I have a New Cam to try, also 2" Headers, 102mm lid, 100mm maf, 103mm tb and changed to a lighter flywheel. Probably will do a run on E85 as well here soon.
Far as the Brodix Cathedral port, I haven't been able to find one person show me a na 427 make more power using them. I'd buy them if someone would. Maybe the BTR canted valve Cathedrals will be the ticket, cause I'm not spending 7k for Mast 295s with everything need to run them.

 

Probably a wise choice to stick with what you have and would only make financial sense had you started with a Brodix or MAST head. But you NA guys sometimes go to extreme lengths to get every last bit of power you can find.

PRC 247 intake valve - 2.120
Brodix BR1 intake vavle - 2.100
MAST 295 intake valve - 2.165

Any consideration to try a LLSR?

I too would be hard pressed to move backwards in valve size especially on a large bore cylinder unless I could be guaranteed improvement everywhere being a road race car.

It's not apples to apples as the examples below are all turbo cars but for the ones who have doubts about a cathedral port:

https://ls1tech.com/forums/drag-raci...ler-388-a.html

https://ls1tech.com/forums/forced-in...goes-dyno.html

Ironically both of those cars were/are owned by the same fella. The 3rd gen is still running an OEM style rocker with untouched BR1's.

I know Pete Harrell is a big fan of the MAST 295's and example there would be Cleetus/Leroy's engine running them.

I'm also really wanting to see more on these BTR canted valve heads in both ports (cathedral and square).

 

Why not LS7 heads?

 

Well tried alot of different things to make some gains.
So far I've swapped Cams
250/260.5 628 620 112+ 1.5
Added 2 inch headers
Fic 750cc injectors
E85 picked up 7 wheel 2* timing added lost adding more.
10 pound lighter flywheel
SD tune
104mm lid
103mm Tb
Magnum-f trans and fresh clutch
Weather was horrible 116 degree dyno room and alot of humidity
She's down power.

 

 

The weather is only 6 degrees higher than your first run on that dyno though. I feel like you stepped backwards on the cam by lowering the lift, maybe not much, but some.

I would say you would see some good gains having the msd opened up and going to a bit shorter runner in it (Ironmask would be my go to on this).

 

Martin Smallwood spec'd both Camshafts.
I ported the Msd and gained over the first dyno trip.
It has crossed my mind to shorten the runner's.
I've got a few ideas on why it lost. But I'm all ears if someone has insite

 

When you look at the graphs laid over each other, it seems like you have a restriction somewhere holding the whole combo back. I have to agree with 02Z06, the lift will limit your total possible airflow into the cyl. That being said, I still think a tweaking on your heads by a pro or going to another head/bigger valve will take it next level. Did you do anything to the PRC's before you dropped them on or ran them as is?

 

You mean the head that's notorious for dropping valves? I'd think that's enough reason to steer clear.

 

he meant Ls7 port heads, only the factory castings have the valve dropping issue, aftermarket Ls7 castings dont have this issue. Also the Ls7 makes way more power and tq and is also not limited when it comes to intakes. Pretty silly to use cathedral ports on a large cubic inch LS.