TO EVERYONE that is making or has made a stroker.

[nando]

I'm never going to turbo this motor, so no worries about cylinder walls - my main reason was the superior piston design, and a bit extra displacement. it ends up being 2823 CC's or 172 C.I. (85 mm would give me 2758 CC's or 168 C.I.).

here's a pretty decent displacement calculator I found:

http://home.earthlink.net/~jalby/puter.htm

[ColdAccord]

i got 10.2:1 comp pistons, stock bore.

2.7 crank w/2.5 rods

should go together in a few weeks, so as I get a cam.

i would be happy with 100k, but I plan on keeping my touring my whole life, and don't see myself putting more than 30-40k on it in that lifetime

[DrMcDave]

what is superior about the piston design that couldn't be duplicated into an 85 mm bore piston?

I'm never going to turbo this motor, so no worries about cylinder walls - my main reason was the superior piston design, and a bit extra displacement. it ends up being 2823 CC's or 172 C.I. (85 mm would give me 2758 CC's or 168 C.I.).

here's a pretty decent displacement calculator I found:

http://home.earthlink.net/~jalby/puter.htm

[nando]

high sillicone content is the biggest part, this allows for a much tighter piston to wall clearance. if you call jim I'm sure he'd be happy to explain to you the differences ;)

[DrMcDave]

high sillicone content is the biggest part, this allows for a much tighter piston to wall clearance. if you call jim I'm sure he'd be happy to explain to you the differences ;)

i've already spoken w/ jim extensively on a few occasions. Usually he overwhelmes me w/ information. I hope you get this done soon as i hope to be right on your heels. start w/ a stroker and go from there. I do want pistons from MM. Jim persuaded me a long time ago.

btw i told you the rings were more. i guess you need his head gasket as well for the 86mm bore.

[e30 gangsta]

Ight Stupid question. I have seta crank rods and pistons. I will be using seta crank and pistons. Do i use the I or E rods?

[Sean]

Ight Stupid question. I have seta crank rods and pistons. I will be using seta crank and pistons. Do i use the I or E rods?

I rods will knock the pistons into the head - so you have to use Eta rods.

That would essentially be what I was planning on doing.



This thread has been quite interesting to read.

Yes, 100k is a pretty long life. Yea, I probably won't put that many miles on it in the 3-4 years I have left in college, and I realize that. No, I never plan on selling this car.

Lets be honest - why would I bother? I'd lose so much money if I did. If I get into some money trouble, this car will be the last to go - it has too much time, and energy invested in it. Not to mention, I'd love to have it still when I HAVE a career and a house and a nice job - then I can pour even more into it. Even though, by then, I'd like to have an E30 M3 to play with.

But, I've been thinking a lot about it.

I've also thought about the fact that people push turbos thru the SuperEta stroker bottom ends, that dawned on me too.

I just really like the idea of doing this right the first time. After thinking about all this, the whole rod/stroke ratio - I just don't like the idea of doing it. The block and pistons and rods have a lot of use on them - over 221,000 miles. Yea, they are probably all strong still - but why not slap down the extra cash and do this right the first time?

By what was said above, if I got MM 2.9i pistons, I would never be able to boost - not even with a thicker head gasket? If I ever did boost, I'd never go more than 7-8 lbs. Is 86mm bore too much to ever think about boost?

I think i'd really like to go the piston route. I like the idea of doing this right the first time. Not to mention, I'd put it together, and have a real torquey motor, then I could do headwork and put out a massive amount or more power - it would be so awesome! :D

So, who wants to donate to my engine rebuild fund??

[nando]

i've already spoken w/ jim extensively on a few occasions. Usually he overwhelmes me w/ information. I hope you get this done soon as i hope to be right on your heels. start w/ a stroker and go from there. I do want pistons from MM. Jim persuaded me a long time ago.

btw i told you the rings were more. i guess you need his head gasket as well for the 86mm bore.

he didn't say I needed the gasket.. actually I think they just modify a stock one, but all they do is make the water jacket holes bigger.

[DrMcDave]

cool man what kind of hp are you expecting?

[nando]

would be nice to hit 200+ at the crank... but I'm really looking for more torque/midrange. when I get a piggyback I'll hit up a dyno and get it tuned properly.

[EtaSport]

My car runs better than ever in its current state. Of course its basically a high revving eta with a little bit larger ports to help make higher rpm horsepower. Ive got at least 400,000 miles on my motor. It revs to 6500 rpm. I believe in this set-up pretty well. However it is getting replaced by a 2.5 for a short time while I rebuild the 2.7 in time for fall and another, more powerful 'OEM plus' set-up.

[nando]

My car runs better than ever in its current state. Of course its basically a high revving eta with a little bit larger ports to help make higher rpm horsepower. Ive got at least 400,000 miles on my motor. It revs to 6500 rpm. I believe in this set-up pretty well. However it is getting replaced by a 2.5 for a short time while I rebuild the 2.7 in time for fall and another, more powerful 'OEM plus' set-up.

yeah I'm not sure what to think about it, when sean posted that I immediately thought of your motor. I still wouldn't want to do a stroker using heavy stock internals though, but that's just my preference.

[SA E30]

I recently learned of some new information that I didn't know before, or quite understand, anyway.

This piece of information is that the BUDGET SuperEta stroker will not lost very long, driven like a BMW is normally driven - hard. For some reason, I thought a rebuilt motor, doing a budget stroker type build, would last just as long as a normal M20 motor. (yea, call me stupid)

The reason for this is the shorter rods. The shorter rods cause a lot more strain on the engine, at the same time, the heavier weight causes a lot of banging around inside the cylinders. These shorter rods are not made to rev high, that's why the I's have longer rods, they are better for revving higher.

The question I have for all of you that build strokers - has longevity ever been a deciding factor for you? From what I read, on Metric mechanic and talking to Jim Rowe, a SuperEta budget stroker, driven hard, will only last to 100,000 miles max. That doesn't seem like a whole lot in relation to what a stock motor will go to.

Am I being anal thinking about this now that my engine is apart, or not?

How long have these engines lasted for other people? What combinations have been done to increase the power, without sacraficing life?

I know forcing more power out of a motor can decrease it's life - but when there's ways to get more power, and still have a long life - why not go that route?

I don't think I can afford the Metric mechanic pistons and rings, at $1300 for the whole deal. These pistons, paired with I rods will last as long as a normal m20, up to 200,000 miles driven hard.

I kind of want to get other people's opinions on my build. If I decide to get brand new pistons, I'll have to let my car sit a while, since I need some cash flow first. OR, I can just put it together with a honed block, possibly a decked block, and the old SuperEta pistons and just go for shit.

Essentially, it comes down to this. Should I wait, spend the money on the more expensive pistons, get more power and more life from my motor (and stick to N/A) or should I cheap out, use the pistons I ahve now, pray that it lasts at least 70,000 miles and possibly do a turbo later in its life which will only decrease it's life more?

And with that, i ask your opinions as well as what you've done. With that, how long have you had it, and how much longer do you plan to have it running?

Discuss. :)

It all depends on the rod ratio... if the rod ratio is correct for the stroke of the motor... then there is no reason why the rods should have any issues... and any motor that is modified is going 2 have a shorter life span, especially if ur trying 2 squeeze more power out of the motor.

[SA E30]

81mm eta crank, S50 rods, 86mm bore. the head has some mild port work and a shrick 284/272 cam. will have rebuilt 19lb injectors, and an AFPR. the rest will be stock for now. ;)

as far as R/S ratios, yes any stroker will decrease the ratio, but the ETA rods are especially unfavorable because they are even shorter. that is one of the main reasons I decided against the 84mm crank.

It's easy 2 get a favourable rod ratio with an 84mm throw crank... So long as u use the right conrods... otherwise known as M40B18 Rods, which measure in at 138mm (which gives a rod ratio of, 1.64) even a std 325i Rod will give a favourable rod ratio (1.6) ... I know what is gonna be said about the pistons, but if using a S50B30E piston, the tops can be cut down, and with the M40 rod, it will be cut 2 a complete flat top piston. and with the M20 325i rod, it will have about a 2mm dish in the piston.

[EtaSport]

Thing about my motor is that it was really an experiment. Since I didnt get much feedback on it and didnt know what to expect, for the cost it was worth it to find out. I really dont consider it a performance motor by any means, as it doesnt have much willingness to rev because of all the heavy components, flywheel, and 2,93. But it is really nice in town, and great on the highway. The powerband comes on from about 1500-3000, then picks up around 4k before it pretty much falls off over 6000. The main goal was with about 500 bucks to get it to run with an iS which it does. Sooner or later, I'd like to build something something lightweight and throw boost on it. I want to have one e30 with an m20, and one with a 24v motor.