sweet99ss

iTrader: (41)

So this Friday I will likely be purchasing a 408 from Thompson Motorsports. I have had this planned for a long time now and I was planning to just go with a stock set of l92 heads, but after speaking with Aaron again today I am thinking about going with a ported set of ls3 heads that should make about 35 more rwhp. Do you think the 35rwhp is worth the $800? I mean everybody puts fast manifolds on for the same price and often don't see the same gains. So my thinking is instead of wishing I had more power later just going ahead and go for the cnc ported heads? Give me your opinions.

SoFla01SSLookinstok

I'd say definitely go with the better heads. Just like you said. You'll be glad you did.

blk00ss

iTrader: (66)

Maybe you should check out lil John and shortunings latest head test. Just saying.

#cathedralmafia

NAVYBLUE210

$800.00 for 35 RWHP is Very CHEAP! For a NA increase!

sweet99ss

iTrader: (41)

I read a few test's and they seemed to be neck and neck. And the cathedral seems to be more expensive once you start going ported, no? Not to mention I can get an ls3 intake, injectors, rails, and 90mm tb for much less then what a fast manifold for cathedral cost's alone.

blk00ss

iTrader: (66)

They picked up 191hp over ls7 heads with a set of TFS 245's. Was with boost tho. But just saying lol

sweet99ss

iTrader: (41)

A stock head to a highly moddified head? Link? Idk ls3 heads seem to be pretty stout on ls3 engines...

blk00ss

iTrader: (66)

No. They were TFS 260 ls7's.

Rise of the Phoenix

iTrader: (27)

I was just going to say the same thing.

sweet99ss

iTrader: (41)

I think the more I read on cathedral vs rectangular port the less I know lol. What I do know is ls3 cars seem to run pretty damn well and ls3's with a cam make around 500rwhp. I have a little more stroke then an ls3 and with a big cam and some cnc'd ls3 heads I don't see why it shouldn't put down 500+rwhp. Find me a set of ported cathedral heads for the same price as the cnc ls3's also? Arent they more pricey? And like mentioned before I can get an ls3 with rails and injectors a lot cheaper then what a cathedral setup is going to cost me... If I had an unlimited bank account I might think about a highly ported cathedral setup..

z twenty h8

iTrader: (2)

Yup, I was in the same boat. I wanted 500+rwhp out of my 408 and found that I needed a lot more coin to accomplish that with cathedral port than rectangle.

blk00ss

iTrader: (66)

I made 505 with a 402 and patriot stage 3 heads. Which are just stock 317 castings ported. That was through a 9" with 4.11 gears, 325/50/15 drag radials, heavy clutch setup, and 1 3/4 pace setters. So I guess it's all in how you look at things.

I just know that you see more cathedrals getting down the track faster as well.

But hey if you want to just have 500whp it's cheaper that's cool too.

z twenty h8

iTrader: (2)

Right on blk00ss, we've all got different view points. Its not lost on me that dyno numbers are sometimes arbitrary numbers used as a proxy for performance.

I picked up l92s for $400, therefore I decided to got that route which is in line with my primary premise about price.

sweet99ss

iTrader: (41)

If there was a better cathedral that would make more power at the same price I would look into it, but the cathedrals I see make the big power are lots of $. I would like it to make over 500 to the wheels yes. My main goal is to break 10's N/A and then hit it with some N20 down the road and I think the cnc ls3 heads will get me there.

xdanny510x

U cant go wrong with prc l92/ls3 stock ported heads if u are on a budget

Spectre86

iTrader: (42)

my 427 stroker made 560rwhp/500rwtq. had a sdpc C&C'd ls3 head. they were like 1500 with the rockers. think they flowed around 360cfm.

I don't think anyone will argue that a trickflow 245 or 260 head is a lot better then a ported ls3 head. but theres a pretty big price difference. specially with the YT rockers too.

I would atleast go with the ls3 valve vs the l92 for weight, specially if you plan on spinning it to 7k.

Rise of the Phoenix

iTrader: (27)

Powdered metal guides in the TFS heads allows you to use stock rockers.

kinglt-1

iTrader: (26)

Cathedral is where my money would be spent...For a street car I prefer a more responsive low end instead of something that feels like a 2 stroke.

sweet99ss

iTrader: (41)

Will Ls3 injectors support this setup?

Ls-x

iTrader: (3)

i believe there is some variables to keep in mind for example the drive train, car weight , aerodynamics all of these come to play a roll.
i made 510 rwhp through dana s60 (9.75'' gear) with very similar build using stock ls3 injectors and i can tell you that between 6000 rpm to 6800 the motor were pushing the injectors to 94% duty cycle on the dyno and even to 96% on the street as you can notice the 2% difference between the dyno and the real world as the dyno will only see the drive train loss but on the street the weight and the aerodynamics will give there contributions.

i am keeping those injectors maybe for a year or so.

and i can see that your combo home is a vette so i wont worry about it much


Good luck with the build !