octane question

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Jul 13, 2010 | 03:39 PM

#16

B Big

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Joined: Feb 2009

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From: Western NC

I had a '70 VW that I really built up the motor. I was running stroked & bored, 3/4 cam, & dual weber carbs etc. I also made the compression low (spacers under the jugs) so I could run pump gas. That car didn't like the AV gas at all, it would run like sh** no matter how much you cut the mix. Running pump gas that car surprised some folks!

Jul 13, 2010 | 04:51 PM

#17

cleatus12r

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Joined: Apr 2004

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From: Reed Point, MT

Quote:

Originally Posted by ckal704

Any body that tells you they saw a performance increase of any measurable significance in a 9.5:1 compression ratio engine running 95 or higher octane fuel is full of it.
These are facts. Google octane if you want more info.

There is no performance increase if nothing has been done in the tuning to take better advantage of the slower combustion rate.

You're right though, there will be no increase in performance.....and most likely a slight decrease in performance due to very high octane fuel.

Jul 13, 2010 | 04:59 PM

#18

MustangMatt96GT

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From: Lakewood, Colorado

I plan on it eventually. Problem is getting bigger metering blocks for my Carb on my budget haha but my fuel system will support it, just a matter of convertoring my Carb to beable supply the extra fuel needed.

Quote:

Originally Posted by MADVAN

Go with E85 for the drag car.
Its the best bang for the buck.
Your fuel and tune will have to be increased approc 30%+

Bill

Jul 13, 2010 | 07:47 PM

#19

MADVAN

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From: Levittown

The leaded fuel will take out your O2 sensors first.
Then limp mode will finish off the cat.

Nat *** street cars are running in the low 13's in compression on the E85 fuel.

B

Jul 13, 2010 | 07:56 PM

#20

MustangMatt96GT

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From: Lakewood, Colorado

Quote:

Originally Posted by MADVAN

The leaded fuel will take out your O2 sensors first.
Then limp mode will finish off the cat.

Nat *** street cars are running in the low 13's in compression on the E85 fuel.

B

Yeah I could run around 38 degrees timing in street trim because of the octane rating of E85. Instead when I wanna drive it any distance I put 91 in it and drop timing to 20 degrees.

Jul 13, 2010 | 08:30 PM

#21

MADVAN

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From: Levittown

Quote:

Originally Posted by MustangMatt96GT

Yeah I could run around 38 degrees timing in street trim because of the octane rating of E85. Instead when I wanna drive it any distance I put 91 in it and drop timing to 20 degrees.

S-Plug change and have seen 40 to 42* before the power falls off.
Most run here. Nova is one of ours.
F.A.S.T. - Factory Appearing Stock Tire - Home -

Jul 13, 2010 | 08:36 PM

#22

MustangMatt96GT

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From: Lakewood, Colorado

Quote:

Originally Posted by MADVAN

S-Plug change and have seen 40 to 42* before the power falls off.
Most run here. Nova is one of ours.
F.A.S.T. - Factory Appearing Stock Tire - Home -

Unfamilar with S plugs. I know my motor likes right around 34-36 on 110 sunoco purple depending on the DA of the day.