Unported Heads------Lift vs. Duration
07-13-2003, 11:41 PM
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Unported Heads------Lift vs. Duration Looking at the flow bench results for a unported LS1 head the flow starts to flatten out after .550 and that leads me to question what kind of power loss (percentage) can be expected by using say a
224 .534 Vs
224 .568 Vs
224 .581
Also @ what lift and duration do you start replacing valve springs every 20-40 K?
My goal (like most people) is to give up the least amount of power and speed without sacrificing any drivabity/reliablity.
224 .534 Vs
224 .568 Vs
224 .581
Also @ what lift and duration do you start replacing valve springs every 20-40 K?
My goal (like most people) is to give up the least amount of power and speed without sacrificing any drivabity/reliablity.
07-14-2003, 09:49 AM
#2
Re: Unported Heads------Lift vs. Duration I don't know what the specifics would be but think of it like this:
TR-224 with ~.560 lift vs a Comp Cams 224 XE-R with ~.581 lift.
The ramp rates are about the same with the Comp haveing more lift. The Comp has ~ 1 to 2 percent more area under the curve. In otherwords, while the extra lift helps a little, it's not worth a great deal all other things being equal.
I don't think you'd see much difference based on lift between the 224 .568 vs the 224 .581 on stock heads, IF the ramp rate on the lobes were the same.
The 224 .568 looks like it might be a Comp Cam XE. The XE has excellent ramps but they are not as fast as the XE-R.
The other 224 .534 looks like it might be another Comp Cam with ramp rates that are slower/less aggressive than the XE.
Personally, I'd favor the TR224 since the ramp rates are about the same as the XE-R but the TR224 has less lift for a set of stock heads. If you don't mind being harder on the valve springs the 224 XE-R will probably work well. There are several folks on the board that have TR224's with stock heads and a few that have the 224 XE-R with stock heads.
On the springs, I think it's better safe than sorry. Part of it depends on how hard you drive and how often you spin to high rpm. Let the car warm up before going over 2,000 rpm and your springs will thank you. I plan to replace my dual 987 springs after about 25,000 miles with my XE-R cam. I know some have went longer like 40,000 to 50,000 miles, but I don't want to worry about it. While many have ran single springs with good luck, I'm not a fan singles. In the early days I read about too many single springs breaking. You never know if there's going to be bad batch of singles. The duals Rev's might be a decent in between.
I think the 02 LS6 valve spring can deal with .550 lift. GM uses it stock, so I would expect it to be able to deal with .550 for say 50,000 miles or so. I don't think the 02 LS6 spring and deal with very aggressive ramps like a TR224 or XE-R.
When you start doing internal mods the reliablity is going to start droping. Just pulling a cam in has a little risk. Sometimes folks don't install them correctly and bugger stuff up. I would worry more about getting it installed right than the parts if you pick a reasonable cam and quality springs for the most part.
TR-224 with ~.560 lift vs a Comp Cams 224 XE-R with ~.581 lift.
The ramp rates are about the same with the Comp haveing more lift. The Comp has ~ 1 to 2 percent more area under the curve. In otherwords, while the extra lift helps a little, it's not worth a great deal all other things being equal.
I don't think you'd see much difference based on lift between the 224 .568 vs the 224 .581 on stock heads, IF the ramp rate on the lobes were the same.
The 224 .568 looks like it might be a Comp Cam XE. The XE has excellent ramps but they are not as fast as the XE-R.
The other 224 .534 looks like it might be another Comp Cam with ramp rates that are slower/less aggressive than the XE.
Personally, I'd favor the TR224 since the ramp rates are about the same as the XE-R but the TR224 has less lift for a set of stock heads. If you don't mind being harder on the valve springs the 224 XE-R will probably work well. There are several folks on the board that have TR224's with stock heads and a few that have the 224 XE-R with stock heads.
On the springs, I think it's better safe than sorry. Part of it depends on how hard you drive and how often you spin to high rpm. Let the car warm up before going over 2,000 rpm and your springs will thank you. I plan to replace my dual 987 springs after about 25,000 miles with my XE-R cam. I know some have went longer like 40,000 to 50,000 miles, but I don't want to worry about it. While many have ran single springs with good luck, I'm not a fan singles. In the early days I read about too many single springs breaking. You never know if there's going to be bad batch of singles. The duals Rev's might be a decent in between.
I think the 02 LS6 valve spring can deal with .550 lift. GM uses it stock, so I would expect it to be able to deal with .550 for say 50,000 miles or so. I don't think the 02 LS6 spring and deal with very aggressive ramps like a TR224 or XE-R.
When you start doing internal mods the reliablity is going to start droping. Just pulling a cam in has a little risk. Sometimes folks don't install them correctly and bugger stuff up. I would worry more about getting it installed right than the parts if you pick a reasonable cam and quality springs for the most part.