Mixing fuel: 100LL, Cam 2, 93 Octane

[Jamesbon]

If I mix 25 gallons of 100LL (or Cam 2)and 25 gallons of 93 octane, does that mean my fuel octane rating will be 96.5?

[HP 600SC]

You going to blow it up mang!!

[CDMA]

Nate the octane relationship is not purely linear but close enough that an average gives you about the right answer. So it should be about 96.5 octane.

Chris

[Eugene Nahemow]

Why mix? :D

[Forrest]

Nate, I hope that you didn't build your engine with so much compression that you need 96+ octane. That could create some expensive Donzi rides!

[Jamesbon]

Thanx HP, I'm good at blowin 'em up.

That's what I like to hear, CDMA.

Eugene, I'm running 10:1 + compression with extremely radical cam and Merlin iron heads...

Forrest, my life long "Donzi ride" has been expensive, why change now...

:) :) :)

Some may think this is ludacris, but I think it's ludacris to have a mild mannered, docile idling Donzi. The more radical, the better...at least for me.

[mphatc]

Nathan,

10:1 should run well on hightest 93-94 octane. . . IF . . .

you have the cam correctly timed, the proper fuel mixture and the correct matching advance curve along with GOOD cooling!

I build 10.5 :1 street engines for a living , all run on 93 octane!

Mario L.

[Eugene Nahemow]

Nathan,
My point was why use the 93? wink

I am also running a 10+ compression on my motors.
I run with 93 but add a product that CP performance sells called Liquid HP.
I bottle treats 100 gallons. It sells for ~ $20.
I have had no problems with the engines.

When are we going to see some new photos?

[smoothie]

Nate,You may want to read gasoline-faq (http://www.faqs.org/faqs/autos/gasoline-faq) part 3,section 6.15. wink

[Stix Magill]

Smoothie,
Thanks for the link. I am totally ignorant to the octane factor. I will read the website link, but to jump in on the topic, I have a simple question.

Yes or no:
Should I use premium or "high octane" (93 or higher) with my stock 1997 350 mag? The only non-stock part is the K+N air filter. If yes why?

I have been using 93 because the previous owner did and he raced Porches. I figured he knew more that me.

Thanks,
Scott

[Stix Magill]

Correction: I will not read that website. I looked at two topics and it is WAY over my head!

Thanks though Smoothie. The more technical guys will get it.

Stix

[GEOO]

Nate,
Mixing fuel is much better then adding octane booster. Octane boost raises the rating only 10ths of a point while mixing race gas can increase the oct half the difference.
Keep the engine temp and air intake on the cool side.

[smoothie]

6.15 Can I mix different octane fuel grades?

Yes, however attempts to blend in your fuel tank should be carefully
planned. You should not allow the tank to become empty, and then add 50% of
lower octane, followed by 50% of higher octane. The fuels may not completely
mix immediately, especially if there is a density difference. You may get a
slug of low octane that causes severe knock. You should refill when your
tank is half full. In general the octane response will be linear for most
hydrocarbon and oxygenated fuels eg 50:50 of 87 and 91 will give 89.

Attempts to mix leaded high octane to unleaded high octane to obtain higher
octane are useless for most commercial gasolines. The lead response of the
unleaded fuel does not overcome the dilution effect, thus 50:50 of 96 leaded
and 91 unleaded will give 94. Some blends of oxygenated fuels with ordinary
gasoline can result in undesirable increases in volatility due to volatile
azeotropes, and some oxygenates can have negative lead responses. The octane
requirement of some engines is determined by the need to avoid run-on, not
to avoid knock.

[MOP]

I know little about fuel ratings etc. But I think alot of the guys that know as much as I do are thinking of playing with octane. If you have these thoughts do a search on Octane. There was an exceptional post where the real pros explained the reality of playing around with running fuel with more octane than needed the post is well worth reading if you want the best performance for you stock mills.

[Jamesbon]

Thanks fellas! Great info.

Nothing for nothing, I will mix at least 1/4 Avgas in my tank for the initial break in. Once I'm familiar with the engine's characteristics, I'll adjust accordingly.

As far as "slugs," I'd really have to believe that all the bouncing around a boat incurs, the gas would mix thououghly...

BTW,
The deck is finally finished. Just have to pick up and find a place to store this thing indoors while rigging...Pics are coming soon...sit tight :)

[Rick]

Nate, You've got the fuel thing squared now where are the pics! Rick