Cam size help and Parts list
06-24-2013, 07:31 AM
#22
It depends on how you define "safety." The beehives will be easier on the other components, but won't have the safety a second spring. You might want to look at some Brian Tooley double springs - some have modest (400 pound) open spring pressure levels that would fit Comp Cams recommendation for those lobes.(The BTRs don't cost much more than good beehives.)
06-24-2013, 08:17 AM
#23
I'll post this, since I always post this. And it has nothing to do with brand whoring. I recommend what I recommend, because nobody bothers to actually investigate what they are putting in their engines or why setups should be done they way they are done.
XE-R and LSK lobes that are used by TSP in their shelf cams are hard on a valvetrain. If you understand that and accept the fact that you need to design the rest of the system to account for this, you can run XE-R lobes - and I'd NEVER run them with beehives. LSK I'd never advocate for a true street car, even one that sees the strip, unless you were willing to check things ever 3-5k miles. However, if you're just adding **** into a shopping cart on TSP's site.
STOP.
LSK and XE-R lobes beat a valvetrain up pretty good. Running LS7 lifters, 5/16" pushrods, heavy stainless valves, stock rockers, and aggressive springs to try and control those crazy lobes and heavy valves = failure somewhere down the line as things degrade over time. What fails? Rockers fail, lifters fail, springs can bind and break, or cams can become galled and take out a lifter. Why is that happening? ****-poor matched components.
With an aggressive cam lobe you generally get "loft" where a lifter will actually come off the cam for a brief moment and then get slammed back down on the cam as the valvesprings try to keep the system together. The more spring pressure you put on the system, the less likely loft is to happen, but it happens because of weak pushrods that flex and allow some spring pressure to be lost and the lifter to take flight. The problem is the lifter comes crashing back down and that can damage the lifter, cam, pushrod, or beat on the rockers and cause them to fail. It usually doesn't happen right away. But after 5-10k miles, you see the issues. As you increase the spring pressure trying to control everything, you put more stress on the rockers, pushrods, and lifters. It just becomes a problem that escalates.
How do you avoid this? First, get an endurance type lobe. Comp has them in LXL, HUC, Xtreme RPM (which TSP will actually sell you if you're so inclined to ask). EPS has them as well with their proprietary lobes. Brian Tooley sells versions of his cams using these lobes too. You might give up a few HP at the top end with more endurance specific profiles, but you gain a lot of stability which can be worth HP and certainly longevity.
When spec'ing out a system take into consideration the two sides of the fulcrum on the rocker: valve side and lifter side. Lifter side, you want stout pushrods like 11/32nds or better, quality lifters designed to take aftermarket valvespring pressures, and endurance cam lobes that won't beat a system to ****.
On the valve side, a lighter valve is easier to control and requires less valve spring. And less spring is usually lighter as well, which just adds to the overall goodness of the system. A lightweight rocker is also important (the GM rocker is the lightest and one of the strongest - keep it).
When you combine lightweight over the valve with strength on the lifter side all with an endurance lobe profile, you end up with a pretty well engineered system.
My valvetrain is setup like that. Lightweight turned-down LS3 valves are 83g vs the stock LS1 100g and 110g for most aftermarket valves. The rockers are stock w/upgraded trunions. The valvesprings are Custom PAC 1900 with Ti retainers which have 150lbs seat pressure but only 400 open to be stock rocker friendly. I went with Manton 11/32 pushrods to eliminate flex and Morel 5206 lifters, because they are billet bodies with oversize rollers to create more surface area contact with the camshaft. And lastly, I have an EPS lobed cam that was ground on a Cam Motion billet core to ensure valvetrain stability. It costs more to do it this way and may require talking to several vendors. But if you're doing the work yourself, it'll be worth it.
If you're just doing the cam, you need to take into account a lifter with 78k miles, heavy stock valves, and stock rockers. Use a quality spring and a stout pushrod to help.
But the other thing you need to look at is valve events. You're DCR is going to be low with that cam on stock heads, which is why I recommended something on a 110 LSA since it will build compression with an earlier IVC. The sooner you close the intake, the more low-end and midrange torque you can build. There are several profiles out there that do a good job with this which I recommended in an earlier post.
XE-R and LSK lobes that are used by TSP in their shelf cams are hard on a valvetrain. If you understand that and accept the fact that you need to design the rest of the system to account for this, you can run XE-R lobes - and I'd NEVER run them with beehives. LSK I'd never advocate for a true street car, even one that sees the strip, unless you were willing to check things ever 3-5k miles. However, if you're just adding **** into a shopping cart on TSP's site.
STOP.
LSK and XE-R lobes beat a valvetrain up pretty good. Running LS7 lifters, 5/16" pushrods, heavy stainless valves, stock rockers, and aggressive springs to try and control those crazy lobes and heavy valves = failure somewhere down the line as things degrade over time. What fails? Rockers fail, lifters fail, springs can bind and break, or cams can become galled and take out a lifter. Why is that happening? ****-poor matched components.
With an aggressive cam lobe you generally get "loft" where a lifter will actually come off the cam for a brief moment and then get slammed back down on the cam as the valvesprings try to keep the system together. The more spring pressure you put on the system, the less likely loft is to happen, but it happens because of weak pushrods that flex and allow some spring pressure to be lost and the lifter to take flight. The problem is the lifter comes crashing back down and that can damage the lifter, cam, pushrod, or beat on the rockers and cause them to fail. It usually doesn't happen right away. But after 5-10k miles, you see the issues. As you increase the spring pressure trying to control everything, you put more stress on the rockers, pushrods, and lifters. It just becomes a problem that escalates.
How do you avoid this? First, get an endurance type lobe. Comp has them in LXL, HUC, Xtreme RPM (which TSP will actually sell you if you're so inclined to ask). EPS has them as well with their proprietary lobes. Brian Tooley sells versions of his cams using these lobes too. You might give up a few HP at the top end with more endurance specific profiles, but you gain a lot of stability which can be worth HP and certainly longevity.
When spec'ing out a system take into consideration the two sides of the fulcrum on the rocker: valve side and lifter side. Lifter side, you want stout pushrods like 11/32nds or better, quality lifters designed to take aftermarket valvespring pressures, and endurance cam lobes that won't beat a system to ****.
On the valve side, a lighter valve is easier to control and requires less valve spring. And less spring is usually lighter as well, which just adds to the overall goodness of the system. A lightweight rocker is also important (the GM rocker is the lightest and one of the strongest - keep it).
When you combine lightweight over the valve with strength on the lifter side all with an endurance lobe profile, you end up with a pretty well engineered system.
My valvetrain is setup like that. Lightweight turned-down LS3 valves are 83g vs the stock LS1 100g and 110g for most aftermarket valves. The rockers are stock w/upgraded trunions. The valvesprings are Custom PAC 1900 with Ti retainers which have 150lbs seat pressure but only 400 open to be stock rocker friendly. I went with Manton 11/32 pushrods to eliminate flex and Morel 5206 lifters, because they are billet bodies with oversize rollers to create more surface area contact with the camshaft. And lastly, I have an EPS lobed cam that was ground on a Cam Motion billet core to ensure valvetrain stability. It costs more to do it this way and may require talking to several vendors. But if you're doing the work yourself, it'll be worth it.
If you're just doing the cam, you need to take into account a lifter with 78k miles, heavy stock valves, and stock rockers. Use a quality spring and a stout pushrod to help.
But the other thing you need to look at is valve events. You're DCR is going to be low with that cam on stock heads, which is why I recommended something on a 110 LSA since it will build compression with an earlier IVC. The sooner you close the intake, the more low-end and midrange torque you can build. There are several profiles out there that do a good job with this which I recommended in an earlier post.
Last edited by JakeFusion; 06-24-2013 at 08:24 AM.
06-24-2013, 08:33 AM
#24
I understand what you are saying but I have not been able to reconcile it with either Texas Speed's website, or the Comp Cams current catalog. Specifically, the Texas Speed website indicates that the OP's selected cam will work with either beehives or double springs. Similarly, Comp Cam's current catalog indicates that similar cams, in terms of duration, lift, and XER lobes should be run with Comp Cam 921 springs which are rated at 408 pounds (spring rate) and a nominal 400 pounds of open spring pressure. So, both Texas Speed and Comp Cams are effectively suggesting that these lobes are not all that hard to control.
06-24-2013, 08:51 AM
#25
That's why you shouldn't just go by what a catalog says. Please talk to some of the valvetrain gurus on here. What I've posted is that knowledge wrapped up into one post.
But to break it down, XE-R lobes are "square" lobes with tremendous ramp rates. They can be controlled with sufficient valve spring pressure, but what they do is they are violent off the seat. This tremendous acceleration causes them to make big power. The square design makes it harder to control - imagine the lifter trying to follow on a basically square lobe. You can see how loft could occur if you have flex in the system that effectively negates the spring pressure. The point is, if you don't pay attention to the rest of the valvetrain, you'll have issues at some point with this design.
Personally, I don't mind the XE-R lobes. My setup would work fine with XE-R lobes. But it's engineered to be able to handle it without issue. On a relatively stock car, I can't say the same thing. But that's just the engineering side of the lobe profile.
The cam profile is another thing all together. And I think a 226-230 degree intake duration with an ICL of 108 is good for avg power throughout the RPM range on these engines. Especially with stock heads. If you go with aftermarket or ported castings and you increase the compression, a bigger cam with a later intake valve closing point can make serious power too. But you've got to optimize the entire setup to get nice results.
Can you throw a 233/239 112+0 into a stock car and make 400rwhp? You bet. It has 12 degrees of overlap @ .050 (actually only 11 - XE-R lobes are 232/238). Can you throw a 227/235 110+3 into a stock car and make 400? It'll be even easier (same 11 degrees of overlap), hold the power as long due to the exhaust duration, and make 20-25ft-lbs more torque everywhere due to the IVC happening sooner. You decide what would be a faster car. Plus if the 227/235 is using lobes that are more stable, you're going to have better reliability and more RPM stability with the use of less spring pressure, which usually results in more power.
But to break it down, XE-R lobes are "square" lobes with tremendous ramp rates. They can be controlled with sufficient valve spring pressure, but what they do is they are violent off the seat. This tremendous acceleration causes them to make big power. The square design makes it harder to control - imagine the lifter trying to follow on a basically square lobe. You can see how loft could occur if you have flex in the system that effectively negates the spring pressure. The point is, if you don't pay attention to the rest of the valvetrain, you'll have issues at some point with this design.
Personally, I don't mind the XE-R lobes. My setup would work fine with XE-R lobes. But it's engineered to be able to handle it without issue. On a relatively stock car, I can't say the same thing. But that's just the engineering side of the lobe profile.
The cam profile is another thing all together. And I think a 226-230 degree intake duration with an ICL of 108 is good for avg power throughout the RPM range on these engines. Especially with stock heads. If you go with aftermarket or ported castings and you increase the compression, a bigger cam with a later intake valve closing point can make serious power too. But you've got to optimize the entire setup to get nice results.
Can you throw a 233/239 112+0 into a stock car and make 400rwhp? You bet. It has 12 degrees of overlap @ .050 (actually only 11 - XE-R lobes are 232/238). Can you throw a 227/235 110+3 into a stock car and make 400? It'll be even easier (same 11 degrees of overlap), hold the power as long due to the exhaust duration, and make 20-25ft-lbs more torque everywhere due to the IVC happening sooner. You decide what would be a faster car. Plus if the 227/235 is using lobes that are more stable, you're going to have better reliability and more RPM stability with the use of less spring pressure, which usually results in more power.
06-24-2013, 12:17 PM
#29
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OP, do some research here, and let some wise engines guys lead you to a path that will build you a reliable setup. The guys that have posted here know what they're talking about, and if you listen, you won't choke your motor in 2k miles or less. Anyone here who thinks they can get by with a "cheap" cam swap is kidding themselves if they want a reliable setup. Lifters are a must, dual springs or PSI beehives are a must, oil pump is a must, healthy push rods are a must, new chain is a must, and for the expense you're already into here, heads mine as well be done, since you can get yours ported and milled for ~1k or less. TEA will port your heads for 1k and add BT .660 lift dual springs for another $300. Search and study. You can create a nice setup, but cheaply, all you'll get is heartache.
