Hypereutectic pistons

[Tim_C.]

2% silicone isn't a hyper u piston like what we are talking about here. Everyone can look for the exception to the rule, but 90% of the hyper u pistons available are not made for boosted engines. The manufacturer will tell you that. These newer, special hyper u pistons are also more expensive, which saving money is the ONLY reason anyone would want to run a hyper u. You might as well go forged and get the best piston for your application. There is more benefit when doing performance mods deeper into the block of the engine. Everything else benefits from it, so it makes it worth the money to go with forged.

 

The large majority of successful high boost hyper u set-ups are MPI.

 

If you don't have MPI, and you want to boost higher than stock, don't even think about running hyper u.

 

Then we can talk about weight. I've seen hyper u's that are heavier than stock cast. Forged are much lighter and much stronger. Most of us on this site who need to save when buying pistons, will also be cutting corners elswhere to make that decision a bad one. Get good forged pistons, and then save money somewhere else. Don't skimp on the pistons.

 

Like I said, there are some better hyper u's out now than before, but why pay extra for less than the best? It just doesn't make sense to me. I've built enough engines to know hyper-u's aren't going in any more of mine.

 

Another thing about the close piston to wall clearance is if the exhaust temps get a little too high, that hyper u piston will indeed start expanding more, thus the ringlands shatter. I wouldn't want that close of a wall clearance in the engine I'm running, sorry. I might want to put a 75 shot on there. I'd hate to see what happens to a hyper u then!

[ColdScrip]

This motor will be replaced with a much stronger build in the future. If the pistons hold up that will be great, if they fail. no biggie. For those thatknow me I drive the car pretty hard from light to light so I have put the pistons thru quite a bit of strain. This past year with the addition of the injectors of course had wooried me as I have had a few lean issues at times and I KNOW that the hypers don't like that at all. but so far things are good. Guess time will tell.

 

Dad

 

I just want to clarify my Dad's post. He is looking at putting a stronger build engine in because hes afraid mine is going to blow his doors off.

[Tim_C.]

I just want to clarify my Dad's post. He is looking at putting a stronger build engine in because hes afraid mine is going to blow his doors off.

 

LoL!

 

Hyper U's are fine if all engine conditions stay in spec. I just haven't been able to trust the parts I have from breaking, etc... Like fuel pump going out to lean it out, filter getting clogged, injector issues, FPR issues, vacuum issues. By the time I get everything reliable, I have hurt the hyper - U's. It's just a lot less headache for me to get the best piston in there. I know, you guys are perfect tuners with all brand new parts. Some of us take longer to learn.

[jinx]

don't think anyone can even say what a stock 2.6 piston is capable of

 

I personally would never run anything but a cast piston, after seen DSMs, GNs, etc stand up to 30+psi repeatedly.

Our highest powered street 1.6L corolla clubmember did so, throwing 38psi at stock supercharged pistons.

These (88-91 vintage) pistons sold for $47ea at greedy toyota dealers for years.

My guess is several piston makers can easily match this feat. 'Profit' changes things tho.

Don't see the reason to "need" more or pay twice more, for a slug

 

CNM sanctioned a 'remarkably strong' inexpensie replacement cast piston. Can't remember if they were "Badger" brand ?

 

I can recall two standout oz/nz 2.6 builds running 30psi on cast pistons. The 10.5sec galant mentions "ACL cast" during some of its escapades. The other used Mahle cast. IIRC, I read Mahle made the piston for ACL? if I'm not mistaken.

 

All hypereutectics aren't created equal

I do believe that is what it all boils down to. Go with the tried & proven

 

I've pushed over 200hp/L on Mahle 4032 slugs

a G54? If so, where did u get 'em ?

[MrWOT]

That was on a 3SGTE, and that was being quite conservative, probably closer to 250 considering drivetrain losses on the awd. Very strong pistons, wouldn't consider 2618 for anything less that 25psi. They have a MUCH higher coefficient of expansion. That means 2618s are far more likely to scuff on leanout, since they will be much larger than a 4032 piston at the same temp, if they were originally the same OD.

[maxboost87]

With all this said....This is what it comes down to....Machining around the engine components for how the engine will be run, and Piston material, boost pressure, ect. this all must be put into the equation, i believe any one of the pistons offered for these cars can be built around to achieve a respectable horsepower number and still be reliable, im sure everyone knows that forged is the way to go...no doubt, me i feel the stock pistons hold up great for a very fast street car as long as the ignition and fuel system are up to par and tuned correctly they will hold every bit of 350 HP. Ive heard of JE's blowin out before even hitting that hp, so that also goes to show the most important part of a performance engine is the machining of the short block to withstand what it will be up against.

[jinx]

goes to show the most important part of a performance engine is the machining of the short block to withstand what it will be up against.

most critical item is tuning. Even the best asembled motor with most expensive components & poorly tuned.... will be outperformed and outlasted by a quality tune on a decent 100k mile oe bottom end as mitsu assembled it.

[Tim_C.]

Yes, the last two posts were well put! Very good info on here. To be honest, I have not had a problem with OE piston quality either. The biggest advantage of an OE built engine is the ring seal. The factory ring seal cannot be improved upon it seems and rebuilt engines that have been bored, etc... will most likely not have near as good of a seal there.

Even a simple honing and reinstall with the same OE pistons will achieve a superior seal compared to a machined rebuild. Of course it depends highly on your choice of rings. I did a bare bones rebuild with steel rings and got the perfect seal back. Some machine shops will do added things like prepping the cylinder walls better for the type of ring used. My Total Seal ring engine sealed very well too, but the machinist had a lot of experience with the rings and used stones to finish the walls accordingly. This issue is one big reason we have 'blow torch' like symptoms too.

Steel rings seal best but don't last near as long. With the way these cars seem to find reasons to blow up, those might just be the best solution of ring for most of us.

Factory spec chrome rings are what most of us use, but they are a little harder to achieve a good seal, and very rarely does the seal equal that of the factory build.

Total Seal rings do give a superior seal, but require the correct wall prep, clearance, etc... to achieve that. They will leak bad if that isn't accomplished.

[akauf]

I'm not finding a part number anywhere on these things.

[akauf]

So are the 2618's the way to go short of dropping the money on forged?

 

I guess stating my goals would help answer that question. I'm not looking to dump money into this motor for two reasons:

 

1) I'd swap a 4g6x motor if I wanted to make power

2) I have an evo to play with

3) This car needs to run reliably but I will end up leaning on it with a 50 trim and tbi so it needs to be a little toughened up

[akauf]

Silvolite

 

these are what I have.

Edited February 19, 2010 by akauf