cutting manifold flange

Post by **virus77** » Thu Jul 22, 2004 6:16 am

I know people do it to their revhard manifolds to prevent cracking and warping, should the same be done to the JGStools manifold?

Post by **andrave** » Thu Jul 22, 2004 6:16 am

I will prolly do it to mine. Just make sure you wait till after you weld it up!

Post by **nab911** » Thu Jul 22, 2004 6:16 am

Do you mean portmatching it? My friend did it to his JGS to help the flow.

Post by **virus77** » Thu Jul 22, 2004 6:16 am

no i mean cutting the exhaust flange between the runners.

Post by **WAbernethy** » Thu Jul 22, 2004 6:16 am

I have a similar manifold and was having some cracking issues until I cut the middle piece out. I'm still keeping my fingers crossed but i haven't had any problems for a while.

Post by **:: orion ::** » Thu Jul 22, 2004 6:16 am

It can't hurt...

Case in point: People have complained or RevHard's cracking...but I opened the bolt holes and cut between the flanges on mine...and it's held up for +1.5 years.

It needs room to expand and contract...separating the flanges is good.

- Brian

Post by **sxseguy** » Thu Jul 22, 2004 6:16 am

My JGS tools manifold came with the flange pre-cut between the runners.

Post by **bbandit** » Thu Jul 22, 2004 6:16 am

mine didnt.. thats why my manifold is leaking all over the place

Post by **Structure240sx** » Thu Jul 22, 2004 6:16 am

i prepped my revhard like ::orion:: along wtih porting it out some and it has been great for for about 15,000mi

Post by **GoldZenkiS14** » Thu Jul 22, 2004 6:16 am

ok im about to use a rev hard and i know about cutting between the flnges and im gonig to that but what is it that you guys are doing to the holes?? someone let me know please .. thanksCarlos

Post by **GoldZenkiS14** » Thu Jul 22, 2004 6:16 am

also anyone using this manifold with the turbo mounted on the bottom? whats the difference for the top is it just to show of the turbo?

Post by **Structure240sx** » Thu Jul 22, 2004 6:16 am

top mount turbo usually will be easier to clear certain items and yes also for show. i guess it might work bottom mounted with the right turbo

we also drill out the bolts holes and i ported out the runners. i used a exhuast manifold gakst to match up the holes to port out

Post by **GoldZenkiS14** » Thu Jul 22, 2004 6:16 am

ok and how am i supose to know how much to drill out the bolt holes?? i can see the runners i can port them by going by the gasket but the bolt holes match up perfect with my mani

Post by **C-Kwik** » Thu Jul 22, 2004 6:16 am

The bolt holes need to be drilled out so that as the manifold expands, the studs from the head do not get sheared off. The holes should be progressively larger as you get to the outer cylinders. Though, you can also get away with ust using larger holes all around, but then it requires that you are a bit more careful in lining up the mani to the head as you tighten the mani to the head. According to Corky bell, I believe it is 0.1 inch larger for every foot from the center of the manifold.

cutting manifold flange

cutting manifold flange

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