tell ya how many people think A/F ratio is the magic bullet... and that 38* of timing in their SBC is still the right thing to do... Despite having modern aluminum heads etc.

They have to be shown on the dyno and even then my guess is the first time they get a chance - they bump the timing back up!

[fleetus macmullitz]

Originally Posted by GregWeld

They have to be shown on the dyno and even then my guess is the first time they get a chance - they bump the timing back up!

Congrats on the results Rob.

Especially since it's a TP headed FE.