E85 pros and cons. Stock ST185

PhantomGT4

New member
ok ladies and gents,

i just picked myself up a beautiful 90 ST185. Currently from research ive done, ive seen that i can raise boost numbers up to about 15psi with no issues. Im now curious to those of you who run/have run E85 on the stock engine. Can the fuel system hold up to it? Can the 440cc injectors handle it without crazy high duty cycles? what percentage can be run safely for a power boost?

ive been a long time Celica fan. had a 91 GTS widebody that i had a ton of fun with. But finally, MY birthday, And Christmas miracle has arrived. My ST185.
 

Toyota1968

New member
Looked at this quickly a number of years ago .. Fri.memory you would need a programmable ecu and probably Uprated fuel pump, lines and injectors.... All due to high fuel demand..... On the plus side though serious power gains possible....
 

PhantomGT4

New member
As for the Programmable ECU, is there any software out there for doing that to ST185 ECU? Or will I have to shell out the big bucks for an aftermarket ECU? also, since idk, can a OBDII harness and ECU be put onto the ST185 engine?
 

PhantomGT4

New member
So no matter what im stuck spending up to $3000 for an ECU? That really sucks the big one. Why cant an OBDII system be installed so tuning can be done easily?
 

MWP

New member
PhantomGT4":wzy93ree said:
Why cant an OBDII system be installed so tuning can be done easily?

Because it cant.
There are a few reasons, and im too lazy to type them out at the moment :p
Cheapest way out would be a Megasquirt Plug & Play module, new injectors, rail and fuel pump.

Anyway, the above suggestion that there would be "big gains" is completely wrong with an otherwise factory setup.
You'll gain a bit of mid range torque due to advanced timing, but you'll gain very little top end power as the turbo will be the limiting factor (be it on unleaded, or e85).
Install a new turbo as well, then you'll be able to push on a bit, but then the factory pistons will likely fail next.

So basically, you only consider e85 when doing a full forged engine build, or if you have a forged engine already.
Its a waste of $$s otherwise.
 

PhantomGT4

New member
I Was just looking into MS stuff, seems to be pretty nice. I am not a wiring fan by any means but looks like they have sets that are plug and play that will work for very cheap in comparison to others.

My overall plans for the car over the next few years, is to hit about 450awhp. I do understand that will take a lot of time and money. but its VERY doable... I have seen a ~900awhp St185 using the 3sgte. So me looking for half that power shouldnt be too much of a pain. Just have to take it one step at a time.
 
Myths abound on this subject.
All fuel has ethanol in it already so your fuel system is fine in my experience.

What I did was get 540cc drop ins from Gen3 MR2 or ST205 engine they run about 100-125 for a used set, ran a dual feed rail by making both ends feed and doing a center return where the cold start injector used to hook in. The stock Gen2 rail shows a bad pressure drop tendency with 540 and a single feed. Many call for boring out the rail as well but I skipped that and it worked great for me. You can buy earls fittings and "ethanol compatible" braided hose for this. I put in a supra TT fuel pump which is drop in and costs about 180.

I also converted to GEN3 MR2 ecu (they run about 150-200) and used the MAPECU in place of the MAP sensor because it has its own and it works by simulating your MAP sensor signal anyways so saved myself from buying a gen3 MAP sensor, but this may not really be needed. You only have to repin a few wires at the ecu to swap from gen2 to gen 3. I ran like that for quite a while. I also figured out a sweet little trick by moving the dowel on the exhaust cam and skipping a tooth on the timing belt to slightly retard the exhaust cam simulating a Gen3 exhaust cam, that increased the power as well. I also ran a base timing of 11BTDC instead of 10BTDC you might get away with more but that was all I was willing to do.

I bought a piggyback for adjusting fuel but I never really needed to at 17psi its called MAPECU (I would sell it for only 100) it only does fuel, but it has lots of datalogging and wideband support and stuff. It can also allow you to switch from regular gas to e-85 by just loading a different map.

There are cheaper ways to go about it than full stand alone and complete fuel system overhaul tank to injectors like most think is necessary. The fueling difference between e-85 and gasoline is that you need aprox 20% more fuel to maintain safe AFR so by going from 440 to 540 you cover that easily. Plus its a lot higher octane so less chance of detonation at the same boost levels.

It definitely is a big performance boost. I would run gas and then go fill up with e-85 and you can feel a big difference. I also bought an Innovate wideband O2 sensor that I never used because everything ran so well. The only reason I am not still running it is the price shot up thanks to the filthy Nazi government taxing it into the same price range as gas. I took that block and swapped a 215 head onto it and put it into a different car and then another car. Still runs great.
Keep in mind your mileage will go down significantly per gallon compared to gas.
Hope this info helps you. Most people that post about this have never actually run e-85 they just repeat what they hear.
 

PhantomGT4

New member
Dude you have tons of info and great ideas. Thank you.
I asked this because my brother runs full E85 in his WRX. just from having E85 and a tune for it, he gained 53hp. That's the cheapest power boost out there.

When you skipped the tooth for the exhaust cam, was that forward or backwards?
 
It is in order to retard it. I forgot the calculations but you also have to move the dowel to one of the other 2 spots that are there for minor timing adjustments on gen 2 engines, and skip the belt also otherwise it will retard it too far. So the dowel movement advanced it like 1.8 degrees or something and then you retarded it by a tooth, if that makes sense? I might be able to find the thread I am not sure if it was on here or Celicatech. So you move the dowel and skip the tooth and it mimics a gen 3 exhaust cam which is exactly the same in lift and duration just slightly retarded.
Another great budget upgrade is the CT20B turbo, it is direct bolt on. I did that also and its a lot better up top.

Happy to help! I also did a coil on plug upgrade that probably didn't increase power but removes some wires and junk when you do tune ups, its a NoddE kit from a guy on MR2OC. No more wires and rotor and cap to replace just your plugs. Pretty cheap too. Obviously the Ebay 3 inch exhaust for like 250 is another good upgrade. And if you swap to the gen3 ecu you can ditch that AFM and run straight 3 or 4 inch filter. Just some more ideas!
 

PhantomGT4

New member
When doing the gen3 ECU swap you said it just a couple pin crossover. I'll have to find the diagram for that. I hate afm and they all need to die. MAP is the way to go. I'll have to talk to you more so I can get this all done. But, I don't want just top end power... I like to be thrown into the chair during mid range revving. That's where I get most of my joy.
 
I have been running e85 on all 3 of my cars for over 6 years and I can not ever think of going back to pump gas.

With that said in the early years there was not many pumps in my area. Now there's three near me range from 10-28 miles away. If this is something you can handle by all means don't look back. It's a poor man race fuel.

The initial upgrade will be pricy larger fuel system and And an ems. But that's just the beginning. I say go large so you won't have to upgrade twice.

Hope this helps.
 

PhantomGT4

New member
Yes i planned on going large, not just going to get XXXXcc injectors that will work for now. was going to jump straight into 1000cc+ injectors so i can add more power over time and not need to worry about getting bigger ones time and time again.
 

Toyota1968

New member
You need to start with a good programmable ecu.... Will allow you to actually use all the other mods you have planned.... Have you thought about your budget for such big ambitions ?
 

PhantomGT4

New member
The plan so far is to just crank up the stock engine a bit, nothing too crazy. Then find a 3s block and head, build it from the ground up over the next "x" amount of time. With the E85 question, I was just curious if there was a way i could tune or flash the stock OBD1 ECU so i could run a small mix. I will be running full E85 after i have built the enging that i plan to drop into it. A beautiful 2.2l stroker will be tons of fun.
 

MWP

New member
I don't normally like to beat on what another member says, but CTechBlueDragon, that is dodgy to the extreme.
What you have done, or are recommending is exactly how you shouldn't go about running E85... or doing anything with engine tuning in general.
PhantomGT4 i very much recommend you ignore everything he has said.
 
Your welcome to your opinion but that is all it is. I have actually done it and it worked wonderfully. I never said there wasn't a better way to go about it. I just told him the cheap and effective way I found of running it and shared my results. Like I said earlier in the thread, many want to chime in never having done it themselves. If you have an experience and method you would like to share go ahead, but don't knock a proven result with just your opinion.
Have you run e-85? What worked for you?
 

MWP

New member
Cheap yes, effective sure... until you crack a piston, split the block, etc.
E85 isn't to be toyed with. Yes you can push an engine further on it, but only if you know what you are doing, and what the tune is doing.
Get it wrong, and you won't know it until it bites back hard and you're up for an engine rebuild.

Basically E85 does not pre-detonate (ping).
You can lean the engine out and run massive amount of advance, and it'll all look sweet, but the high temps and cyl pressures will break things with no warning.
 
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