I was just wondering the strong and weak points of both, like if one is better for forced induction over the other, etc. It doesn't have to be a novel either, lol. I'd hate for someone to go through that much trouble for this. I see a lot of 23° users and I remember something a while back about a member going with the 18° heads instead. It was a SB 427 twin turboed engine if I remember correctly in an 82ish vette. I'll be going with a similar engine, just naturally aspirated. Thanks in advance for those that shed some light on the differences.

 

Considering all that needs to be changed to take full advantage of it (Jesel valvetrain, custom pistons,intake, header flanges, etc), and the extra cost over conventional 23 degree stuff, I doubt its worth it on any NA setup. I have looked into it for my twin turbo small block project (buying all new parts anyway), and I'm not convinced its worth it even for that. One magazine article on Troy Trepanier's TT "Chicayne" had a quote from turbo engine builder John Meaney saying it was worth 150hp over a set of 23 degree heads, but at the 1000+ hp level is another 150hp really that important?Not in a street car. Another factor is replacement parts; sure, you can order them from Summit, but that does you no good on the side of the road in BFE! I'll likely stick with a good set of 23 degree AFRs.

 

What are you talking about all the extra stuff that has to be changed???
I have G2 TW heads that have 16* int / 18* exh angles. Nothing out of the ordinary on my engine.

 

Most 18 degree heads require completely different valvetrain setups...the 23 degree stuff won't work. From the Summit catalog, under Trick Flow 18 degree heads:
NOTE: Offset shaft mount rockers and mechanical roller cam with offset lifters required.

The Brodix 18 degree heads don't require any valvetrain changes, but thats the only one I know of that uses the old 23 degree stuff.

The pushrods are typically different length, the aforementioned intake manifold (not many choices there, none for EFI unless you're building a system from scratch), the header flanges are different, pistons (if you're running lots of duration and lift) have to be notched differently...you name it. Too much hassle.

 

My TF's and the TF 18 degree heads your looking at are two different heads. Those new 18 ones flow ungodly amounts of air.
Mine are ported G2's. I use regualr harland sharp rockers. Regular hydralic flat tappet comp cam xe274.

 

Oh, you have the Twisted Wedge heads...different animal completely.