Does Anyone Know How Much Power .......

[EVOthis]

Quick question for everyone......does anyone have an idea as to what the stock bottom/center end of a 2005 STI can withstand... horsepower wise and boost wise?

[idosubaru]

you have to define "withstand". there's a big difference between a daily driver and racing...and everything in between. as well as what style of driving to be done, whether you want 200,000 or 50,000 miles out of it. and how much you're putting into it?? the more you bump it, the more risk you incur...so where do YOU draw the line, where other people tell you? there's no magic line where at 498 they all last forever then at 498.1 they all of a sudden blow up the first time you start them. the questions you're asking are very subjective and vague.

 

NASIOC is probably a good source...there's guys building 400+ horsepower engines over there. you're asking a ton of questions that are very similar in scope, i think searching google, here, and other sites (like NASIOC) and reading as much as you can about subaru options should give you a well rounded base to start from. i guess i sound like a party-pooper but i feel like you're shooting in the dark in a way.

[EVOthis]

you have to define "withstand". there's a big difference between a daily driver and racing...and everything in between. as well as what style of driving to be done, whether you want 200,000 or 50,000 miles out of it. and how much you're putting into it?? the more you bump it, the more risk you incur...so where do YOU draw the line, where other people tell you? there's no magic line where at 498 they all last forever then at 498.1 they all of a sudden blow up the first time you start them. the questions you're asking are very subjective and vague.

 

NASIOC is probably a good source...there's guys building 400+ horsepower engines over there. you're asking a ton of questions that are very similar in scope, i think searching google, here, and other sites (like NASIOC) and reading as much as you can about subaru options should give you a well rounded base to start from. i guess i sound like a party-pooper but i feel like you're shooting in the dark in a way.[/quote

ok i will put it this way.......can you put 600 HP to the stock bottom end....make a pass on the track at full throttle and keep the engine in one piece? I will check out NASIOC......thanks for the tip.

[idosubaru]

I will check out NASIOC

i think that's where you'll find the most information on this. it all comes down to cash, with enough resources yes it can be done. the stock transmission and driveline is going to start falling apart though with this kind of use. the transmission will not likely take it for very long and that strain will be passed throughout the rest of the components as well. spend some time on other sites and you'll see plenty of WRX transmission shreading threads. and you still have semantics to consider, do you want the car driveable after that track run? how many miles? are you going to rebuild after every track run? upgrading the ECU? exhaust, pump fuel, EGT's, intercoolers, turbo, intake, fuel controllers???...and on, and on, and on...there's a lot to consider and i think you'll learn more at NASIOC about all of this. that you're asking such open ended questions seems to almost answer the question itself...no, it's not going to happen. if you're really going to do this and understand engines then you should have a good idea of what this kind of project is going to take if you're that determined to hit those kinds of numbers. if you don't know much of this stuff then read all you can at NASIOC and check out Corky Bell's book.

[Phizinza]

Gotta also remember, not all are equal. There are many different things that can go wrong when making engines that won't show up at stock power, but once modded may just decide to say good bye. Then again, you may have one of the better castings of what ever production and it may take quite a bit more power.

From the little I've read in magazines, stock STi blocks take upto about 300-400hp. Anything beyond that and people start swapping in stronger parts.

[calebz]

ok i will put it this way.......can you put 600 HP to the stock bottom end....make a pass on the track at full throttle and keep the engine in one piece? I will check out NASIOC......thanks for the tip.

 

 

600 Wheel? Not likely. That kind of power is going to come from a large turbo pushing some pretty decent boost. The stock internals might handle it for a pass a the track - once.

 

Recently, a local NASIOC finished his 05 STi. It was putting down the kind of power you are looking for. But it was also a $20k motor .

 

There is one guy running around here with a decently tuned 40R STi. Last I checked he was still running the stock bottom end, but I know he doesn't take it to the track or spend much time at WOT.

 

You are trying to effectively double the horsepower of that motor. You can do it, but you better have cash on hand for when it breaks.

 

Oh - and moved to new gen.

[1 Lucky Texan]

guy at nasioc has a built motor that goes 804 hp. Stock crank.

 

But yeah, who knows what the durability is gonna be if he's got his foot in it all the time!

 

 

Carl

[porcupine73]

One thing I've seen a few times on nasioc is chipped/damaged gears, forgot if it's differential or gearbox, from hard launches etc. on WRX and STI.

[ericem]

You can always do the H6 swap and get 600HP+

[1 Lucky Texan]

One thing I've seen a few times on nasioc is chipped/damaged gears, forgot if it's differential or gearbox, from hard launches etc. on WRX and STI.

 

Yep, with 4 wheels 'hooked up' there's less 'burnout' and more 'break off'(of gear teeth). It can be a problem with stock power. Kids think they can rev to redline and sidestep the clutch with no consequences. 'Dog tooth' (RA) gear sets (full or sometimes first and second only?) are a stronger - if noisier - set up.

 

That's what Ive read anyway. probably someone here has some experience with that.

 

Carl

[Hotshot]

From what I know from reading around on nasioc, around 400whp is probably about the "safe" limit of the stock block for most people.

 

The STi 6 speeds are supposed to be pretty durable though. I know that about have the people on nasioc have completely shredded the stock 5 speeds on the WRX, then swapped in 6 speeds and havent had much of a problem.

 

As mentioned before though, getting a PPG Dogbox is probably your best bet if you want to push a whole lot of power. I don't think I have ever heard of anyone breaking one. As far as the nose issue, I believe they offer the option of either helical or straight-cut gears. I think it is pretty common for the 4 speeds to have 1-2 straight cut and 3-4 helical for quieter cruising.

 

So... What exactly do you have in mind?

[EVOthis]

just browsing a few possibilities at the moment.......

[1 Lucky Texan]

just browsing a few possibilities at the moment.......

 

In addition to nasioc for high performance, I think there are some sandrail guys doing internals and other major upgrades. maybe outta Australia?

 

carl

[jamal]

Conveniently enough, this was just posted on nasioc:

 

http://forums.nasioc.com/forums/showthread.php?t=1393580

 

However, once you get over 400hp, the headgaskets tend to float around a bit, and there are even dowel pins. Someone who knows more than me has two closed deck 2.2 blocks stashed away that he intends to stroke to 2.35l.

 

The STi 6-speed is not something you have to worry much about breaking unless you do really stupid things. generally a CV or two will break first.