"Cathedral" or Rectangular" Cylinder Heads ?
Teching In
Joined: Mar 2010
Posts: 46
Likes: 0
From: Pensacola, FL
Rotofab, Kooks LTH's, 223/232 .625/.598 112 +0 cam, heads ported, polished, decked .030", .036" cometic head gaskets, ported/polished intake by Rick, ported TB, 2800 Coan Triple disc converter, ZL1 fuel pump, LS9 valve train w/PAC-1219x springs, LS7 MAF, ported throttle body.
My compression is between 11.7-11.8:1 and we did end up fly cutting the pistons even though we had plenty of clearance. I am going to switch over to a vararam intake and install a set of tri-y headers (better power through the curve) and put in a set of 3.27 or 3.45 gears and I will hit 10's with that.
My compression is between 11.7-11.8:1 and we did end up fly cutting the pistons even though we had plenty of clearance. I am going to switch over to a vararam intake and install a set of tri-y headers (better power through the curve) and put in a set of 3.27 or 3.45 gears and I will hit 10's with that.
Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
I like the sound of that but how can you be sure that similar spec rectangular port heads would not provide a similar result (if not better)?
Looking at the flow charts on their website they do outflow my budget CNC LS3 heads but aren't they like twice the price?
If anyone has heads to sell me please PM me, I really want the best from this combo but new heads dont fit the budget, used heads will though.
Looking at the flow charts on their website they do outflow my budget CNC LS3 heads but aren't they like twice the price?
If anyone has heads to sell me please PM me, I really want the best from this combo but new heads dont fit the budget, used heads will though.
Teching In
Joined: Mar 2010
Posts: 46
Likes: 0
From: Pensacola, FL
heads are only part of the equation with a proper L92 setup. The cam is the most important part as bigger cams with these heads on a 4.000" bore setup may yield a higher peak HP but will suffer greatly though the low and mid range as they are incredibly sensitive to timing events.
Thread Starter
TECH Enthusiast
Joined: Apr 2010
Posts: 651
Likes: 10
From: North Carolina
heads are only part of the equation with a proper L92 setup. The cam is the most important part as bigger cams with these heads on a 4.000" bore setup may yield a higher peak HP but will suffer greatly though the low and mid range as they are incredibly sensitive to timing events.
Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
OK this is where I also hit a hurdle, rocket - are you saying that cathederal heads are less sensitive to valve timing? I know flow numbers are not the be-all-and-end-all obviously but cathederals just seem to flow so much less than LS3 style heads, though there are some nice cathederal heads on the used market. Definitely worth a look.
OK this is where I also hit a hurdle, rocket - are you saying that cathederal heads are less sensitive to valve timing? I know flow numbers are not the be-all-and-end-all obviously but cathederals just seem to flow so much less than LS3 style heads, though there are some nice cathederal heads on the used market. Definitely worth a look.
Cathedral heads have much smaller ports, but are more appropriately sized for engines under 400ci (unless you use a big aftermarket casting). They tend to be more forgiving to valve events that are not optimal.
Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
I would agree with that. The L92 style heads are too big for most applications so the cam timing band aids that. If you don't nail down the cam just right, then overall power takes a hit.
Cathedral heads have much smaller ports, but are more appropriately sized for engines under 400ci (unless you use a big aftermarket casting). They tend to be more forgiving to valve events that are not optimal.
Cathedral heads have much smaller ports, but are more appropriately sized for engines under 400ci (unless you use a big aftermarket casting). They tend to be more forgiving to valve events that are not optimal.
:
If you were to take two identical 400-420 in shortblocks and put a correclty set of ported cathedral port heads on one and factory casting ls3 on the other,with the correct cam events for both,as well as a intake sufficient of feeding both engines needs,you wouldnt see any difference in the two
Now aftermarket square port heads on a large cubic inch engine would have a power advantage, but ,they arent always cost effective
The correct combo will aways make the most power regardless of the choice in port design
Now aftermarket square port heads on a large cubic inch engine would have a power advantage, but ,they arent always cost effective
The correct combo will aways make the most power regardless of the choice in port design
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
If you were to take two identical 400-420 in shortblocks and put a correclty set of ported cathedral port heads on one and factory casting ls3 on the other,with the correct cam events for both,as well as a intake sufficient of feeding both engines needs,you wouldnt see any difference in the two
Now aftermarket square port heads on a large cubic inch engine would have a power advantage, but ,they arent always cost effective
The correct combo will aways make the most power regardless of the choice in port design
Now aftermarket square port heads on a large cubic inch engine would have a power advantage, but ,they arent always cost effective
The correct combo will aways make the most power regardless of the choice in port design
How would you know you didnt like the results of a "certain cam", unless you took the time to match everything else in the combo to it,tested things as far as you could,found honest repeatable data,then made a change and started all over again?
To many times people chase the "part" and not the "combination"
Good luck
To many times people chase the "part" and not the "combination"
Good luck
Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
Originally Posted by crossbreed33
Too many times people chase the "part" and not the "combination"
Good luck
Good luck
