im building a pre he v12, and was curious as to what anyone has done on here for performance? im most likely bringing the car to 7l with a TWR crank, im just interested in the heads, valves and such. Anyone who has any information let me know! thanks

 

I'm doing the same here in melbourne. Heaps of bottom end info, but I'm coming up blank on heads. I'll have to give Rob Beere a call and chat to him and see what he recommends.
Let me know how your build goes..

Regards
Chris

 

I will! im told you can use.the stock valves for up over 500 hp. but we will see what happenswhen I put it together

 

I understood that in the US, Tullius Group 44 used almost all of the pre-HE heads in his XJSs, depleting the used supply of heads to re-valve?

 

i dont think Grp44 used all pre heads, i just junked 6 of them, i got $10. each.

also junked 3 V12 pre engines,got $75. for the lot.

junk is junk, until some one needs it.



grp 44 went thru a lot of engines because they are not that strong, after around 450hp they show the weak areas, but back then we didnt have a lot of experiance with V12 Jag.

for a perspective; the latest Nascar engines, use test specs, like 9500rpm, at full output, for at least 2hrs, steady, on the dyno.
try that in your spare time!

and using a marine engine for reference, is not realistic for road car, boat engines have an ocean of cool water before they overheat, unless someone does something silly.