which pistons?

[cheetah993]

I have the 2.7"i" that I have made. My engine has all of the i accessories on it. But I want more. I wanted to know what pistons to get to make it a 3.0 instead of the 2.7. I also want to get a 284 cam for it as well. It even has the 3.73 LSD in it instead of the 2.93 which is nice. I was contemplating a 6 speed instead of the 5, but I am gonna finish the engine first. Any ideas? Thanks also no one has been able to answer me, but about how much hp does the engine have from being the super eta engine which mine is, to the 2.7i, how much hp does the 2.7i have? how much should I expect out of the 3.0 with the 284? Thanks for any input.

[jlevie]

Just changing pistons won't turn that engine into one with 3l displacement. The block would have to be bored out and I think you'd have to change the crank and rods.

[nando]

you need an 86mm crank and pistons at minimum to reach 3 liters on an M20.

with motronic I'd expect it to be about 200-210 at the crank with a broad torque curve (284 is good for that). With standalone and a tune you'll make more.

2.7i is usually 150-160whp

[cheetah993]

Maybe I was confusing, and now Im kind of confused. I realize I have to bore the engine, thats kind of how you get displacement is a bigger piston, which of course you need to bore it out to a bigger size to seat the piston. This may be a stupid question and sorry in advance for asking it, but why do I need a new crankshaft? why can't I use the 2.7l one I have? If you get the piston arms made to fit the original, it will still push them up and down, right? I mean 86mm isnt much bigger then o.e. Any idea on where to buy these pistons? I have looked, and cannot find it.

[nando]

because you can't make the bore size big enough to get to 3 liters by itself. Common sizes are 85 and 86mm, you can go up to 87mm but you're really pushing the limits and it still won't reach 3 liters.

So that means you have to increase the stroke, and you can go all the way up to 89.6mm (from 75mm on a 2.5).

[cheetah993]

ah yes that would make sense. Now another question, where would I go about getting these pistons and crank? I have the car in a buddys paint shop he is redoing the body and paint, and I have the engine, so I am trying to get it done this winter and I figure this is a good headstart.

[884door]

It would be much cheaper to swap an s52 into the car.

[lennon]

It would be much cheaper to swap an s52 into the car.

thats a very vague statement, too vague to be wrong or right. OP- SEARCH. how many threads about stroked m20s are there??

[DSP74]

[quote=nando;1681649 you can go up to 87mm but you're really pushing the limits
[/quote]

Really?

Who has, or where did you hear that?
What head gasket would we use?

not saying your not right, just wondering, as I would take it all the way to 87mm if it were safe

[nando]

Really?

Who has, or where did you hear that?
What head gasket would we use?

not saying your not right, just wondering, as I would take it all the way to 87mm if it were safe

Jim at MM used to on race engines. he probably still would but I don't really see a reason to push it that far.

I'd think the stock headgasket would work, but I'm not sure. it works fine for 86mm pistons though.

[884door]

thats a very vague statement, too vague to be wrong or right. OP- SEARCH. how many threads about stroked m20s are there??

It was kinda vague I guess.

My point was for the cost of properly building a 3.0 liter m20 and tuning it correctly you could buy and swap in an s5x engine and save yourself some time and work in the process. I suppose the m20 could be cheaper if you REALLY know what you're doing and plan to do ALL of the work yourself including the machining (or you know someone that will do it for dirt cheap).

[nando]

It was kinda vague I guess.

My point was for the cost of properly building a 3.0 liter m20 and tuning it correctly you could buy and swap in an s5x engine and save yourself some time and work in the process. I suppose the m20 could be cheaper if you REALLY know what you're doing and plan to do ALL of the work yourself including the machining (or you know someone that will do it for dirt cheap).

wow you are a genious, I've never heard anyone bring up that argument before!

:roll:

[884door]

wow you are a genious, I've never heard anyone bring up that argument before!

:roll:

Excuse me for elaborating on a previous statement after it was called vague.:roll:

If the OP couldn't search to find all this info thats been covered before he probably hasn't heard the s5x vs. m20 stroker argument. I was just stating an alternate idea.

[Danny]

Brand new rebuilt M20 stroker > 100k mile S5x

[nando]

Excuse me for elaborating on a previous statement after it was called vague.:roll:

If the OP couldn't search to find all this info thats been covered before he probably hasn't heard the s5x vs. m20 stroker argument. I was just stating an alternate idea.

I guess if you assume he is completely daft and missed the section titled "24v swaps", the fact that it's been done like a billion times and he's probably seen one if he's ever been to an E30 meet.

it's like somebody asking how to cook a steak and then posting that they should eat tofu because it's cheaper, healthier and better for the environment.