400 whp on a 900whp rated block?

[Mtlsangalang]

I have the opportunity to buy a low mileage built VA chassis STI. It has an outfront v3 closed deck block with 9:1 CR. Has some head work. Its running an fp black and it is tuned to 420 on 93 18 psi and 622 on e85 27psi. I want it to be a DD and am likely gonna detune or change turbo so it makes low -mid 400s on e85 and 350-400ish on 93.

Will this have more wear and tear than me running it at 600whp? Im trying to see if I can get at least 60-70k mi out of the build. I drive 100mi/week max. Any input would be appreciated. Kinda worried that clearances will have an issue with this. Educate my newb brain please!

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[rtv900]

Originally Posted by Mtlsangalang

Will this have more wear and tear than me running it at 600whp?

facepalm

[Mtlsangalang]

Originally Posted by rtv900

facepalm

I know it sounds stupid but Ive read somewhere here that doing 400 whp on an engine built for 800 whp can be detrimental since clearances are different for that said build? Thats why im asking. ***128517;

[Alistairh]

Built subaru motors aren't known for their extreme longevity. Also by your math you're asking to get 11-13.5 years out of the motor. You'd be lucky to get that with a stock engine.

[rtv900]

Originally Posted by Mtlsangalang

I know it sounds stupid but Ive read somewhere here that doing 400 whp on an engine built for 800 whp can be detrimental since clearances are different for that said build? Thats why im asking. ***128517;

it certainly isn't ideal, but you aren't thinking about it right

the 800 build would be done different clearance wise, etc, due to that power level. Not going to very streetable.

but running at a lower level isn't going to be any worse, bottom line, you have what you have, period, so you are stuck with that build.

If you are on the street it doesn't matter if you make 9 million hp, you aren't going to be able to touch 800 on the street for more than a few seconds, maybe 10 absolute tops if you have a sick stretch of highway that is empty for a solid mile

You will be outputting 100hp pretty much all the time
a lower hp tune will likely make it at least a tad more streetable

not sure the status of the engine (in the car already, on a stand??) but you should consider selling that thing and getting something that makes sense

Frankly, even if you did put 800 hp through it the wrx platform at the end of the day will be a nightmare on the street. It will be less fun than half that power level

[19std]

Im calling check engine light in 50 mi.

[K3rm1tth3fr0g]

Originally Posted by rtv900

it certainly isn't ideal, but you aren't thinking about it right

the 800 build would be done different clearance wise, etc, due to that power level. Not going to very streetable.

but running at a lower level isn't going to be any worse, bottom line, you have what you have, period, so you are stuck with that build.

If you are on the street it doesn't matter if you make 9 million hp, you aren't going to be able to touch 800 on the street for more than a few seconds, maybe 10 absolute tops if you have a sick stretch of highway that is empty for a solid mile

You will be outputting 100hp pretty much all the time
a lower hp tune will likely make it at least a tad more streetable

This^

Detuning a 900hp block to use it as a 400WHP daily is simply going to result in accelerated wear from increased clearances with 0 benefit from the overly built motor. It's going to suck when you spin a bearing in traffic at 30K miles having never touched the potential of that block. You'll be wishing you were in the RA block cast piston club when the motor goes.

Either get rid of it and use the money to put in a more sensible motor for your goals. Or send that b1tch to the moon and slap an ETS 6466 kit on there and blow the doors off of everyone Or keep it an enjoy it as it is, knowing detuning it won't do virtually anything to extend it's life from where it is right now unless you plan to be pushing it to the limit of the tune/turbo often, like at the track. Then detuning can certainly make sense for the sake of longevity - but for where you're at and for your use case, assuming your oiling is under control, dropping the boost and power won't give you much more longevity on the street. I'd also argue running ~450WHP on 93 can be more dangerous than ~600 on ethanol assuming everything is configured safely to run 600, as pump gas varies so much and can knock significantly.

Edit: after rereading your post its important to note explicitly that detuning your setup to 450 on E85 from the 600 it's on now will likely not substantially reduce wear, as much of it happens on cold starts or during lean conditions or knock events - both of the ladder shouldn't be present if you have a good tune and run E85.

[Dave D.]

if you want to run in the low 400s, just run it on 93 -- it's already there, and it's doing it at 18psi. Sounds pretty "safe" to me for a DD. Then, if you decide you want some extra fun here or there, throw in the ethanol. You can always turn the boost down a couple of psi on E-85 to save a bit of stress on the motor. Why mess with a good setup that can already do what you want it to?

[K3rm1tth3fr0g]

Originally Posted by Dave D.

if you want to run in the low 400s, just run it on 93 -- it's already there, and it's doing it at 18psi. Sounds pretty "safe" to me for a DD. Then, if you decide you want some extra fun here or there, throw in the ethanol. You can always turn the boost down a couple of psi on E-85 to save a bit of stress on the motor. Why mess with a good setup that can already do what you want it to?

Agreed

[FuJi K]

You know what 400whp is on your setup? Going half throttle. Who says you have to be 100% throttle? You control the amount of load/ boost with your foot. Can you not manage that?

A motor built and clearances set for 800whp is built for that added stress and heat range. Metal expands a certain amount with different boost levels and sustained time in boost ex: lapping.

If you just want that much power only, drop down to a smaller turbo. SIMPLE Cobb 20G so you'll have a better powerband at least. Unless you like that later pull to redline.

[benflynn]

Really best thing is to swapp it with someone who has a 450ish short block, oh look a spare right here…