Higgs Boson

iTrader: (3)

In this combo, what will be the bottleneck?

LS6 motor
Forged pistons, rods, ARP fasteners all over
Ported Ls6 heads
LS6 Intake
LG 1 3/4 Longtubes w/cats
Cam something like a 230/240 600/600 on a 114 or so

I would like to peak power around 6700, rev limit at 7K. Will be running a 200 shot.

I don't want to get bigger headers. I don't want to get bigger heads. I could get a bigger intake.... FAST 78? FAST 90/90? Ported? I could get a different cam....

What's the right combo for ported LS6 heads, 1 3/4 longtubes, medium cam, nitrous? Thanks!

ls2 bait

iTrader: (11)

def the intake. "bigger" heads wont help much but a "better" head would be benificial. but right there the first thing is the manifold.

SOMbitch

iTrader: (8)

^^^^^ I 2nd his advise. Intake AND TB first. Go 90/90. Then heads if you want to get serious. You could also pick up a few HP by gutting your cats.

1badA3Z

iTrader: (58)

I 3rd there advise,get ya a fast 90/90!

Higgs Boson

iTrader: (3)

I'm not looking to go nuts with this car. I have an NHRA/IHRA Super Stocker.... This is just for fun/something to kill my buddies Cobra on a regular basis. I ran a 10.8 with the headers and a 150 shot and 500/530. I am looking to bump to 650 rwhp with the motor mods and 200 shot..... I think I can do that without aftermarket heads....

Will the worked LS6 heads flow with the 90/90? Is it pointless to port the FAST setup?

How many CFM does the FAST flow ported and unported? I am guessing the heads will flow close to 300 @ .600 so I would need an intake to flow around 330, right?

Also, does my cam choice coincide with my RPM/HP goals?

2000_SS

iTrader: (24)

i ported my FAST90 myself. not running juice, but went from 393rwhp (through 10-bolt with a RICH tune) to 417rwhp through a Moser 9" and no tune to compensate. i have a smaller cam than what you're suggesting, but i'm waiting to re-tune the car with some PRC 5.3 heads on it now and i expect ~445-460rwhp.

Don't bother with a FAST 78mm intake. YES you'll see gains over a LS6, BUT YES the 90mm is worth the extra cash....and it's not that much extra considering the gains you'll see. porting is easy if you're capable, expensive to have done though, and i would recommend one of our sponsors like Vengeance to do the work if you take that route.

Get a FAST 90/90 setup, have the LS6 heads milled down to ~59cc chamber (assuming you'll have valve reliefs in your forged pistons) and you should see close to 650rwhp on a 200 shot

Zero4488

iTrader: (10)

I completely agree....when building a setup like yours why not go with the 90/90 setup and get better flow?

Higgs Boson

iTrader: (3)

I don't want to overkill the intake based on the heads or headers, that's why. I want synergy in my combo.

I believe that the smallest way to accomplish your goal is the best way.

If a ported LS6 intake flows enough to maximize ported LS6 heads, why use a 90/90? Key word here is maximize.....

That said, I hear what you guys are saying and it sounds like I will go with a 90/90.... Question now is, should I port it or it is pointless? I know 2000_SS says porting is easy and do it, but my concern is whether it's the RIGHT thing to do....

2000_SS

iTrader: (24)

well....you're gonna wanna AT LEAST port-match the intake runners to your ported heads. that's easy and you can go slow and do it by feel and sight. while you're in there, there's an obvious "wedge" in the intake runners right before the port itself. it's easy to level out and DOES improve flow drastically.

A ported LS6 would NOT maximize ported LS6 heads (from my experience). The FAST intake runners are different entirely from a LS6 runners. They're are capable of many more CFM than a LS6 intake with any amount of porting. I've read from many 'professionals" on here that they have difficulty getting a very-well-ported FAST 90 to flow over 300 CFM. Since most CNC'd factory heads flow ~310 @ .600", and a FAST flows more the higher you twist a motor, i would say it's not just a way to go, but THE way to go. you will have your synergy with a ported FAST 90. even unported, it should show gains over a ported LS6.

what it boils down to is you asked what the bottleneck is. it IS the LS6 intake. i can understand not wanting to front the $$$ for a FAST, i know, my *** is still sore from buying mine. AND i can understand not wanting to go to town with a sander of any kind on a $750+ intake if you DO buy one.

either way, LS6 or FAST, you'll have a fast car

2000_SS

iTrader: (24)

Plus a paint-matched FAST looks SICK with some of our sponsors' direct-port N20 kits

Higgs Boson

iTrader: (3)

Well, it's not the money. I just want to do it right. Sometimes right is cheaper. It just depends on how it works out. I don't like to redo stuff.

Thanks for the advice. I will get a ported FAST 90 to go with my combo.

ls2 bait

iTrader: (11)

an ls6 will never come close to maximizing the use of a ported ls6 head. buy a fast 90. then take off the cats.

2000_SS

iTrader: (24)

cats are for the birds

Higgs Boson

iTrader: (3)

Cats are staying on. They are LGs high flows and are part of the header/X-pipe system. Removing them are only worth a few HP and stinky pollution and noise. That's not for me.