Hello guys just curious on what you guys think on this build. I'm going to buy a tmp forged 6.0 with -2cc flat top pistons. Trickflow 255cc heads and either a Holley high ram or fast 102r intake. And then I'm going to do a 88mm turbo along with a little John turbo cam. Do you guys think this is a good set up for high hp numbers. It's going in a 68 camaro for street use backed by a t56

 

Out the box those heads are not worth the money. Plus your cam man not a fan of rectangle port heads. He love saying #cathedralportmafia

Anyway i seen 7 hp difference between a cnc L92 head vs the TFS 255 heads Out the box. Both heads tested on a 427ci ....

 

Oh I really didn't know, I just read some good stuff about the heads. And why go cathedral? I haven't bought any of the stuff yet but that was the route I was going to go

 

Why go cathedral ? Various reasons why...
To really make a LS3 head shine you need a 408 ci or bigger motor right off the bat.
Cathedral heads are easier to cam.
You'll have to rev the car to the moon and back to get power out the LS3 heads... which is not all that good for a Valvetrain.
Cathedrals tend to have a flatter torque curve when you it's hard to be achieved with a rectangle head. It can be did but the cam has to be PERFECT. By you having a street car you may not see 7000 rpm very often.
Ls3 heads are very sensitive to overlap.
What always look good on paper do not shines shined in the real world.

Guys on the here just focus on the peak intake number and that's why they $h!t don't run well at the track. They never look at the exhaust side of the head.

Cylinder heads are like boyfriend and girlfriend. The intake and exhaust have a relationship. The percentage of the relationship of a good cathedral head is way better than a LS3 head.

The flow numbers you really want to focus on is 2,3,4, and 5 on the lift. It's where a street car spends of they time in the powerband.

Someone may agree with me or disagree but I'm speaking facts.

 

Call Lil John and see what he recommends more than like any Cathedral style heads.


One thing also:
That is so true about overall TQ with Cathedral style heads VS rectangular port heads here's the thing: YOU WILL NEVER EVER be able to use the TQ down low on the street with any F/I and decent HP numbers.

LilJohn says what he likes and Dislikes here.
https://ls1tech.com/forums/forced-in...317-s-why.html

 

I never knew that. Thank you guys. So if I went 317's should I still go with the high ram? Or maybe the tbss intake?

 

So my tuner said to do 317 heads also with twin turbos because I'm in a manual. What sizes do you think? 68mm? And what intake do you guys think will work best

 

Smaller is generally better no Lag with them. I'd talk or call LilJohn and see what he recommends and give him a general idea of what you wanting and looking to make. Better to get if from the Horses mouth. As the guy has done more than his share of turbo cars. May I ask you one question what type of Hp are you looking for either @ the crank or wheels if you don't mind me asking. Reason i'm asking is you did say street.

 

Not only did he mention street.... look at that thread Dark Energy linked you too.
He basically said the same thing I said about cubic inches. 370ci or so do cathedrals .... 408ci consider going LS3 heads.

 

Well it will be street/strip and I was looking for 600-700 at the wheels. But thank you guys for steering me in the right direction guys!

 

Your power goal is easy achieved with a L33 with 243/799 heads and a 76 mm turbo.

Motor made 825 horse at the crank for less than 6k dollars. Google One guys garage 5.3 staying alive.

 

http://www.camaro5.com/forums/showthread.php?t=91275

Even better & BTW with Ls3 heads and Stock short block.

 

I'm still wanting to do a 6.0 I'll just have to give lil john a call tomorrow

 

So I just talked to lil john and he said to run 317 heads with a tbss intake with 66mmturbos and a custom cam. He also said the heads stick will be good for 1000hp stock. So looks like I'm going to go this route