CR Exhaust Ports

XLR8R

XLR8R

Crew Chief
Joined
Sep 10, 2007
Messages
2,364
Anyone ever grind out the bottom of the exhaust ports of a CR to match an aftermarket manifold (full-round, same as the gaskets)? Short-side radius, if you will.

... can't imagine the step would be beneficial as anti-reversionary in a turbo exhaust tract.
 
My ex. ports were bigger than the HTT manifold after they were ported. So I spent a day porting the manifold to match the head. Plenty of material can come out of those head ports.
 
mine are ported along with a little taken out of my ATS manifold then it was jet hotted. There's a lot of metal that can come out of the ex. side.
 
this seem to help spoolup or egt's more, or has anyone done a before/after on this rather than do it while its being built and changing muitlple things?
 
Here's a couple picks of a manifold off a late 05' HO. Looks like the holes vary between 1.5" and 1.56" diameter. How big are the HTT/ATS/BD manifolds? Might get an idea how much material the porting experts are removing.
 
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Since being in a pressurized system, it might help. On a N/A motor, if you cut out the bottom arc, you better be spinning 8K to make up for it. Arc usually helps guide the exhaust out of the valve.
 
IMG_0644.jpg



:woohoo:
 
I agree Erick; D-ports are best on medium-RPM NA gassers (Pontiac proved that back in the '60s), but I'll take round instead for a CTD's tight exhaust side... I'm grinding the exhaust ports to match the gasket and radiusing the manifold's entry/runner where the milling machine stopped.
 
Mine were done at time of install didn't want to have to remove it all to many times. Everyone is right alot of material will come out and still have alot left. Inside has been polished to. But didn't look that pretty^^^^^^^^^.
 
Waiting on stock and ported and polished hard data- then we can talk about public consumption thru a very reputable vendor.....
 
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