Can a 2.00 intake valve be used on a 5.3 cylinder head?
#26
12 Second Club
iTrader: (49)
This is true, after port work an ls head is an ls head. With exception of the ls6 heads and rectangle port heads.
But what the op wants to do is put ls1 intake valves in an inferior 5.3 head to raise compression. But without port work to bring it on par with a stock ls1 head, it's pointless.
But what the op wants to do is put ls1 intake valves in an inferior 5.3 head to raise compression. But without port work to bring it on par with a stock ls1 head, it's pointless.
#27
On The Tree
Join Date: Oct 2011
Location: Dirty South
Posts: 102
Likes: 0
Received 0 Likes
on
0 Posts
The old 5.3 heads can be machined to accept 2.02 on the intake and 1.57 exhaust. Take a stab at DIY port and polish . Even if you screw them up, these heads are dirt cheap.
#28
10 Second Club
iTrader: (10)
This is true, after port work an ls head is an ls head. With exception of the ls6 heads and rectangle port heads.
But what the op wants to do is put ls1 intake valves in an inferior 5.3 head to raise compression. But without port work to bring it on par with a stock ls1 head, it's pointless.
But what the op wants to do is put ls1 intake valves in an inferior 5.3 head to raise compression. But without port work to bring it on par with a stock ls1 head, it's pointless.
#29
I would appreciate it if you would edit your post and remove these statements as to not confuse others about my intentions. Thank you.
Since it seems people are mixed up about what I'm trying to do, I will try to clarify.
I have a stock ls1 engine.
I am thinking of building a set of heads using 5.3 castings. These would be hand ported and receive a valve job to accommodate a larger 2.00 ls1 intake valve.
Why 5.3? For the compression boost and the fact that they are cheap.
Thanks to everyone's input I now know that the 2.00 valve swap is possible after a valve job, the seat does not need to be replaced. Now I am trying to find out if further work is needed to make this work. I am concerned about the issues with shrouding that chrisfrost and bww3588 mentioned earlier in the thread. Is this going to be a problem? What would need to be done to correct it? Thanks.
Last edited by RedVertTA; 01-27-2012 at 12:45 AM.
#30
12 Second Club
iTrader: (49)
You need to read the thread. I never said the heads wouldn't be ported. I said they would be ported. See post 17.
I would appreciate it if you would edit your post and remove these statements as to not confuse others about my intentions. Thank you.
Since it seems people are mixed up about what I'm trying to do, I will try to clarify.
I have a stock ls1 engine.
I am thinking of building a set of heads using 5.3 castings. These would be hand ported and receive a valve job to accommodate a larger 2.00 ls1 valve.
Why 5.3? For the compression boost and the fact that they are cheap.
Thanks to everyone's input I now know that the 2.00 valve swap is possible after a valve job, the seat does not need to be replaced. Now I am trying to find out if further work is needed to make this work. I am concerned about the issues with shrouding that chrisfrost and bww3588 mentioned earlier in the thread. Is this going to be a problem? What would need to be done to correct it? Thanks.
I would appreciate it if you would edit your post and remove these statements as to not confuse others about my intentions. Thank you.
Since it seems people are mixed up about what I'm trying to do, I will try to clarify.
I have a stock ls1 engine.
I am thinking of building a set of heads using 5.3 castings. These would be hand ported and receive a valve job to accommodate a larger 2.00 ls1 valve.
Why 5.3? For the compression boost and the fact that they are cheap.
Thanks to everyone's input I now know that the 2.00 valve swap is possible after a valve job, the seat does not need to be replaced. Now I am trying to find out if further work is needed to make this work. I am concerned about the issues with shrouding that chrisfrost and bww3588 mentioned earlier in the thread. Is this going to be a problem? What would need to be done to correct it? Thanks.
so let me get this straight...
you have LS1 heads that flow good and already have 2.0 intake valves and unshrouded valves.
you want to BUY a set of 5.3 heads, PAY for a valve job for 2.0 intake valves, then port the heads and chambers to make them work just to raise your compression?
but....you already have LS1 heads that
1. already have unshrouded 2.00 intake valves
and
2. just need ported to your liking...
and
3. need milled to get the same compression ratio your going to get with 5.3 heads, all with unshrouded valves...
or do you not have the LS1 heads....I'm not sure after "re-reading" the thread. either way you stack it, what your wanting to do does not make any sense unless you already have the 5.3 heads and dont have LS1 heads like you stated. I just dont get why you want to buy and inferior head and put more money in it to make it what you want when you have what you want right in front of you with most of the work done already.
sorry, I'm not editing my posts.
#31
12 Second Club
iTrader: (49)
You need to read the thread. I never said the heads wouldn't be ported. I said they would be ported. See post 17.
I would appreciate it if you would edit your post and remove these statements as to not confuse others about my intentions. Thank you.
Since it seems people are mixed up about what I'm trying to do, I will try to clarify.
I have a stock ls1 engine.
I am thinking of building a set of heads using 5.3 castings. These would be hand ported and receive a valve job to accommodate a larger 2.00 ls1 valve.
Why 5.3? For the compression boost and the fact that they are cheap.
I would appreciate it if you would edit your post and remove these statements as to not confuse others about my intentions. Thank you.
Since it seems people are mixed up about what I'm trying to do, I will try to clarify.
I have a stock ls1 engine.
I am thinking of building a set of heads using 5.3 castings. These would be hand ported and receive a valve job to accommodate a larger 2.00 ls1 valve.
Why 5.3? For the compression boost and the fact that they are cheap.
do you have LS1 heads or 5.3 heads? if you have LS1 heads you need to start there. mill them to what CC you need for whatever compression ratio you want. then port them. done.
if you do not have LS1 heads, only LS1 intake valves and are thinking of getting 5.3 heads solely for compression...dont. get LS1 heads and have them milled and port them.
by the time you buy the 5.3 heads, have the 2.00 valves installed, port them, open the chamber up to unshroud the valves and have them milled, you will have more time, money and effort wrapped up in these heads then they are worth. not to mention probably twice the amount of money in the 5.3 heads as you would if you would have just gone with LS1 heads in the first place.
FYI, LS1 heads can be had just as cheap as 5.3 heads.
#34
Moderator
iTrader: (20)
I would start with the 5.3L heads.
The main reason is that when all is said and done, you won't have to mill as much to get the chamber volume down. The 241's I did ended up at 69cc's after a valve job and blending in the chamber. A 5.3L will probably be about 3-5cc's less, which translates to roughly .018-.030" that would not have to be milled, which would give you more PTV for a larger camshaft.
As far as a valvejob goes, I would recommend one whether you start with the LS1 head or the 5.3L head. A good shop could cut you a valve job for a 2.00" valve on that 5.3L and perform better than the LS1 head with the stock valve job, simply because the stock valve job is not that great.
As for shrouding, most shops use a cutter with an entire profile built in and those cutters typically have a portion to cut away the chamber and unshroud the valve. Not all shops do this, but the good ones do.
The main reason is that when all is said and done, you won't have to mill as much to get the chamber volume down. The 241's I did ended up at 69cc's after a valve job and blending in the chamber. A 5.3L will probably be about 3-5cc's less, which translates to roughly .018-.030" that would not have to be milled, which would give you more PTV for a larger camshaft.
As far as a valvejob goes, I would recommend one whether you start with the LS1 head or the 5.3L head. A good shop could cut you a valve job for a 2.00" valve on that 5.3L and perform better than the LS1 head with the stock valve job, simply because the stock valve job is not that great.
As for shrouding, most shops use a cutter with an entire profile built in and those cutters typically have a portion to cut away the chamber and unshroud the valve. Not all shops do this, but the good ones do.
#37
TECH Enthusiast
iTrader: (5)
Join Date: Jan 2010
Location: Huntsville, Alabama - SA, TX is home
Posts: 676
Likes: 0
Received 1 Like
on
1 Post
RedVertTA - I've noticed this forum is great for a lot of quality information. But also, like in your thread, there are a lot of people that are confusing the point of this thread by not being capable of seeing your goal.
I understand what you are trying to do and am currently doing the same. From my research (mostly on this forum) 5.3 heads are almost identical to LS1 heads. Flow rates and all. People on this forum have noted 10 rwhp from the compression of just bolting on a set of stock 5.3 heads. I'd just use stock LS1 valves and get a good valve job. If your feeling up to it go ahead and take out a bit in the combustion chamber around the intake valve to deshroud it. Thats it. I believe you'll be happy with it.
If you want to go further, there are a lot of people on here that will help guide you to port them yourself which isnt too difficult to at least remove the large obstacals in the port. I have posted a quick video on youtube of porting a set of 853 heads with flow results. I learned from LS1tech and its helpful members. I am currently posting step by step videos of porting a pair of 862 heads (same as 706). Be wary of 706 cast heads because some have been known for cracking. May want to have the pressure tested. Supposedly, 706's were cast at two different plants. One of them was known for cracking.
Here's my vid: http://www.youtube.com/watch?v=kqVvY...ure=plpp_video
I understand what you are trying to do and am currently doing the same. From my research (mostly on this forum) 5.3 heads are almost identical to LS1 heads. Flow rates and all. People on this forum have noted 10 rwhp from the compression of just bolting on a set of stock 5.3 heads. I'd just use stock LS1 valves and get a good valve job. If your feeling up to it go ahead and take out a bit in the combustion chamber around the intake valve to deshroud it. Thats it. I believe you'll be happy with it.
If you want to go further, there are a lot of people on here that will help guide you to port them yourself which isnt too difficult to at least remove the large obstacals in the port. I have posted a quick video on youtube of porting a set of 853 heads with flow results. I learned from LS1tech and its helpful members. I am currently posting step by step videos of porting a pair of 862 heads (same as 706). Be wary of 706 cast heads because some have been known for cracking. May want to have the pressure tested. Supposedly, 706's were cast at two different plants. One of them was known for cracking.
Here's my vid: http://www.youtube.com/watch?v=kqVvY...ure=plpp_video
#40
12 Second Club
iTrader: (49)
Really guys? Talk about misinformation....
First of all, 10 HP from stock 5.3 heads? Seriously? Remind me again why they are so much cheaper than ls1 heads?
2nd, the cylinder bore is only part of the equation when it comes to shrouded valves. The 5.3 combustion chamber is smaller in diameter to match the smaller bore of the 5.3 block, when you put a valve that is larger it puts it closer to the wall of the chamber, shrouding the valve. In order to take full advantage of the larger valve, it needs to be un shrouded.
First of all, 10 HP from stock 5.3 heads? Seriously? Remind me again why they are so much cheaper than ls1 heads?
2nd, the cylinder bore is only part of the equation when it comes to shrouded valves. The 5.3 combustion chamber is smaller in diameter to match the smaller bore of the 5.3 block, when you put a valve that is larger it puts it closer to the wall of the chamber, shrouding the valve. In order to take full advantage of the larger valve, it needs to be un shrouded.