Mixing race fuel with regular

[Ghoste]

Just wondering how many of you dilute racing fuel with regular gas for your street cars and what you think is a good ratio?

[8WHEELER]

I have done it for years nothing wrong with it, I run 12.5 to 1 comp and no longer race the car.
I run about 3-4 gallons of race gas per tank then I can drive it on the street with premium pump gas
filling the rest of the tank. If and when the motor goes bad I am going down to 9.5 comp don't
need the hassle anymore.

Dan

[Ghoste]

I do it too.  I just have been running a strong ratio.  Anything from 50/50 to more.  My car is is only 10.5 compression though so I know it's overkill.  With current fuel prices, I just thought it was time to spend my money a little more wisely in that area.

[471_Magnum]

Leaded racing fuel goes a little further than the unleaded stuff. The octane response is non-linear (i.e. 5 gallons of 93 octane plus 5 gallons of 103 octane does not yeild 10 gallons of 98 octane).

When I was running iron heads, I'd splash in about 2.5 gallons of 110 leaded per tank of 93 unleaded with good results.

[MoparYoungGun]

My Uncle does it in his '68. He will fill up will 93 and then add a couple of gallons (3-5) of some race fuel.

[Ghoste]

Was the 452 an iron head one?  What are you mixing up for fuel in the 471?

[471_Magnum]

Was the 452 an iron head one? What are you mixing up for fuel in the 471?

Yes. The first stroker had iron heads (452s then 906s) and about 9.5:1 compression.

I generally don't need race fuel with the 471 (good quench, aluminum heads and 10.6:1), although I'll add a splash on occasion.

[derailed]

would to much racing fuel in a stock motor hurt anything?

[Ghoste]

Just your wallet.

[derailed]

any kind of fuel does that these days

[471_Magnum]

would to much racing fuel in a stock motor hurt anything?

In theory it could. The SG (specific gravity) of racing fuel is different than pump gas. Some more so than others. The different SG affects jetting. Worse case, you could get into a lean condition.

In reality, you would have already had to have been running really lean for the difference in SG to put you over the edge.

Also, one could make the argument that higher octane generally has lower energy content. Without the higher thermal efficiency associated with higher compression (which requires the higher octane), you may actually make less horse power with a low compression motor and race fuel than you would on pump gas.

For maximum power, the general rule is don't use more octane than your motor requires for knock resistance.

But then again, it sure does smell good.

[Ghoste]

You remember my buddy Lee?  He used to measure the sg of his fuel all the time for that 70 Mach 1 of his. 

[Afflyer]

Ghoste,

     If you can find an airport that sells AVGAS (100 Low Lead), that might be better for you.  Racing gas has no lead, as far as I know, and it's more expensive than AVGAS.  I ran five gallons of Sunoco 105 racing gas with every fill up.  I paid $5 a gallon for the stuff.  Then I began using AVGAS instead of racing fuel.  At that time, AVGAS was $2.75 a gallon, plus it threw in some lead, which is what I preferred. 

     Now that I've moved to the Florida panhandle, I'm having a tough time finding an airport that will sell me AVGAS.  I'm still looking.

     My vote is for AVGAS over racing fuel anyday, with every fill up of 93 octane, add 5 gallons of AVGAS.

     Bradley 

[Ghoste]

Local airports here won't sell the stuff.  I can get racing gas in Detroit which is less than an hour away and some of it is leaded so no worries there.  As to cost, well, that's another matter altogether.  Although with the price of fuel in Canada right now, racing fuel in Michigan becomes a bargain.