Danny

iTrader: (16)

I ported my old LS3 heads on my old LS2/LS3 setup and it worked pretty good. The C5 made 482/433 w/ full boltons (1 3/4 headers) thru a set of 3.90s and a M6. I basically just cleaned up the casting on the runners, shaved down the spark plug hump in the bowls and blended them and blended the area just below the seats to help the air transition better. I also sharpened up the valve guides, with more more attention paid to the exhaust side to help the air get out. I did not enlarge any of the runners. I mainly just cleaned up the castings to help the air get in and out more smoothly. Heads were milled down to 60cc and no valve job was done.

Now, I'm building a L92 motor. I'm thinking of making a stroker motor (416) and I was thinking of porting the heads again on this setup.

Here's my question...
What part of porting a set of heads gives the bigger gains and which are not worth doing?
Does cleaning up the castings, like I did on my previous heads, really make a difference?

Thanks guys

eyerideakfx400

I've heard mixed things on polishing intake ports. The general concensious is that the intake should have somewhat of a rough finish (minus the bumps) to help velosity,atomization,and carbon buildup. From what I have read is the rough finish on the walls helps increase air velosity because when the air flows through the port it rolls over the roughness causing the rest of the air to flow through the port faster due to less friction. As far as the exhaust side, Polish away. I dont know the actual facts on this, but thats what I hear. Thoughts anyone? This would make a good topic for dicussion. How much did you have to shave off to get 60cc chambers and what thickness head gasket did you use, and do you know what your compression ratio ended up at?

Danny

iTrader: (16)

That's what I've heard from others as well. I would figure that the carbon buildup would not be a good thing.

As for the milling, I'm not sure how much was milled off the heads since they were used. I just told them I needed 60cc chambers. I used stock LS3 head gaskets which I think are .051. I think my compression was around 11.4, not too sure. I did have to flycut the pistons to get proper PTV clearance.

eyerideakfx400

I see..Im putting on LS3 heads on my stock LS2 and was just curious. I'm looking for more compression than what I had. So you had to flycut. Are you running a cam with a big intake dur? Im shooting for around the same compression ratio as you, my cam is 224/.581intk and 236/.601exh. I'm hoping that my cam is small enough on the intake to avoid having to flycut. Dont even know how to get that done. I live in MA and there's not much around here as far as perf machine shops go, or perf anything.

sweetC5

Not shure about LS heads but on my stock and edelbrock oldsmobile heads you wanted to raise the intake port roof to match the gaskets and leave a rough finish not polished, and I would do basicly the same thing you did to the exhaust side. Definitly helped my cars... I dont think a gasket match and a good clean up would hurt on the intake side.

eyerideakfx400

The edge of our gaskets are about 5mm away from the port walls.. Part of the intake holds the rubber gasket (rectangle o ring)insert in place. It does look like there is plenty of material there to shave. I wondered about this, how would we port match the intake to the cylinder head. Maybe use some talcom powder or something on intake and bolt it down to heads and look at the marks it leaves on the head? Then shave off some head to match.. Do you guys know if anyone has done this? I havnt measured the manifold port demsions and compare to cylinder head, maybe there identical from factory.. (lol I doubt it)

1badeagle

iTrader: (9)

How much power do you think was gained just by porting your heads?

Danny

iTrader: (16)

My cam was a bit bigger than your Low 23X and low 24X duration with something like 114+X. I don't think you'll need to flycut but you might want to double check. Just to be on the safe side.

I'm not too sure. I added all the goodies at the same time.

1badeagle

iTrader: (9)

Damn, I'm just trying to find out if it's worth the Money to port them while getting milled.

Danny

iTrader: (16)

I think milling the heads and a good valve job should give you as much as any porting job on a LS3/L92 head. But that's just my opinion.

WKMCD

iTrader: (2)

To get the CC down to 60cc you would have to mill the heads more than .060. I've never heard of anyone going that far and not having intake manifold fit problems. With a .060 mill the surface starts to get pretty thin.

Just my $.02

1badeagle

iTrader: (9)

I'm pretty sure a .050" mill gets you to 61-62 cc chambers.

WKMCD

iTrader: (2)

Stock they are 70cc. Figure 1cc per .006 mill.

Danny

iTrader: (16)

So, back to the topic at hand. Does anyone else have any input?

Tainted

iTrader: (9)

if you do go the 416 stroker route, I beleive thats a large enough motor to say having the heads ported would be worth it. On smaller 6.0 and 6.2L it seems people dont port the intake side as it already flows a **** ton. either way, id clean up the castings and have a valve job done and opt for the lighter ls3 valves

Mike454SS

iTrader: (4)

Where in MA?...there's a lot depending on what you are looking for.

eyerideakfx400

Well I work in Charlton, but I dont mind a little drive if I have to, expecially to get quality work. Just looking to get them milled and get some exhaust port work done on LS3 heads. Maybe a vlave job if its worth it? (to maybe gain a bit of PTV clearance) Not sure, they are brand new complete heads I picked up from my work. Tossing up the Idea of getting intake and throttle body ported or portmatched but I don't think the gains are worth the hassle though. My altimate goal is to get as much compression as I can with 93 octain. Wish there were E-85 stations around here but no luck.

Mike454SS

iTrader: (4)

I drive through Charlton on the pike every day, and live in Worcester.

There are some shops in CT that do great head work and are a quick ride down 84 for you. There's also places in NH just about an hour away, there are shops in MA that do machine work, but I haven't found one I'm really happy with without traveling to CT or NH...less than an hour in either direction though. Shoot me a PM if you want some names of places I've had work done.

Danny

iTrader: (16)

Back to the topic at hand. Anyone else have any input???

1badeagle

iTrader: (9)

I wish someone knew whether or not it's worth the cost to get the ls3 heads ported(even if it's only the exhaust side) for a lq4 370. One person says hell yea do it, and the next says its not worth it and that power gained is only form milling and a valve job.