Also believe that put compression at 10:1 from the stock head-stock bottom end compression of 9.2:1 ....and that was a BIG bump to my Ecam w/ head porting.
These are the real GT40's. Found only on Cobras and 96 Explorer only. (From what I've heard)
I don't know what thermactor ports are. Do you mean the smog tube connections? If thermactor ports are the smog tube holes, then no, they don't have them.
Yes, the smog tube connections. There are a few versions of the GT-40 head. You are correct that that head is found on the 96 explorer and Cobra, but it should be a 94-95 Cobra head. the 1993 Cobra WILL have the thermactor bumps.
The F3 part number is curious though.
It doesn't matter for your application. It's more my curiousity and info gathering
Yes, the smog tube connections. There are a few versions of the GT-40 head. You are correct that that head is found on the 96 explorer and Cobra, but it should be a 94-95 Cobra head. the 1993 Cobra WILL have the thermactor bumps.
The F3 part number is curious though.
It doesn't matter for your application. It's more my curiousity and info gathering
Negligible difference in performance. Only a concern if you are running a stock H-pipe with the 4 cats. The thermactor ports feed O2 to the first pair of cats during engine warm-up to help with the "conversion" process. After they warm up, the ports are closed off.
Some guys are concerned with that sort of stuff working as it should. Some could care less.