M20 B3x Naturally Aspirated Stroker build past, present and future

[digger]

Those pistons look badass. Can you share the cost?

I've been working on my N52 build and I'm sure the pistons I have (with like 280k miles) are well worn, but most aftermarket stuff is far inferior to stock Mahle (people like to say things like 'forged' without having any idea what they're talking about). Also I think it could use a bit more compression, but basically there's no OTS pistons for the N52 other than bone stock. A member here had some custom pistons from an old Turner race N52 engine but he gave them away before I could get to them. :(

Also I've known this for years, but basically all of the stuff on the MM M20 pistons is basically bullshit. The only thing I will say is they never made any noise and they have never broken. Also Jim at MM is really nice. But if you want to make actual power, you can do a lot better..

if i could get a modern cast piston for mine i would probably use that.

yeah some of the stuff with MM's pistons is a bit questionable.

[nando]

Those pistons look badass. Can you share the cost?

I've been working on my N52 build and I'm sure the pistons I have (with like 280k miles) are well worn, but most aftermarket stuff is far inferior to stock Mahle (people like to say things like 'forged' without having any idea what they're talking about). Also I think it could use a bit more compression, but basically there's no OTS pistons for the N52 other than bone stock. A member here had some custom pistons from an old Turner race N52 engine but he gave them away before I could get to them. :(

Also I've known this for years, but basically all of the stuff on the MM M20 pistons is basically bullshit. The only thing I will say is they never made any noise and they have never broken. Also Jim at MM is really nice. But if you want to make actual power, you can do a lot better..

[digger]

The 885 is one of the few heads that doesn't have a flat squish pad. Those pistons look like they have a raised rounded section on the edge. They may actually use a small portion of the squish band around the circumference, but it's hard to tell

[Reichart12]

Love the information and work you have put into understanding the m20 to the max. Wish I could find the spec sheet from when I got my pistons. CP from VAC, made to be 11:1 to be used with 135mm rods and 84mm crank for about a 2.9L. Always thought it was weird/different that my pistons were almost flat on the top when it seems like most others were rounded.

[digger]

Ireland Engineering, mate. As I said earlier, only asking you because they have a stroker kit and it seems pretty legit, so I was wondering if you've had any experiences with them at all. Thanks in advance.

Generally speaking I would steer clear of stroker kits from any store as you can piece parts yourself for cheaper. Also I'd steer clear of generic piston. the IE 2.9 ultimate street ones are good as they aren't generic

[Zambuzan]

You have to be slightly more specific.

Ireland Engineering, mate. As I said earlier, only asking you because they have a stroker kit and it seems pretty legit, so I was wondering if you've had any experiences with them at all. Thanks in advance.

[digger]

digger, opinion on IE, if any??

You have to be slightly more specific.

[digger]

Excellent engineering! One of the best postings I've ever seen in a car forum.

Thanks, I posted a lot of the information so people can conjure up their own designs for something a bit outside of the box. For example if one wanted a oe style piston for the 89.8mm stroke it's not very difficult. This way people wouldn't gravitate to the 2.8 option

[Zambuzan]

digger, opinion on IE, if any??

[hasa]

Excellent engineering! One of the best postings I've ever seen in a car forum.

[digger]

Nice work, great post Digger!

Having weighed many +.5mm stock replacement pistons, I would have to gather they are closer to 502g on avg, I seem to recall having a few over, but not by much (only know this because they had to be matched to the lighter ones, and wasn't happy about it). You are extremely close, not that ~10gm will make/break your post. :)


Also, even though the 885 head is not a true "hemi" in the classical sense, it is hemi within a hemi, no? lol

Finally, when you decided that "11.5:1" was the upper limit of knock sensitivity with 290° cam, was that based on others' input? A bloke that works with me at the shop has a 3.1 m20 with a lesser cam and only knocks with <89 octane on a decent timing table with 11:1. Going off memory, he has a 280/274 bump stick.... a 290 single pattern would bleed off more pressure, bringing down the dynamic, correct? I have a strong feeling you will have a very viable combination!

i think its classified as a semi hemi ? there is a german name for it i've seen but cant find the name

its not a hard upper limit by any means, for sure you can run higher compression in ideal conditions but the pros (less than 5hp for 1/2 a point) vs cons don't make it worth pushing it too hard for a street car that at some point in its life will see quite adverse conditions. In theory it does bleed off more pressure, but the more VE the engine makes the more mass that is trapped and therefore the pressure and temperature are higher and you get closer to the limit. The dynamic CR is a ball park estimate.

[ForcedFirebird]

Nice work, great post Digger!

Having weighed many +.5mm stock replacement pistons, I would have to gather they are closer to 502g on avg, I seem to recall having a few over, but not by much (only know this because they had to be matched to the lighter ones, and wasn't happy about it). You are extremely close, not that ~10gm will make/break your post. :)


Also, even though the 885 head is not a true "hemi" in the classical sense, it is hemi within a hemi, no? lol

Finally, when you decided that "11.5:1" was the upper limit of knock sensitivity with 290° cam, was that based on others' input? A bloke that works with me at the shop has a 3.1 m20 with a lesser cam and only knocks with <89 octane on a decent timing table with 11:1. Going off memory, he has a 280/274 bump stick.... a 290 single pattern would bleed off more pressure, bringing down the dynamic, correct? I have a strong feeling you will have a very viable combination!

[digger]

An MLS gasket that has 86.5mm bore

[Zambuzan]

What head gasket do you use for an 86mm bore? Also, have you had any experiences with Ireland Engineering and their products? I'm planning to build a stroker kit and IE seems to have some solid stuff.

[Blake B]

You win. I don't know how I walk out to my car now knowing I will never be able to give it anything that.

I'm speechless