Do you self a favor, stay unnder 10:1, most guys don't tune the engine proper, such as a colder spark plug, less timming. You can curve to compression with a larger cam to bleed off cylinder pressure.
Most people that want to run 11 or 12 to 1 on the street, we end up selling them 2 set's of pistons cause the break the first set.

How much DCR this calculator gives you?: http://kb-silvolite.com/calc.php?action=comp2

With that cam, good quench (0.040"-0.050") and efficient coolant system (try to keep it under 200), I don't see a problem running 11.5:1 compression on pump gas.

Or you could run 13:1 or even more with E85, especially with that big cam.

We have tuned 13.0:1 using
E85 , this biggest thing we find with E85 is inconstancy in the octane, from pump to pump

I have ran as much as 11.8 on a 383 L-t1 fuel injected combo, that was tuned. It also had enough cam, enough gear, and a stick, with a sharp owner, that understood how to drive it. Which means, don;t lug the engine. Light cars, loose converter, steep gears, all help. More cam, that reduces cylinder pressure, all help. The biggest killer, is if you lug the engine at low rpm. Depending on the application, aluminumn heads, 10.5:1 is no porblem at all. 11.5 is about max, for a car thats a but more radical, if the owner understands a few rules, and, might add a bit of race gas, or low lead 100 octane aviation fuel at certain times. If its a "true" street car, where you never plan to race it, then, I would actualy run less compression, say 9.5:1, and tune it on 87 or 89 octane. That way you can run any fuel you may come across.

I have ran E-85 on 13.5:1, with no issues. Typicaly, the difference in octane, rating, or, the amount of ethanol, in the fuel, is less only in the winter, when its cold, and no one is driving their race/street cars anyhow. Its typicaly around 70% then. If you set your tune up a bit on the fat side, which, doesn;t hurt power nearly as bad as gas, then, when you have a batch that might be a bit lower in ethanol, you have a safety factor built in. Or, buy it in barrells. I know racers who do that. They just buy drums.

Frank
Advanced Performance
www.get-ap.com

how much does barrels of e85 or e98 cost? and where can you buy them? sorry to hijack NightStalker.

not sure if they sell it by the barrel, we have it at most every pump, about $2.20 a gallon

i going to run around 10:50 and the car will see little street time
mostly strip and the machine shop suggested always using
racing gas to be on the safe side, can you add octane booster
to the 95 octane or does that not work? going with a EFI system :shock:

that octane booster doesnt add much, your better off mixing race gas with the pump gas.

new bikes are high compression-
time it the best to avoid the pre detonation
use good gas stations -
some stations fuel- wouldn't run my mower!!!

Where are you living that you have to use race gas for 10.50 -1? Or maybe I should say soemthing against the advice you were given but he built your engine so he may know lots about it that I don't.

I don't have a street performance engine out there running on 92 octane from gas pump that is not at least 10.50 -1 and a few that are 11.25 -1 compression. Iron Head BB Chevys, Mopars, and Fords that are 10.60 -1 compression. Iron Head SB Chevys at 11.00 -1 compression and aluminum head SB Chevys at 11.30 -1 compression that work just fine with 92 octane gas pump gas.

Of cource there is more to it than just compression ratio. The complete combination needs to be built for it and be compatable. If you have hot spots in chamber or on piston, or a tight low overlap cam or extremely heavy vehicle, That could all make a big difference as well as if you have a large quench distance clearance. I have SB engines with 11.00-1 compression driven on 92 octane that go for 100,000 miles and farther with good gas mileage on the road.

You can do much more in camshaft with an EFI engine too.

Ed