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

Anyone actually running E85 in run of the mill twin engine v-hull, not some 10 second at wot v-drive or jet boat. Yes, i know it will have less range, yes i know it attracts moisture and yes i'm fully aware that it varies in content between about 68% and 87% depending on time of year. NOT looking for opinions on weather someone should run it or not, looking for real world experience on a good compression number to build the motors with (540 bbc w efi), I'm thinking 12.8 to 13-1 range accounting for fact it often test closer to 75 or 80% so you need some margin of safety. I'm 95% sure I figured out how to input a flex fuel sensor into a typical mefi efi ecu and will be testing my theory on my dyno in near future before going forward with build. Biggest concern I have is to take advantage of the benefits of the alcohol you need a fair amount of compression, to run that kind of compression you need a appropriate cam. A typical cam for even a 12.8-1 motor is usually so big that hp peak will end up well into the 6500 plus range and dry sumps and 30 or 40 hour valve train life are a little more than I'd like to be doing, thanks in advance for any REAL WORLD experience input, Smitty
I DO have some experience running it in supercharged street engines, have dynoed with it before and a twin turbo jet boat and know how to test its content so its not amateur hour.

No responses yet Smitty... :-( Following.

Personally, I not sure I see the benefit of it in a NA application. But as far as the build goes, i guess I would sort of look at it like it's going to be an engine made to run on C12 or equivalent since it's about the same octane rating as E85.

As far as the sensor goes. A buddy of mine has successfully run a system where he runs 93 octane and methanol separately and it has two tanks, two fuel rails/injectors etc.

Got any questions give me a buzz!

I know Nauti Marine ran alcohol but not sure it was E85. American Ethanol is running E85. Both boosted applications and obviously those mills aren't built for endurance. Otherwise, haven't really seen or heard of any NA applications in pleasure/poker run boats. Hopefully someone chimes in. Otherwise, maybe lean on those doing it for more extreme use and get their thoughts on your intended application?

The Factory Billet boat , 51 Outerlimits, twin turbo engines run on E85. They run sensors in the fuel system that monitor water content in the fuel. You can mix fuels, E85, 116 , 93 octane and the computer will adjust. Mike Faucher is the engine builder who would have the answers you are looking for.
https://speedonthewater.com/boat-res...-billet-bullet
https://speedonthewater.com/new-boat...inter-progress

The only thing I've seen after running E85 in the boat for 6 years now is some valve seat wear. I don't know why you would need a monster cam if you run decent heads.

i dont want a monster cam that peaks at a super high rpm but if you bump compression up enough to utilize the octane content you'll need a pretty narly cam or motor will have pretty extreme cylinder pressure, looking for some input, sure somines done it,Smitty

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.

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My experience with Sprint Car Engines on methanol , we tried up to 17:1 but they were a ***** to fuel correctly . Granted this was mechanical Injection , but we settled in between 12.8 - 14.0
depending on circumstances during a refresh. The nascar stuff runs 12.0 mandated by rules, with fuel very similar to E85 , the valve seats are the biggest problem on those engines.
I would think you could use the cam to your advantage , to build cylinder pressure , and not have to rely on static comp for fuel burn efficiency .
Ive been waiting on the E85 revolution in Marine builds , just because we may not have much choice down the road !

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,

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

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!

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!

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.

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