Are we sure the 918s can handle the new XE-R lobes?
03-26-2002, 02:39 AM
#21
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Re: Are we sure the 918s can handle the new XE-R lobes? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>Of the 10 second heads cam cars, at least three (Raughammer, GeorgeC and Cmarsh93Z) all run XE-R lobes or even more aggressive ones</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">And the other two were solid rollers weren't they? Was GeorgeC & Chris both using 226 duration cams?
I think most of their short blocks went south didn't they. Raugh's, Chris's, George's, anybody else go into the shortblock already?
I can't decide whether or not to do it with my Stage I heads & slow ramp rate 224 .535 lift cam or update and see what she'll do with a real cam. Hmmmm... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<strong>Of the 10 second heads cam cars, at least three (Raughammer, GeorgeC and Cmarsh93Z) all run XE-R lobes or even more aggressive ones</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">And the other two were solid rollers weren't they? Was GeorgeC & Chris both using 226 duration cams?
I think most of their short blocks went south didn't they. Raugh's, Chris's, George's, anybody else go into the shortblock already?
I can't decide whether or not to do it with my Stage I heads & slow ramp rate 224 .535 lift cam or update and see what she'll do with a real cam. Hmmmm... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
03-26-2002, 03:20 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? Anyone know the base circle of the GMPP Hotcam?
<small>[ March 26, 2002, 03:24 AM: Message edited by: love2xlr8 ]</small>
<small>[ March 26, 2002, 03:24 AM: Message edited by: love2xlr8 ]</small>
03-26-2002, 08:17 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Carlitos:
<strong> And if you think about it, CompCams also recommends their lifters with the XE lobes. How many TR224s, B1s, T1s are running with new lifters? From what I understand, most people don't upgrade lifters until they upgrade their heads, and there are alot of cam only LS1s out there. If I'm not mistaken, most of the newer LS1 cams use these XE lobes.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I think the stock lifters and 918 springs would be fine for B1/T1 cams that are shifting at a reasonable rpm. There are many people on here that have logged quite a few miles (and track passes) with that setup.
What is exactly the difference between an XE and a XE-R cam?
<strong> And if you think about it, CompCams also recommends their lifters with the XE lobes. How many TR224s, B1s, T1s are running with new lifters? From what I understand, most people don't upgrade lifters until they upgrade their heads, and there are alot of cam only LS1s out there. If I'm not mistaken, most of the newer LS1 cams use these XE lobes.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I think the stock lifters and 918 springs would be fine for B1/T1 cams that are shifting at a reasonable rpm. There are many people on here that have logged quite a few miles (and track passes) with that setup.
What is exactly the difference between an XE and a XE-R cam?
03-26-2002, 08:40 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? I'm pretty sure Chris Marsh and I were using the same GTP 226/226 .591/.591 cam. I can't say with absolute 100% certainty, but I'm pretty sure the lobes are not as aggressive as the new Comp XE-R stuff.
I was fine with Comp 918 springs/Ti retainers, but only had the 226 cam in the car a short time before the shortblock expired (not in any way a result of the cam) due to 2 years of heavy abuse and 7000+rpm shifts...
I was fine with Comp 918 springs/Ti retainers, but only had the 226 cam in the car a short time before the shortblock expired (not in any way a result of the cam) due to 2 years of heavy abuse and 7000+rpm shifts...
03-26-2002, 08:43 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? One more thought...
If Comp is strongly recommending upgraded lifters and double springs, that should be a clue as to the highly aggressive ramps of these lobes. I would follow Comp's advice as far as valvesprings/lifters go.
If Comp is strongly recommending upgraded lifters and double springs, that should be a clue as to the highly aggressive ramps of these lobes. I would follow Comp's advice as far as valvesprings/lifters go.
03-26-2002, 08:59 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? I would look at double springs with this cam as the 918's will be on the edge. I believe you may have a PR length issue or something similar affecting your combo.
Good luck,
Chris
BTW the XE-R grinds with the right spec'd spring will work just fine in a street/strip car. There will be increased valvetrain stress from the ramp rates but it is by no means extreme.
I think the 228/228 .585 lift 112LSA XE-R based cam would make great power and peak around 6400rpm. With LS1edit tuning and the ramp rates of that cam driveability wouldnt be worse than a TR224 cam but power would be nicely improved <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> You would also only need a 6600-6700rpm shift point.
Cheers,
Chris
Good luck,
Chris
BTW the XE-R grinds with the right spec'd spring will work just fine in a street/strip car. There will be increased valvetrain stress from the ramp rates but it is by no means extreme.
I think the 228/228 .585 lift 112LSA XE-R based cam would make great power and peak around 6400rpm. With LS1edit tuning and the ramp rates of that cam driveability wouldnt be worse than a TR224 cam but power would be nicely improved <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> You would also only need a 6600-6700rpm shift point.
Cheers,
Chris
03-26-2002, 10:42 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? I personally wouldn't use the new XE-R lobes without dual springs and comp R lifters - I think they will work with 918's though as long as you use the comp R lifters though.
As for measuring how agressive a cam lobe is - dividing lift by duration only gives you an average of the entire profile - that will tell you on average over a given duration which is more agressive, but that's not what really matters the most. What requires new lifters, springs, etc. is the absolute velocity/change in inertial of the lifters, valvetrain, etc. This is a function of both lobe agressiveness and rpm - with a given lobe the more rpm you turn the faster you are actually moving the lifter (in a linear velocity sense).
If you were limited to under 4000 rpm you could run a *MUCH* more agressive (at all points pretty much) lobe than a higher rpm vehicle - simply because the lifters/valvetrain will not see the same absolute velocities/change in inertia.
So smaller XE-R or whatever lobes with earlier peaks are easier than larger just as agressive lobes.
There are also other events that are very important to how well the cam works with a street setup - you have to worry about your maximum change in inertia (if you go to great at any point the lifter collapses) as well as how agressive your valve closing events are, esp. the intake valve. If you slam the intake valve shut sooner you build up more compression, etc. - but if you do it too quickly you just end up with valve bounce and you loose power at high rpm's.
As for measuring how agressive a cam lobe is - dividing lift by duration only gives you an average of the entire profile - that will tell you on average over a given duration which is more agressive, but that's not what really matters the most. What requires new lifters, springs, etc. is the absolute velocity/change in inertial of the lifters, valvetrain, etc. This is a function of both lobe agressiveness and rpm - with a given lobe the more rpm you turn the faster you are actually moving the lifter (in a linear velocity sense).
If you were limited to under 4000 rpm you could run a *MUCH* more agressive (at all points pretty much) lobe than a higher rpm vehicle - simply because the lifters/valvetrain will not see the same absolute velocities/change in inertia.
So smaller XE-R or whatever lobes with earlier peaks are easier than larger just as agressive lobes.
There are also other events that are very important to how well the cam works with a street setup - you have to worry about your maximum change in inertia (if you go to great at any point the lifter collapses) as well as how agressive your valve closing events are, esp. the intake valve. If you slam the intake valve shut sooner you build up more compression, etc. - but if you do it too quickly you just end up with valve bounce and you loose power at high rpm's.
03-26-2002, 10:49 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? So ChrisB, how do you feel about 918s with stock lifters on a B1/T1 cam? I know many (including me in two more weeks) have this setup and it seems to be working, but should we be watching for possible issues?
03-26-2002, 03:51 PM
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Re: Are we sure the 918s can handle the new XE-R lobes? The XE-R 224 lobe has virtually the same opening/closing profile of the TR224 lobe yet I don't see anyone pushing 977s on that camshaft. The only difference is the XE-R 224 has a tad bit more lift. I would hardly say a difference of over 100 lbs. of open pressure is needed to accomodate the XE-R 224 lobe over the TR224 lobe in the RPM range most of use are running them. With stock LS1 valves there just aren't alot of options when it comes to springs (single or dual). The install heights needed to use the 977s or 978s would require a very deep pocket to be machined. The 99893 Crane springs look decent but they are a 1.46" diameter spring and there are no 1.46" diameter locators or retainers out yet for LS1 valves.
I would say the use of 7.350" pushrods is the problem here. There will be little to no pre-load on the lifter. I would do a leak down test. That will quickly tell you if there is a valve sealing problem. I honestly don't see the 918s as being inadequate.
Tim
<small>[ March 26, 2002, 03:51 PM: Message edited by: TimZ28 ]</small>
I would say the use of 7.350" pushrods is the problem here. There will be little to no pre-load on the lifter. I would do a leak down test. That will quickly tell you if there is a valve sealing problem. I honestly don't see the 918s as being inadequate.
Tim
<small>[ March 26, 2002, 03:51 PM: Message edited by: TimZ28 ]</small>
03-26-2002, 05:04 PM
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Re: Are we sure the 918s can handle the new XE-R lobes? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>In fact if I cared about having a kick *** drag engine I would use the XE-R lobes and would take the 220 for my intake lobe and then throw alot more duration at the exh. Have you ever seen a GM LS1 cam that has the same int and exh duration? No, they are separted by 9-14 degrees.
Just my thoughts.
Bret</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Lets take a look at the 10 second heads cam cars of this board:
06. Raughammer............10.66@124.02mph (1.38) A4, HC, 346cid, 3200lbs. 224/224 XE-R lobe
10. GeorgeC...................10.83@123.35mph (1.39) TH350, HC, 346cid, 3185lbs. 226/226 GTP "Pig" cam
11. Cmarsh93z...............10.94@123.50mph (1.50) A4, HC, 346cid, 3475lbs. 226/226 GTP "Pig" cam
14. CARTEK Dave......10.98@122.01mph (1.44) A4, HC, 346cid, 3500lbs. 224/224? Cartek grind
Just thought I would point out the fact that every single one of those cars runs a single pattern cam...
<strong>In fact if I cared about having a kick *** drag engine I would use the XE-R lobes and would take the 220 for my intake lobe and then throw alot more duration at the exh. Have you ever seen a GM LS1 cam that has the same int and exh duration? No, they are separted by 9-14 degrees.
Just my thoughts.
Bret</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Lets take a look at the 10 second heads cam cars of this board:
06. Raughammer............10.66@124.02mph (1.38) A4, HC, 346cid, 3200lbs. 224/224 XE-R lobe
10. GeorgeC...................10.83@123.35mph (1.39) TH350, HC, 346cid, 3185lbs. 226/226 GTP "Pig" cam
11. Cmarsh93z...............10.94@123.50mph (1.50) A4, HC, 346cid, 3475lbs. 226/226 GTP "Pig" cam
14. CARTEK Dave......10.98@122.01mph (1.44) A4, HC, 346cid, 3500lbs. 224/224? Cartek grind
Just thought I would point out the fact that every single one of those cars runs a single pattern cam...
03-26-2002, 05:35 PM
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Re: Are we sure the 918s can handle the new XE-R lobes? You can't draw any conclusions on a single vs. dual pattern debate off of 4 cars. 2 of which weigh less than a theft recovery vehicle. In fact I wouldn't look at a cam based off of single vs. dual anyways. It's the valve timing events that are going to be the most critical aspects of a cam. Everyone is always talking in terms of LSA or single/dual. Those are very high level views and really only tell you anything in very specific comparisons. If you look at the actual timing events there may be a very good argument for a single pattern camshaft on a given setup but those 4 cars don't provide any evidence.
I picked my XE-R grind of 224/228 by using the most practical means I had... simulation. With stock heads I found power in the upper end (without sacrificing mid-range power) was maximized with a larger exhaust duration. Ideally I would love to take 4 or 5 different camshaft grinds and dyno each one of them with the tuning tweaked for each but that isn't going to happen any time soon. The truth is that most of the camshaft/HC combos out there produce about the same top end power. I've seen a 226/234 grind make a few more ponies than a 226/226 on ARE Stage II heads. The dual pattern also extends that band further.
It all depends on the entire system.
I picked my XE-R grind of 224/228 by using the most practical means I had... simulation. With stock heads I found power in the upper end (without sacrificing mid-range power) was maximized with a larger exhaust duration. Ideally I would love to take 4 or 5 different camshaft grinds and dyno each one of them with the tuning tweaked for each but that isn't going to happen any time soon. The truth is that most of the camshaft/HC combos out there produce about the same top end power. I've seen a 226/234 grind make a few more ponies than a 226/226 on ARE Stage II heads. The dual pattern also extends that band further.
It all depends on the entire system.
03-26-2002, 06:57 PM
#33
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Re: Are we sure the 918s can handle the new XE-R lobes? What spring pressure puts lifters at threshold of deflating at high rpm? We need input from people who have found the limit with stock lifters.
03-26-2002, 08:13 PM
#34
Re: Are we sure the 918s can handle the new XE-R lobes? This is an excellent discussion guys! I've been doing a lot of research on the XE-R cams as well, and I'm torn as to whether or not I should swap out the stock lifters, too. There are quite a few guys running the TR224 cam with no problems, and the ramp profiles are virtually identical between the cams. I saw all of the data comparing advertised duration, then measured at .050", .100, .150, .200, etc. The intake and exhaust valves open and close right at the same time in relation to BTDC and ABDC. As mentioned, the only difference is in the lift of the two cams. However, that added lift with stock lifters at 6,500+ RPM could make a big difference. I'm just going to sit back and read some more. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
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03-26-2002, 09:11 PM
#35
Re: Are we sure the 918s can handle the new XE-R lobes? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Chris ARE 360:
<strong>BTW the XE-R grinds with the right spec'd spring will work just fine in a street/strip car. There will be increased valvetrain stress from the ramp rates but it is by no means extreme.
I think the 228/228 .585 lift 112LSA XE-R based cam would make great power and peak around 6400rpm. With LS1edit tuning and the ramp rates of that cam driveability wouldnt be worse than a TR224 cam but power would be nicely improved <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> You would also only need a 6600-6700rpm shift point.
Cheers,
Chris</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I understand all of that, and I totally agree with you.
I just don't want people to pick a camshaft because "this guy has it and he runs 10's" Every engine has it's own needs. Yes if you take all of the mods and heads/cam package from what someone else has and add the same tranny (A4/M6) and then put the same rear gear etc... you might get there.
I know that I don't really want a 10 sec Camaro. My car goes to work with me even with 3" of snow. It also AutoX's once a month and does dragstrip duty. I really want a different engine from what these other guys have. My powerband from 2500-6500 matters, not 5000-6500. So I think of a street engine as needing different things.
I really don't see the NEED to put the XE-R Lobes in since, that extra money needed for the lifters and dual springs can go to my AutoX budget.
ChrisB ,
I agree with what you said, I was just trying to explain it in a easier manner, and also to the non-engineers like myself.
TimZ28,
Good post, yeah the valve timing events are basicly a mathematical byproduct of duration,LSA, and Advance/Retard of the Cam. With stock heads you will almost always want more exh duration. That can be a by-product of emissions, but it is also how the ports were designed originally. If you even out the ports and manifolds/headers then you might need the same intake and exhaust duration. I really don't think that those guys running in the 10's proves anything other than those heads are really good and they are close to the duration that is needed with that setup.
Bret
<strong>BTW the XE-R grinds with the right spec'd spring will work just fine in a street/strip car. There will be increased valvetrain stress from the ramp rates but it is by no means extreme.
I think the 228/228 .585 lift 112LSA XE-R based cam would make great power and peak around 6400rpm. With LS1edit tuning and the ramp rates of that cam driveability wouldnt be worse than a TR224 cam but power would be nicely improved <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> You would also only need a 6600-6700rpm shift point.
Cheers,
Chris</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I understand all of that, and I totally agree with you.
I just don't want people to pick a camshaft because "this guy has it and he runs 10's" Every engine has it's own needs. Yes if you take all of the mods and heads/cam package from what someone else has and add the same tranny (A4/M6) and then put the same rear gear etc... you might get there.
I know that I don't really want a 10 sec Camaro. My car goes to work with me even with 3" of snow. It also AutoX's once a month and does dragstrip duty. I really want a different engine from what these other guys have. My powerband from 2500-6500 matters, not 5000-6500. So I think of a street engine as needing different things.
I really don't see the NEED to put the XE-R Lobes in since, that extra money needed for the lifters and dual springs can go to my AutoX budget.
ChrisB ,
I agree with what you said, I was just trying to explain it in a easier manner, and also to the non-engineers like myself.
TimZ28,
Good post, yeah the valve timing events are basicly a mathematical byproduct of duration,LSA, and Advance/Retard of the Cam. With stock heads you will almost always want more exh duration. That can be a by-product of emissions, but it is also how the ports were designed originally. If you even out the ports and manifolds/headers then you might need the same intake and exhaust duration. I really don't think that those guys running in the 10's proves anything other than those heads are really good and they are close to the duration that is needed with that setup.
Bret
03-26-2002, 10:32 PM
#36
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Re: Are we sure the 918s can handle the new XE-R lobes? Dude, just put your Stock pushrods back in there.
My understanding is that for our aftermarket cam's to fit back in the car, because of the cam bearings or whatever gets in the way, the ONLY way to increase lift and have the cam fit is to REDUCE the base circle. This requires longer pushrods. Unless you've milled the heads.
So, Stock Cam at 1.550" Base Circle. Average .560 Cam has about a 1.500" Base Circle. You ave even more lift.. an educated guess is 1.490" Base Circle. So, Stock pushrods would put you around .020-.030 Preload which would be ok. A touch low, but good for higher than stock RPM's. 7.350" pushrods would bring you to ZERO PRELOAD and a noisy as FU@K valvetrain.
Switch back to stock pushrods and post feedback.
My understanding is that for our aftermarket cam's to fit back in the car, because of the cam bearings or whatever gets in the way, the ONLY way to increase lift and have the cam fit is to REDUCE the base circle. This requires longer pushrods. Unless you've milled the heads.
So, Stock Cam at 1.550" Base Circle. Average .560 Cam has about a 1.500" Base Circle. You ave even more lift.. an educated guess is 1.490" Base Circle. So, Stock pushrods would put you around .020-.030 Preload which would be ok. A touch low, but good for higher than stock RPM's. 7.350" pushrods would bring you to ZERO PRELOAD and a noisy as FU@K valvetrain.
Switch back to stock pushrods and post feedback.
03-27-2002, 12:31 AM
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Re: Are we sure the 918s can handle the new XE-R lobes? "the valve timing events are basicly a mathematical byproduct of duration,LSA, and Advance/Retard of the Cam."
Actually it's the other way around but I'll let it go. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Tim
Actually it's the other way around but I'll let it go. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Tim
03-27-2002, 05:07 PM
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Re: Are we sure the 918s can handle the new XE-R lobes? Sheesh!!! I'm away from the computer for a couple of days and I come back to read all this drama! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
J/K I thank everyone for their help. I'll hopefully have time to re-install the stock pushrods on Friday and I'll let you guys know whassup.
'Los
J/K I thank everyone for their help. I'll hopefully have time to re-install the stock pushrods on Friday and I'll let you guys know whassup.
'Los
03-27-2002, 05:11 PM
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Re: Are we sure the 918s can handle the new XE-R lobes? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by RPM WS6:
<strong>[QUOTE]What is exactly the difference between an XE and a XE-R cam?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The XE-Rs have faster ramp rates to achieve higher lift within the same (or close to the same) advertised duration and duration at .050".
'Los
<strong>[QUOTE]What is exactly the difference between an XE and a XE-R cam?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The XE-Rs have faster ramp rates to achieve higher lift within the same (or close to the same) advertised duration and duration at .050".
'Los
03-27-2002, 05:25 PM
#40
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Re: Are we sure the 918s can handle the new XE-R lobes? Well hold on.
If you have a part # for your cam Carlitos you should have the base circle info, what is it?
----------
Using those 10 second 346ci cars as a reference does not work. Some are very light and we have little info on the others.
----------
Comp R lifters look for lower preload than stock.
Less preload = noisier valve train but equals more power
----------
Agressive ramps = solid roller like characteristics = higher spring pressure needed
If you have a part # for your cam Carlitos you should have the base circle info, what is it?
----------
Using those 10 second 346ci cars as a reference does not work. Some are very light and we have little info on the others.
----------
Comp R lifters look for lower preload than stock.
Less preload = noisier valve train but equals more power
----------
Agressive ramps = solid roller like characteristics = higher spring pressure needed