New Project...another stroker but different internal design.

[modifiede30]

Well, I just purchased another eta crank, and since I have my old 325i engine, I think I might make another stroker, but do it a little differently to see what happens. I'm thinking I might use the 325i rods and pistons (or eta rods), whichever work with the 325i pistons. I know this won't work without some machining of the pistons. Anyone familiar with the specs on what needs to be machined off the tops? I'm also wondering if the piston pins can be moved down an appropriate length rather than have the tops machined. When the other machine work was done, the guy told me he could move the location of the piston within the rod when he pressed in new bushing for the piston pin. I'm assuming the same could be done here, and possibly lighten then at the same time. I'm also interested in have the crank "knifed". I've read about this but never seen it. Sounds like they just reshape the leading edge of the crank so that when it hits the oil, it slices through easier than a blunt object (current shape of the crank).

Opinions?

[E30godz]

im not sure what the benefit of moving the pin location is over shaving the piston tops a couple mm's.

[M-technik-3]

im not sure what the benefit of moving the pin location is over shaving the piston tops a couple mm's.

Wants to retain BMW pistons cumbustion chamber design, with iS head and a stroker crank. Not possible with is rods and crank.

[E30godz]

whats the design of "i" piston tops?

[M-technik-3]

differant than e pistons.

[modifiede30]

The 'i' pistons have a concaved-dome top, with the dome positioned to maximize the energy of the combustion once it fires. The eta pistons are basically flat. If I shave the pistons 3mm, I'd loose some of the engineering that went into the shape. If I move the pins the same distance down, I'd acheive the same thing without screwing up the designs. Guess I'd have to use eta rods though, but that's not a big deal.

[ma7008o]

A solution is to use non 325i rods but any of the other stroter ones and reduce the block high by 2 mm.

[modifiede30]

I did that on my current stroker, but would prefer to keep block specs in tact this time.

[rs4pro3]

Do what I was going to do with the Euro 325e pistons, even the standard Euro 325e pistons have a higher cr ratio then u.s pistons so you'll still have a decent compression ratio. Or you can go with the pre 5/85 525e 11:1 cr ratio pistons but they are very hard to come by.

[modifiede30]

Can't get my hands on the Euro pistons so I'm going to do something that I know I won't get frustrated with.

[rs4pro3]

I'd shave the pistons then, when you measure off 3mm you really don't alter the shape of the piston any, all your doing is shaving off that one ridge.

[M-technik-3]

If mine didn't get scuffed up by my daughter I would have gladly sold those. can't tell you if I can find more.

[ma7008o]

modifiede30: I am planning on taking 2 mm off the block as I think it is the easier and cheapest way to go. What results did you get? Why you do not what to do it again?

[modifiede30]

The results are good, but I have the parts to build another one and want to go a different route to see which is better. I know shaving the pistons will produce greater compression so I'm betting its going to be a better stroker.

[trent]

Why not be a man and build a real motor? Fuck those heavy ass factory pistons. Pony up the money for a set of custom JEs or something similar and run the longer "i" rods. Or, be a real muthafuckin man, and have a custom set of longer than "i" Pauter rods to go along with the JE piston set.

The difference in smoothness and revability in doing just pistons is amazing.