Old thread I know but have you thought about water injection? A simple mixer (like a carb) or a pressure based switch (above a certain vacuum) may do the trick. Attached is an article, short answer is that 0.6 times the fuel volume in water led to approx 20 point improvement in MON, 98 becomes ~118 etc. The system doesn't need to be complex and the water rate can be fairly constant as the ocane requirement drops with increased engine speed due to higher turbelence and so on.

[Edit: whoops the file's too big, try the link http://www.rbracing-rsr.com/downloads/naca_H2O.pdf]

For Volvo 142E's & 1800ES , they make a thicker gasket for the exact reason you're looking for one. At 10.5-1 they will often ping on 91 octane. I do have one question on the motor, what Camshaft is in it. The compression ratio and camshaft usually go hand in hand, depending on the cam lowering the compression may have adverse results (nothing fatal just annoying)
As for the guy saying higher compression engines will implode.................that's a total pile of dog poo. A series race engines are at 14-1, the short service intervals have more to do with the high RPM's than compression ratio.
I've always stuck with 10-1 because I just don't want to be bothered with running race gas, it's availible at our local track but I like being able to fill the car at the gas station as well as the lower price.

Tom

Yeah it certainly seems to be good stuff.

I went and had a look at a few stations that apparently sell it and they were shutdown.... recently by the looks of things.

It also turns out the compression ration of the engine is much much higher than what the original engine builder had stated. I cc'd the combustion chambers and later matched the head up beside an untouched GX head and the differences were fairly amazing.

So I guess everything is a shambles at the moment.

Looks like I'm certainly going to have to decrease the comp ratio with a rather thick shim/gasket.

Not a problem mate, Fast fours and rotaries also did a comparison on E85 and apparently tuned engines loved it WHEN they were tuned for it. We dont have it where we are :(

AvGas is gasoline which has been developed for piston engine aircraft. there are a few types, 100LL which is essentially 100 octane low lead, then theres 110/130 which is 110 octane rating in a lean mixture configuration and 130 octane in a rich mixture equivelent. Avgas has a certain glycol content to prevent freezing at high altitudes (Avgas is used up to about 13000 ft AMSL which in standard atmosphere conditions is -11°C outside temp)

All avgas has lead in it to help boost the octane rating and keep combustion temperatures down. It also acts as a good upper cylinder lubricant and keeps valve seats happy. It is not good for oxygen sensors or catalytic converters if you have them fitted.

Many people believe that high octane rating means more power and harder on the engine but this is not true, it just equates to a more controlled burn and thats the main factor. Sure, there are other effects of higher octane but the main is higher octane = less prone to detonation which is caused by too lean or too high compression ratio.

Avgas shouldnt be used on the road because it doesnt have any road tax attached to it and you are in the crap if you get caught. Your car should also be tuned to take advantage of it and i think this involves a little leaning and more ignition advance than what you would use for pump gas.

Hey Fenix,

As far as I'm concerned they're considering bringing it in on a larger scale. AT the moment it is sold at independent service stations and I believe some larger farmers are planning on producing it in bigger quantities, so they must know something.

AvGas simply isn't on the agenda. It is far too aggressive for my liking and I am not prepared to pay the risks or the prices.

The methanol blend is interesting but I really need a fuel available from the pump as I don't have the means to store any fuel at my residence.

Sikyne nailed it on the head. E85 does not have the power as gasoline does. But by increasing the stock compression ratio your differences in power compared to a gasoline 11:1 engine would be fairly surprising I suspect.

Personally I am expecting good results from this fuel. AT the moment I am double-checking my compression ratio just to be ABSOLUTELY sure that I have it right and then I'll move to basic jetting.

EDIT: Thanks dd, I wouldn't expect Ferrari and Datsun to come together very often! I could always try water injection to cool the high-comp charge but I really don't have the knowledge.

The new F458 has 12.5 compression ratio and runs on Premium pump fuel. But then it is an advanced, brand new combustion chamber design...

Anything over 11.5 you should use 100+ RON. I had a DC2 Type R and i couldnt run it on anything less than 98 and it was 11.2 C/R from memory. Also, a mate has a built 250 chev in his HZ ute that had a 12.4 C/R and not even 98 could help it, if u floored it you could here it pinging like crazy. Im not a fan over octane boosters but they may be necessary. I remember reading something about mixing methanol and normal fuel in the latest motor magazine and they said the perfect mix was 60% fuel to 40% methanol. The Meth was damn cheaper than the fuel and it still worked out to be cheaper...

Hope i helped :)

**
Av-Gas is illegal to use in cars ont he street obviously, and if your vavles arent up to scratch you WILL burn the valves and seats out. Getting it isnt hard but it is nearly 3 times the price of normal fuel.

I heard SA moved away from the E85 blend? Interesting...

Yes, Ethenol and methanol make less power(pound for pound)than petrol.

BUT, you have to burn a lot more of it to get the same Lambda readings which brings the BTU`s(heat energy)per combustion cycle close to petrol.

The other thing is the higher octane rating, This allows timing to be optimally set on higher comp and higher boosted engines and allows for boost to be safely increased. This allows for higher HP than pump petrol.

If an engine doesn`t require the extra octane, ie a standard A12. little or no power may be gained with the use of ethenol. The engine would still have to be tuned to find this out.
If someone was to drive their car into a petrol station and just fill their car with an ethonol blend there would be a big power drop and the higher the ethenal in the blend the higher the HP drop.

So, The engine MUST be tuned for it. And to get the most from it the compression or boost should be raised from standard.

I'm going with E85 and I believe it is sold at a depot near me. Have to make a few phone calls first to confirm it's availability.

It is cheaper or as cheap as standard fuel, produces a little less power which I probably would have lost in the advanced spark anyway running the BP Ultimate [98-102 RON].

I am convinced it will not affect the current fuel system components and I'm convinced that with the higher compression, the power results may not be as [comparatively] low as expected.

AvGas still burns very hot and I'm not sure on the specifics of the lead contents of the fuel so it sounds like a fairly aggressive fuel to me. I know the OG Speed Shop here in Adelaide sells it but it's a fair drive just to fuel up. I'll have to find out more about it first so I'll start with E85 and perhaps dilute it even further to achieve a higher gasoline - ethanol ratio.

To me E85 sounds like a rather tame, high-octane, cool burning fuel, and I'm pretty sure that's what I'd like to run.

Does anyone run AvGas in their street car? Costs? Whats with the lead content too?

EDIT:

Hey Bert,

That certainly is how things are looking but I don't have the gear to reduce the comp ratio at the moment so finding an oval port head means I'll need a new manifold to suit[ current manifold is port matched]. So the costs to change aren't really within my grasp.

Have you hd much to do with this ethanol blend stuff?