Tom M'Guinn

So I finally decided to try E85 now that it's getting easier to find. At $2.09 a gallon, it's a fraction of the cost of the 100 octane pump gas I normally get.

I'll start by saying my motor is prone to knock. However, on 100 octane with 75/25 water/meth, and careful tuning, it can run 20+psi with no or very few knock counts. One E85, however, it seems to be getting multiple (KLR) knock counts -- even at 12psi to 14psi -- no matter how I tune it. I've even tried E85 with water/meth, which helped, but still no where near as knock-free as 100 with water/meth. I'm a bit surprised after all the glowing reviews of E85, though perhaps those reviews were comparing mostly to pump gas? I would have been happy if E85 equaled the 100 water/meth (since it's so much cheaper) but so far it's not even close. Our E85 is probably only E70 at this time of year, so maybe that is part of the issue?

I did switch over to Injector Dynamics injectors at the same time, so that's another variable I'll eliminate to test, but if idle and cruising quality is any indicator, the ID injectors are running smooth as glass, so seems hard to believe they are contributing to the knock issue.

Any similar experiences or thoughts?

pole position

100 octane plus meth is probably close to 110

Most likely you are running E70 now and depending where you live in Kali it is not particular cold which further does not help with E so you are just down on octane

One thing for sure Racegas is more consistent than E85 IMO

refresh951

What timing changes did you make? I get essentially no knock even at 22 psi+

Tom M'Guinn

I suspect its just the way my motor is -- the compression of those Andial/Mahle is way higher than advertised, and even higher after a decking the block and head. It took me a while to find a way to keep the motor together at 20+psi -- less timing, water/meth/, stronger ignition, colder plugs, steam vent, 100ft lbs on racewares, etc. I tried retarding the timing a couple degrees when I saw the knock, which seemed to help a smidge, so I didn't try to advance it further than I originally had it-- seemed suicidal... Tried it richer and leaner (mid 10's to mid 12's), but it didn't help. Adding water/meth helped a bit.

Tom M'Guinn

That's sure how it seems right now...

George D

Injector size? E-85 uses much more fuel than gasoline. I get you know this, but most of the guys using E85 are flowing at least 30% more fuel with higher pressures at the rail. I'm not converting to E85. On 91 fuel I have zero knock counts at 20psi and when I get to the track I only use racing fuel. I keep the boost at 16psi when driving around town. Jeff Dicicco, who now has my old blue 951 with a basic 3.0 is running 23psi with a Snow Performance Meth system with no issues. We re-built that motor here in Tucson, and it's running great.

I'd send Sid (Blown 951) a PM, he likely has keen input.

refresh951

What CR do you think you are running? Multiple knock counts at 12-14 psi does not seem right. At 12-14 psi I cannot make my car knock. E85 has an octane of about 105, runs cooler, and generally wants more timing.

Paulyy

Check the fuel quality. Could be watered down. You can buy testing kits for this.

alxdgr8

What's your fuel system? Could be running out of pump/injectors/fuel line.

Tom M'Guinn

Injector Dynamics 1300cc injectors with 044 pump. Way more than enough for the modest boost levels I've been trying. Watching lambda on wideband -- plenty-o-fuel...

Despite advertising them as 8:1, these pistons cc out to about 8.8:1 with a 2.7 head (maybe the advertised ratio was with some other head, I dunno). That was before skimming the deck and then the head a few times, so probably around 9:1 now. This motor has been this way from the start, so nothing new to me to see knock counts at low boost (and largely why I've started on another motor) I'm just surprised how much better the 100 with water/meth does than E85. I can go over 20psi with very little knock count with the 100 and injection, so was at least expecting something close with the E85 -- but if I have to pull timing and boost to run E85 I'll have to pass I'm afraid.

Maybe I will, though it would be kind of academic since there is only one company selling E85 near me.

Paulyy

Well if your e85 isn't quality, stick to what you originally had.

having 1 e85 station isn't so great IMO. because technically you cannot go more than 300 miles from that station unless there's another one near by.

Tom M'Guinn

I suspect the E85 is ok, it's just not as knock resistant as the 100 with injection. I know at least one other in the area running 20+psi on the same E85 (although he doesn't monitor for knock and just blew a head gasket, so maybe the jury's still out). There are a handful of stations in my area now, which is why I thought I'd give it a whirl, but they are all the same company selling fuel from the same source.

refresh951

What plugs? What gap?

Tom M'Guinn

BPR7ES .26 MSD 6A with HVC-II coil.

refresh951

I did some reading of the Evolution forums and several guys had success reducing the gap (say 0.022") and leaning out a bit (11.8-12).

What is your timing at peak torque?