I raced this guy this weekend and he was the only car that came close to me on all motor. It was a close race but he took me by .4 tenths in the end. He basically had all the same stuff I do but the only differences are he had his heads ported, he had slicks( I was on streets), he had true dual, and 4.10 gears. He is running his motor up to 6500 rpm! Here a comaprison:

-94 LT1 350 with ported heads
-LT4 HOT cam w roller rockers
-hooker headers with true duals
-T-56 with 4.10 gears and slicks
-Cold air intake

My 355 with vortecs should bacially be the same as an LT1 with the exception of my heads being iron. We have the same cam, rockers, headers, manuals and exhaust. He said that porting his heads made a HUGE difference and that's why he is able to pull it to 6500 rpm. I wanted to know if it would be worth it for me to pull my heads and port them. I figure that with slicks alone I should be within .2 tenths of him, could porting my Vortecs get me those two tenths? I heard they like to be ported.Thanks

 

The vortecs can really come alive with some port work. Chevy High Performance had an article on porting them and they almost doubled the exhuast flow. The intake only improved slightly but the exaust is where you will see your gains.

 

Actually that was Car Craft http://www.carcraft.com/techarticles...ort/index.html

I'm going nearly the same to mine, but I'm not gonna bother with the intake side. As RB says, the size of the cheese is not big enough of a reward for the maze you have to go through..... or something like that.

Keep in mind that those before and after numbers are not a direct comparison. While the gain was still good, the simple addition of the 1-3/4" pipe AFTER the porting probably added 30-40 cfm to those numbers.

 

Don't port the intakes you'll only make them worse. You have to know exactly what your doing and even then woll only gain 5cfm. Really just port the exhaust to improve flow.

 

Thanks every one, I have done some porting before but I was afraid to mess up my new vortecs at the time. Yeah I heard the intake runners are great just the exhaust sucks. So just do the exhaust side, OK. Should I just do bowl work or the actual port too? Thanks

 

Do the port on the exhaust side. It needs a lot of help.

I'm in the middle of doing a pair now (whenever I have any time). I'm just doing the basics like tapering the valve guide down, removing and smoothing the casting lines, and getting the bowl opened up to ~1.75" (i.e. 90% of the valve size).

He took it a bit further according to the magazine, but I don't trust myself yet. I'm not that experienced to be playing with port velocity.

If I gain anywhere from 20-30 cfm @ .500" lift I'll be happy, although I'll never pay the money to have them flowed. I'm not that worried about it. My main goal was to smooth the port.

I'm also smoothing out the chambers. There's a nice ridge around the valve seats that just doesn't need to be there IMO. Seriously, I'm just removing the rough edges and smoothing them so it will reduce hot spots and carbon build up. No other reason.