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-   -   Safe HP range? (http://www.wrxtuners.com/forums/f103/safe-hp-range-44394/)

yamahauler27 01-27-2014 09:53 PM

Safe HP range?
 
Hello, I'm new to this site and still fairly new to Subaru's but I've been building engines for over 15 years. I've built some monster small block and big block chevy's. I've built a few Honda engines that ran in the high 6 to low 7's on a 1/8 mile. I picked up a 2006 2.5i with a blown engine a few years back and I have lost interest in everything else but Subaru's since. I rebuilt that engine to handle NOS but never added it as I decided to keep it a daily driver. I bought an 07 STI a year later. I ported and polished the heads but it's mostly stock and I have really enjoyed it so far. I picked up an 03' WRX last week that is nearing 200,000 miles for a price I couldn't pass up. I bought it to make a project out of. I am planning to tear it down soon and rebuilding the bottom end with the strongest components available and I want to make as much HP as I can reliably get and still keep decent driveability. What would be a good figure to aim at. If possible I would like to be in the 400 to 450hp range. I would like to hear some experienced advice. I won't be pushing it very hard except for a few passes down the drag strip ever so often. Any input will be greatly appreciated.

Sub14WRX 01-27-2014 11:17 PM

For the 03 WRX?
From my knowledge, you would def want to swap in an STi Transmission if you're looking at the 400-450WHP Range as they have rarely any Flex. So that is one thing to look into. Secondly with some Stronger Pistons/Rods, your motor should handle 400-450. You can also look into building the head, but from what I hear they can handle power. Your best bet is to find a local tuner to talk to. Maybe someone who works mostly on Subaru's, My Tuner is mostly all about Subaru's. Maybe I can ask him what he thinks if no one else has a more detailed response for you.

Jkas 01-28-2014 12:06 AM

It is very possible to put that type of HP out of a 2.0. My buddys 02 wrx is pushing 425 and just fine. He does complain that it is not DD-able. Sub14 is right though. You may want to upgrade to the STI trans to handle the power unless you want to rebuild the 5speed. IMO, I would rebuild with a stronger Albin gears.

[url=http://albinsgear.com.au/products/category/gearsets]Products ? Albins[/url]

I went with a hybrid build. 2.5 block with 2.0 heads. I'm partially bald now. I still have my 5 speed.

(I will edit this as I think of more)

Sub14WRX 01-28-2014 12:17 AM

@Jkas

but doesn't rebuilding your 5 Speed cost just as much as getting a Bulletproof STi Trans Swap?

Jkas 01-28-2014 12:57 AM

I wish I could answer that one honestly. But that I do not know I will do some research on it in the morning and get better figures. As far as the current research I have done. It really comes down to what you prefer; 5 speed or 6 speed.

mosc 01-28-2014 09:15 AM

[quote=Sub14WRX;429122] @Jkas

but doesn't rebuilding your 5 Speed cost just as much as getting a Bulletproof STi Trans Swap?[/quote]

No, the 5-speed rebuild is considerably cheaper because you can use every other piece of the stock WRX driveline. Swapping in the 6-speed requires a lot of conversion work as you're going to match up different front and rear diffs. DCCD also takes some serious work to get working on a WRX.

man show 01-29-2014 09:07 AM

My Albins 5 speed rebuild was just shy of $6k and I reused every other piece of my stock WRX driveline except the trans mount and crossmember bushings, which I upgraded at the time. My stock clutch was still in good shape and my stock flywheel was able to be resurfaced.

turmic 01-29-2014 07:38 PM

[quote=man show;429634]My Albins 5 speed rebuild was just shy of $6k and I reused every other piece of my stock WRX driveline except the trans mount and crossmember bushings, which I upgraded at the time. My stock clutch was still in good shape and my stock flywheel was able to be resurfaced.[/quote]

That's because you went with quality John...;)

psinuse 01-30-2014 02:42 PM

Not sure I should comment in this thread...

brfatal 01-30-2014 02:48 PM

^ me either brother

*Engine #8 and currently on year 2.5 of downtime

yamahauler27 01-31-2014 10:37 PM

Thanks for the input..I have a friend who recently put an STI tranny in his 03 WRX. He said that it's not real hard to do but that it does require having some custom axles made because the splines wouldnt work. This guy owns a custom shop and I've seen him do all kinds of engine builds and swaps. I do alot of custom welding for him and I weld roll cages for him..He mentioned that those transmissions weren't that good with extra power, so I'm gonna probably either take the route that man show took or look for a six speed STI tranny.

I should have been a little more specific.My main concern is the engine itself,once I rebuild it with all new forged internals and start putting more power under the hood, I'm trying to figure how much HP and torque to aim at to keep the engine itself dependable and still fairly easy to drive on the street.I do know a lot of that depends on me and how I drive it and maintain it. I think I have read enough info on this site and a few others to make a decision. I should have the rods,pistons,bearings,crankshaft,oil pump and timing gears on Monday. I'm looking forward to get this thing started. Like I said, this is my first Subaru build and I am curious to see how it ends up running against some of the other imports out here at the drag strip..I know they aren't built for drag racing,but they are so much fun..I would love to try some time attack racing if there were a track near me.


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