Porting Standard Exhaust Manifolds

[manage13]

Hi Everyone, just wondering if anyone has ported standard RB26 exhaust manifolds. I'm thinking of opening up the the side the turbo bolts on to. Is this something I can do? Or is it best left to a professional. Not too sure if I'd effect the flow of the manifolds.

Has anyone attempted this before?

[R31Nismoid]

Can be done, few people have done it over the years.

It's pretty cheap (i think $300, can't remember the exact price). There is a mob that does changeover ones so nice and easy.

Somewhere in Syd im pretty sure, might have been UAS.

The issue though, is the turbine housing is the restriction. Have a look down there, don't matter how much flow you get to it, it's only going to go past that little hole so fast.

If you can make 380rwkw and run some of the fastest circuit times in the state on OEM, don't know why you'd need to port something that at the end of the day is limited by another factor.

Money better spend elsewhere IMO.

[gtr fan]

I recently paid an exhaust $60 to open up the turbo flange on both manifolds (I think this is what your after). A lot of people have done this themselves with the right tools / grinding bits (I am pretty sure theres a tutorial or thread someone created showing what they did.

Either way at least open up the flange so it matches the flange opening on the turbo.

[Lukas 33]

If you trust yourself a die grinder will do the trick

[XRATED]

Match it to the gaskets (on the inside) that go with the turbo's your putting on. Then get it extrude honed for max flow.

I made 398rwkw with dead stock ex-manifolds with T517Z's tho.

If you've got them off, dooo iiiittt.

[manage13]

I made 398rwkw with dead stock ex-manifolds with T517Z's tho.

Results speak for themselves. Thanks all for the input my just get the standard manifolds hpc coated and slap them on.

[R31Nismoid]

Match it to the gaskets (on the inside) that go with the turbo's your putting on. Then get it extrude honed for max flow.

I made 398rwkw with dead stock ex-manifolds with T517Z's tho.

If you've got them off, dooo iiiittt.

People have made 440rwkw off 100% factory, unported/touched items

[doo doo]

Your flow is fine with standard, the benefit is not flow, but boost response- I reckon i got between 200- 500 rpm better boost response after port matching the turbo side of my ex manifolds, which makes a difference with a GTR. If your bolting higher flowing turbos on the gains will be even more valuable to combat a laggier setup. Easy to do, if your manifolds are off, use the old gaskets as templates. Just need a decent die grinder and burr, and a good care factor.

[Dale FZ1]

It comes down to balancing the cost vs power gain vs response improvement vs application, and/or whether you or your mate has the time and gear to do the job. Be mindful of what a set of fabricated manifolds cost too.

Casting quality ex-factory isn't bad, but they are mass produced and not subjected to any significant finishing once they've left the foundry.

There will always be a "weak link" when you start modifying from stock, but I think the important bit is to reduce restrictions where possible. There might only be percentage gains, but if you've got access to the gear and a bit of drive to learn and improve things, then go for it.

[XRATED]

If they're off allready... port match them before you coat them. It's worth the ccouple of hours to grind them out.

If they were allready on, I wouldn't bother.

[bbe]

don't know why you'd need to port something that at the end of the day is limited by another factor.

Money better spend elsewhere IMO.

What a useless response, nearly in every car modification their is always something else that will limit something.

Every mod always contributes to something in the end.

Match porting would not have been thought of if it was useless.

If manifold are off mate atlest get them match ported if not extrude honed if have the coin.

i had extensive porting done on my manifold/exhaust housing with noticeable differences !

[manage13]

People have made 440rwkw off 100% factory, unported/touched items

I hear ya Ash but I had a quick measure of how much meat I can take off and it's quite a bit. Have a look at the pics below (used red markings to better display the area I'm going to grind away.)

I think I might get some (however little) benefit grinding this section out.

Not sure about what tool to use to grind this section off so I might have to visit All Tools. I have a good burring tool (pictured below) for stainless but I'm not sure if that will do to smooth the area out.

Any advice?

[D_Stirls]

the finish won't be to bad with the Burr, if your really worried then grab some of these and to finish it off.

[GTRNUR]

Don't match port to the gasket size as per your picture, you will be removing too much material. You want to match port to the inlet side of the turbine. Use your gasket as a guide to measure how much material has to be removed by comparing the exposed metal visible with the gasket on the turbo, and then on the manifold, then mark the diference.

Depending on what turbo's your using the amount of material you remove will vary. Ive match ported some standard manifolds to a pair of HKS GTRS's and the amount of material that had to be removed was only about 4mm.

You carbide burr will be fine, just be sure to have someone assist by spraying the burr and manifold with water when your die-grinding, or the generated heat will damage the burr pretty quickly. Water works as a cutting agent too so the whole porting process will only take about a minute per manifold.

I wouldnt be too concerned about finish. When you get them ceramic coated the outside and inside of the manifolds are garnet blasted which prepares the surface for adhesion of the coating. Then once sprayed, the internal ceramic coating will fill any surface imperfections very quickly.