Low Comp M20 + E85 = ???

[DmcL]

right.. ive posted this on another site as well as thinking about it for a couple of days before that but im considering trying to get my 89 325i running on E85 to determine if theres any performance or money saving benefits.

i understand all the mumbo jumbo about increasing fuelling and a little more ignition advance and have those areas covered but what i want to know is will E85 eat the inside of my petrol tank and the fuel hard lines under the car? from about 1985 on manufacturers were required to make things ethanol friendly but thats only for about 10% ethanol not 85% like im looking at here.. also seems to be 2 trains of thought both seemingly with supporting evidence. one side of the fence has all the "replace the whole fuel system" nazi's and the other side has some people saying it wont actually harm the fuel system with the exception of having to change the fuel filter after about 500 miles due the the ethanol basically cleaning out the fuel system after all those years of running petrol (latter assumes car is newer than 85-86 which mine is).

anyone in the know with running E85 on here? i know its popular with big BHP cars and boosted cars (id like to in future) but not alot of info on "normal" cars running E85..

if anyone wants to sift thru the aforementioned thread about this on another site heres the link:
http://forums.bimmerforums.com/forum/sh ... ?t=1550302

[GeoffBob]

[GeoffBob]

[Gunni]

Also it seems Morrisons is going to stop selling E85.

Then. How much more power did you plan on running?
If it´s not in the 600 + then you don´t really need it.

8.8:1 compression ratio M20 engine can do well above 400 on stock pistons and rods, stock headgasket and ARP studs.

[DmcL]

over here in ireland its Maxol that sells it. apparently its made from a byproduct of a cheese manufacturing process..

i know ill definately be looking into E85 if i ever get around to boosting the car just wasnt sure if there might be any savings to be had running E85 as the car sits now since i have full tuning/mapping capability so i can increase ignition, fuelling, etc, etc.

as for tuning with no knock limit.. thats how it is already even on normal petrol. ive gone high enough to notice power dropping off and had to retard timing back a bit. seems to like runnong between 36-42 degrees of advance in and coming into the mid revs then retards back a bit and then back up to between 34-38 degrees from about 5000rpm onwards.

i was also trying to find if there was any benefits to running E85 in the form of cheaper tax or any sort of government encentive or something along those lines which might help to offset the extra price of running E85 but as i dont really know how much of that extra fuel consumption i could claw back only thru ignition timing and mild breathing mods such as MAF and BBTB its really a shot in the dark asking about it. i presumed there was a reason u dont see tons of E85 converted vehicles on the road and thats probably it..

oh well, still something to look into in future if i ever do manage to stick a turbo on it.

[GeoffBob]

over here in ireland its Maxol that sells it. apparently its made from a byproduct of a cheese manufacturing process..

Personally I think they should leave the ethanol in the cheese. Then I could save on wine, not to mention the fun that could be had making cheese-on-toast under the grill.

as for tuning with no knock limit.. thats how it is already even on normal petrol. ive gone high enough to notice power dropping off and had to retard timing back a bit. seems to like runnong between 36-42 degrees of advance in and coming into the mid revs then retards back a bit and then back up to between 34-38 degrees from about 5000rpm onwards.

That would be due to the fact that you are running a low compression motor. The higher your compression ratio and/or the greater your intake pressure and temperature the greater the likelihood of detonation at increased timing advance.

”¦ but as i dont really know how much of that extra fuel consumption i could claw back only thru ignition timing and mild breathing mods such as MAF and BBTB its really a shot in the dark

Unfortunately, you won’t regain one iota of your lost fuel consumption by adjusting the ignition advance or by fitting any form of breathing mod. To reclaim that lost fuel consumption you absolutely have to take advantage of ethanol’s increased detonation resistance by operating the engine at higher combustion pressures, and thus at higher thermal efficiency. Within a low compression engine, such as yours (running at a dyno verified optimum spark advance) you will see a 40% to 50% reduction in your fuel economy. In other words, you will need to fill your tank almost twice as often! This down to the fact that ethanol has a substantially lower chemical energy density than petroleum distillates. The only way to get the same mechanical energy (at your wheels) out of ethanol (compared to the same volume of petrol) is to play with that process (within the combustion chamber) that determines what percentage of the chemical energy comes out as heat, and what percentage becomes mechanical energy, and that requires that you either go forced induction, or that you raise your compression ratio substantially (as is the case with flexi-fuel cars).

Oh and before I forget, my earlier statement that ethanol has greater energy content per unit mass compared to petrol is rubbish. Ethanol comes a poor second on both the volumetric and mass scales compared to petrol. It’s only redeeming factor is that it combusts at a lower AFR with oxygen. Hence you can burn more of it per unit amount of oxygen.

oh well, still something to look into in future if i ever do manage to stick a turbo on it.

Unless you are dead set on using up a tanker full of free E85, stick with petrol. The advantages of increased thermal efficiency apply equally to petrol as they do to ethanol. The only time you need to consider adding ethanol or methanol to petrol is when your combustion pressures become so high that you NEED ethanol or methanol added for it’s increased resistance to detonation. And as Gunni said, you won’t find that on an M20 until you reach very high power levels.

[Gunni]

People who have switched to E85 have noted that they only require 5-15% more fuel to travel the same distance in motorway driving, despite the fact that the fuel has less energy content. I´m not sure why this is , but that´s how it is. This is on new subarus without compression change.

I would run probably 12.5:1 on a NA engine, maybe even 13:1 .

9:1 on a turbo and whack in a great deal of boost.

[GeoffBob]

People who have switched to E85 have noted that they only require 5-15% more fuel to travel the same distance in motorway driving, despite the fact that the fuel has less energy content. I´m not sure why this is , but that´s how it is. This is on new subarus without compression change.

Most likely because these are either modern high compression engines or turbocharged engines. In other words they are already designed to operate at high thermal effciency. For certain, it would not be possible to achieve such a figure on an 8.8:1 CR M20 engine.

I would run probably 12.5:1 on a NA engine, maybe even 13:1.

Personaly I would go higher, maybe 16:1. But then this engine would be for E100 ethanol only and would not be able to run on petrol if ethanol were unavailable.

[Mikey_Boy]

Hi Folks - Geoff is absolutely correct with his comments and the bottom line is you cannot escape the chemistry that is going on. Ethanol is a great high octane component and is currently used by the oil industry as such to boost octane ratings. Current EN228 standard for gasoline in Europe shows that 5% ethanol is allowed and this is soon to go to 10% with various bio incentives.

Outside octane ratings, ethanol is not so good - it corrodes pipes and tanks, gives seals a really hard time and despite what the threads stay it WILL affect fuel economy and power - calorific value is definitely lower and that's the part you really cannot escape - compared to gasoline, it's really not so good.

For sure, ethanol is great bio-component and is used extensively in Brazil from sugar cane (and has been since the 80's), but as a performance component - I am not so sure.

As Geoff rightly points out, Octane is just 1 part of a good fuel - in Formula 1, Octane isn't important at all as at 18,000rpm+, there isn't really time for detonation to happen - good calorific value and a mix of molecules with single, double and cyclic bonds are far more important to ensure the burn is started, maintained and finished in a short timeframe.

It does work well in turbo applications (Indycar proved that, but METHANOL was used there for bizarre safety reasons I couldn't work out) but you would really need a fully dedicated engined boosted pretty hard to see the rewards - an M20 engine interchangable between gasoline and E85 doesn't make much sense to me, unless you are seeing mega tax breaks.

Cheers,
Mike

[DmcL]

was afraid it might not be suitable on such a low CR. pity the prices arent low enough to make use of it, would be interesting tuning the car to run on E85 but at the current prices it would also be completely pointless

[e301988325i]

was afraid it might not be suitable on such a low CR. pity the prices arent low enough to make use of it, would be interesting tuning the car to run on E85 but at the current prices it would also be completely pointless

How's the LPG (propane) supply over there? Octane of 115 IIRC is highly suitable for turbo's, and here it's 51% the price of petrol, giving my 9.4:1 M20 b25 44petrol mpg equivalent.

Clearly you'd have to fit a multipoint sequential LPG for tha later planned FI setup, but I've no doubt you would be capable of fitting it yourself.

[DmcL]

have thought a little about LPG but not mad on the idea of a piggyback injection system.

[Gunni]

Depending on the injector resistance you can run a standalone on them, and a switch for another map that turns those off and normal ones on.

So when you flip the LPG/PETROL switch the main ones turn off, the map totally changes and the lpg ones turn on. Pretty simple to do.

[petrol_1]

Depending on the injector resistance you can run a standalone on them, and a switch for another map that turns those off and normal ones on.

So when you flip the LPG/PETROL switch the main ones turn off, the map totally changes and the lpg ones turn on. Pretty simple to do.

Gunni
Most sequentical LPG injectors are 3ohms (a few are 1 ohm)
i have found that LPG loves turbos and gained 30 bhp on 1,8 t vag as the knock sensors do nt yrim retard on lpg !

Ant is in the process of doing me mult maps for my 2.7 ,its currenly runing strong with 4 degrees advanced in it on lpg

, but my next motor will be a hi comp one 13, poss 13.5 or more to make the most of 110 octane rating , max i can get away with , but may have to warm up on super unleaded . but am hoping on warm up with excess afr and low load / revs may get away with normal unleaded
I feel LPG has more advantages than E85