97MysticZ

iTrader: (16)

I had a few questions about cylinder heads specific to the LS1 since I'm new to them. I know there are a few differences between the 98 and the rest of the years the made the LS1. Are the heads differen't on 98 LS1's? Basically what I'm asking is can I buy a set of heads off of a 99+ car and bolt them to my 98 block? Also, how much can you improve upon the stock heads by porting and polishing? Or is it not worth it? Also, what kind of gains can you see from using 5.3 heads? and do you port and polish them before you put them on usually or just bolt them on? Thanks for any help guys.

2000TransAmWS6

iTrader: (12)

on the 98s the valve cover bolt on around the outside of the cover, and the valve covers bolt on in the middle for the 99+ LS1s.
the best flowing LS1 heads have the 241 casting numbers. and i think that you can bolt them right up to a 98 if you have the correct valve covers.
porting and polishing is a good idea if you have someone who knows what they are doing port them. 5.3 heads should be ported before installing them to make it worth the work of installing them, and to get good hp numbers out of them. you need to have a cam and heads combo that work well together to maximize you hp.

97MysticZ

iTrader: (16)

Okay thanks. So I can put any LS1 or 5.3 head on my motor as long as I have the correct valve covers to bolt up? Which would give me more power- ported and polished LS1 heads or ported and polished 5.3 heads? Its kinda a budget right now til this semester of school is over.

Gold Z

iTrader: (3)

Yes, but you'll need to change the coil mounts also. The 5.3 heads seem to offer slightly better flow than the 5.7 head when ported. Check with the various head porting companies web sites to compare flow numbers and prices. I hope you actually have a LS1 engine to put the heads on. I'm a bit confused since your 97 Z didn't come with a LS1 engine in it.

97MysticZ

iTrader: (16)

Haha, yeah I have an LS1. I have a 98 Z28 now, but I've just been too lazy to change my sig. Do you know what a rough estimate would be to port and polish the heads? On my LT1 heads local places wanted around $700 to port and polish with the valvejob. If its that much I might as well just buy some Patriot heads or something.

Gold Z

iTrader: (3)

Most local porters don't have a CNC machine and a pattern for porting heads so they have to do it by hand, which isn't bad, it's just very time consuming and therefore very expensive if they do it right. I personally would recommend TEA for a set of inexpensive heads that make good power. http://www.totalengineairflow.com/pr.../gmhead/gmls1/

2000TransAmWS6

iTrader: (12)

it does seem like a port and polish job (and valve job) is about $700

both Livernois and Patriot have CNC'd LS6 heads for less than $1000, and they will flow better than PnP LS1 heads.

ssheets

iTrader: (1)

5.3 heads have 1.89" intake valves compared to 2.00" on the LS1 heads so you'll need to replace the valves with 2.00" or larger to take advantage of the smaller chambers (higher compression). 5.3 heads are 61.15cc stock while 5.7 heads are 66.67cc. The ports are the same, but on the 5.3 heads the chambers are about .030" lower or closer to the piston.

If you're really budget constrained you can also look into milling your 5.7 heads and running a thinner head gasket to raise compression. Although most thinner non OEM gaskets are 2x to 4x the price of OEM gaskets, but still cheaper than a set of heads.

97MysticZ

iTrader: (16)

How much could I pick up from doing this?? Also, is it completely necessary to do a valve job whenever porting and polishing? I remember calling a place to get a price when I had my LT1, and they said you had to get the valvejob done. But I know guys have ported and polished their heads themselves at home and haven't done a valve job. If I wanted that done, but only in a professional manner, what exactly should I ask for when I call a machine shop??

Gunnar@Patriot

iTrader: (20)

We have CNC ported 243 castings assembled with LS6 springs and 2.00"/1.55" (non-sodium) valves for $865.00. These heads flow 300-302 @ .0600" and are a great deal.

97MysticZ

iTrader: (16)

How much lift are the LS6 springs good for? Here is the cam that I was wanting to get: Comp- XE-R 228/232 .588/.595 110LSA +2 on 108 ICL. If I were to get those heads, should I upgrade springs with the cam that I am wanting to get?

Gearhead1

I'm under the impression that the LS6 springs are only good to .550 lift. With the cam you're looking at, you'd probably do best to go with a dual valvespring setup.