Factory forged STI internals, How much power can they handle?

[Guest]

Just scored me a cheap verson 3 shortblock with the factory forged pistons and rods, just needs new rings and bearings etc... Pistons and rods are in mint condition

How much power can these handle with the right set-up before something breaks like the pistons or rods? Roughly how much HP or/and Boost ?

Also I will be putting 96 WRX heads onto it since i dont have any STI heads for it, Should be all good aye?

Thanks in advance

[nt_a_foz]

If its run a bearing id be checking the rods good and proper as often the rod that runs a bearing is toasted....

I just snapped a rod on a factory v8 sti motor at 232kw at 18psi.

But have heard of them doing more.

Depends on the rest of your setup though obviously

[log1call]

Ha, how much do you think you can produce?

No offence but...

Perhaps a more relevant question for a street car would be, how long will they last if I start trying to improve on subaru's design?

[Guest boostcut]

v2 or v3 heads mate? i would be checking valve-piston clearances in any circumstance. id say reliably 240ish kw at the motor is reliable as its not too much more than factory. it all depends on the tuner as they can dick around and make 300 kw and send you on your way to blow up 5 mins down the road.

[Guest]

So really the factory forgies are not much stronger than cast pistons? I have heard that alot of fake forged STI engines out there with cast pistons in them... and maybe the reason why they get blown up easy..

Also I think the version 8 and onwards are not forged either not sure on the rods tho

[nt_a_foz]

yeah version 8 cast..

They dont generally blow up cause of the pistons the majority of subaru engines that get killed are due to running a bearing...

Most people forge the motor if they are wanting big power

[Guest]

Yea I would love biggish power ;D but unfortunately I dont have the pingers to do a proper job of it yet :'( but unless i use the existing rods and pistons... I be happy with 280-300kw atc, if these internals can handle it, which I think they should.

Thats another thing about these subaru engines... so common to run bearings... i think someone on here was saying that the block flex causing premature bearing failure... so how would one recify that problem?

Although I am wandering away from the original post.. so i better stay on track hehe

[funkytown]

how many kms has that block, bearings, pistons done? I'd say your not going to hold 280kw in that block in its factory state for long eh

;D

save up and do it properly, other wise it'l be more money wasted

and id say its detonation, lack of oil and poor maintenance coupled with trashing them that causes BEB failures

[nt_a_foz]

good luck with running 300kw on the factory internals is all ill say

Youl need it

[Guest Raynes]

Redline STI is factory internals at about 270kw i think

[nt_a_foz]

yeah it was....not for that long though..

Its only running like 230kw or something again IIRC...

By what i meant by 300kw was on the track taking a good hiding it wont stand up to it...iv proved that lol

[WRXER]

+1 on that one, to be honest I haven't seen factory forged internals last long on anything above the 220kw atw mark. Not saying that everyone has had that issue, but just from here in chch I just haven't seen any wrx's posting anything above 220kw without going bang shortly after especially at trackdays.

[4ORGD]

iv got a mate with a factory v3 sti block in his 89 rs making 240kw atw all day.that was done by kent @ speed source on a power fc.iv been told that version 3 internals are strongest factory forged internals you can get.can anyone support that

[nt_a_foz]

i was making 232kw all day every day..till i went to the track...and then it snappped a rod..

Probably fine on the street but if you take a car to the track and start beating on it with higher power than factory apparently it doesnt last to long..

[funkytown]

 nt_a_foz said:

i was making 232kw all day every day..till i went to the track...and then it snappped a rod..

Probably fine on the street but if you take a car to the track and start beating on it with higher power than factory apparently it doesnt last to long..

i totally agree with brad - its been said above by a number of members.. +220kw atw given **** on factory internals (forged or not) is likely not to last.

however for the sake of the question above.. brad ran stock version 8 sti which had cast rods (and pistons..??) and died on the first track day.. tune lasted all of about 2 months if that.

To answer your question - I cant see any of the factory forged engine bits being discriminately stronger than any other factory forged bits from different years dude.

Yes the early blocked were closed which made them stronger.. but the later ones run rear thrust and cross drilled cranks which in their own right also stops helps reduce engine destruction.

EDIT:To take this conversation in another direction, using my car as an example.

I run a v5 (rear thrust) block with a cross drilled crank and a fully forged bottom end. It has been built with all new bearings, pumps and seals, fancy headstuds and standard v3 sti heads.

You might agree that this should stop what we are calling "engine failure".. well thats pretty short sighted and wrong frankly.

All I have effectively done is allow more power in the heart of my set up and will shift the weakest point to somewhere else that wont handle its power. examples..

What i havent said yet is that i also have an oil cooler set up to keep temps lower than factory, bigger fuel pump so i dont get issues there, and the right head gaskets to keep compression at the right ratio. I should also do a baffled sump but to date havent. These are all things that go towards removing more points of failure. There are bound to be a stack other points to date that i havent mentioned or fixed.

yes i've also updated the turbo to flow more and boost higher - but all on a factory 5spd gearbox.. which we can all atest doesnt like 240kw atw.

What isnt mentioned above in these "factory forged" engines is the supporting bits which go towards a) making that power and b)protecting it like i mentioned above.

At the end of the day its all about how the engine is looked after, and its history. From what the lads see day in day out is most factory engines wont do to much more kw atw consistently for very long - fact.

you get one that does, a)thanks the gods b) touch wood and treat it nice

[Pappu1]

a mate had 238kw the wheels on stock sti block.. not sure if took to track but he had the car for over an year and not a single issue i know of.. it was driven hard but obviously only as hard as u can on the street..

i reakon a good tune - read proper time spent on dyno and no detonation etc + proper fueling setup - u should see 240-250 at the wheels (280 kw engine ?).. dont see why not...

[QRAF]

also get a link or aftermarket computer so you can bin your afm, sigh

[nt_a_foz]

 pappu said:

a mate had 238kw the wheels on stock sti block.. not sure if took to track but he had the car for over an year and not a single issue i know of.. it was driven hard but obviously only as hard as u can on the street..

i reakon a good tune - read proper time spent on dyno and no detonation etc + proper fueling setup - u should see 240-250 at the wheels (280 kw engine ?).. dont see why not...

pappu i had a link and had a road tune then 2 dyno tunes and was no det...proper fuelling setup

Agreed with what funky said though if youve got a few bits and pieces it could last a bit longer but ideally you wont want to be smashing big power through the factory internals jsut asking for explosion the size of vietnam thatl destroy everything which in the long run is much more expensive

[nt_a_foz]

they may handle 300kw...i know of a factory 2.5 sti block running 360kw BUT has had hours and hours of tuning

It may handle it but itl DRAMATICLY reduce the life of the internals and it wont be a matter of if itl break itl be when

[WRXER]

+1 to the above thats exactly how I was trying to write it up brad.

[funkytown]

 WRXER said:

+1 to the above thats exactly how I was trying to write it up brad.

+10 i just dribbled on a bit

[Guest]

Great to get your fellows feedback and yes definitely alot goes into it besides forgies to get more power

Yea I was hoping for around 280-300 kw at the Crank not the wheels which probably workout to 250-260kw at the wheels....

I've heard of some racers in australia getting upto 500hp at the wheels on factory Forged internals but obviously they done alot of work to get that.. but then again they might of been blowing alot of smoke from their arses not their exhaust

So has anyone here Blew up a factory forged engine like a smashed forge piston or/and snapped or bent forged rod? I mean a genuine factory forged engine not some cast wannabe... if did what power you were doing before it did?

[Solja]

i got a factory v3 sti engine last year had 170k on the engine so possibly why it went but i got it dynoed at 184kw on vf23, went to a trackday and done bout 800km over that week and broke a rod i learnt my lesson so rebuilt a closed deck and forged it

[Tony]

 substirex said:

So has anyone here Blew up a factory forged engine like a smashed forge piston or/and snapped or bent forged rod? I mean a genuine factory forged engine not some cast wannabe... if did what power you were doing before it did?

AFAIK only the pistons are forged on the "factory forged engines". The subaru rods are all pretty much the same skinny breakable things with crap rod bolt/nut design up until V7 STI (when they went to a chunkier rod with a better rod bolt).

[Guest SPANKU]

i had never snapped any rods yet. or if ever as im ussing forged rods and JE pistons and closed deck block. ive blown countless of BEB due to over boosting sometime at at 25psi on a sti motor, opendecked block RA heads ( which is pretty much just a wrx head IMO)

220+ kw u wont have that motor for long, it will be ok for everyday daily driving car but once u slap that on the track say buybye to your motor.

totally agree with funky about regular service oil change and well maintinace

im selling my JE forged short block very very soon