MR2 Owners Club Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Does any one know an alternative for the stock pistons in the 3sgte gen 3
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
Yh I've seen a few that are at 8.8...but do you personally recommend any specific ones
 

·
Registered
Joined
·
1,540 Posts
Look up discussions on 4032 vs 2618 Aluminum for forged pistons. Long story short:

2618: Is low Silicon alloy, has a higher ductility than 4032 so it doesn't crack as easily (read: detonation less likely to damage them). But that has the draw back of making the piston expand more with heat, which means you have to run larger PTW clearances. Couple disadvantages to that: piston slap is a potential issue, and it allows the piston to rotate on the pin (piston rock). If you look at the piston rings and notice how they have flat sides with square edges, they're supposed to sit flat and square in the bore. Piston rock slowly wears the edges down and rounds the ring out, the ring lands also lose their shape slowly. It'll be significantly worn around 50-60k mi typically. Most 4032 makers recommend 0.030-0.035" PTW. Engine builders are nervous about having an engine lock up from too little clearance and will almost always want to go closer to 0.040", which is a lot.

4032: Is a high Silicon alloy, it is harder than 2618. It will crack more easily, but it expands less than 2618 so you can run PTW clearances about as tight as OEM. Your rings stay squarer in the bore and will last about as long as stock. They're ideal for street driven cars (99% of builds) but are less tolerant to operator error... Poor tuning and detonation namely.

Aftermarket cast: Just had a motor with a set of these I'm rebuilding. They seem like they duplicate the casting of the OEM piston, and are supposedly all sourced from Nippon pistons whom made the OE pistons, but who knows for sure. They seem OK but still made to be as cheap as possible. I've seen them for $30-40/piston.

Mahle is the only manufacturer that makes 4032 pistons for the 3SGTE (86.5mm ONLY) anymore, I just got a set. Their recommended PTW is 0.0016-0.0024". The coating on the pistons seems to be a bit under 0.001" thick so the "real" PTW is generally going to be a hair under 0.003", very close to stock.
 

·
Registered
Joined
·
25 Posts
That pretty much sums it up, I would be extremely careful with parts selection, internal combustion engines are frankly incredibly delicate things when you start getting into the guts of them.
 
1 - 8 of 8 Posts
Top