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To those of you considering aftermarket forged pistons...


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A compromise between piston strength and engine durability would seem to me to be what many people would be looking for in a somewhat modded daily driver. Wondering if such a thing exists :confused:

 

 

It does.

 

Top-notch machining, a competent builder and cossy pistons.

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The extra clearance means a couple things. It gives the aftermarket pistons more room to expand in the cylinder, and this may be good for very intense driving and high horsepower setups. You don't want your pistons to seize. However, because the clearance is greater, your motor will have increased blowby and increased wear on the cylinder walls.

I thought rings did the sealing between piston and cylinder, so why would you get increased blowby with forged pistons?

I do a leakdown test and still measure less than 12% leakage. So what would you get from a stock setup?

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CP pistons.

 

Given that my original engine cracked ringland on STOCK tune, I don't have much confidence in stock pistons.

 

That suks, I'll be interested to see it opened up. Whats next? Wiesco, JE, Woosner? Ls1 swap? :)

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CP pistons.

That's what I put in after ringland #4 failed on Cobb stage 1 tune.

 

A local shop had some Mahle for the same price but I had already ordered the CP's, I'd rather the Mahle but I was "less" informed last summer.

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  • 2 months later...
my engine blew up on my 05 lgt, the turbo took a dump first, i replaced it with a vf52, now something in the bottom end went bad. i am thinking of rebuilding it with tight fitting pistons like the woosners? i have a fairly mild build with 280awhp, and 300 tq but i might turn the whick up to 300whp since i have to rebuild anyway. are stockers good enough for a 300whp dd?
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  • 8 months later...
A compromise between piston strength and engine durability would seem to me to be what many people would be looking for in a somewhat modded daily driver. Wondering if such a thing exists :confused:

 

It does.

 

Top-notch machining, a competent builder and cossy pistons.

 

 

I was talking with my engine builder yesterday. When I told him what I had learned from this thread. He said he would still use Wiseco's in my engine. He can put it together so things are nice and cossy. He does a lot of work for the local Subarus dealers. He has built other high HP Honda's for us. I'll trust him and go with the Wiseco's. I'm not looking for a lot of hp just around 380 at the crank for my DD.

 

He did say he has seen a of these engines (turbo-charged) with spun rod bearings and/or valve problems. I think most of us know the OEM ECU map has a issue with knock.

305,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.

 

Engine Build - Click Here

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  • 1 month later...
Are the pistons in the STI's different than the LGT's. I'm asking because I hear they are the same. Also I heard from a builder that the engines with unmatched blocks have more problems ie: AA on one side AB or BB on another. Any ideas on this? I have an 07 STI that came from the factory with an SPT intake and exhaust. People are screaming all over the forums that an intake like this on a factory tune is a receipe for disaster but no problems for the first 25,000 miles. Been stage II with a protune for the last 23,000 miles now pushing 23 psi and no sign of trouble on stock internals. I think I'm with the crowd that believes the tune is the problem when pistons go.
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  • 2 weeks later...

Well, I'm fixing my engine thanks to the dealer tech leaving the FPR vac hose off, they admit it but disagree that it was the fault. Took it to SOA and they sides with the dealer. Stinks, I know!

 

So, for Stg2+ DD with a 5EAT I'm thinking of going with CP, Wiseco, or Manley and boring the block to 100mm. Temps here don't drop that much and the coldest is mid 20's for a few days out of the year so slap might not be that bad. Slowboy is close to me and so is S&R so checking who has the best price and reputation.

Edited by Leonardo
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  • 7 months later...
I'll be honest, the ringland thing is really a Subaru deal... not that it doesn't happen in other cars, but I NEVER hear any other car community talk about it. I never hear "Oh shit I lost a ringland on the LS1 at the strip." On Hondas people start freaking out about the stock sleeves (I had a friend drop a sleeve on his Integra), but you don't hear people with other types of aluminum blocks worrying about sleeves much.

 

On 7M Supras and twin turbo 3000GT's spun rod bearings are a major concern (I had rod knock on my old Supra), but you don't see people with Subarus freaking out about that much. On a DSM it's a timing belt jumping or crank walk in some cases which makes owners fret. On Rx-7s it's apex seals but it's almost never bearings or the crank. You don't need a built motor to make 500whp on that car as long as you can control heat and detonation. Every car has its strengths and weaknesses and then the internet forums can just amplify whatever concerns people have. And remember that many car communities have a "silent majority" of people who are happy with their car, don't have many problems, and don't feel the need to post on the internet about it.

 

Well it seems I am in the minority ... but I have had two motors with spun rod bearings. I am looking for a short block to get my poor XT back on the road. Any of you have suggestions about the best route to take ... I am not running any major mods or even any tune Mostly stock.

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Well it seems I am in the minority ... but I have had two motors with spun rod bearings. I am looking for a short block to get my poor XT back on the road. Any of you have suggestions about the best route to take ... I am not running any major mods or even any tune Mostly stock.

 

I would just a new shortblock from Subaru. At least then you have a warranty with it.

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how long do you run your oil? you may want to look into an AOS or something, it sound like you're running low on oil or you have a pickup issue or something.

 

Changed oil right on time ... the first motor blew because the dealers mechanic pinched the oil filter o-ring and the oil dumped out on as my wife was on the way home. Turbo went first and immediately follwed by the motor. The dealer tried everything to get around it but ultimately replaced it ... they gave us a new short block, turbo etc. but they said they had the heads rebuilt because they could not get new heads from SOA. When we tore down that motor the heads looked much more worn than 14K ... it had 48K on it when the dealer killed it. But when this new motor lost its turbo (had tons of debris in the oil line filter screen, which was hard to explain why it was even there at that point, I think they threw a bunch of the stuff back on without cleaning it properly) and then spun a bearing at 14K They tried to say I had not changed the oil as prescribed in the manual ... I came up with reciepts for three out of the six oil changes that I did and since I could not find the reciepts for two more of the actual three more I did they tolds me to hit the pavement, I had no idea I had to have reciepts. I found another motor in CO and put it in, it ran for about four months and then had a spun bearing as well. She has been sitting for over a year now in my garage. I want to get her back on the road so I have been accumulating parts ... Just wanted to hear what all you guys have to say about the best most reliable short block. Can I use a EJ257 and if so what issues does it bring to the table? Is it better than the EJ255?

 

I have a BNR EVO turbo, STI turbo oil lines, Cold air kit, New Uppipe (catless) and an AVO down pipe. Gonna go with a Magna flow exhaust and do some suspension mods to tighten her up ... but intend to only tune her for the BNR Turbo. Nothing radical ... any opinions, suggestions or pointers?

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  • 8 months later...

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