forged pistons with alloy block?

[barryogen]

Anyone know what the "best practice" with this is?

My reading seems to suggest that either

"you really don't want to do that as the pistons will rip the cylinder walls to shreds"

or

"there will be no noticeably different wear characteristics, go for it"

Asking around engine re-conditioners I get the same two answers... which are pretty much the exact opposite of each other.

[thaphatty]

pistons shouldnt be touching cylinder walls anyway. I cant see how forged or un forged would change anything

[barryogen]

I'm still learning about engines.

This is the sort of thing I'm meaning.
http://www.monkeywrenchracing.com/wiseco_pistons_toyota_celica_gts_2zz_ge.html

Due to the wear characteristics of the stock 2ZZ bore we STRONGLY recommend that the block be sleeved with Darton iron sleeves when forged pistons are used to ensure long life and maximum durability.

As no-one else seems to have done anything to a 2zz, I'm at the mercy of those who I deal with, or stuff I learn myself, but I'd rather not fcuk my car up un-necessarily, so will probably end up sleeving it.

[Mr Revhead]

see here for info on the 2zz block

http://forums.toyspeed.org.nz/viewtopic.php?t=58219&highlight=2zzge

seems they dont use a steel liner.

so it seems adding liners could be an idea.
however im not an expert in that field

[barryogen]

Thanks for that Revhead, had already read them.

Will look into the cost of lining... if nothing else, it will be a bit of a safety measure.

[AceSniper]

hmm stock liners would be fine if ya staying n/a?

[RomanV]

Hahaha, what you do mean 'no ones done anything to 2zzs'

Lynn Rogers builds these motors, for the toyota race series!

If there were any tricks to building one up, or any flaws which make them explode at high RPM or something, he'd be the person to ask! or build your engine, more to the point...

Also, I'm fairly sure that TRD does a whole lot of bits for them, arent there like 13 or 14:1 compression pistons available for them?

And yeah, it seems odd that they dont have steel sleeves, I thought that all alloy block engines did...,.

[Mr Revhead]

barry is looking at boosting.....
so a lot of what has been done by the likes of lynn doesnt apply in the same way.

yeah i thought they did too, seems toyota have made some fancy stuff they use

[barryogen]

hmm stock liners would be fine if ya staying n/a?

Hahaha, what you do mean 'no ones done anything to 2zzs'
And yeah, it seems odd that they dont have steel sleeves, I thought that all alloy block engines did...,.

barry is looking at boosting.....
so a lot of what has been done by the likes of lynn doesnt apply in the same way.

Indeed Lynn has done a lot, but all of it NA as far as I know, and I'm looking at adding a bit of boost.

Most of the yankys seem to just add boost(~6lb) and use everything stock, and an emanage to control spark/fuel... but I'd like to do it properly, with low comp forged pistons, forged rods etc, but I don't seem to be able to get consistent answers about to sleeve or not... so I'll probably just sleeve it.

According to the pdf about the 2zz that Revhead mentioned, the MMC(Metal Matrix Composite) Cylinder block has better bore temp, bore rigidity, bore strength, and a better head gasket seal.

[IH8TEC]

if your doing it properly, and do decide to get it sleeved, why not run 10-1 compression like the honda boys do when they sleeve their alloy blocks. obviously you'd need good rods as well. but just an idea if you go to that effort of sleeving

[fivebob]

Coated cylinders like the 2ZZ shouldn't suffer from wear problems just because of forged pistons. However as I don't think they can be rebored, or even honed out because of the coating they have, there may be clearance issues when using forged pistons which are typically made from 2618 low silicon alloy.

My preference would be to keep the stock bores and use a higher silicon forged piston made out of 4032 alloy, have a look and see if Mahle make a suitable piston

[barryogen]

Thanks guys, very helpful.

[Grrrrrrr!]

I think fivebob hit it on the head. got curious about this and browsed the honda forums..

Quote:
Originally Posted by NotoriouSH
FRM is a softer material, forged pistons cause scoring in the cylinder bores. There's probably a lot of weird chemistry involved with the different materials but forged pistons have been tried with the FRM liners before and it didn't work out very well!

<snip>

The scoring has to do with the shape of the skirts and the additional thermal expansion a forged piston has. Generally, you run larger clearances with a forged piston, which causes the piston to rock when cold, which causes the skirts to come in contact with the cylinder walls.

The S2k and NSX 3.2L have forged pistons with FRM bores, and have no problems. The real key is to look at the metulurgy of OEM pistons for those engines, as well as skirt shape and factory clearances. The S2000 is probably the better engine to look at, seeing how it has (with the 2.2) similar stroke and bore to the H22. I've seen "spoon" s2k pistons, and they appeared to have some coating on the skirts- this may be important.

[DFECTED]

So are the bores alloy?

Its the rings that wear the bores anyway! the pistons dont touch the cylinder walls.

Usually forged pistons need more clearance than a normal piston due to the way they grow when it heats up

[IH8TEC]

So are the bores alloy?

Its the rings that wear the bores anyway! the pistons dont touch the cylinder walls.

Usually forged pistons need more clearance than a normal piston due to the way they grow when it heats up

did you read any of what has been posted?

[Dragger_Dan]

Now IIRC the Toyota Racing Series cars are stock spec motors with dry sumps and intake/exhaust?

[fivebob]

Here's the pistons you need

http://www.monkeywrenchracing.com/mahle_piston_set_toyota_2zz_ge.html

[barryogen]

Here's the pistons you need

http://www.monkeywrenchracing.com/mahle_piston_set_toyota_2zz_ge.html

heh, thats where I'm doing most of my shopping at the moment... hadn't noticed those ones.

Am going to have a chat with some guy who is apparently one of the best in Dunedin at lunch time... so comment back when I get back.

[Mr Revhead]

Now IIRC the Toyota Racing Series cars are stock spec motors with dry sumps and intake/exhaust?

yep, rebuilt and blueprinted.

[barryogen]

They guy said that usually when it is done, they sleeve for an extra bit of safety... but also said that for what I'm wanting, to just go with the Mahle pistons as they address this sort of problem... and should I want to take the car a bit further, sleeve it before doing so.

For the Dunedin guys who read this, it was the guy at the bottom of High Street, just opposite the entrance to the warewhare.