ProStreetBiker

Guys, I'm having some trouble making my mind on on this one- so, I'm seeking a little help. What would you perfer, a heads/cam 347 with a F.A.S.T. 90/90 or a heads/cam 383 with a LS6 intake manifold?

I'd imagine both would make similar power (different torque curves though) or a slight advantage to the larger motor. Only, the bigger motor would have more potential growing room when I could afford a 90/90 later down the road.

Each would have a cam suited to the respective motor and the correct heads, only one would be choked by the LS6 intake. I'm looking for both setups to be very streetable and n/a. Later, when I have more available funds, I could upgrade to a 90/90 on the stroker or spend all of my money now on a 347 with a fast intake.

Comments?

Grimes

iTrader: (3)

if you had the cash, 383 would definitely be better in my eyes

wws699

iTrader: (3)

Ive been tossing the 383/347 thing around also.. The 402 is not much more than a 383... But then again im bad at math

Lythropus

iTrader: (13)

If it's an NA motor, go 383. If it's an N20/FI motor go 347 and put all the money in rods/pistons/rings...

99blancoSS

iTrader: (115)

bigger is better. If you can afford the crank for the 383 then do it. There is no difference in rods, pistons and ring prices. The difference is the crank in this case.

Brian Tooley Racing

iTrader: (13)

I see 383's that don't seem to make much more power than a 5.7, so I would go for a killer H/C setup.

slow trap

iTrader: (22)

i say save up for a 408,but i'm biased though.you can get a base 408 to your work place or house for around 4k or so and have all them cubes.

Bader-X

iTrader: (2)

hmmm another option there .... tfs or etp heads on the 347 with the ls6.

badpewter-z

iTrader: (4)

i say 383. it'll have alot more potential down the road and have alot more under the curve which is where it counts on the street

Sigforty

They may not make more power, but the torque number should be a major increase across the board for the 383. I have also seen 402 and 408 combos that do not make power like some killer H/C setups on 346s. It all depends on how well the combo is setup.

Pray

iTrader: (7)

I went with a 383 on the premise that I would already have the rotating assembly when I want to step up to a 408-440. Just a LSX block and piston change away. But for now I am starting from the ground up. I am also stuck with the LS6 intake. I will have dyno numbers in a couple of weeks. I will post up when I get them. I am running AFR 205's, with a 239/244 .651/.612 112+2 with all the bolt ons. It should make 475/450rw.

Lythropus

iTrader: (13)

Got any more details on that cam? lsk/xer lobes? That's about the size cam I'd like to run.

Who makes it (custom grind?) and do you have it running yet?

Pray

iTrader: (7)

I am not trying to steal this thread. I just think this info might help and I was asked.

The cam is a Comp "custom" if you want to call it that. It is a mix of an off the shelf LSK intake lobe and a XER exhaust lobe. It was speced for my 383 from Predator-z and confirmed by Patrick-G. I think taken together to be gospel around here. Although Pred speced it out on a 111+2 lobe sep Pat said with my longer stroke I could get away with a 112+2. The intake lobe number is a 2130R and the exhaust is a 2732R. The R denotes LSx so it is ground true to spec. That is what the guy at comp told me.

The car is not up and running yet. I am waiting on the rotating assembly right now which is supposedly getting shipped today. But once I have it figure a week for "blue printing" and machining, and a week to install. (I have kids) Then some break in time and on to the dyno and track. So I probably won't have solid numbers for another month. Wow that was depressing to type.

Here is the set up.

02 Z06
Eagle 4.00" rotating assembly with -7cc Diamond pistons (all balanced)
AFR 205's 59cc 8019 springs 11.8:1 SCR 8.69 DCR
Cometic .040
TSP 7.35 push rods
Comp 850's
239/244 .651/.612 112+2
Dynomaxx 1 3/4" LT's with gutted cats, Borla stinger
ASP UD
42lb injectors
LS6 w/ Shaner ported TB
Vararam and Air bridge

I think that is about it. It should run pretty well. We will see.

02SOMWS6

iTrader: (6)

I'm going back and forth with this too. Is the extra $1400 over the price of pistons worth it. I put down 452rwhp and 408rwtq with a stock bottomend, ported 241 heads, 12bolt with 4.30 gears, Denny's steel heavy *** driveshaft and a little 224/228 581/588 110 cam. I'm pretty sure if I go with a set of forged pistons with vavle releafs and a huge cam I should be able to get 500rwhp or real damn close. I want to see some 550rwhp and some big rwtq 383 numbers to sell me on making the switch

david vericker

iTrader: (1)

Gee, you guy's from NY & NJ sure are fast...just think if you had a good set of heads and a big cam...8.xxx would be no problem for you!! Why bother to go big (383) your faster than 99% of those cars now. It must be the air or whatever you drink out east that makes your cars extra fast.

Camaro99SS

iTrader: (4)

The 383 will give more torque everywhere and be the better street motor. But not being able to run a bigger head will not help in making more peak hp, so keep that in mind. If you go with the 383, at least spec a bigger cam. Otherwise make the decision based on gearing. If you want to stay with stock or close to stock gearing, go 383. If you want 4.10's or steeper, go 347.

383's don't seem to get alot of credit as the bigger bore motors overshadow them. But with good heads like Trickflow or EP 215's, well matched cam, and 11+ compression with a tight quench, a 383 would be a killer street motor.

Jason

N4cer

iTrader: (11)

Forged 383. Then the intake won't matter when you spray the ***** off of it.

02SOMWS6

iTrader: (6)

383's don't seem to get alot of credit as the bigger bore motors overshadow them. But with good heads like Trickflow or EP 215's, well matched cam, and 11+ compression with a tight quench, a 383 would be a killer street motor.

Jason[/QUOTE]

What about for a all out track engine that will see high rpm's. I'm thinking I better just stick a set of forged mahle pistons in it and go with a huge cam and have slowhawk work his magic tuning it

BigBake

You mean peak power. A 383 will make more power through the entire curve, and have a much better lower end. The fact that you are using the same bore size as a 346 with a little more ci only gains a small amount of top end performance. But you make a lot more torque in the lower end, and a much broader power curve.
Also a lot of 383's are poorly concieved from the begining. Sometimes due to funds or just not enough information. You have to keep in mind you are using a stock bore size, you cannot slap on a set of heads made for a large bore motor and expect to make even more power. People tried putting the biggest cams they could find since they had more cubic inches to feed. Well that is the wrong approach, the additional 37ci really does not amount to a change of 20 degrees of additional duration over a radical 346 cam.
A solid setup uses a close to stock bore size heads, and a cam that falls into the range of the mid 230's to lower 240's, dependant upon heads, SCR, and DCR. I went with an AFR 205 head, at the time this was the only option, they had not come out with the AFR 225's small bore, or just the 225's for that matter. The low end velocity of those heads just feeds those cylinders with that extra stroke. It makes for a killer package with the right cam. Case in point is Tony's thread for a 383, of course well after the time I had put mine together. I might have went with the 225 small bores after reading that.
My only other thought on this is the intake, I originally stuck to the LS6, because also at the time there was no FAST 90/90 setup, the 78's were just starting to trickle out. The stock LS6 style intake will limit your top end, and I think the 78 might actually be better suited for a 383 if it is port matched and ported. I have a 90/90 setup, yes it made a difference mostly in the top end, but I think a 78 setup would have been optimal for performance throughout the range. I will once again site that the bore size remains the same, and your not really pulling much more air in at high rpms over a 346. It is all low range draw, and a 78 would meet those requirements. The drawback is of course if you go bigger in the future the 78 will not meet the expectations of larger bore motor.
The point is most people took the approach of a bigger motor means bigger parts are needed to get max performance. The end result was poor gains, sloppy performance at the track, and questioning the worth of a $1600 part for additional cubic inches. A properly setup 383 will drag a 346 down the track, no matter if the 346 made 30rwhp more at 6300 RPMs.

BigBake

This is exactly what I was stating, a very good setup.