I'm more used to doing V8 stuff, but I'm about to get involved in a speedway car here in NZ that specifies production block and 2 valve cylinder head, fed by 2 barrel carb through a restrictor plate, with max 10:1 compression and .500 valve lift. The 2 most popular engines are V6 Commodore and inline Falcon. Of course, I'm going blue so I'm trying to figure out the best combo to use.
Research I have done thus far leads me to believe that the AU block is best due to better bottom end integrity with the alloy sump with crossbolted mains and the steel main bearing cap brace.
When running a bigger cam the AU beehive shape valve springs run into coil bind issues and require significant machining in the valve spring seat area to enable the use of conventional style valve springs so tha EF/EL cylinder head is the better one to use as it already has regular style spring seats.
So, based on the above, it would seem that the best combo to use would be AU block with EL head (ideally Tickford).
Does this sound about right to any of you 6 cylinder gurus out there?

I'd say AU with a EF head.


All a muchness when built properly.

How far are you planing on reving it?

as far as heads go, If no porting is allowed, take you're pick of any of the tickford heads.
if you can port the head, start with an AU head.
AU rods are weaker then EF/EL rods.
the EF is the only engine to have the fully counter weighted crank.
People have also put more then 400RWKW through pre AU bottom ends.

I would be looking for an EF or EL tickford engine and have a good mains girdle made for the engine.

Won't be super high revs, maybe 6500 tops. Porting is allowed but a carb restrictor plate is required so there is no point in going too radical, just a general clean up. Most people use a centre point injection manifold with adaptor plate to run 2 barrel Holley or the OEM Weber. A couple of guys have started using the broadband manifold and milling off the throttle body mounting area and fabbing a carb adaptor to mount the 2 barrel onto and that's what I am looking to do.
Oh yeah, OEM exhaust manifold must be used.

just find an EF XR6 engine and give the ports a light tidy up.

Sorry to hijack the thread here but what about a full tilt drag engine running forced induction. same revs (possilby higher) but lots of boost. Still the EF engine with girdle or would an AU engine with beefed up girdle be the way? And what about grout filling? Considering it being a competition engine it wouldn't get that hot that quickly, would it?

with lots of boost i'd say the AU engine due to the sump bolting into the main caps. I'd still be having a better main girdle made though.

I'd also look at an external oil pump (staying with a wet sump) so you can run a full girdle.