gpi ported ls3 heads

[04silverado6.0]

Anyone wanting a true comparison of ported heads on a cam and bolt on ls3 then here you go. Only changes were the port job, .040 cometic gaskets, tune revision. Car was slightly knock limited before the new goodies which cured the issue 100%.

[blindsquirrel]

.040 gasket - so, tighter quench than before? Higher compression AND less knock?! Amazing what that chamber turbulence can do, ain't it.

[04silverado6.0]

I even was able to add 2-3* with no knock just didnt net a gain. 2-3hp at various points in the curve and 1hp at peak. Just did some smoothing on the spark table and left it where it was at wot pre head swap. Started with 2* pulled and made 5-8hp gains putting the 2* back in from the previous tuning session.

[RDF1]

Whats that calculate out to? $65 per 1hp?

[04silverado6.0]

Whats that calculate out to? $65 per 1hp?

Too much money, too little gain.

Edit: 118.47 per hp not counting buying a set of core heads, fluids, etc.

[RDF1]

Too much money, too little gain.

Edit: 118.47 per hp not counting buying a set of core heads, fluids, etc.

WOW that hurts.
Ive got one of those customers that has spent so much money on small stuff that makes no sense.
GPI LS3 Ported and Rod/MoD intake and a GPI Ported stock LS3 throttle body, and a heatsheild or something.
Had me take the heads off and send them to Texas speed for a cnc port job.
Then back to the dyno for disappointment.
Almost $2600 for about 24rwhp gain.

[Cringer]

Anyone wanting a true comparison of ported heads on a cam and bolt on ls3 then here you go. Only changes were the port job, .040 cometic gaskets, tune revision. Car was slightly knock limited before the new goodies which cured the issue 100%.

The GPI CNC work only does intake and exhaust runners (they don't touch chambers) last I heard. Same on these?

[04silverado6.0]

The GPI CNC work only does intake and exhaust runners (they don't touch chambers) last I heard. Same on these?

Chambers were not touched.

[04silverado6.0]

WOW that hurts.
Ive got one of those customers that has spent so much money on small stuff that makes no sense.
GPI LS3 Ported and Rod/MoD intake and a GPI Ported stock LS3 throttle body, and a heatsheild or something.
Had me take the heads off and send them to Texas speed for a cnc port job.
Then back to the dyno for disappointment.
Almost $2600 for about 24rwhp gain.

Not to be funny but this car has all of those mods listed. Rod mod, gpi ported tb, heatshield under intake. Got about 6hp from the intake port so this car made the same 23-24hp from the same mods.

Edit: 23.76hp gain from the same exact mods

[RDF1]

Not to be funny but this car has all of those mods listed. Rod mod, gpi ported tb, heatshield under intake. Got about 6hp from the intake port so this car made the same 23-24hp from the same mods.

Edit: 23.76hp gain from the same exact mods

Atleast its a consistent number!
Added a flex fuel sensor to it and ran E83 it picked up a whole 6rwhp.

[04silverado6.0]

I usually only get 5hp from e on these. I see shops gaining 15-25hp on a na ls setup, the same shops charging 100 bucks extra to tune ethanol blends. I have a buddy i tuned a ss silverado 6.2 swapped with e85 capability. He is claiming 8-9mpg on 93 and 11-12ish on e85. The setup he has i would be surprised if it got 8-9mpg down a mountain in neutral.

[Alvin]

25-35 rwhp is about what I would expect on this. We use two other shops for our CNC work and thats about all that you see. At this level though, there is nothing else you can do to get those sort of gains.

Got to remember too that stock LS3 heads are pretty damn bad ass so making a big difference on them is going to be hard.

[04silverado6.0]

I expected more like 25hp but we did not get it. You definitely feel the difference off idle where its down some. Still very driver friendly with the stage 2 cam. I lugged it to 1k rpm cruising for a test with no bucking.

[edcmat-l1]

Whose "stage 2" cam?

[Cringer]

Whose "stage 2" cam?

GPI SS2

In./Ex. Duration
228/240

In./Ex. Valve Lift
.646/.637

LSA
112

ICL
+4

[blindsquirrel]

needs moar cam

[edcmat-l1]

needs moar cam

Needs a better cam. But I agree the gains in general aren't impressive. Not that that is surprising for many reasons. Not knocking the OPs methods.

[04silverado6.0]

Needs a better cam. But I agree the gains in general aren't impressive. Not that that is surprising for many reasons. Not knocking the OPs methods.

I just tune and take the money. What it needs is a 150-200 shot.

[RDF1]

I just tune and take the money. What it needs is a 150-200 shot.

Boost Fixes everything.

[04silverado6.0]

It needs some bushings a diff upgrade and a clutch upgrade. Its ok as is but definitely could use some help.