slideland

And the subaru motor Is subaru built... Toyota doesnt have any fingers lifted on that whole engine setup...

Hoovey689

iTrader: (16)

So then you've reiterated my point..

TrueStreet

Hoovey, yea no doubt, it's just I see so many people on here cry that the piston is SOOO different that no one can make anything for our engines and I think it's a bad speculation to spread on these forums.

Slidland, yes you are corret, I know the 4GR doesn't have port injection it just has the D-4 system, that's how I got the picture of the piston since it was a rebuild on an IS250. Apparently the port injection helps keep the valve clean. However the design of the piston head won't be different than one from a 2GR as you can see from the 4UGSE. But I bet the difference between say piston A, B, and C are small variations from production runs or toyota's suppliers. But if a company were to make low CR pistons they wouldn't need to conform to those exact specifics since it would have much different purpose in mind instead of being on the edge of high compression. And Toyota and Yamaha had a HUGE hand in the development of the 4U-GSE/FA20.

And it wasn't till the 08 model run of the IS350 that they started having the A, B, and C marked pistons. 06 and 07 just has one part number for the pistons.

jdmSW20

iTrader: (12)

I have to agree with what Gville said. Why go lower compression because of boost? a high compression motor with boost on top of it make just the same power on less boost and the drivability on the street is better as well. I think if boosting these cars were more common place, that would be a better setup anyway.

even though its a completely different animal, even on my mr2 im going to eventually go higher compression pistons vs going back even lower compression and have to drive the turbo harder boost wise

TrueStreet

I think it's for those who would want to make a turbo setup, if they're going to spend 10K they want it to be worth it, not just 100hp increase. At least that's what I'd figure. Monkey Wrench has shown the potential of high CR turbo applications, but it's difficult to tune from my understanding.

slideland

to further explain what isnt stated.
Im a lexus tech in atlanta and what they tell us at tech school is that we arent allowed to bored or core an aftermarket block because of the varations in cylinder wall variance. the blocks are different because of the FORMATION method. they mold completely different than they are expected to therefore pistons were made to compensate. is350's are different issues not a 250 motor.
and toyota had a huge hand in this subaru motor like my ford ignition system in my bmw motor (retro)... nothing but electronics and fuel control...and if they wanted to make low compression pistons im not saying they would fail at making proper copies... im saying if they dont make copies.. i see a future of seized engines or scored blocks.


and is350 have a b and c pistons also on all years. I HAVE A 350 block right in front of me... locked up on travel..

Token1

This is all so reminiscent of the IS300 game so many years ago. Give it time, the right economics and demographics, and parts will develop. IMO the lack of supply is too fold, not enough demand, and for some product options (DI injectors, DI injector control etc), they are not developed yet.

As far as the FR-S/BRZ, that scene is so hot, so full of the "type" that want to mod, the aftermarket is clamoring to fill that demand and try to cash in on it. IMO where there is a will, there is a way.

TrueStreet

This I agree completely.


slideland,
You're telling me that they can't hone out what? .002? I talked to the tech where I got the picture from, it's just match set pistons to the block. Instead of honing the block perfect to the pistons they use this method. If what you were saying was the case basically no one could do a proper rebuild on a lot of engines or build up a car with custom pistons. I don't think Toyota's engine management and fuel system is something to scoff at, as well as piston/cylinder head design.

slideland

i think you both lost me...

TrueStreet

Part of what Token said is that it will be a while before stand alone units will come up for cars with DI systems since it requires different drivers for the DI then it does regular injectors. And that it's a cyclical issue with the 2IS, no parts for people to mod the engine, thus no interests, no interests for modding the car no company will make parts.

As for what I said, from my understanding between A, B, C pistons is because Toyota uses match setting instead of how it used to be, so they catalog the different parts and assemble with which parts work best. The difference is the bore size of the pistons, so sometimes piston A fits better in one block while piston B may fit better in another block. And from what my friend told me 80% of the engines are fitted with piston B. And the difference between the piston bore isn't huge. So you make a low CR piston for the largest bore size and since if you're installing new pistons you're going to be honing the block anyways you can hone it out the small amount needed if the piston is a tiny bit larger than the cylinder.

If you're lost on what I said about Toyota's involvement with the 4U-GSE/FA20 I think you fail to realize how much collaboration Toyota has had with Subaru to develop the engine. And making it seem like fuel management and cylinder head design is nothing I think is kind of a slap in Toyota's face. And I'm not exactly sure, but there's also a chance that Yamaha did the flow tuning of the heads since it has the G designation and usually Toyota has Yahama work on it when they have that designation in the engine code. I mean look at Subaru's previous NA engines. The EJ25 made like 170hp and their new 2.0L in the impreza doesn't even make 150hp.