Yes, another m20 turbo questionaire

[raoke]

Maybe this topic has been beaten a lot, and before you shoot me by saying," go use the search" have no fear, because I have already.

It has been a while too, so many things may have changed with more people getting into this.
Anyway, I would like to know if the m20 turbo should be accomplished by going the 325e route, or 325i route. That is if I plan to just use what the car has and not drop a 325i head on the 325e block.

If I were to that route, I suppose its better to start with the 325i- correct me if I'm wrong..

Also, I believe someone stroked their 325i to 2,7l by introducing an m50 cam? Is that true?
Would this be better, or would the 325e blcok better suit the car?

[Jarvis]

Re: Yes, another m20 turbo questionaire

Also, I believe someone stroked their 325i to 2,7l by introducing an m50 cam? Is that true?

Never heard of doing that. I don't know which cam you'd pick though... M50s have 2, M20s have 1 :? And how do you think you can get 0.2L more with a cam swap???

Making a 2.7i isn't as simple as slapping a 325i head onto a 325e block/bottom end. There's a lot more that goes into it, but I'm sure someone else who'd done it will chime in. Or you can search, since it's been beaten to death.

I vote that you just stick with a stock 325i engine (M20B25) and turbo it. You might want to learn more about these engines, or engines in general, because you go and try to turbocharge them.

[raoke]

I know I may seem to be talking as if I am a guru, but really Im just trying to get out some quick general questions.

Is it much difference to just turbo the m20b25 as to turbo a stroked m20?
Will either enable me to reach a goal of 300hp+ rwhp?

[Brew]

I know I may seem to be talking as if I am a guru, but really Im just trying to get out some quick general questions.

Is it much difference to just turbo the m20b25 as to turbo a stroked m20?
Will either enable me to reach a goal of 300hp+ rwhp?

You could reach 300+whp on either route, but a lower-compression stroker will allow you to run more boost on lower octane fuel with less risk of detonation, and give you some more low-end, off boost power.

As for the M50 cam, I think you are referring to the crankshaft, which can be be put into the M20, although I believe it takes some modifications. I think that most 3.0 stroker m20s use a s50 crank.
No offense, but if you didn't know that a cam doesn't increase displacement, maybe you should rethink building a custom turbo stroker motor.

[Jarvis]

I know I may seem to be talking as if I am a guru, but really Im just trying to get out some quick general questions.

Is it much difference to just turbo the m20b25 as to turbo a stroked m20?
Will either enable me to reach a goal of 300hp+ rwhp?

TCD's stage 2 kit made 290rwhp on their project car. That was 15psi intercooled on an internally stock M20B25 with no tuning. As far as I know, he's had no reliability issues on that car. No real turbo lag either. Just a very quick crescendo to about double the power of a stock engine.
So yes, 300whp is possible on even a stock 2.5L. Todd at TCD said that with good tuning from a piggyback or stand-alone unit, he would expect another 50-60whp.

PM "Matt325is". Be built a 2.8L M20 and then turbo'd it - very impressive power.

About M20 stroking... there's a lot of combinations. You'll find more info than you can read in one sitting by just using the search button. I'm not trying to be an ass, that's just the easiest way.
From what I've read and can remember, the easiest way to make a 2.7i is to start off with a complete "super eta" M20B27 from an '88 528e or 325. It's a normal ETA bottom end and block, but an 'i' head with ETA cam and valve springs. Get the 'i' throttle, intake manifold, exhaust manifold, double valve springs, cam, injectors, and wiring harness - bam, you've got a 2.7i. I think the super eta's had 8.5:1 compression, which would be even better than the 'i's already good-for-boost 8.8:1. I would do that if I could just find a good condition '88 325 super eta to start off with. *Please someone correct me if I'm wrong about any of this.

There's 2.9 and 3.0L kits available, a couple of R3V members have gone the 3.0L route. You probably wouldn't want go that extreme if you're doing FI anyways, since the cylinders walls maybe not be able to reliably handle a lot of boost.

You can't simply bolt an 'i' head onto a normal ETA block. The pistons for the two engines are shaped different and the ETA ones would hit the 'i' valves. You
could use a head spacer to get the needed clearance, but then the engine timing is altered because the timing belt that goes from the camshaft in the head to the crank won't be the ideal length/tension. And there's dispute about the exact compression ratio you'd end up with. It may be way too low, or right at the streetable limit for M20s - which would be a problem if you wanted to boost it.

If you can find them, super eta rods/pistons I think work in a normal ETA block with an 'i' head. Also, early 80s Euro 525e's had 11:1 compression and those pistons can be used for making a well built M20 stroker. Good luck finding them though. Many members here have tried without any luck. Or if you want to shell out the cash, get custom pistons. That would probably be the best method, as you would be able to pick your exact compression ratio, you'd be able to buy stronger than stock internals, and you wouldn't have to worry about the reliability of used parts.
I still think a stock M20 w/ boost would be the best choice. You could easily spend $10K building a turbo M20 that's also stroked... if you want to do it right and have reliable 300+whp.

[raoke]

As for the M50 cam, I think you are referring to the crankshaft, which can be be put into the M20, although I believe it takes some modifications. I think that most 3.0 stroker m20s use a s50 crank.
No offense, but if you didn't know that a cam doesn't increase displacement, maybe you should rethink building a custom turbo stroker motor.

I was trying to cover my ignorance, but I fouled out. I really dont know much about cars except what I would want to make. I just hope with an ambition I can learn as I move along, so sorry for that dumbass question.

Cost is an issue, but if the output and overall performance/maintainence is extremely unmatched with the stroked turbo, I would rather shoot for that vice the stock 325i turbo.

As for initially starting off, you say a 325e is the choice for you?
My concern is the rev limit on the 325e.

Yet again if you say an e30 w/ stock internals can hit 290 w/o tuning then thats quite an accomplishment so far. And because of that, I wouldnt see why one would need to really put down a few grand for a stroker.

[Brew]

Nah, I would start with an "i" motor or build a stroker as Jarvis suggested.
Don't apologize for the questions, we all asked them at some point. The point I was trying to make was that a custom turbo setup is not a weekend project. It will takes months of planning, part gathering, and fabrication. That is, unless you get a kit from TCD or something similar.

[Matto]

I don't think you will be getting 300 rwhp out of a stroked m20, probably not much over 200.

[Matt86es]

I think that was turboing a stroked M20

[StereoInstaller1]

I just gotta say this, please dont think anything other that I am trying to help, OK?


READ A FUCKING BOOK!!!!!

Go get hugh McInnes's wonderful 1979 classic "Turbocharging", then find Cork Bells' excellent "Maximum Boost". Give up on reading the heavy tech crap till you have read the basic text of both, then go find the 1912 book that both of these books refer to, something like "Principles of Turbocharging Thermodynamics"...you will then have read all 3 books written on the subject.

Since 1985, I have owned turbo cars. My current is a 1986 Sunbird, custom ECU, custom turbo, custom intercooler, fuel system, etc. Quaife LSD and Muncie trans too. Ran out of speedo in 3rd, hauled ass up the grapevine at about 130 MPH in August 1999....I get about 10,000 miles out of a crank (yes, forged) and break everything else under the hood. Car has sat for 4 years now, gonna sit more.

Call Electromotive, get yerself a TECII or III. Call JE pistons, order a set. Get busy with a dremel, make a copper headgasket, have your head o-ringed. 300RWHP? No problemo...
Luke