what fuel can i run

[2 fast z28]

hi guys putting my big block mopar together and before I buy a carb I was wondering what fuel im going to have to run here are the specs on the motor 500 ci with wiseco pistons for a 4.150 stroke and 6.760rod flat top pistons book says 11.5 to 1 compression with 78 cc heads I have the trick flow 240 power port heads with a 40 thousands head gasket and a 15 thousands deck clearance wondering what my actual compression will be in the end and what fuel im going to run 93 octane e85 or if I can run 91 octane thanks cj

 

[Ironbuilt]

With 11.5 to 1, you are teetering on that "Race Fuel" precipice. I have 11 to 1 and like to find "real" gas or use a mixture. I would definitely stay away from e85, it is NOT engine friendly. I am sure that the race crowd will chime in to help you further.

 

[1967coronet440]

If it truly ends up at 11.5:1 you’re probably looking at at least 100? My engine is 11.9:1 and my builder recommended 108-110 fuel

 

[493 Mike]

What are the cam specs?
Mike

 

[67belvedere/225]

you want the less ethanol in your fuel as possible and you will want/need to mix in some racing fuel, i bought a drum of sunoco racing fuel
and we mix it in all our vintage cars at the shop , and they love it. smells good and runs better.

 

[Jerry Hall]

I go to the local small Airport and buy their 100 octane low lead. I add 4 oz. Marvel Mystery Oil with each 5 gallons. I also add some additional lead additive and Sta-Bil 360. In my 13:1 Race Hemi I mix this 50/50 with 112 Race Fuel. I'm sure the 100 octane will run fine in your 11.5:1 engine.

 

[Ironbuilt]

I go to the local small Airport and buy their 100 octane low lead. I add 4 oz. Marvel Mystery Oil with each 5 gallons. I also add some additional lead additive and Sta-Bil 360. In my 13:1 Race Hemi I mix this 50/50 with 112 Race Fuel. I'm sure the 100 octane will run fine in your 11.5:1 engine.

Must get very costly for a Friday night cruise. LOL

 

[2 fast z28]

cam spec is
HUG SEH4246BL-8

BB HYD FLAT TAPPET CAM 242/246 -108ºLSA

LOBE LIFT .375"/.382" with 1.6 rocker

 

[Ironbuilt]

cam spec is
HUG SEH4246BL-8

BB HYD FLAT TAPPET CAM 242/246 -108ºLSA

LOBE LIFT .375"/.382" with 1.6 rocker

Cam specs won't matter, it's final compression ratio that will matter. If it is over 11 to 1, seek alternative fuels.

 

[2 fast z28]

I think I might call wiseco and tell them my specs and see what they tell me what my final compression ratio will be my engine builder said 10.5 but that makes no sense to me

 

[Ironbuilt]

I think I might call wiseco and tell them my specs and see what they tell me what my final compression ratio will be my engine builder said 10.5 but that makes no sense to me

If you're starting off at 11.5 to 1, I find it hard to believe that you are going to end up at 10.5 to 1. That would require a lot of head spacing. the thicker the head gasket the lower the CR. That IMO is not a proper way to build an engine.

 

[Jerry Hall]

Must get very costly for a Friday night cruise. LOL

Actually its only about 40 cents a gallon more than 93 with 10% ethanol. The additives add a little to the cost, but you would be amazed at how much better these old original engines perform when they can be tuned correctly. My 440 cars get almost another 3 mpg running on this fuel. The Hemi Dart is another situation, but the detonation is completely gone.

 

[493 Mike]

http://www.empirenet.com/pkelley2/DynamicCR.html

Read this for an explanation of how cam specs affect octane requirements.
Mike

 

[Bill Monk]

I agree with others here on more octane at that compression. I never liked av gas though. I put 5 gallons of 112 race fuel into a tank full of 93 and that eliminates any valve knock. You may have to experiment to see how much of what you need to run to see what your engine likes. I wouldn't just fill er up with 93 and stomp the throttle until you are sure you are safe. You can retard your timing but then you aren't getting all the engine has to offer.

 

[Ironbuilt]

http://www.empirenet.com/pkelley2/DynamicCR.html

Read this for an explanation of how cam specs affect octane requirements.
Mike

I understand that, but 11.5 to 1 Static CR, regardless of cam specs and DCR, is still going to require higher octane than pump gas. I seriously doubt that his cam is going to close the intake valve with the piston barely above BDC. I could be wrong, but only his engine builder will know that.

 

[Jerry Hall]

It's not that I really like having to use AV gas, but it in my opinion is a better alternative than anything with ethanol. Ethanol is going to turn to water in a steel gas tank at some point in time. Then the real problems happen. Rust in the tank, sticking floats in the carburetors, stopped up fuel lines, etc. I like to drive my cars some, AV gas is more economical than straight race fuel. Another plus is I can get full performance out of my engine, without retarding timing, or other tuning sacrifices. There are concerns using AV gas, as it is very dry so it will perform at high altitudes. Adding Marvel Mystery Oil puts needed lubricant back into it. If you like putting alcohol in your fuel go get some real moonshine it works well and doesn't turn to water.
As our government is doing their dead level best to get older cars off the road by eliminating the great fuels of the past, taking the zinc out of the oils, and other things, I'm doing what I can to stay on the road. Also on another topic, they aren't going to eliminate guns, there just going to quit making bullets.

 

[2 fast z28]

called them today looks like im at 11.45 to 1 comp thanks for the help do you guys know what a drum of 110 is going for

 

[Jerry Hall]

I bought 2 5 gallon cans at the track 2 weeks ago, it was $100.

 

[Bill Monk]

called them today looks like im at 11.45 to 1 comp thanks for the help do you guys know what a drum of 110 is going for

I buy 112, but they have a pump so I take 5 gallon cans. if I'm not mistaken, it was better than $6 a gallon

 

[coloradodave]

Just a word of caution about buying AV gas. Since they don't add in state and federal road tax, in most areas it is illegal to sell it, or buy it for a vehicle that is used on public highways. Years ago in California it was a very hefty fine. They did several sting operations to scare off potential sellers, mostly at small rural airports. That dried up our sources...