mark kibort

Ive got quite a few of these out there now, and am building another 5 liter euro S, this time CIS (finally)

Glen, i dont think you will have any problem, plus, i dont think the compression bumps from 10.0 to 11:1, just for shaving the heads .5mm. I think scot's 5 liter, with the euro S stuff is 10.5:1 and that is with the 5 liter and a shaved head. I run near 11:1 and run 91 pump gas with 372rwhp on my 6.4 liter.
scots is still running stock timing, and gets 290rwhp and has been racing it for a few years now.

If you use the calculator for the values I think we all agree with, i dont think the compression would come up that steep.

48cc for heads (Glen, what are your shaved head chamber volumes now?)
98mm piston cylinder bore
6cc valve relief. (we got 8cc with a 84 4 valve piston and then the 2cc cuts like the later euro S pistons)
(so another note, euro S pistons from 85 are 2cc and its compression ratio is still only 10:3)
1mm gasket, for 7cc
standard 78.9mm stroke, and there you go. plug it all in.

it all calculates near stock quote levels. dynamic with our anemic cams will be less.

Mark

BC

I will be ducking and covering before the dog-pile jumps on me, but there is a solution to your compression ratio and a way to really ring out the engine to get the most from your work. E85.

And being in MN it will be cheap and plenty. A few changes to the rubber fuel lines, and you can never worry about detonation again.

LT Texan

and duck you should.

Glen, you wont ping on good gasoline.

You won't ping on a lower energy density E85 either.

BC

Fixed it for you.

GlenL

Thanks for the idea but E85 has 40% less power than pure gas.

At the track I'll seek out the non-oxy gas (available right outside the gate, unsurprisingly) for the extra 5% power it offers. It's only found in 91 octane in these parts now so I mix in some 110 at the same station. 8 gallons of 91 plus 2 gallons of 110 is 95...or thereabouts.

BC

You are confusing, in this instance, power with efficiency.

E85 usually allows a high performance engine to gain about 5% EVEN with no other changes. The mere fact of the "colder" fuel and the resistance to detonation only helps the situation.

ESPECIALLY with track duty, having a fuel like E85 could really benefit the engine. With the higher CR being discussed here, other than race-gas, its almost mandatory.

There is alot of misinformation, and that is one of the main issues with the fuel today.

GlenL

BC,

You're either way off or confusing the issues. Here we go:

Gasoline has an energy density of 46.4 MJ/kg. E85 has 33.1 MJ/kg. That's 29% less per unit mass. That's an important when actually burning the fuel as gas has a stoichiometric ratio of 14.7:1 and E85's ratio is 9.76:1. So you're able, at stoich, to burn 34% less fuel.

That's a total loss of 53% of maximum power! For the same engine, of course.

Now you can open the throttle or supercharge to get that power back, but the fact remains, E85 provides a lot less power than gas.

I read a few comment about making more power with E85. They're comparing a engine tuned for power with E85 to a stock gasoline engine. Stock engines are tuned for mileage, emissions and reliability.

918-S

I agree. Unless you totally tune the engine for corn you can't push enough of the stuff through a gasoline system to make up for the loss in energy. Not to mention the effects of corn on the fuel system parts.

GlenL

Well, Mark, I don't think you followed the thread. I'm pumping 98mm diameter's worth into my shaved '80 heads along with having the small-cut later pistons. The shaved deck isn't a factor. I should CC one piston and see if they enlarged those reliefs to compensate for the extra 1mm width.

DE REPORT:

The engine ran great. Zero noises. Zero oil consumption. Low temperature. No coolant used. A few minor hiccups and I blew the PS hose Sunday afternoon but it couldn't spoil the weekend. I chose to run 2:1 91 to 110 for anti-knock confidence.

I received several compliments on how fast it was on the straights and, especially, how fast it was in the corners. A typical comment was "I thought you may be fast on the straights but was really surprised that car could corner like that."

(No smilies can do this justice!)

918-S

Hey Glen, Glad to read this. Your car is the perfect sleeper. I tried to get free to see you run but this weekend was a calamity of errors ending with one nasty sun burn. Sandy and I have been talking about the coming weekend event. Keep us posted when you get a final date.