e85 and flex fuel

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lumley32
Posts: 2
Joined: Sun Nov 17, 2013 10:27 am

e85 and flex fuel

Post by lumley32 »

ok so a little background, I am running a small capacity high rpm(17 000) NA engine, with a Life racing ECU, we are getting really good power but always looking for more..... (130bhp at the wheels)

the only information i can find seams to be running huge amounts of boost.

I was talking to a customer that is running a supercharged engine and he was saying that E85 might be a good option for us to try. it's my understanding that to get the most out of alcohol you need a high compression ratio, we are over 14-1 already on petrol I am guessing that this should be enough?

I get that I will have to inject about 30% more fuel with e85, we have enough capacity to do that with the system we have now, but I may well be increasing the injector size to get the duty cycle down.

being that E85 has a lower calorific value than petrol I guess any gains come from the fact that you can get more of it in for a clean burn, but will this net more power? i am only looking for small gains in power (5% would be amazing) but putting less heat in the engine would be a really good by-product for us.

is going for the full flex fuel setup worth it or should I just give it a try with some E85 race fuel and see if I get any gains then go for the sensor and the dual maps blending?

what sort of changes in ignition advance should i expect?

anyone got anything to add to my thought process?

stevieturbo
Posts: 898
Joined: Sun Dec 07, 2008 2:04 pm

Re: e85 and flex fuel

Post by stevieturbo »

you're 14.0:1 CR on normal petrol ?

That sounds extremely high, but I know little of bike engines etc.

if the comparison is against race fuel, then potential gains are probably much less even with ethanol.

But with the petrol and 14:1 CR....is the engine knock limited already for the boost level used ? If not, then that might reduce the prospect of big gains. But I've yet to find or hear of anyone using ethanol who doesnt think it's great ( other than potential water issues, injector, filter etc so all of these need to be compatible and possibly checked regularly, especially if it isnt driven often )

If it's a race vehicle, which it sounds like...is it worth the hassle to need to change fuels to run on petrol again ?

Although if it's already well tuned on petrol, then it shouldnt be too difficult to tune for the ethanol on the relevant fuel/spark etc maps which in effect covers the transition if/when you did add a sensor.

lumley32
Posts: 2
Joined: Sun Nov 17, 2013 10:27 am

Re: e85 and flex fuel

Post by lumley32 »

yes Stevie, 13.9 to 1 is standard for this engine, to be fair I haven't measured the engine I am running at the moment, but its higher than standard by a fair amount so 14 to 1 is a good guess.

purely race-based, but long races think 100miles in less than an hour.

we are running shell vpower at the moment. race petrol is allowed, but on the dyno, we don't see much of a gain apart from the constancy of the fuel. basically, I've not seen enough gain to warrant running it all the time! this is sort of what leads me to try E85, my thinking being if race unleaded isn't giving us gains then try something else.

not running a knock sensor, but at full chat anything over 46Degs advance and you lose power on the dyno these engines are very tolerant in that respect. i think its knock related rather than the flame front catching the piston on the way up.

long run we would have to run a sensor, there is one race that the amount of fuel we need to carry the weight would probably negate any gains, so there may well be playing around with the mix to get the fuel economy to power ratio right.

looks like ill be getting a can of it and playing on the dyno!

stevieturbo
Posts: 898
Joined: Sun Dec 07, 2008 2:04 pm

Re: e85 and flex fuel

Post by stevieturbo »

46deg of advance at full load !!! wow.

Surprised on such an engine that a race fuel wouldnt see gains, but it's clearly something way beyond anything I've ever touched.

MReilly
Posts: 24
Joined: Fri Jan 19, 2018 7:05 pm

Re: e85 and flex fuel

Post by MReilly »

Probably worth trying to confirm if it is knock or not that is limiting her on the V-power, as otherwise there's probably not loads in it. What sort of power would be worth it, 5+hp? 10+? Probably better measured in power:weight like you say.

If it isn't knock limited on petrol currently, then perhaps next time you could build something that is, with even more compression to suit the ethanol more?

Ethanol has a good % of Oxygen in it too, so there may be something for you there power wise, be interesting to see.

Last thing I can think for a bit of an ethanol boost would be to have injection outboard of the trumpets if not already, with a nice spraying injector you should see a nice evaporative cooling effect that might help you get a little bit of a density boost in the cylinder come bang time.

Definitely worth a go if you have easy access to the dyno and the time to play. I'd be very interested to hear your results and thoughts afterwards. Enjoy!

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