Do I need a new Exh manifold? (Pics)

[hypnoticpimp]

As im pulling of my exhaust manifold to start porting it to a 7cm gasket, i realized it was already port matched to a 7cm gasket and whoever did it decided to make knife edge divider on the collecter...

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There are cracks on the inside of the collector as you see and on both side of the "knife edge" divider there are chunks that are missing... New manifold? Or can it be saved?


Oh yeah, Never buy arp stainless steel turbo bolts...dont ask why...

 

[lasertrash]

I would be worried about were the chunks are going. Those would probably be rough on the exhaust turbine. You should just buy my Fp manifold (). I would replace for safety.

 

[cougarelimin8or]

You'll need to get another manifold unless you or someone you know can brase.

 

[fwdmaster]

I would be worried about were the chunks are going. Those would probably be rough on the exhaust turbine. You should just buy my Fp manifold (). I would replace for safety.

I agree, you dont want junks flying in your turbine

 

[Rob10_99]

If something broke off, theres more cracks and more to fall off, get a new one.
How does your turbine look? =)

 

[kenamond]

The cracks on either end of the divider are 100% normal.

If you have the tools and don't have the money for the FP cast mani you can probably just shave the divider down, round it nicely (not knife-edge) and slap it back on. I assume you have the tools to do this, because you pulled it to port in the first place. I'm not sure what the performance impact would be if you only shortened the divider maybe 1/2"...play dentist and grind the divider down to where the "cavity" is gone and see how deep you have to go. The divider separates the cylinder 1 and 4 putts from the 2 and 3 putts for smoother flow to the turbo (which means less backpressure in the exhaust ports for your pistons to fight during the exhaust stroke and more efficient flow through the turbine), so you want some divider in there (check out Garrett turbo's "turbochargers 102" page about divided manifolds and turbine housings...it has the DSM exhaust mani as an example), but I have no clue how much difference 1/2" of divider makes. That FP mani is sexy, though.

It looks like #3 and #4 were running a bit lean. If it was hot enough to eat iron, I wonder what happened to the pistons.

 

[hypnoticpimp]

The fins are fine...none bent or chipped although they did look a lil grey...I guess I need to back down the boost... Im running my boost controller all the way out and the lowest boost i can hit is 14psi... If I run a line straight from the nipple to the wastgate, would that help lower it a psi or two?

 

[kenamond]

The fins are fine...none bent or chipped although they did look a lil grey...I guess I need to back down the boost... Im running my boost controller all the way out and the lowest boost i can hit is 14psi... If I run a line straight from the nipple to the wastgate, would that help lower it a psi or two?

Minimum boost will depend on your WGA and boost creep. The stock WGA pressure is around 9psi on a 2g. If I run min boost by unscrewing the MBC all the way, I get 9psi. If I run a vac line from the compressor to the WGA, I get 9psi, but this is on a FPB28 with ported turbine housing and 7cm^2 ported 2g mani. I think that means my WGA is the same as a T25, but who knows what FP does to their turbos? If you want to shitcan your boost, you can always disconnect the WGA arm from the hotside (0 boost if you have no creep).

 

[hypnoticpimp]

Yes, I also have the t25 wastgate arm and its ported just like yours but the lowest I can get is 14???? I think it has to do with my Megan o2 housng. The Megan recirculted dump does no match perfect with the wastgate exit hole on the turbo...


This is what I mean...

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This gasket mates perfectly with the hotside on my Fp bigt28. You can see the wastgate hole on the megan o2 housing is alot smaller. I tried porting the flange a lil to angle the exhaust into the hole but at the time i only had grinding stones and that took forever. Now that I have carbide burs Ill ange it even more. What you think?

 

[crimsondragon]

Nobody made a knife edge divider in your manifold. All stock manifolds have them. I also agree with Ken. Just port that divider down. As long as there's no cracks on the actual manifold itself, you're fine.

 

[jrohner]

Take the manifold off any turbo dsm and it will look similar to yours. I wouldn't worry about it.

 

[PieEyedPiper]

I think the manifold is junk and that it isn't worth the effort to restore. Mine with 115k miles on it looked nothing like that.
Why? Well it just isn't. A non cracked and burned to hell manifold can be had from the classifieds for $30.

Then again you might be surprised (in a positive way) if you try to clean it up.
Good luck.