Stock exhaust manifold question

[uber95]

I'm not having much luck with the top mount thing, so I thought what the hell. Anyone have any luck porting a stock exhaust manifold? I figure it can't hurt.

[themadscientist]

depends on your goals. Are you talking about an RB20/25 or 26?

[uber95]

It's an RB20. I'll be upgrading ECU, injectors, turbo, adding meth/H2O injection and have a very good front mount. Looking to make a very safe 300+ whp

[SeVa-S13]

300whp is nothing for the 20. If you know what you're doing, mild porting should help flow and spool...but I seriously doubt you'll need any sort of injection w/ a bigger turbo.

[DriftingisLame]

Have a little faith in the stock exhaust manifold.. The only beef I really have with it is that its ugly. It fits perfect, bolts up a grip of different good turbos, and it will probably never ever break...

If you get discouraged about the lack of flow, think of all those benefits, and the fact that it will spool faster than most aftermarket mani's

[uber95]

I'm a real conservative when it comes to build ups. I'd rather have a whole lot of "head room". The turbo is a custom hybrid from a local shop, I'll be running 93 with 18PSI and I live in hot and humid central Florida. The water injection is cheap insurance that I've run on the last half dozen turbo cars turbo cars for the past 10 years, very simple to build and works well. I hadn't planned on removing the exhaust due to not finding a suitable top mount in the range of $$ I was willing to spend, but it has 2 broken studs that just were found I removed the mani and thought what the hell, may as well port it as long as it's off. I did notice that gasket matching will be a breeze, it seems to be really close as it sits.

On a side note, SeVa I see you have a VR4, I owned #666/2000. Sold it locally about a year ago (wife HATED that car )

[Darius]

Yeah the head ports are very close to the exhaust manifold ports. The biggest advantage will be to remove the casting bumps and burrs. A lot of guys in Australia have had good luck and gains with extrude honing the stock manifold. However, many balk at the price because a custom manifold can be had for about twice the price of an extrude hone. I dunno, maybe you have connections to that though.

[themadscientist]

That manifold will take you to 300, concentrate on more important things, a nice upgrade turbo bigger injectors, RB26 OE would be good, a FMIC and some good fuel control SAFC at least.

[Chaos the Xile]

I'll sell you mine it is tapped w/ a Tial 38mm w/g makes 405WHP no problems