exhaust manifold choices benefits and waste gates

[compactfean]

So I've been rockin the ss autochrome equal Length mani for about 7 years now. upgraded Turbo to a gt3071r and been running that with supporting mods and have been running that for a year or so. Problem is even with the hks actuator I cannot keep boost stable because the internal waste gate and t2 flange. My question is. A: is there a t2 Mani w/ external gate? If not then I have to get my Mani fanned for external. Here is the next thing. With the t2. Flange and excess backpressure would a 38 NM wastegate be too small? I will be at 21psi. Also anyone have any luck with header wrap helping?

[codyace]

I can't believe the MR manifoild lasted that long...that's actually very good.

In regard to holding boost pressure the only true fix to the issue is going external (which you obviously know). The problem is most of the t2 setups that did offer them are gone (as they were s***). You can still use the OEM manifold and have the flange welded on, which is (ultimatly) the best setup of them all. Strong cast construction, good heat retention (helps spool up) and OE fitment.

38mm will be more than fine for the setup...when running such high boost, the wastegate does not need to work nearly as much as it will at 10 or so lbs. Even still, a 38mm will regulate 10 psi just fine on yoursetup.

I've been external now for 3 years and would never go back to internal if possible

[compactfean]

Thanks alot man. I just wanted some info from someone that's been in my boat. I think my buddy would trade me for his stock Mani. Can the stock Mani flow good power externally gated? I like the idea of more umph down low but will it hurt any top end? I've never ran a upgraded Turbo on a stock Mani.

[codyace]

Thanks alot man. I just wanted some info from someone that's been in my boat. I think my buddy would trade me for his stock Mani. Can the stock Mani flow good power externally gated? I like the idea of more umph down low but will it hurt any top end? I've never ran a upgraded Turbo on a stock Mani.

The stock manifold has proven to really be the best manifold for any t2 based turbo. Most tubular setups actually reduce spool up, and don't make any more HP up top...ultimatly we're all limited by the restrictive housing, so getting the gas their faster doens't help anything.

The OE manifold is actually a nice divided manifold (as it keeps 1-3 in the same side, and 2-4 in the other) to help create a better path to the turbo (not to mention it's divided all the way to the turbo gasket, sweetness).

If you really want a badass manifold, send it out to extude hone, and then to swain coat...you can't touch it!


In terms of power production, you'll see another 20ish troque from the stock manifold, faster boost onset, and good top end. I've had my setup copied a few times now all making 385-410 whp...not bad! Even the FWD cars (granted slightly different stock cast manifold) do well!