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Guest Message by DevFuse

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Forged Rods & Pistons

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8 replies to this topic

#1 subpilot


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Posted 18 August 2006 - 08:22 AM

I have done a lot of reviewing the archives and there have been some serious EA-82T's built. My question is at what point do forged rods and pistons become necessary? My engine will see at least 10 minutes at 4700 RPM and have to cruise at 4000-4200 RPM for extended periods. TDO4 with intercooler will be installed but boost will be kept to "normal" levels. Really not trying to make more than 105 HP but am a little concerned about the RPM for extended periods.
Thanks in advance,

#2 soobscript


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Posted 18 August 2006 - 09:43 AM

My 225k stock EA82T did those RPMs everyday for 100-150 miles.
4000rpm ~ 80mph = highway cruise. 4700+ rpm = backroad rally. 6000rpm = accel.
No problems.
Make sure cooling system is in good condition.

#3 bgd73


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Posted 18 August 2006 - 10:07 AM

Oh No. Are you having an American automobile owner relapse? Just the aluminum heads were made under 6 tons of pressure (If I'm not mistaken American cast iron didn't even go that far). I have had some crazy runs in old subes -- and not once have I encountered a catastrophe. Your build sounds disciplined enough as well. I did find a place on the web for EA81 and EA82 forged stuff, very expensive. I personally have gone to rpms "not likely" in just an n/a. My doubts are gone. Mistakes with your build snapping something is a mechanics prob no doubt.I was a v8 breaking fan for several years and *sighed* relief at this 3 main bearinged wonder called the "EA82".Exceeding oem numbers for performance is all over this board. Below is an interesting site:

#4 idosubaru


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Posted 18 August 2006 - 10:33 AM

ram engines is the way to go for engine internals. they are great guys and know their stuff. there's an XT6 running around with those forged pistons in it and he likes them. whether it's necessary or not i have no idea. probably not on stock boost. you'll have temp problems before anything is my guess. make sure the radiator and cooling system is pristine. forged water pump maybe....

#5 NorthWet


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Posted 18 August 2006 - 12:19 PM

Short stroke = happy RPMS :)

Should be no problems running the stock engine at 7500-8000rpms... except stock valve springs probably float before then.

As other have typed, the cooling system is the important piece here. Also oiling, as I suspect that some of the "boredom of the rod" incidents that I have seen was a seizing rod bearing and a high-angularity rod... SNAP!

#6 subpilot


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Posted 18 August 2006 - 04:25 PM

Thanks everyone, I will proceed with stock.

#7 NoahDL88


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Posted 18 August 2006 - 05:05 PM

IIRC, the rods and pistons are forged stock, so i wouldn't worry too much.

Its the head gaskets that you'll have to worry about

#8 NorthWet


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Posted 18 August 2006 - 06:24 PM

IIRC, the rods and pistons are forged stock...

Pistons are cast, and I am pretty sure so are the rods.

#9 GeneralDisorder


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Posted 18 August 2006 - 06:24 PM

Yeah - the turbo pistons are pretty burly. More so than the N/A ones it seems - people have blown the ring lands, and cracked pistons using N/A blocks (pistons too) with turbo parts.

All the subaru rods I've ever seen were cast - but they are so short and stubby.... very tough units.


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