6cm gasket to 7cm gasket

[91-gsx]

i have a 6cm gasket, has anybody modified it into a 7cm. it is a new 6cm so i was hoping that i might be able to do this. the reason i ask is because i bought a 2g manifold that i want to port match to the turbine housing. i am having boost creep problems and this would hopefully eliminate it. 6cm= 2.36220472 inches, and 7cm= 2.75590551 inches. so i could cut out the old gasket to match 2.76 inches, but do you think it will match other 7cm turbine housings so that i do not have to port an aftermarket turbo when i get one? any experience will help.
thanks

 

[oldman]

If boost creep is what you have then it's the turbine housing which you need to port, not that port matching both the manifold and turbine housing to a 7cm gasket is a bad thing, just want you to know that porting the manifold will do absolutely nothing for boost creep.

 

[91-gsx]

oldman: If boost creep is what you have then it's the turbine housing which you need to port, not that port matching both the manifold and turbine housing to a 7cm gasket is a bad thing, just want you to know that porting the manifold will do absolutely nothing for boost creep.

o i see, i always thought i had to port match them so that the exhaust actually flows into the wastegate a little more easily. so oldman, i do not actually have to make the turbine housing a 7cm opening, i can open it more or less right? just as long as the wastegate passage is a lot easier to get to? do you think the idea that i had about modifying the 6cm gasket into a 7cm gasket is a good idea, or do youhave another idea, because i do not want to spend $20 for a 7cm gasket if i do not have to.
thanks for the help

 

[WatchItExplode]

If you're porting your manifold to match the 7cm housing, you definately need a 7 cm gasket, whether you buy a 7 cm one or modify your 6cm, or else you're wasting your time porting. Modifying your 6 cm gasket might work okay for a while but it's more likely to blow out and/or leak than, for example, the stainless steel 7cm gasket RRE sells. In my opinion, 20 measly dollars is worth it for a gasket that will last forever.

But yeah, as oldman said, doing this will not fix boost creep. If you do a search, there's all kinds of pictures and stuff of how-to and where-to port to reduct boost creep.

Good luck

 

[larsrya8]

How to cure boost creep by porting

 

[oldman]

o i see, i always thought i had to port match them so that the exhaust actually flows into the wastegate a little more easily.

Nope, port matching both the manifold and turbine housing to a 7cm gasket is always a great idea but it's purpose is to increase flow and improve spool, boost creep is a different animal all together. Go through this thread here carefully and you will know what I'm talking about, this is the thread which eventually developed into the tech article larsrya8 linked you too. Study both links then come back and ask questions if need be. We can also have you post up pictures as you proceed with the porting project to ensure everything is done right.

do you think the idea that i had about modifying the 6cm gasket into a 7cm gasket is a good idea, or do youhave another idea, because i do not want to spend $20 for a 7cm gasket if i do not have to.

If your 6cm gasket is thick enough, go ahead and modified it yourself, just make sure you clean it up really well so both surfaces are flat.

The key to successful porting is the attitude. If you're looking to just do enough to get by, especially porting for boost creep, you'll most likely fail and you should stop wasting time and just go for an external setup. If you're looking to do as much as humanly possible, whip out the grinder and let's get to work.

 

[bullettdsm]

Skip the gasket. I tried that on my 7cm (the port of the turbo was bigger than 7 and I don't like interference). Worked for a little while then blew out. Use Permatex Ultra Copper High Temp RTV. Others on here swear by it and it REALLY does work! Use it everywhere on your exhaust except the head to mani connection. Cost: $4.95 + tax.
MB

 

[91-gsx]

i understand what to port out and how much of it, basically as much as i can not as much as my lazy ass wants to.... i was just simply asking if anybody had modified there gasket to do this and got my answer. i also thought that i had to port match the manifold, and i got my answer on that. the high temp rtv stuff sounds good as well. one other question, is the housing cast iron softer then the exhaust manifolds cast iron, just wondering because i thought i heard that somewhere?
thanks for the help you guys

 

[oldman]

i understand what to port out and how much of it, basically as much as i can not as much as my lazy ass wants to.... i was just simply asking if anybody had modified there gasket to do this and got my answer. i also thought that i had to port match the manifold, and i got my answer on that.

So you're the guys who just want to do enough to get by.

one other question, is the housing cast iron softer then the exhaust manifolds cast iron, just wondering because i thought i heard that somewhere?

Yes, the manifold is much harder than the turbine housing, you'll know when you port them. Good luck.