I have a 10.5 hotside due to arrive this week and while I was preparing for the install, I noticed that the OEM echaust manifold's outlets to the turbo housing are appreciably smaller than the inlets for the old 9.8 hotside. The OEM gasket is also sized more closely to the turbo than the exhaust manifold.

I plan to try this with my car, but I was wondering if anyone else has ported out the OEM exhaust manifold exits to more closely match the turbo inlets and gasket?

 

how much material are we talking about? just curious cuz i have a 10.5 hotside coming also.

 

anyone got picture of that?

 

I gasket matched my exhaust manifold and turbo inlet. I later ported the exhaust manifold out even more, (not the gasket outlet, just the ports themselves).
There is ALOT of casting flash in the exhaust manifold and hot side. I was really suprized at the amount of flash at the turbo outlet where the gases meet the turbine wheel. There were flakes up to 1/16" going accross the outlet.
By the way, the exhaust manifold is very hard. It chewed up my burs.

 

My new 10.5 hotside showed up yesterday and it was even slightly more open than my old 9.8 one. After looking things over I'm having both matched to the gasket. That will open the 10.5 hotside about 1/16" most of the way aound both ports and will open the exhaust manifold about 1/8" around most of both ports.

I was a bit luckier than you; there was essentially no flash in any of the castings I have. Did you match the exhaust ports leaving your head to the exhaust manifold? In my car the runners on the exhaust manifold are slightly larger than the exhaust exits on the head. I've thought about matching those as well, but since the head work was done and verified on a flow bench, I'm feeling a bit more catious about making changes to the head.