From several active threads, people have said that you should not/cannot use headers with a turbo. This makes no sense to me. The currently available turbo kits all use an "up pipe" from the exhaust manifold to the turbo, right? The Borla headers outlet is in the same position as stock, right?

So what's the problem? Cracking from the heat? I've seen photos of the Cusco headers, which can certainly take the heat from a turbo WRX motor.

The intended function of headers--evacuating exhaust quickly with as much velocity as possible--is completely compatible with a turbo.

Any insights?

The Minnam kit uses the stock 2.5RS header but it positions the turbo very low so there have been some oil return issues.

Will the custco headers fit on our engine? I thought the exhaust ports were in the same positions at the EJ20. Anybody?

If you want to use those headers, you need to get the turbo front cross member.

Jim

God, Chuck, you almost called them Costco, hehe. Its CUSCO and yes they fit, but yo have to get a WRX x-member and waterpump and do few other minor mods.

Most of the headers use larger diameter pipe from the head to the collector. While this is good on a NA motor, It is not "desireble" on a turbo motor, especially ours, with the turbo sitting 2 miles downstream from the exhaust valve. The velocity of the gasses slow down in the larger dia pipe, which in turns causes more lag because it can not spool the turbo up quick enough.
Another thing to consider is the thickness and type of the tubing. Our turbo's are not mounted solid to the motor, but rather it sits on top of the exhaust.... red hot pipe bends REAL ez and it won't be long before it cracks. On the WRX, the turbo is mounted to the Cyl head with a bracket which takes the load off of the header pipe.

MY2C
Andre

Thank you Andre, that's exactly what I wanted to know.

Brings up another question, though. If there is an "ideal" sized primary (header) which maximizes velocity and power for a given engine, does adding a turbo make that ideal size smaller? That doesn't make sense to me.

Well, you can only have that theoretical (SP?) ideal size at a certain specific RPM. So like everything else, you have to search for the ideal compromise....
That is where the smaller tube size on turbo motors becomes the best overall compromise. Yes, if you remove the turbo the car will be slower with the "turbo" header, and NA. Same thing if you install a turbo on a header designed for a NA aplication only. At wide open throttle, the car will probably perform better than the "turbo" specific aplication. But in everyday or track use, the lag will affect drivabilety, as well as track time.
Hope it makes a LITTLE more sence.... http://www.i-club.com/ubb-files/wink.gif
Andre

[This message has been edited by Andre Vandenberg (edited October 12, 2000).]

The larger header diameter headers will cause more lag, but it will also make more power up top.