How much of an engine needs strengthening for more power?
 

Hello, I was wondering, I know people say certain engines can't take much

more than x-amount of power, for example, say on a uk turbo 320 bhp max,

but I was wondering, is this all the bits in the engine, or is it just pistons and

the crankshaft, could you build an engine to take a safe 340/350 bhp with

put replacing everything in it, or would it just class as a rebuild?

Hope the question makes sense, thanks

Put it this way if your going to open a engine you might aswell strengthen it properly as you are more likely to crave for power later on. It would also be more sensible to use forged pistons & rods instead of just using forged pistons together with OEM rods.

are these the weakest bits on an engine, I want to know why it is or what it is that causes certain engines to only be able to take a certain power, if you were to rebuild a uk turbo engine, would everything be replaced?, what is replaced?

At the end of the day the answer lies behind your requirements. For example if i wanted a reliable 400 then i would replace pistons, rods, gaskets, bearings & crank with aftermarket ones along with uprated gearbox etc. If a UK engine was rebuilt then everything would need changing depending on damage etc. Some engines can take certain amounts of power because the internals are not the best of quality to handle high power. Therefore this causes the restriction.

If you intend on opening up the engine, then it would make economic/future proof sense to stick in a set of the many and varied c.500+bhp rated pistons and rods/ACL bearings all round and obviously a checkover of the block's, crank's and head's condition, etc.

no wonder it's so expensive, so in some cases even the block itself might not be up to it?

If damage has occured then yes.

cool, just wondering as I know people say the uk turbo can take - whatever bhp- but wasn't sure why, so basically, weaker parts, but , in the long run upgrade with parts rated up to 500bhp, makes sense

....Then there's the rest of the drivetrain to think about........... ;)

Start with V7 engine tough as old boots good for 360bhp

My V7 STi is currently at 416 bhp on standard internals and just passed the 100K mile mark. Yes to goto further a rebuild is required partially due to milage. Ran for 4 years at 360 bhp on standard turbo, replaced turbo to get 400 then exhaust to goto 416

whats safest bhp for a jdm bug? i know they closed blocks.

The max its VF35 can make (c.340-360) should be okay.

360ste above, said he ran his for 4 years at this level.


Or are you talking about the WRX?

i was going to add, the sti v7 blocks can take 425 from what i was told by some of the tuners.

with a 16g mines kicking 341.4bhp, & 338ftlbs of torque
thats a uk car too :)

but as said, depends what you want at the end of it all.
it will mount up

but you need to also think reliability
if some thing fails, as you scimted alittle, it will cost more in the end

A sti v7 block is semi closed deck and will handle over 500bhp with proper forged internals, the standard internals in the v7 block have been run up to 450bhp.

Banny

Pretty much what everyone else said, if its open then replace the lot, go for the twin scroll nitrided/cross drilled crank (better oil feed), uprated rods (weakest part on a classic, standard across the range so they normally fail first), pistons, gaskets etc, and you may as well do the oil pump and modine whilst your at it, no point taking it apart and leaving old stuff in there.

Tony:)

360ste, what mods did you have to get 360bhp on the standard turbo on your sti?

These are a pretty penny aren't they? :eek:

Yep, 3k (fitted) for a 6 speed from a new age Sti

Oh, and you'll be wanting an aftermarket ECU for a classic (another 1K or so fitted and mapped)

And brakes, for a 500 bhp power car, it'll be the 2k (without fitting) AP 6 pots you'll want!

And suspension; there's another 1k or so (fitted)

It goes on and on.

:D

2 of the things im looking at soon too, 6 speed box, and a better after marcket ecu.
also a slightly bigger turbo

I'm not planning on doing anything, well not yet....

but wanted to know the weak points, so I can understand it better and I saw why now,

thanks to all the replies

Basically for reliable big bhp, the remedial things are:-

Decent brand of forged rods/pistons, ACL big end and main bearings, ARP head studs, metal HGs.

PPG or Scooby Clinic or STi 6-sp gearbox.