Go Back  Offshoreonly.com > Technical > General Q & A
max compression on endurance motors with e85, anyone have FIRSTHAND experience? >

max compression on endurance motors with e85, anyone have FIRSTHAND experience?

Notices

max compression on endurance motors with e85, anyone have FIRSTHAND experience?

Thread Tools
 
Old 01-05-2019 | 10:20 AM
  #11  
articfriends's Avatar
Thread Starter
Platinum Member
20 Year Member
Platinum Member
 
Joined: Jun 2004
Posts: 7,317
Likes: 1,037
From: frankenmuth michigan
Default

Originally Posted by hogie roll


You are correct. Most guys running it are drag racers with huge cams to bleed off cylinder pressure, and carburetors which will run cooler. Chris Uratchko claims to have run it as high as 16/1. But with a boat cam, and durability in mind I think you are on the right track that it needs to be much lower.

I suspect that many people run E85 way too lean but it tolerates it. Those might be the guys claiming you can only run 12.5-13 on it, but I’m speculating.

You are in somewhat uncharted territory. But that extra 4% of power per point of compression sure is tempting isn’t it?

If it were me I’d run it on 100LL from an airport with a lead additive. That should get you similar octane, be cost competitive and a 40% better fuel economy. You could also pull all of the timing out of it in a pinch and run on pump piss with out changing your tune.

Are you going to run MEFI?

good luck, keep us posted
Yes, I have transmission customers running a million lbs of boost and insane compression ratios on their e85 drag engines, what they DONT do though is hold it a wot real long. I have heard from many of them that the cooling from the e85 does make lean conditions, high compression etc more forgiving. I dynoed my pontiac 455 on it after tuning it on 93, it had 11.3/11.4 -1 compression but it was already happy on the 93 octane, I also tested 104 unl race gas, we saw about 20 ft lbs of tq above and below the tq peak and around a 10 hp gain at hp peak, after trying more timing, more/less fuel but it wasnt squeezed for max power.
Yes, Im going to use mefi, Im also going to wire a flex fuel sensor in and test it BEFORE building the motors. IF I can make the flex fuel sensor work work properly I'm also going to dyno the 12.8 motor on e85, keep adding 93 to it until I see KR to know how much gas you could actually mix in if you had to. Im thinking high 12's is going to be a safeCR, maybe Ill do the calcs for 13.3 or so w a .040 head gasket and build it that way and if im seeing kr on long hard pull start raising heads to lower cr,
articfriends is offline  
Reply
Old 01-06-2019 | 08:56 AM
  #12  
Registered
 
Joined: Nov 2005
Posts: 4,554
Likes: 3
From: Fredericksburg, Va
Default

Smitty, as you know we have been racing on E85 for over 6 years now, love the stuff, we only use in boosted apps. Its great on boosted apps with its cooling effect, we run 25lbs with on innercooler, without boost would need about 12-1 to make worthwhile. You will burn about 40% more fuel and need to be able to move that much more, so fuel system needs to be capable...call me if you want to go over anything..Rob
ezstriper is offline  
Reply
Old 01-06-2019 | 09:30 AM
  #13  
articfriends's Avatar
Thread Starter
Platinum Member
20 Year Member
Platinum Member
 
Joined: Jun 2004
Posts: 7,317
Likes: 1,037
From: frankenmuth michigan
Default

So valve seat erosion/degradation is a concern too, hate to have all the seats pulled and changed in two sets of new heads, hmmm!
articfriends is offline  
Reply
Old 01-06-2019 | 09:42 AM
  #14  
articfriends's Avatar
Thread Starter
Platinum Member
20 Year Member
Platinum Member
 
Joined: Jun 2004
Posts: 7,317
Likes: 1,037
From: frankenmuth michigan
Default

So as far as using mefi, going to test THAT in near future on mule motor. IAT on 500 efi is filled w zeros there is pw modifyers from top to bottom based on 0 to 5 volt analog reference. Ive also filled them in on builds based off what innovation does on their 500 efi, made pretty much ZERO difference as iat is pretty constant on a boat. So flex fuel convertor puts out a 50 to 150 mhz signal, you can buy a convertor box that changes it to a 5 volt analog output. This can be inputed into iat table and pw modifyer adjusted accordingly. I also bought a IAT extension with both ends on it so i dont have to whack the factory end off to make a connection. So my idea is to install a gm continental sensor on return line as they are only avaliable w a 3/8 oem style tube and its too small to be on supply side. So my plan is to find where straight e-10 analog voltage falls on table at and where e85 signal falls at and scale everything in between . Can do this just cycling fuel pump w motor off. Then pull mule motor w various mixtures and make sure afrs follow. If this works and im pretty sure it will then bump compression on mule motor w piston change and see what happens. Of course fuel pump, lines and injectors will be appropriately sized. Fun stuff!. As far as fuel temp, go, wont be able to compensate for that at all BUT thats really for oem applications where you would be running it in real cold weather!
articfriends is offline  
Reply
Old 01-06-2019 | 10:32 AM
  #15  
Registered
10 Year Member
 
Joined: Oct 2012
Posts: 2,230
Likes: 536
Default

Originally Posted by articfriends
So valve seat erosion/degradation is a concern too, hate to have all the seats pulled and changed in two sets of new heads, hmmm!
I can't speak for a marine engine but having been using e85 in my street car for about 8-9 years, love it. Turboed small block Ford running 15psi-900hp.

My 10 year old engine with 8-10,000 miles did not have any valve seat wear. I do run alcohol lube in every tank of fuel. Alcohol has no/very low lubrication properties. Most don't run lube because there is some gasoline in the mix. For the price of the alcohol lube I think it is a no brainer.

I also run a flex fuel sensor and have my after market ECU adjust the boost, fuel and timing depending on alcohol content.

The flex fuel sensor has a linear output- 0 volts at 0% alcohol and 5 volts and 100% alcohol.

I can tell you its not as simple as just adding say 40% fuel at 85% alcohol, it is not linear. My engine needs less fuel at lower rpms/loads than at higher loads-boost. I would have to check my table but it could be +25-30% at lower loads and 40% at higher loads.

e85 has a much wider "safer" a/f window. My alternator failed about 6 years ago and I didn't realize the voltage was about 10v. I did a pull on the street with 15psi and the a/f was 14:1. I was on it for a bit before I realized what was going on. Engine never skipped a beat or got hurt. I was a true believer of e85 than. If that was on gas I could have hurt a piston or blown the head gasket without a doubt.
underpsi68 is offline  
Reply
Old 01-06-2019 | 03:44 PM
  #16  
GPM
Registered
20 Year Member
 
Joined: Mar 2004
Posts: 2,696
Likes: 93
From: Pa
Default

Originally Posted by underpsi68
I can't speak for a marine engine but having been using e85 in my street car for about 8-9 years, love it. Turboed small block Ford running 15psi-900hp.

My 10 year old engine with 8-10,000 miles did not have any valve seat wear. I do run alcohol lube in every tank of fuel. Alcohol has no/very low lubrication properties. Most don't run lube because there is some gasoline in the mix. For the price of the alcohol lube I think it is a no brainer.

I also run a flex fuel sensor and have my after market ECU adjust the boost, fuel and timing depending on alcohol content.

The flex fuel sensor has a linear output- 0 volts at 0% alcohol and 5 volts and 100% alcohol.

I can tell you its not as simple as just adding say 40% fuel at 85% alcohol, it is not linear. My engine needs less fuel at lower rpms/loads than at higher loads-boost. I would have to check my table but it could be +25-30% at lower loads and 40% at higher loads.

e85 has a much wider "safer" a/f window. My alternator failed about 6 years ago and I didn't realize the voltage was about 10v. I did a pull on the street with 15psi and the a/f was 14:1. I was on it for a bit before I realized what was going on. Engine never skipped a beat or got hurt. I was a true believer of e85 than. If that was on gas I could have hurt a piston or blown the head gasket without a doubt.
I agree, I think the key is running a modern ECU that automatically makes the changes you describe above.
GPM is offline  
Reply
Old 01-06-2019 | 06:21 PM
  #17  
Registered
20 Year Member
 
Joined: Jan 2006
Posts: 3,860
Likes: 793
From: St. Pete Beach, FL
Default

Originally Posted by 14 apache
I think the guy with the 388 skater by me runs his supercharged motors on it he owns western beef. I am planning running 12.5 on 100ll plans are to run e85 if I get stuck some ware. I think the exhaust seats might suffer over time.
Nice. Is it possible to measure octane?
hogie roll is offline  
Reply
Old 01-06-2019 | 06:49 PM
  #18  
14 apache's Avatar
Platinum Member
20 Year Member
Platinum Member
 
Joined: Apr 2005
Posts: 2,150
Likes: 15
From: Northport N.Y.
Default

Originally Posted by hogie roll


Nice. Is it possible to measure octane?
I didn't think so.
14 apache is offline  
Reply
Old 01-07-2019 | 08:35 AM
  #19  
Registered
 
Joined: Apr 2013
Posts: 203
Likes: 0
From: Lake Winnebago
Default

Wonderful fuel......I have a lot of experience with it.

Unfortunately, my experience falls in the turbo/jet boat/drag/street category.

Ive strongly considered it for my large boat....but availability on the water and range reduction deterred me.

The closest thing Ive used it for endurance is I set up a turbo 460 ford tow vehicle (crew cab F350, ZF 5 speed) for a buddy.....twin tanks staged injection....flips over to E85 at about 3 lbs of boost.....normally runs 87 oct on small primary injectors
SS496 is offline  
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.