LS-6 valves verses Oversized valves
Thread Starter
Joined: May 2009
Posts: 1,539
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From: columbus,ohio
LS-6 valves verses Oversized valves I have a set of heads casting #799 that I would like to upgrade.My question is would I see more gains with the LS-6 hollow stem,sodium filled . Or over sized valves something like at least 2.02 intake and 1.57 exhaust.I am thinking that there is probably not much of a gain with the LS-6 valves.
The only thing you'll gain with the LS6 valves is valve control and RPM potential due to their light weight. With the larger diameter valves you'll pick up a few cfm of air flow. I'm not sure how much, but if you've got 'em apart and don't mind sending them out to have the seats cut, I'd go with the larger valves and stiffer springs.
As far as gains in power/torque, I wouldn't imagine you seeing any gains from the LS6 valves. You'd see gains with larger valves and a valve job. What the LS6 valves will help with though, is a lighter valve train, therefore longer valve spring life and more a controlled valve train in the upper rpm range. I ended up using some LS6 valves, titanium retainers and 918's. I'm happy with my decision. Good luck with yours.
TECH Fanatic
Joined: Jun 2002
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From: Upstate NY
A difference of opinion is what makes horse races...and sometimes horsepower. 
There is probably more power and torque to be gained from a really good valve job on stock sized valves rather than by going to 2.02/1.57 valves...even with a good valve job on them. David makes a good point also.
There are other stock size valve options that you might explore with your head guy. Personally I would be wary of a head guy who recommended larger valves for a 3.90 bore. Tons of experience with the traditional SBC is not necessarily good proparation for working with LS engine heads.
Jon
There is probably more power and torque to be gained from a really good valve job on stock sized valves rather than by going to 2.02/1.57 valves...even with a good valve job on them. David makes a good point also.
There are other stock size valve options that you might explore with your head guy. Personally I would be wary of a head guy who recommended larger valves for a 3.90 bore. Tons of experience with the traditional SBC is not necessarily good proparation for working with LS engine heads.
Jon
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in my own oppion, i would worry about the exhaust valve being larger. if you get more (for lack of a better word) dirty air out, you can get more cleaner air in. i would recomend a 1.60 valve on the exhaust, and stay with your 2.00 intake valve. a 1.57 is only .02 larger than a std exhaust valve. if you have the exhaust seat back cut, i will flow much better also.
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Verdad Gallardo Thread Starter
Joined: May 2009
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From: columbus,ohio
Well some well know head porter is using 1.57 on exhaust side on there heads for a 5.3 So I'm confused why some of you are concerned about the valves being shrouded on a 3.9 bore.But the porting in this version stock head may be cleaning up any shrouded area to accommodate the larger valves.
Well some well know head porter is using 1.57 on exhaust side on there heads for a 5.3 So I'm confused why some of you are concerned about the valves being shrouded on a 3.9 bore.But the porting in this version stock head may be cleaning up any shrouded area to accommodate the larger valves.
Thread Starter
Joined: May 2009
Posts: 1,539
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From: columbus,ohio
Well its the relationship between the head and cylinder bore,is it not like a marriage they both have to be compatible or its not going to work very well.You just cant blame the guy the head,or the girl the cylinder.OK may his valve is to large for her cylinder,alright if your going to blame someone in this case go ahead blame it on the cylinder ,us guys are usually right any way! If there is a shroud affect again ,why are some porters using larger valves on 5.3 versions where the bore is even smaller?
Last edited by omc8; Nov 1, 2009 at 11:44 AM.
I have had both the over size valves (my last set up) and the light stock sized hollow/sodium filled (which I have now) I my self feel that the lighter valves give me the potential of running a bigger cam and with the valve train being as light as it is I do not see the lag in reaching my RPM power band point that I did with the over sized solid valves. It seems like I am not lagging as much, and no amount of tuning can help that.
The lighter valves combined with lets say a set of Yella Terra rockers you are able to really run a very light very efficient valve train. That will let you reach your power band quicker and more efficient and no issues with clearance if you so choose to mill your heads and run smaller chambers (ie 59CC).
The lighter valves combined with lets say a set of Yella Terra rockers you are able to really run a very light very efficient valve train. That will let you reach your power band quicker and more efficient and no issues with clearance if you so choose to mill your heads and run smaller chambers (ie 59CC).
Last edited by 02*C5; Nov 3, 2009 at 01:06 AM.
Thread Starter
Joined: May 2009
Posts: 1,539
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From: columbus,ohio
I do understand that bigger is not always better .But could you explain in detail why your concerned ,when these are being used on the smaller 3.78 bore.
a 2.00 valve is all a street car really needs, it will be improved with a vj and a backcut.
Thread Starter
Joined: May 2009
Posts: 1,539
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From: columbus,ohio