Porting stock heads?

Wanted to see what people thought about porting factory set of heads. I have a spare set of factory heads and thought about porting and polishing the intake, getting a 3 angle valve job done, and just overall try to increase airflow for the engine to see if any gains could be done on the cheap. If you have any input or experiences please let me know. Open to all ideas and opinions, even the "are you crazy" thoughts.

You can make great power with the stock heads, just start out with some #243 LS6/LS2 heads as they have bigger ports to start with. Check to see what castings you have and post up the numbers.

ALOT of companies offer ported stock 241s. and they can make good power.

for a budget its a good way to go.

even just milling them down, and putting bigger valves in them can free up alot of power on the cheap.

The casting is 853's I believe. They are from a 98 LS1 I think. Good idea about milling them down a little to get the bump in compression. I got these heads for cheap so see what I could do. If mill them down a little and put high ratio rocker arm with a little larger valves and may have a nice package. Intake could be limiting factor. Have LS6 intake now, how much HP will that support?

Porting the 853 head is a complete waste of money, even if you have a 97-98 LS1. Not only that but you'll need new valve covers and will need to modify your existing ignition coil setup to work.

About the cheapest you're going to get for a halfway decent head is around $1000-$1200 for a ported 5.3L heads. It may sound like a lot, but by the time you pay the machine shop bill for porting the 853 heads, valve job and milling, IN ADDITION to the valve covers you would be almost at the cost of the [b]new[b] ported 5.3s. Good luck getting a local average machine shop or head porter to get decent results from those 853 heads. If you are in NoVa there is a very little known shop, Hoops, that's good with the LS1 stuff and might be of some help.

Thanks for the info about the heads. Where is Hoops located. I am all around the NoVA area with my job so would love to stop in some time and talk to them.

Why would you need new valve covers? 853's are a stock ls1 head. They aren't a different bolt pattern are they?

If you're thinking of bumping compression you can also go with a thinner head gasket. I'm piecing together a H/C with ported 241's and I'm having those milled .020 and it was suggested to go with a 3.910 bore gasket @ .030 thickness. I was told that combo would achieve a .7 bump in compression. Of course you need to be mindful of your piston to valve clearance.

Why would you need new valve covers? 853's are a stock ls1 head. They aren't a different bolt pattern are they?

97-98 LS1 heads used a perimeter bolt valve cover. 00-04 LS1 used centerbolt valve covers.

I thought I read somewhere about a company doing a port job on the 853 heads and getting decent hp gains just in that area. I believe it was in GMHP magazine some time back. Oh well, I got the heads cheap so no big loss if I decide to go and get different heads. I may still use them for a stock rebuild for a truck I am planning a build for. Didn't think about bolt pattern for valve cover from earlier years so thanks for info on that.

I have AI port the 241s (and all the others), greenbean has a GTO now that puts down 400 to the tires with bolt ons, STOCK CAM, and a set of CNC'd AI 241s.

Can pick up a used set of 241s around $150 if you need them, as for the other heads, I do not really know, we just have seen the 241s.

I thought I read somewhere about a company doing a port job on the 853 heads and getting decent hp gains just in that area. I believe it was in GMHP magazine some time back. Oh well, I got the heads cheap so no big loss if I decide to go and get different heads. I may still use them for a stock rebuild for a truck I am planning a build for. Didn't think about bolt pattern for valve cover from earlier years so thanks for info on that.

That article may have been years ago. Chances are they were high dollar hand ported heads for the early LS1 cars as that's all that was available several years ago. They had no choice. Now that they do everyone steps up away from those heads. No sense in going back to them, no matter what you bought them for. You may see nice gains from porting them depending upon who you choose, but the bang for the buck will be found elsewhere.

Thanks guys. Luckly I can get about the same I paid for them turning them into scrap metal if it really came down to it. I couldn't do that though. I will just end up using them on a stock rebuild for a cheap engine for my truck.

Thanks guys. Luckly I can get about the same I paid for them turning them into scrap metal if it really came down to it. I couldn't do that though. I will just end up using them on a stock rebuild for a cheap engine for my truck.


You can sell them to someone with a 98. They are useful for those of us with perimeter bolts. :D

I have AI port the 241s (and all the others), greenbean has a GTO now that puts down 400 to the tires with bolt ons, STOCK CAM, and a set of CNC'd AI 241s.


Watch out! You'll start a flamewar with numbers like that!

Phil just told me the news.. That's bad as hell.

:D :D :D

You mean these numbers:

04 M6 GTO with bolt ons and Advanced Induction CNC'd 241 heads.
Bolt ons include: Fast 90, NW 90TB, Kooks Headers, Catback, !cats, Comp RRs, Mez EWP.

NOTE: this is the STOCK 04 GTO CAM. And in Speed Density.

http://www.advancedinduction.com/Dyno/RELS1GTO_StockHC_vs_StockCamCNC241.jpg

Stock cam 346 making 430rwhp with poorly done 241 castings... :lol: :rolleyes:

Those numbers could only come from around 11.5:1 compression on a number happy dyno with the operator using every dyno trick in the book. I hope the GTO owner is happy with his dyno sheet, because the track performance will be disappointing if he expects it to run like a 430rwhp GTO should - trapping MINIMUM 119-120.

Stock cam 346 making 430rwhp with poorly done 241 castings... :lol: :rolleyes:

Those numbers could only come from around 11.5:1 compression on a number happy dyno with the operator using every dyno trick in the book. I hope the GTO owner is happy with his dyno sheet, because the track performance will be disappointing if he expects it to run like a 430rwhp GTO should - trapping MINIMUM 119-120.
11.1:1 compression
this dyno reads the same as another one in same town.
Tracks times forthcoming. Looking forward to the results as well.