eng/exhaust direction

[Innkeepr]

We are almost ready to start the engine build. I was going to just replace rings/bearings/gaskets, as the motor has 44K on it.
I was thinking of a new set of cams, and a larger turbo, which led to a discussion on the exhaust.
according to what I read - this motor made 280hp. would like to see mid 3s, without going boost crazy.
I am trying to stay away from replacing everything ( injectors/TB/) - Mgt will be via Megasquirt.

Has any one used an equal length header set up ? I have always used equal length on my V8 builds, applying same principle with this.
This is the first Turbo build for me, Is one exhaust more restrictive thus detrimental to having a "happy" efficient turbo ? or is the restrictive header better for a faster spool ?
I have heard both and still confused. I have heard both installed on a stock WRX and they have different tones, some like it, others don't.

As far as cams, specs on the ej207 for duration/lift. are listed as (adv) 256°/256° (at .050) 205°/210° (lift in inches) .325"/.339
Have seen Crower cams that will fit a 207 as a plug & play listed 266°/268° 220°/222° .400"/.400"
Has anyone used these cams? are they worth it ? do you recommend something different ?

As far as the header, looked at the Perrin and the Tomei - both comparable in price.
Any thoughts/advice ?

Thanks for the input.
"E"

[longislandwrx]

a few benefits of headers... weight savings. slight power increase.... that's about it?

unequal length headers are easier to produce (read a little cheaper), don't require an sti oil pan and maintain the subaru rumble

the equal length obviously equalizes pressure, aids in scavenging, costs a little more and requires a new oil pan on a wrx engine. maybe you make a little more power...

also most elh should be really be called almost equal length headers with the exception maybe of the holy header, the tubes are close to equal but in my experience, I'm guessing a few inches off. ground clearance is also an issue with certain header models.

tube size is critical for a good spool time vs top end power by increasing exhaust velocity. Perrin actually offers two sizes of primary tubes for different hp goals, most builds are better off with the smaller tubes.

you also need to keep the heat in there too so wrap/coating will be essential.

you used to be able to send your stock manifolds to grimmspeed for porting, and a new high flow crossover pipe. all the benefits of the factory manifolds, heat retention, lifespan etc with the flow of a header.

that being said now that grimmspeed isn't porting stock manifold and most people don't have the time, carbide bits or flaps to do it yourself, a header is really the only option... although just a crossover pipe will give you a small boost. grimmspeed and element still make them.

in the end I went with the Perrin header. $300 in like new condition, hard to say no to.

sorry for ranting, heh.


It can always be a down the road project... the underside of the engine is very exposed and you should be able to change it out later easily. someone correct me if I am wrong.

[STiPWRD]

would like to see mid 3s, without going boost crazy. I am trying to stay away from replacing everything ( injectors/TB/) - Mgt will be via Megasquirt.
If I understood correctly, you've got an ej207 sti motor, with sti injectors, correct? If so, you'll be close to maxing them out with hp (at the engine) in the mid 300's. You may want to upgrade your injectors, especially if you're thinking of upgrading your turbo. I'm using modified wrx injectors flow tested at 824cc. I think they were $150.

Headers: IMO equal length headers will make the motor sound like a civic. I'm running the Megan stainless UEL headers, which are much lighter than stock, keep the subaru rumble, flow better and clear the 02 wrx oil pan (although I'm using an 06 sti pan).

Cams: If you're upgrading the cams, I'd recommend also upgrading the springs as well. I'm running the crower 264 cams, springs, and retainers. I also went ahead and got ferrea valves and sti shimless buckets. I'm still breaking in my motor so have not dyno tuned it yet but otherwise it's running very nicely.

Turbo: My goal is also to be around 350 hp and I'm running the 18G. There are lots of good options out there.

[TrickyPete]

+1 on the ground clearance comment. I bought a set of UL wrx headers and they are about 2" below the frame. They will most likely be ripped off on a small bump if I attempt to use them on the road. I'll post a picture this afternoon when I get home.

[Sgt.Gator]

I've had the header discussion with my tuners at Cobb. The problem with all headers is that a large % of them will crack. And it doesn't matter how well they are made or who made them, Cobb has seen them all crack. Wrapping and coating them actually makes it more likely to crack. The Perrin ELH may spool you up 300 rpm faster and add a few HP/TQ.
The stock system virtually never cracks.
So the risk for me is that at a race weekend if the header cracks my weekend could be lost. Or at least that one race is over when I'm black flagged. So far we've decided the risk is not worth the gain. I could get as much power by dialing up the tune a little bit. I'm already at the limit for HP/WT in the ST class so it's not worth the risk.

[Innkeepr]

OK -valid insight as to the elh vs stock - didnt think about clearance.
STi - did your Crower come as a kit ? looking at the website, I cant see that cam. Website says use of the cams requires upgrade to fuel system -
Found some 800cc injectors for under 300, looks like 70 mm TBs are under 100 bucks.
Any idea what the stock TB is ?

[longislandwrx]

iirc stock internal diameter intercooler to throttle 65mm, throttle to manifold 60mm

for your power goals, you don't need an aftermarket throttle body though.

Gator, why would you get black flagged for a cracked header, are you saying in the event of a catastrophic failure?

[STiPWRD]

I purchased the cams and springs back in 09 from here:
http://www.jscspeed.com/catalog/Subaru/02_07_WRX_STI/Engine_Internals/Crower_Camshafts_Valve_Train_Kit_for_02_07_Subaru_ WRX_STI.html
Looks like the current prices are $683 for the cams I got and they recommend the spring and retainer kit 84185 for another $304, so the price has only gone up a little bit in 6 years.

Upgrading the fuel system is a good idea if you're planning on making more power than stock, this basically means a better fuel pump and higher flowing injectors. Does your engine use top feed injectors or side feed? I had my top feed wrx injectors modded and flow tested by Andrewtech for a reasonable price, I believe it was $150 but this may have changed.

[Innkeepr]

I purchased the cams and springs back in 09 from here:
http://www.jscspeed.com/catalog/Subaru/02_07_WRX_STI/Engine_Internals/Crower_Camshafts_Valve_Train_Kit_for_02_07_Subaru_ WRX_STI.html
Does your engine use top feed injectors or side feed? I had my top feed wrx injectors modded and flow tested by Andrewtech for a reasonable price, I believe it was $150 but this may have changed.

I have SIDE feed injectors. Have looked at a few different shops that sell 850CC injectors for $400, I can get mine modded & flowed for less than half ? that's a no brainer.

[STiPWRD]

I have SIDE feed injectors. Have looked at a few different shops that sell 850CC injectors for $400, I can get mine modded & flowed for less than half ? that's a no brainer.
Well looks like Andrewtech no longer offers injector modding but they said to contact Deatschwerks. So give that a shot, I'm not sure what they charge though.
http://www.deatschwerks.com/services/fuel-injector-services