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

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Lots out there. I guess the budget is the thing you'd need to look at. They do tend to bump compression up to 9 rather than the lower stock number in the 8s. I think the GEN3 3SGTE is lower than the GEN2. Maybe 8.5 vs 8.8.
 

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

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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.
 

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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.
 

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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.
Good info in this post. I'll add that 2618 piston engine life is really affected by cold starts/light usage. It takes a solid 10-15 mins to get pistons up to a normal operating temp window, and that's where the engine wear (rings/pistons/bores etc.) will mainly happen when PTW clearance is high. A 2618 piston engine driven on the street will still have a lower life than a cast or 4032 piston engined all things being equal, just because on the street you're going to have a bigger PTW on a 2618 piston vs. 4032/cast piston (it'll close up as you get the pistons really hot on track), but if you're sitting there doing a ton of cold starts and driving your car around town, you can definitely see yourself having all the symptoms of worn rings/bores in as little as 30-40k mi.

Side note - it's weird that 4032 is not more common than it is, but I think most who build engines don't want to admit they will primarily use it on the street, and always like to think they're building some 800+ HP capable engine.

OP - just to add a bit of advice, building an engine gets pricey in a hurry, and you have to bore/hone the block to put forged pistons in on anything but a near factory fresh engine - and even that is a risk because you need to verify PTW. Most people who do it the first time underestimate the cost as they're looking at the big ticket pistons + maybe rods. In reality, bearings, seals, fasteners etc. all add up in a huge hurry. Just go into it with eyes wide open and expect that you missed things in your estimate that all add up. I know I did my first engine build. I made the mistake of totalling up receipts after I was done... :sick:
 
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