porting 6cm to 7cm?

Big Red 211 · Aug 4, 2002

I was wondering if anyone knows the measurements for a 7cm turbine housing or how far you need to port a 6cm housing to get the right a/r ratio so I can use it with a Big 16G. I've seen a 7cm and 6cm housing setting side by side in a pic and have some idea on what needs to be done to the inlet and outlet ports but I've seen nothing for the inside of the housing where the wheel sets. I'm assuming something needs to be done to the inside right? I've done a search on this and a lot of people said they had a problem with the housing cracking when they ran high boost (over 20 psi) and it also kills power above 5000 RPM cause the a/r is way to small.
I want to do this cause it's an extra $200 for the 7cm housing and I would rather put that toward something else if I can.

Thanks,
Rusty

GSX4LIFE · Aug 5, 2002

The best thing to do is to port & remove the step at the top of the housing. Do not remove much, if any, metal from the bottom of the housing(where it narrows down). Removing material here will get it to the size of a 7cm, but the A/R will be all screwed up & cause severe lag issues. Then open up the area behind the flapper door. Now you can go nuts polishing. Polish the inside of the housing as far down as you can reach

Big Red 211 · Aug 5, 2002

So to raise the a/r all you do is port the bottom part of the inlet? So what parts are measured for the area and radius?

GSX4LIFE · Aug 5, 2002

No, you misunderstood me. You will not raise the A/R by porting the bottom part. It will open it up, but in the wrong way. Trust me. Trying to open the housing too mush will result in serious lag issues. If you really want the a 7cm housings, then buy a 7cm housing. But I dont think small A/R exhaust housings are a bad thing at all. Once again, do not remave much material from the bottom(where it narrows) part of the exhaust housing.

Big Red 211 · Aug 7, 2002

So do you know what areas need to be enlarged to increase the a/r ratio? Or what you measure to figure out the a/r?

I don't care if it has a little lag but I know I don't what it to run out of steam at 5000k.

NEO95GST · Aug 7, 2002

I just rebuilt a 14B and ported the HELL out of the exhaust housing even DEEP in and that mofo spools FAST shy of 2900 RPM's and i also have top end past 5000rpm...

trbotsi · Aug 7, 2002

If you're trying to port the 6cm exhaust housing to the size of a 7cm housing, it can't be done. The actual difference is in the scroll area, which can't be reached by porting bits.

NEO95GST · Aug 7, 2002

trbotsi said:
If you're trying to port the 6cm exhaust housing to the size of a 7cm housing, it can't be done. The actual difference is in the scroll area, which can't be reached by porting bits.

Thanks for clearing that up for me....

Big Red 211 · Aug 8, 2002

Thanks

It was just an idea I had. Thanks for the info.

porting 6cm to 7cm?

Big Red 211

GSX4LIFE

Big Red 211

GSX4LIFE

Big Red 211

NEO95GST

trbotsi

NEO95GST

Big Red 211

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