1badeagle

iTrader: (9)

I have been looking into all the different companies that port LS3/L92 heads recently and they all claim 20-40rwhp gains. Ive googled the hell out of this and im curious how much gain actually comes from the port work compared to the milling. I have a new forged 370 short block set up to turn high rpm and be hit with a 200 hp shot of nitrous. Would head porting be benifical to my motor or should I just have the heads milled down and call it good?


P.s The motor will be running a Patrick g spec'd eps cam. 235/243 .62X/.62X 110+4 LSA

Tainted

iTrader: (9)

Porting is to increase flow, while milling increases your compression. Both are essential. For stock ls3 heads id mill .020 and have a good port job done with the lightweight valves

1badeagle

iTrader: (9)

I know for sure that Im going to mill the heads .040" with stock LS3 gaskets. My question was wether or not it is worth the money to port the LS3 heads on my high revving(7400rpm) 370 ci motor.

gnx7

iTrader: (28)

An LS3 head has a very large intake valve. With a 4" bore from the LS2 you are limited to how much you can mill the head as well as limited cam selection. Make sure you are aware of this.

A TFS 225cc cathedral port head may be a better choice. Better PtV clearance and it will flow plenty for your little motor. More power in the mid range for sure and a thicker deck to begin with.

1badeagle

iTrader: (9)

The motor was originally a LQ4. Its a 4.030 bore now with forged flat tops that have the LS3/L92 Valve reliefs. I already have new LS3 heads, Intake, and head gaskets. I plan on a .040 mill to bump the compression back up to close to 11.0:1. I think with the .040" mill it will be about 10.87:1 which should be decent. I want to get as close to the 500RWHP as possible for this motor before the nitrous, so thats why im asking if the heads need to be ported or not.

gnx7

iTrader: (28)

With 370ci I'd think 500rwhp would be a very optimistic goal.

Every point increase in compression is worth around 3-4% increase in power. You want as much compression as possible.

LS3 intake valve is also 2.16" which is massive even running a hollow style lightweight valve.

1badeagle

iTrader: (9)

The motor is getting a victor jr that has been ported, so maybe that will help it peak a bit higher? What is a realistic number to expect on power?

4.030 iron lq4
Ls3 heads milled .040
Ported victor jr
235/243 .621/.629 110+4
2" primary long tubes
T56

Will the porting be worth the money to get me closer to my power goals or should I have them milled and leave them umported?

How much power is there to be made with porting alone?

lilmiller74

id say youll probably be making around 356/372

1badeagle

iTrader: (9)

Awwww Casey was that a attempt to be humorous?

lilmiller74

Yes

1badeagle

iTrader: (9)

Fail fail fail. If I wanted a shitty clutch setup and 350 wheel I would have bought a vette.

bww3588

iTrader: (49)

Ls3 heads typically don't like a lot of compression, they like more timing than anything I have heard. With nitrous I would shoot for around 10.5 ish with a good bit of timing for na, then retard it for the sauce

1badeagle

iTrader: (9)

I think i remember seeing that they like alot of timing to.


Anyone have a idea on porting yet?

davidws6

iTrader: (36)

for HP gains, it's a guessing game as every combination is different. If your wanting to obtain the max hp out of your engine, do it and don't look back.
More air in, usually equals more air out !

3pedals

iTrader: (3)

I milled .050", no problems - doesnt even come close to the intake valve seat - so no loss in flow(contrary to popular belief), and whoever thinks LS3 heads dont like compression, is........wrong.

KCS

iTrader: (20)

With that small of a motor and that intake, I wouldn't make the port any bigger than what it is. If anything, just a little bowl work and a port match is about all I would do.

87silverbullet

iTrader: (11)

^^^Agreed. You will already have a loss of bottom end grunt from that intake and 2" primary on that 370. The runner is already big enough as is and porting it will only make it bigger. If you were going 4xx cubes then I would say get them ported.

bww3588

iTrader: (49)

care to back that up?

raymond mckinney

iTrader: (4)

It will run good no matter if you get the heads ported or not. I smoothed my intake runners, ported my exhaust and did a valve and mill job on my Ls3 and it ran great 104 mph 1/8 traps with a 220 duration cam. Btw my compression was 10.9.

87silverbullet

iTrader: (11)

The key is your 220 duration cam. You are able to keep your powerband in check with a smaller cam.