Big Cathedral Ports
Agreed it could be good thread. I know OP's dyno thread is quite impressive with the current cathedrals.
Mike Lough uses the Brodix BR1-13's on some of his builds and HED just put those MAST 295's on Leroy's 388. Brought it it down from 427 to get more RPM, as in 9000rpm if need be.
Looking at port size, intake/exhaust valves, and valve angle
Brodix 245cc - 2.10/1.60 (13.5 degree valve angle)
FED 265cc - 2.13/1.61 (10 degree valve angle and also uses a LS7 rocker)
MAST 295cc - 2.25/1.60 (12 degree valve angle)
OP, maybe give HED a call and discuss those MAST heads for NA, I'd be hard pressed to say that you wouldn't pick up some more power over your PRC's. Probably would be time to start thinking about a porting your MSD too.
Mike Lough uses the Brodix BR1-13's on some of his builds and HED just put those MAST 295's on Leroy's 388. Brought it it down from 427 to get more RPM, as in 9000rpm if need be.
Looking at port size, intake/exhaust valves, and valve angle
Brodix 245cc - 2.10/1.60 (13.5 degree valve angle)
FED 265cc - 2.13/1.61 (10 degree valve angle and also uses a LS7 rocker)
MAST 295cc - 2.25/1.60 (12 degree valve angle)
OP, maybe give HED a call and discuss those MAST heads for NA, I'd be hard pressed to say that you wouldn't pick up some more power over your PRC's. Probably would be time to start thinking about a porting your MSD too.
295cc cathedral ports, WHEW!! Should have plenty of flow, but makes me wonder about airflow speed. I agree this would make a dandy FI head. Also the only head I've seen-Cathedral or rectangular-with 2.25" intakes!! 
Agreed it could be good thread. I know OP's dyno thread is quite impressive with the current cathedrals.
Mike Lough uses the Brodix BR1-13's on some of his builds and HED just put those MAST 295's on Leroy's 388. Brought it it down from 427 to get more RPM, as in 9000rpm if need be.
Looking at port size, intake/exhaust valves, and valve angle
Brodix 245cc - 2.10/1.60 (13.5 degree valve angle)
FED 265cc - 2.13/1.61 (10 degree valve angle and also uses a LS7 rocker)
MAST 295cc - 2.25/1.60 (12 degree valve angle)
OP, maybe give HED a call and discuss those MAST heads for NA, I'd be hard pressed to say that you wouldn't pick up some more power over your PRC's. Probably would be time to start thinking about a porting your MSD too.
Mike Lough uses the Brodix BR1-13's on some of his builds and HED just put those MAST 295's on Leroy's 388. Brought it it down from 427 to get more RPM, as in 9000rpm if need be.
Looking at port size, intake/exhaust valves, and valve angle
Brodix 245cc - 2.10/1.60 (13.5 degree valve angle)
FED 265cc - 2.13/1.61 (10 degree valve angle and also uses a LS7 rocker)
MAST 295cc - 2.25/1.60 (12 degree valve angle)
OP, maybe give HED a call and discuss those MAST heads for NA, I'd be hard pressed to say that you wouldn't pick up some more power over your PRC's. Probably would be time to start thinking about a porting your MSD too.
I seen something about a motor making 615 tire with some 275cc cathedral deals years ago... I think I'd need to see 40-50 more to justify the 6k plus im seeing.
Belive the BR1 gets finished out around 250cc or so, not sure if the valves are enlarged with the work over though.
I seen something about a motor making 615 tire with some 275cc cathedral deals years ago... I think I'd need to see 40-50 more to justify the 6k plus im seeing.
I seen something about a motor making 615 tire with some 275cc cathedral deals years ago... I think I'd need to see 40-50 more to justify the 6k plus im seeing.
Last edited by grinder11; Oct 7, 2023 at 01:58 PM.
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With everything I've been told from the mouths of experts, a raised square port design with shallower valve angles and straighter shot to the port will have the greatest high rpm potential. I would not run a cathedral in a big cubic inch racing setup, especially boosted. Maybe if you are in the market, you should call mast motorsports and ask Darren yourself, I'd be curious why these exist. Must be a market for them somehow.
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With everything I've been told from the mouths of experts, a raised square port design with shallower valve angles and straighter shot to the port will have the greatest high rpm potential. I would not run a cathedral in a big cubic inch racing setup, especially boosted. Maybe if you are in the market, you should call mast motorsports and ask Darren yourself, I'd be curious why these exist. Must be a market for them somehow.
No, but I like the idea of the 10° angle on the FED heads, but that's not the end-all, be-all. But on a smaller bore, it would definitely help with shrouding. Dont know the minimum bore size, but guessing LS3s 4.065?..