Stock "high" Compression + Boost + E85 =?

Hey, experts. I drive a 96 Roadmaster wagon that is pretty mild so far with just custom, paint, nice exhaust, TT2's, slammed suspension, tint, etc. I ran across an old Paxton SN2000 last spring for a price I couldn't turn down. The plan was to save the coin and build an all-forged shortblock with dished pistons to bring compression down and then put the blower on. That would be great but its going to be a long long time before I have the cash. On a hunch a couple weeks ago I checked E85 availability around here and its actually real good. I was wondering if you guys think a stock 133k mile LT1 shortblock with original hypereutectic pistons has a chance against 8-10lbs of boost on 105 octane E85. The car will be dyno tuned and get supporting mods such as a big fuel pump or two and some monster injectors. I'm also planning on getting my hands on some Aluminum F-body heads with appropriate springs, roller rockers, and a "kind of obnoxious but still drivable" cam. Your thoughts?

I dont think it will last to long even at 8lbs boost, But im not the LT1 superstar lol. Most guys say 7-8psi and it is still on borrowed time.

Jay

Jay, If I understand correctly its not boost that pops motors but detonation. The fact that boosted engines have a much higher propensity to knock is the issue. I am wondering if E85's resistance to detonation will allow me to run knock-free.

I'll let you guys know how it works in a couple weeks. I'm running a stock 96 LT1 at 8lbs of boost so far taking out 1 degree of timing per lb of boost and I have no spark knock or retard so far. I would make sure you have enough fuel (I'm using 2 in tanks and 60lb injectors) and I think you will be fine. I'll be bumping mine up to 12 lbs as I dial the tune in and I'll let you know when she comes apart. I'm running the 2bar setup on the factory computer and now that I have enough fuel it's like using one of the standalone systems....REALLY easy to tune and she runs like a dream.

You will need alum. heads. A lopey cam will help blow some of the boost into the exhaust and reduce cylinder pressures.

If you keep the charge air cool, the cylinder temps down with a nice cooling system, and it tuned rich (like 7:1 with E85), it should work, but will be on borrowed time. I drove around for 6 months with 8 pounds on my 90K bottom end until my blower let go. I have a FMIC, PCMforless tune, AFR heads (slightly lower comp), Electric WP and the LT4 hot cam.

I will be swapping my setup to a single turbo within the month and I hope for another 8 months from my bottom end.

Hmmm....I'm using my wideband that is still set for Gas and at W.O.T. when I get below 10.5 on there it seems to be way too rich and at about 10.9 to 11.0 it feels and sounds much better. I'm betting the E85 will let us get away with more than most people think because before I figured out my fuel pressure was dropping like a rock I have some data logs that put me at 8 lbs of boost and 14.0 on the A.F.R and not a bit of spark knock or retard. Try that with 93 octane and you would be walking home. I've also been running the cruise ratio around 15.3 and it runs great with not that big a loss in fuel mileage compared to gas.

Oh and I do have a large front mount intercooler so my I.A.T.'s stay under 98 deg. unless it get's really heat soaked.

i have a 100k stock bottom end and heads and cam twin turbo 5psi of boost uping boost to 10lbs today.. 10:8:1 comp ratio not one bit of knock gotta love that alky injection.

I am thinking about running an air to water intercooler just because it will be easy to package in my application. I would like to have a heat exchanger in the front as well as a reservoir in the back of the car all plumbed in series so I can put ice in it for track blasts.

Just to clarify, FL-LT1, are you burning E85 or gasoline? You mention alky injection, are you injecting water/meth too? How many miles have you run so far on this setup?

Hmmm....I'm using my wideband that is still set for Gas and at W.O.T. when I get below 10.5 on there it seems to be way too rich and at about 10.9 to 11.0 it feels and sounds much better. I'm betting the E85 will let us get away with more than most people think because before I figured out my fuel pressure was dropping like a rock I have some data logs that put me at 8 lbs of boost and 14.0 on the A.F.R and not a bit of spark knock or retard. Try that with 93 octane and you would be walking home. I've also been running the cruise ratio around 15.3 and it runs great with not that big a loss in fuel mileage compared to gas.

Oh and I do have a large front mount intercooler so my I.A.T.'s stay under 98 deg. unless it get's really heat soaked.

You are using E85? An AFR of 15.3 is a perfect cruise ratio for regular gas. Power potential of E85 is nonexistant unless you are 30 - 40% richer compared to regular 93 octane gas. (most people aim between 8.5:1 and 7:1 under WOT for E85)

Here's GM's flex fuel chart. It's some decent info if you're curious on stoich Vs the percentage of ethanol.

http://www.ls1tech.com/forums/attachment.php?attachmentid=141058&d=1216840105

You are using E85? An AFR of 15.3 is a perfect cruise ratio for regular gas. Power potential of E85 is nonexistant unless you are 30 - 40% richer compared to regular 93 octane gas. (most people aim between 8.5:1 and 7:1 under WOT for E85)


Yup E85 and 15.3 works pretty darn good for cruise where I'm really not interested in making more power than gas. Now when in boost I do run richer than I do for Gas BUT if I went to 7:1 I'm thinking I would be pouring fuel out the tailpipe. Remember I'm still using the wideband set for Gas. If I set the wideband for E85 I would be looking at a much richer mixture but I am so used to looking at the gas settings that I much prefer to see it that way.

With my wideband set for gas running e85 I shoot for 12.0 WOT.

I think the 7:1 being talked about is with the wideband calibrated to e85

this is on pump 93 octane not e85 and with alky injection pure meth. i have close to 12 months with this setup bout 15 passes down the track 4 dyno pulls and about 1000 miles car is only used on the weekends.