Trying to get STI pistons to work....

Heads, valves, pistons, rods, crankshaft, etc...

Moderators: Helpinators, Moderators

douglas vincent
Knowledgeable
Knowledgeable
Posts: 3336
Joined: Sun Apr 27, 2003 5:50 am
Location: OR, Portland
Contact:

Post by douglas vincent »

I am installing a 3-bar map sensor and the MEth injection kit tonight!

Gonna shoot for 400 on a dyno probably sometime this month. I don't want to street tune it too far, I like watching the AFR's on the computer as I ramp up.

But.... I will up the boost a little this weekend if all goes well! Gonna shoot for a 12.5 or better at Woodburn.
Reddevil, Awaiting new heart, will it ever happen?
1990 wagon, EJ25 12.3 @ 116.5 FAST Family wagon getting new motor soon
1992 wagon, wifes daily, high compression
1992 Touring wagon, should I keep it?
tmarcel
First Gear
Posts: 138
Joined: Sun Nov 05, 2006 2:55 pm

Post by tmarcel »

Careful with those STi cast pistons man. A little det and they'll be done quickly. As far as your build, I admire what you've done. Thinking out of the box is the way I do it ;)

On my current motor (in my WRX), I actually reverted backwards from a EJ257 block to a EJ25x 'phase 1' :lol: Well, I expected it to be temporary but I've actually re-thought this after 3k miles or so on the motor. It's got a nice set of Crower I-Beam rods, Wiseco 2618 forged pistons, ACL Race bearings, and a balanced crank. This is all set up with a zero deck and .051" Cometic gaskets. Estimated CR is about 9.1:1 This is the right way to do it when you've got the motor set up properly. At 20-22psi on pump gas it's been good to go. I haven't had it on the dyno yet but I would estimate it at 400whp -/+ based on other cars I've tuned etc. I will probably push it to 30psi on the dyno for a short time to dial in a race gas map. I think it should hold fine. Certainly the rods, pistons, and crank will LOL!

BTW, Phase 1 rods are the longest of the 2.5 motors at just over 5.18", where as Phase 2 NA are 5.16" and the turbo rods are just under 5.14". We acheived a zero deck by cutting .030" from the top of the pistons in a mill per direction of Wisecos maximum specs.

On the Legacy EJ22 related, I've got a WRX manifold, STi up-pipe, WRX DP, and WRX turbo that will be going on my 1991 Legacy. Nothing big, maybe 8psi WG pressure along w/ a TMIC, WRX fuel pump, etc. Now I've got to figure out a safe way to tune it. Sucks not having a tunable ECU so I may get a simple piggyback which should do the trick.
1.) '02 WRX-2482cc-TD06H-20G-FMIC (just sold)
2.) '90 Legacy-2.5 turbo, VF39, Haltech E8 in-hand - waiting for the 5mt swap
douglas vincent
Knowledgeable
Knowledgeable
Posts: 3336
Joined: Sun Apr 27, 2003 5:50 am
Location: OR, Portland
Contact:

Post by douglas vincent »

Brittle like this?

Image
Reddevil, Awaiting new heart, will it ever happen?
1990 wagon, EJ25 12.3 @ 116.5 FAST Family wagon getting new motor soon
1992 wagon, wifes daily, high compression
1992 Touring wagon, should I keep it?
tmarcel
First Gear
Posts: 138
Joined: Sun Nov 05, 2006 2:55 pm

Post by tmarcel »

Did I miss that part :shock: Is that the STi piston? If so, that's a pretty bad one. Hell, I wouldn't trust cast pistons (regardless of being high-silicone) to high heat, high power situations. Sure, some folks are able to ring out 450whp out of them and maybe more, but they ALL fail at some point. Even the con rods will go with enough effort :shock: I had two bent rods (factory 257) on my last motor. Granted, nobody really knows what happend as the pistons were in perfect shape (no det evidence on the tops or on the sparkplugs), but one rod was bent about 3mm laterally and the other one about 1mm off. It looked to be a hydrolock problem with either the fuel injectors and/or the computer that caused it. That or they were just over powered.
1.) '02 WRX-2482cc-TD06H-20G-FMIC (just sold)
2.) '90 Legacy-2.5 turbo, VF39, Haltech E8 in-hand - waiting for the 5mt swap
Post Reply