lets talk about porting
lets talk about porting ok so i ported my 317's and this is the first porting i have ever done. these are on a twin turbo lq4. i havent driven it yet so i dont know how well they will work but i want some feedback. one of my questions is, how far can you port the exhaust until you will run into waterjacket or cracking problems? i ported my exhaust ports almost as big as the gaskets and i see alot of people leave them kinda oval. are their different ways to port heads for turbo, nitrous, or NA? also i didnt really port the intakes much because they matched the gaskets pretty well so i just smoothed the castings off. heres some pics
ported exhaust ports on left, and unported on the right
all ported
and heres some 706's i ported
ported exhaust ports on left, and unported on the right
all ported
and heres some 706's i ported
Looks good. The intake side takes a little more finesse as the gaskets are a little big. Just keep the basic shape and take down the rough casting. Blend the bowl to the runner and give the valve guide boss a knife edge.
Don't be afraid to take the casting bump down all the way and expose the rocker bolt hole. Just make sure you use a good sealant on the rocker bolts or you will have a small vacuum leak.
I argee with farmington, those are pretty much junk now. You should have went with
a d-shaped port. Should have searched head port shapes on here before doing any
porting. https://ls1tech.com/forums/generatio...6k-beware.html https://ls1tech.com/forums/generatio...-can-help.html
Not trying to be a butthole, just my .02
a d-shaped port. Should have searched head port shapes on here before doing any
porting. https://ls1tech.com/forums/generatio...6k-beware.html https://ls1tech.com/forums/generatio...-can-help.html
Not trying to be a butthole, just my .02
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there is really no restriction in the upper half of the port, you will gain basically nothing for the work you did as you didnt port around the valve seat, which is about the only spot that matters.
Also moving the floor of the port down to the gasket basically ruined those heads, IMHO you will make the same power or LESS than if you wouldnt have touched them at all
Your work looks good though, nice and smooth, FWIW
Also moving the floor of the port down to the gasket basically ruined those heads, IMHO you will make the same power or LESS than if you wouldnt have touched them at all
Your work looks good though, nice and smooth, FWIW
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Verdad Gallardo Thanks for the input guys. I never researched about the D shape and wish i would have. I focused more on the smoothing and no bumps and i think for three most part i did a good job on that. I should have blended the stem area allot better. Well we will see how they do when i start running the truck. The turbos are fairly small so the spool can't be terrible but only time will tell. Worst comes to worst I'll buy another used set and port them right.
Port the ceilings, but not so much the floors.
Valve guide area could use some.
Short-side radius, if it hasn't been done.
Behind the seat.
The exit, into your manifold/exhaust, should be smaller than the manifold.
Valve guide area could use some.
Short-side radius, if it hasn't been done.
Behind the seat.
The exit, into your manifold/exhaust, should be smaller than the manifold.
I agree. The porting may not be AI, or TSP, but it sure beats a stock head.
There's a good thread going on by "AGearHeadForLife". He has several videos on YT, which are in his signature.
Otherwise, he can be found on YT "LS1 Head Porting".
There's a good thread going on by "AGearHeadForLife". He has several videos on YT, which are in his signature.
Otherwise, he can be found on YT "LS1 Head Porting".
Last edited by gMAG; Feb 16, 2013 at 02:58 PM.
This is in picture #4 of your orig post, where you see the exhaust valve...then the valve seat area turns (arch/radius) and becomes the floor of the exhaust runner.
Where the turn is, is the short-side radius. The opposite of this would be the turn on the ceiling, which is longer.
Likewise for the intakes.
This is discussed in those videos.
Here's the link to his porting thread on LS1Tech...
https://ls1tech.com/forums/generatio...-can-help.html
Where the turn is, is the short-side radius. The opposite of this would be the turn on the ceiling, which is longer.
Likewise for the intakes.
This is discussed in those videos.
Here's the link to his porting thread on LS1Tech...
https://ls1tech.com/forums/generatio...-can-help.html
Last edited by gMAG; Feb 16, 2013 at 08:23 PM.
thats alot of really good info. i didnt have plans to fully port these heads and get too out of hand with it because i didnt want to risk messing them up really bad because their my good set. i have two other sets like the 706's and 862's laying around that i ported the same way just for some practice. if these do end up making things worse then ill go through that video on that guys post you linked and do a diff set of 317's the right way.
Got that right! So little is gained by hogging out ports like that, GM engineers did the work for you with the stock shape. If you want bang for your buck, work on the bowls and guide boss, that's where the restriction is. Blend the bowls to the valve seats, remove swirl step and lay down/streamlne the guide bosses so the incoming charge doesn't hit a wall of restriction. Those heads are practice heads now.
