2.8l stroker for future turbo setup q's

[LJ851]

And S50 pistons will not work for a few reasons. I believe they will be too sunken in. The S50 crank stroke is 86mm I believe, so using it with a 81mm crank and the same length rods, simple math and logic tells me they will be 5mm away from where they should be at TDC.

Not 5mm, 2.5 mm.

[acolella76]

umm... that combo won't work. Have a look at this: http://www.e30tech.com/forum/showthread.php?t=48288

(forgive my cross post to another forum almighty moderators)

Bobbing the counterweights and pistons is something any machine shop can do, and since you will be taking everything to a machine shop anyways, it's not big deal for them.

[Kozworth]

Ok, since I'm still learning I feel that cutting down skirts and such is out of my reach.

I think ill stick with a 2.7 with eta crank, 325I pistons, and s52 rods.. is this going to give me much of an advantage over a regular 2.5 for boosting? I'm now debating since I want nothing too crazy just buying a spare m20 if a 2.7 isn't that much stronger and probably save money

[MR 325]

The easiest way to get to 2.8 using stock internals is M52 crank, 325e 130mm rods, and M20B25 pistons.

Winner!

The crank AND piston skirts will have to be cut down to clear each other though.

[acolella76]

Sorry, I used the stock bore size when calculating displacement. It would be 2.8L.

I get that you want to rebuild it to have a fresh motor to boost, but I think buying custom pistons isn't entirely necessary for a low boost build.

And S50 pistons will not work for a few reasons. I believe they will be too sunken in. The S50 crank stroke is 86mm I believe, so using it with a 81mm crank and the same length rods, simple math and logic tells me they will be 5mm away from where they should be at TDC. Those pistons are also flat topped where the 885 head is made for domed pistons. So if the -5mm didn't drop compression enough the domed head will drop CR even more.

The easiest way to get to 2.8 using stock internals is M52 crank, 325e 130mm rods, and M20B25 pistons.

[Kozworth]

Yea that's right boring it would only affect cr.. not the stroke for displacement.

I would, but I am an auto student and figured best way to learn is doing it yourself. Also, my m20 runs but has nearly 215k on it. If I were to turbo, I would like to put it on a beefy setup. I got some engine bay work to do too, so id rather put a more reliable setup in while the engines out.

Lastly, if I bored why couldn't I use s50 pistons.. they are 86mm and aren't they 'beefier'?

[acolella76]

That is 2.7L not 2.8. The eta crank has an 81mm stroke.

Also, since you will have to use custom pistons for the 86mm bore you can make the compression ratio whatever you want it to be when you order the pistons.

For your power goals, I would just run a stock motor. It's pretty easy to get into the 250whp range with a stock b25 motor and 8psi boost.

[Kozworth]

Hey guys, I have been researching a lot and just want to make sure I'm retaining the info correctly before dropping a ton of money into this build.

I'm looking to make a 2.8l m20 stroker.

I have:
885 head
Ix block gutted
Eta crank
Soon to be s52 rods

I was looking to bore out to 86mm.. so I would be at 2.8l correct?

Not sure if I'm milling this, or what gasket but what would the cr be at approx?

I keep reading that the ix block has a different lubrication system.. will I run into any issues with this? I thought all 2.5 blocks were the same when I got.

I am basically looking to mostly beef up the bottom end a little, so I have a safe engine for a turbo. Will do the head later on. I'm looking for 250 to 300 whp type build.

Ps: I am going to keep this my gen 'stroker q thread' to prevent clogging the thread and for easy help for those looking to build this.

Thank you in advance