7m exhaust manifold HKS ? or port stock ?

[LPC]

Hey Guys,

I am after a little more information on the above. Have removed the exhaust manifold on my 7mgte due to a previous owner stripping the nut that connects the oil return line back to the block, but that really is another story...

Now that the stock manifold is off, I am wondering if it would be a good performance upgrade. Now there is no question about it, I am, and always will be running a ct26. I have searched for quiet a bit of time today, and found that HKS did a cast exhaust manifold for the 7mgte, however, want to know if it is only for a t4 stud pattern, or if they did one for the ct26 stud pattern ? Failing this, could I use a t4 to ct26 adapter ?

OR, would be be worth porting out the stock manifold ?


Your input would be greatly appreciated,


Thanks, Jon.

 

[Compton74]

As far as I've seen hks only made the cast longrunner manifold for t4s.

And I really don't see any reason porting the exhaust manifold as it's already pretty well gasket matched.

 

[Quin]

I've heard from several people you can get decent gains from it. If you look inside a stock manifold, there are huge lumps where the studs for the heat shields sit. You can also take a lot of the meat out of the divider.

 

[Poodles]

Removing the lumps where the studs are can induce leaks.

If you're only running the CT-26, the manifold is not the bottleneck in the system, the turbo is. People have run bolt-on turbos over 500HP on the stock manifold.

 

[Dan_Gyoba]

If you're only running the CT-26, the manifold is not the bottleneck in the system, the turbo is. People have run bolt-on turbos over 500HP on the stock manifold.

This.

The stock manifold isn't a the problem. If you want to change to a different turbo, then choose the turbo first, then choose the manifold to suit. Don't rule out "bolt-on" turbos just because they use the stock manifold though, it's really not a problem.

 

[SideWinderGX]

Porting the stock manifold spools the turbo about 4-500 rpm quicker iirc.

 

[mk3_7m]

^ I reckon it would probably do the opposite and lose some low-end since you making more space to be filled in.

Not like it would make a noticable difference.

 

[SideWinderGX]

Ovenrude ported/ceramic coated a spare one I bought a few years ago and I had it dyno tested. Spool time was decreased...the thread is on SF I believe, and I have the dyno chart lying around here somewhere...

 

[Enraged]

some of your pictures don't work, but a very helpful post anyways: http://www.supraforums.com/forum/sh...manifold-EBC-results&highlight=manifold++port

I sent ovenrude a PM to see if he still does it. how much did yours cost for the porting?

 

[mk3_7m]

Well I guess theory can't always be correct.

Maybe restriction was freed up more.

 

[SideWinderGX]

Shit, all of my pictures don't work. They might've been on his photobucket account, unless mine got deleted. He might've emailed them to me, lemme see if I have them anywhere, theres a good picture of the inside...

Last I checked he doesn't work at that machine shop anymore, although he still might know the owner(s). I think it cost $250 for the porting and ceramic coat together (package deal), I'm pretty sure it wasn't over $300. Difference in top end power on that dyno graph is because I put in a boost controller, but spool time wasn't affected (did a run with BC off on wastegate spring pressure).

edit: Kidding, he sent me those links and I pasted them into the thread. The ones that work are the only ones that I have =\ One of them shows the smooth ports though.

 

[Enraged]

some of the links worked

 

[IJ.]

You can only get a couple of inches in from either end so it's a waste of time and effort...

Look into "Extrude Honing" if you're at all serious about porting a stock manifold to get some real gains.

 

[SideWinderGX]

He got very nearly all the way to the center on that manifold, and I'm happy with the results :shrug:

 

[IJ.]

He got very nearly all the way to the center on that manifold, and I'm happy with the results :shrug:

Can't see how you could do it with any degree of accuracy/surface finish, there are a bunch of spots from memory you can't get to at all, at least with Power Porting (extrude hone) it's a uniform material removal from one flange right through to the other.

 

[Enraged]

last time I asked for a quote on extrude honing, it was over $500