Looks like you need to run 98 octane to get stock HP.

[1966 Sunbeam Tiger]

Buddy of mine just put his new GT350 on a state of the art dyno.

http://www.skunkriverrestorations.com/

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[EFI]

Vague post is vague. How about a little more details on what the numbers were with 93 and then after with 98.

To our surprise switching fuels netted a gain of 25.5 horsepower with this car.

I for one am not surprised he gained hp with more octane. So far, all of the dyno results I've seen put the power right where it should be. There was a recent one where the final result was 447rwhp, which is exactly 15% less than the flywheel rating of 526 from Ford.

Maybe the guy had piss in there for fuel and that's why switching to real 98 octane got him some good power.

 

[AMpowerJ]

There were no details so what are they using to base their claim that 98 octane is required to get 526HP at the crank? :shrug:

 

[Nataphen]

526 is the rating for 93 octane. Everyone has been dynoing right in line with that. If you add more octane, the stock tune will adjust for even more than 526. Do some research before posting stuff like this.

 

[1966 Sunbeam Tiger]

Initial tests were with 91 octane. Flush and fill with 98 got it to stock crank HP.

 

[Nataphen]

91 octane loses 15-20hp compared to 93 octane. Your friend is making over 526hp on 98 octane.

 

[EFI]

Initial tests were with 91 octane. Flush and fill with 98 got it to stock crank HP.

Next time do the baseline with 93. Basically this test just told us that the engine cannot make more power with 98 compared to 93, since it can achieve the same kinda power with 93 as it did in this test with 98.

Here's an example, stock with 93 octane 454

http://www.mustang6g.com/forums/showthread.php?t=46503

 

[Grimace427]

Initial tests were with 91 octane. Flush and fill with 98 got it to stock crank HP.

How do you know you got stock crank HP? Did you pull the engine and put it on a dyno? Are you fudging numbers with make-believe drivetrain loss percentages?

 

[ohtobbad]

that dyno is rear wheel, not at the crank.
He needs to take engine out and put on an engine dyno
to prove Ford right or wrong on the #'s

 

[1966 Sunbeam Tiger]

Are you fudging numbers with make-believe drivetrain loss percentages?

15% loss for standard transmission. WOW, arn't you guys a little touchy.

 

[Nataphen]

15% loss for standard transmission.

No. Every dyno is different. You can't just take a percentage off of the crank and get a rear wheel number. Antiquated thinking.

We've seen GT350s dyno anywhere from 442 to 483 in stock trim. The cars don't vary that much in power, the dynos read differently. SAE correction helps equalize things, but it's still not exact.

 

[Grimace427]

No. Every dyno is different. You can't just take a percentage off of the crank and get a rear wheel number. Antiquated thinking.

This. A Mustang dyno will read significantly lower than a Dynojet showing a higher drivetrain loss.

 

[1966 Sunbeam Tiger]

No. Every dyno is different. You can't just take a percentage off of the crank and get a rear wheel number. Antiquated thinking.

So is every engine dyno different. You would have to pull the engine from your car and put on the dyno that Ford uses. Too easy...

 

[Nataphen]

So is every engine dyno different. You would have to pull the engine from your car and put on the dyno that Ford uses. Too easy...

Frankly, I don't know anything about engine dynos as I have not dealt with them. I do know that chassis dynos aren't consistent the world over. If you do, you need to do a little bit of research. The car will make 526 to the crank on 93 octane. It will make more with higher octane, less with lower. Simple as that. Like I said above, we've seen stock chassis dyno numbers on 93 octane measure over 40whp apart. That's not the cars, it's the dynos. Dynos are for measuring power changes after modifications, not figuring out the exact crank horsepower that your engine is making.

 

[GT P-TREE]

I just think people are "upset" because you didn't say that the initial run was on 91. Kind of a given that a high strung high compression engine will make more power with more octane. Hell, look at the gains with E85 (~100 octane). Voodoo=a beast

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