FCar2000TA

iTrader: (7)

Having a debate with a friend, and we were talking about what would be the best option for heads on a big CID resleeved LS block that would be a 99% daily driver. I said LS7 style heads because the LS7 design is supposed to be a significant improvement, but he said that the 245cc cathedral would be better for a car the spends 99% of the time under 5k RPMs, because the cathedral heads perform better under 5K RPMs.

Is that true? Would cathedral heads perform better under 5k RPMs...assuming all other aspects are identical (obviously intake would be different, but both LSXR 102)?

Tuskyz28

50ft lb torque difference between the 2 heads at 3500 rpm.... i have a link to prove it.

Tuskyz28

https://www.streetmusclemag.com/tech...ls7-head-test/

Great article

bortous

I'm also building a 434 too and I have cathedral heads on this motor.
Based on my correspondence with Tony Mamo, the cathedral setup has much sharper throttle response and power under the curve off idle till around 4000rpm.
This is something that can't be measured on a dyno so the way it feels and behaves is something you have to actually experience.
The power curves cross over at about 5-6000rpm with the ls7 obviously making more peak power after that.
Because mine is also a street vehicle I wanted to prioritise the driving manners and fun factor and to also consider my 4L65e transmission.
I don't not want to be shifting at 7500rpm.
If I was racing and revving to 7500rpm+ the ls7 head would certainly be the head of choice for me.

If you read my thread you will see all the information there.

FCar2000TA

iTrader: (7)

I read that one, but I saw on here where people were saying that the companison wasn't fair since the TFS LS7 heads are the worst LS7 heads out of the box. That's why I didn't believe it... I guess I have learned something today!

JRFed

LS7>The Rest on big cube NA builds

Darth_V8r

iTrader: (4)

I'm with you

speedfreak440

iTrader: (9)

Different intakes on those motors in the link that will effect powerband characteristics...... With 434ci either is going to have a pile of torque everywhere, would be tough to actually use it down low, at some point you need the wheel speed to help keep it from blowing the tires off anyway so with big motors I tend to prefer the higher peaking engine, you don't have to run it flat out but it's there if you want it but I just have a little 376 so I'll just sit back and dream a bit.

TTur1996

That is not a fair comparison at all. A 245 AFR head uses a 2.16 intake valve. And you would have to change the cam to a higher lift to equal the difference in the rocker ratio. Then lets see what it does. The 245 cathedrals are torque monsters. The article proves it. Only 10 more hp. and more torque with less lift. And i can tell you for sure. The track says way different. We kill those LS7 heads out of the hole. Fact. With a 1.19 60ft. we almost always have them by 2 cars by the time they pass the tree. You can get a set of completely CNC'd AFR's for 2200.00 minus parts. Thats 1100.00 a piece. So if you mess one up it is very reasonable to replace. Your not going to do that with LS7. So don't be fooled. Our motor put down 706hp and 616trq with a big nitrous cam in a Dart 427. Would have been more with a NA cam. Most racing anymore is 1/8th mile. Very hard to make that up.

But you guys keep selling those LS7 heads. We love the money they generate for us. Thank You.

NAVYBLUE210

For a Street Car shifting below ~ 6500 RPM, 1/8 mile, or 3500 lbs+ I would go Premium Cathedral (I like MMS 250)
For a Street Car, shifting Above ~7000 RPM, 1/4 mile or Longer I would go Premium LS7 (I like MMS LS7 265)
Just my .02

Che70velle

iTrader: (6)

Hasn’t this discussion been beaten to death like 586 times already? Why does this keep getting brought back up?

Bob570

For a daily driver, how much torque do you really need? Are you going to daily a sticky tire that can actually hold that much torque? A 434 makes huge torque by accident, even with high RPM heads like the LS7 head.

I personally would rather trade some of that massive heap of low end torque for more torque up top, it will make it more easier to control too.

Darth_V8r

iTrader: (4)

That must be engine dyno? The torque number is. Good point about 1/8 vs 1/4 too.

DualQuadDave

iTrader: (6)

This is an interesting conversation, I am having the same debate myself for my daily TBSS. I am planning a big bore build, like your 434 and I have looked at nearly every LS7 or cathedral out there. The new FED F110's look really interesting as do the new Brodix cathedral. Would love to see some actual numbers of these ran with an intake that'll support the flow. JR@FED, do you have dyno #'s of your Freakshow cathedral intake running on motor? It's probably the best flowing cathedral intake out there.

At the same time, it's hard to not look at a CID, Brodix BR7 or F710 just for the raw huge flow.

Also, 400cfm cathedrals are a real thing. Anybody running a serious set-up like this?

TTur1996

It has, agreed. As long as people pound their chest like these LS7 heads are the end all do all. I will disagree. Then put an article up and the motor only made 10 more hp but less torque with less chamber and less lift. Sorry but i don't see what all this chest pounding is about. Most guys on this site are looking to go as cheap as they can and still make great power. Telling them the cathedrals are inferior door stops is a bunch of pure crap. And you, of all these guys, know it.

Are there LS7's that make big power? Yes there is. From what I have seen, they are few and far between. Just like this site, they all act like your inferior with cathedrals, then when you smoke them, they get mad and go home. Since the beginning. How many times has it been proven, a smaller chambered head in most cases will kick the **** out of bigger heads?

Now if your building a max effort motor with big boost. Yes the LS7 head may be way to go. Then you see guys like Kenny in the drag race section make over 1900rwhp on 41 pnds of boost with 245 cathedrals and it makes you wonder if its worth changing everything. At the end of the day these guys have street cars that most likely will never see the track. Do you really believe the giant *** LS7 heads are the most optimal head for that? Be honest. Don't just appease the band wagon.

Che70velle

iTrader: (6)

Ummmmm....I said nothing. Just trying to get to the bottom of why people keep asking the same questions over and over and over. But you sure do get offended over this type of discussion easily.

TTur1996

Yes it is at the flywheel. Best part is it was only spun to 7000 to make those numbers. After opening the intake adapters all the way up. Our car went .35 faster on motor only. That has to be worth a few more ponies and a few more pnds of torque. The 1/8th is the closest to the street.

TTur1996

Not at all. I just don't like the fact that people come on a site to get honest info and all they get is opinions with no validity, and are far from accurate. Sorry if I offended you in any way. Not my intention at all. I just want everyone that reads this to know, there is always 2 sides to every coin. Just because the band wagon says so doesn't mean its true.

What are your thoughts on the subject?

Launch

TOP 25 Fastest All Time N/A Any Cubic Inch
STOCK CHASSIS / STOCK SUSPENSION CARS

ET @ MPH--Cu.In.--Name--Raceweight--Solid or Hydraulic--Cylinder heads

1) 8.12 @ 170.08-- 427in-- Judson/SAM-- 3130#-- Solid-- C5R
2) 8.14 @ 166.xx-- LME 446in-- Joe/Amber-- 2852#- Solid-- Edelbrock Canted LSR
3) 8.29 @ 164.49-- 440in-- JBM-- 3290#-- solid-- Edelbrock Canted Valve
4) 8.535@162.61-- 418in-- DBN-- 2900#-- Solid-- MOZEZ
5) 8.60 @ 158.41-- 468in--Stripes1987--3160#--Solid--MOZEZ
6) 8.61 @ 157-- 427in-- Land down under ls1--3100#--Solid--C5R (Former Matt346ls1 Car)
7) 8.74 @ 155-- 427in-- Matt346ls1--3125#-- Solid-- C5R
8) 8.74 @ 154.xx-- 427in-- TNTAddict-- 2952#-- Solid-- LS7 (Ported by MTI)
9) 8.805 @ 156.25--425in--Neal Owens--3500#--Solid--LS7
10) 8.92 @ 150.50-- 430in-- Coleman Roddy-- 3070#-- Hyd-- T/F Cathedral
11) 8.95 @ 149.92-- 4xxin-- Camnhawk-- 3100#-- Solid-- C5R (1ST N/A LS1 IN THE 8's)
12) 8.96 @ 154-- 460in--ATVracr--3100#--Solid--MOZEZ
13) 9.07 @ 149.85--447in-- Mikey--3200# Solid--All Pro LSW
14) 9.09 @ 150.xx-- 460in-- Firehawk441-- 3040#-- Solid--MOZEZ
15) 9.18 @ 148.xx--431in--RayZO6--3200#--Solid--LS7
16) 9.23 @148.27-- 418in-- Revlimiter-- 3250#-- Solid-- ET canted valve
17) 9.27 @ 145.xx-- 427in-- RUQWIKR-- 3100#-- Hyd-- LS7
18) 9.39 @ 141-- 445in-- TXCAMSS-- 3110#-- Hyd-- Cathedral
19) 9.432 @ 140.69 -- 454in. -- 1cdub -- 3274# -- Hyd -- L92
20) 9.47 @ 140-- 427in-- RUQWIKR-- 3130#-- Hyd-- Cathedral
21) 9.504 @ 141.06-- 427in-- LTZSS-- 3408#-- Solid-- Square
22) 9.505 @ 143.31-- 427in-- AshWS6-- 3220#-- Hyd-- Square
23) 9.56 @ 139.9-- 421in-- TomTheRoofer-- Solid-- Cathedral
24) 9.532 @ 145.1-- 427in-- redvette1077-- 3015lb-- solid-- LS7
25) 9.575 @ 140.48-- 403in-- Quick Time-- 2975#--Solid--ETP 225

bortous

That's an amazing list launch.