your input on valves ?
your input on valves ? Okay i just got my 243 back from getting a full pp work done and my question is. Is it really worth swapping the stock valves to a 2.02 and exhaust to 1.575 i just caint see my self spend $300 for maybe 1 or 2 hp if u will even see that. Or maybe im wrong what yall imput
Won't see much more of a difference than what you noted, a few HP accross the board is what you get. Now if you have a big bore (4" or more) and go with say 2.055 or bigger valves you might see more of a bump than a few HP.
@Red thats what i thought im still on stock bottom end ls1 so i should be fine for now then
@96 it was mentioned to me i told them i just wanted to pp first and go back to the valves later as i thought i wouldnt see much gains but need to see other ppl input i just don't see spending $300 plus cutting it to see little to hardley any gains
@96 it was mentioned to me i told them i just wanted to pp first and go back to the valves later as i thought i wouldnt see much gains but need to see other ppl input i just don't see spending $300 plus cutting it to see little to hardley any gains
Depending on the rest of your combination I'd say it is worth it, I have 3 sets of CNCed 799s all by the same guy & put them all on the bench but I'm not sure I have the flow sheets.
1st have stock valves, 2nd have Manley stock size valves, 3rd have Manley 2.02 hollow stem intakes.
Set 2 with the stock size Manleys were like 6-10 CFM better than the stock valves & saw about the same gains on set 3 over set 2.
1st have stock valves, 2nd have Manley stock size valves, 3rd have Manley 2.02 hollow stem intakes.
Set 2 with the stock size Manleys were like 6-10 CFM better than the stock valves & saw about the same gains on set 3 over set 2.
Could a different backcut on the stock valve do the same thing for flow as the Manley stock size valves?
If there was 20hp in 2.02" valves then no porter would bother reusing stock. You keep racing that bench HARD pretty soon you will have 1000hp, stock idle that is happy with a stock stall and last indefinitely.
If there was 20hp in 2.02" valves then no porter would bother reusing stock. You keep racing that bench HARD pretty soon you will have 1000hp, stock idle that is happy with a stock stall and last indefinitely.
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Could a different backcut on the stock valve do the same thing for flow as the Manley stock size valves?
If there was 20hp in 2.02" valves then no porter would bother reusing stock. You keep racing that bench HARD pretty soon you will have 1000hp, stock idle that is happy with a stock stall and last indefinitely.
If there was 20hp in 2.02" valves then no porter would bother reusing stock. You keep racing that bench HARD pretty soon you will have 1000hp, stock idle that is happy with a stock stall and last indefinitely.
the only thing I will add is Advanced Induction seems to think stock valves work fine and they have produced plenty of results to support their theory.
Okay i just got my 243 back from getting a full pp work done and my question is. Is it really worth swapping the stock valves to a 2.02 and exhaust to 1.575 i just caint see my self spend $300 for maybe 1 or 2 hp if u will even see that. Or maybe im wrong what yall imput
The 6-10 CFM gain was with stock size Manley valves.
Google it, like 2-2.5 HP/CFM so 20 HP for 8 $17 Rev 2.02 valves=$136
Yeah its a waste of money & no one does it
Google it, like 2-2.5 HP/CFM so 20 HP for 8 $17 Rev 2.02 valves=$136
Yeah its a waste of money & no one does it
That means that my ported heads (which flow 87cfm more than stock) gained me 217hp
Last edited by redtan; Dec 9, 2014 at 09:12 AM.
Depends what you consider shrouded. Lots of people have success with a 2.165" valve in a 4" bore LS2 or LQ9. That's a valve diameter that is 54% of the bore diameter. That same percentage for a 3.898" bore is just a tad larger than a 2.100" valve.
The point was that a 2.02" valve is a long ways away from 2.100" and would be further away from the wall in a 3.898" bore than a 2.165" valve in a 4" or even 4.030" bore.
Could you tell us more about those heads , what casting # , do you have any flow numbers and pictures of them bare ported. Details , did they mill them , valve job , new guides , new seals , what cc the runners are now and how much did they charge you ?
Would that not depend on angle of the head as well? For example, A 11 degree aftermarket head would place the valve further away from the cylinder wall thus effectively reducing "shrouding" and taking better advantage of the larger valve compared to a stock casting?
That's along a different axis, but yeah, the shallower angle should help but up to a certain point. If you're rolling that valve angle over and the port isn't being raised as well, you're making a sharper turn for the air to make before it gets to the valve, so there is some give and take there.
