Why not 918s with certain XE-R lobes?
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From: Orlando, FL
Why not 918s with certain XE-R lobes? I'm currently in the process of changing the configuration of my car. The old powertrain is gone. I bought a complete 98 engine (totally stock) and 4L60E this weekend. The current plans are to run with untouched heads (except for springs) and a cam. I've decided to run a grind based off of the Comp XE-R lobes (224-228 range).
I looked at the various dual springs available and calculated the resulting seat/open pressures for the appropriate install heights.... The open pressure assume a lift of 0.581-0.588.
Comp
987 121/320 (1.800")
978 126/388 (1.850") <- difficult height to achieve
977 155/441 (1.850") <- difficult height to achieve not to mention the lifters may have trouble with those pressures
918 130/318 (1.800")
918 139/323 (1.770") <- 0.030" shim
918 149/333 (1.740") <= 0.060" shim
Isky
6105 139/335 (1.800")
Crane
99893 (Hyd.) 149/378 (1.800")
The Crane spring looks like the most appropriate spring but the 918s are certainly right there with the Isky spring. The Comp dual springs are definitely less than ideal in this scenario.
I realize it would be more desirable to have the load spread across two spring coils as opposed to one but from a spec point of view does anyone see a reason why the 918s would not work for what I would like to do? If I were to go to a double spring it would very likely be the Crane spring.
Tim
I looked at the various dual springs available and calculated the resulting seat/open pressures for the appropriate install heights.... The open pressure assume a lift of 0.581-0.588.
Comp
987 121/320 (1.800")
978 126/388 (1.850") <- difficult height to achieve
977 155/441 (1.850") <- difficult height to achieve not to mention the lifters may have trouble with those pressures
918 130/318 (1.800")
918 139/323 (1.770") <- 0.030" shim
918 149/333 (1.740") <= 0.060" shim
Isky
6105 139/335 (1.800")
Crane
99893 (Hyd.) 149/378 (1.800")
The Crane spring looks like the most appropriate spring but the 918s are certainly right there with the Isky spring. The Comp dual springs are definitely less than ideal in this scenario.
I realize it would be more desirable to have the load spread across two spring coils as opposed to one but from a spec point of view does anyone see a reason why the 918s would not work for what I would like to do? If I were to go to a double spring it would very likely be the Crane spring.
Tim
Re: Why not 918s with certain XE-R lobes? From experience Tim if you decide on the Cranes you will most likely need Jesel rocker arms secondary to the 1.46in diameter of the springs.. Cant wait to see someone try the new XE-R cam...
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From: new england
Re: Why not 918s with certain XE-R lobes? 918 spring no shim should work, more pressure may deflate hydraulics, your rpm dictates needed pressure as well as cam profile.Where do these new lobes fit in with other cams such as Hammer cam?
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From: Orlando, FL
Re: Why not 918s with certain XE-R lobes? XE Hammer style lobe:
#3714
0.006 275
0.050 222
0.200 140
Lift: 0.566
XE-R Hammer equivalent @ 0.050"
#3721
0.006 271
0.050 222
0.200 144
Lift: 0.581
I'm leaning towards a 224/228 112 XE-R based grind
#3722
0.006 273
0.050 224
0.200 146
Lift: 0.581
#3724
0.006 277
0.050 228
0.200 149
Lift: 0.588
I'm expecting this grind to peak in the 6000 area. With a 4400 TP and 6500-6600 shift points things should get moving.
#3714
0.006 275
0.050 222
0.200 140
Lift: 0.566
XE-R Hammer equivalent @ 0.050"
#3721
0.006 271
0.050 222
0.200 144
Lift: 0.581
I'm leaning towards a 224/228 112 XE-R based grind
#3722
0.006 273
0.050 224
0.200 146
Lift: 0.581
#3724
0.006 277
0.050 228
0.200 149
Lift: 0.588
I'm expecting this grind to peak in the 6000 area. With a 4400 TP and 6500-6600 shift points things should get moving.
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From: new england
Re: Why not 918s with certain XE-R lobes? Tim your choice sounds good, keep in mind larger duration lobes with same lift are easier on springs and require less pressure to maintain control. Also longer exhaust duration hurts low speed characteristics more than longer intake duration.
Thread Starter
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From: Orlando, FL
Re: Why not 918s with certain XE-R lobes? The longer exhaust duration is also going to help out in the 6000+ range. With a 4400 stall the slight hit in the bottom end is not going to matter one bit.
Tim
Tim
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Re: Why not 918s with certain XE-R lobes? Yeah that's some pretty interesting info, where'd you find it?
I'm putting in a cam with XE-R lobes soon. I'm gonna use 918s so hopefully they'll be up to it.
<img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />
[ March 06, 2002: Message edited by: Onyx ]</p>
I'm putting in a cam with XE-R lobes soon. I'm gonna use 918s so hopefully they'll be up to it.
<img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />
[ March 06, 2002: Message edited by: Onyx ]</p>
Re: Why not 918s with certain XE-R lobes? The information I have says Comp does not recommend the 918s but recommends the double springs. Last time around, Comp said the 915s would work with the XE lobes and we now know that wasn't such a good recommendation. I don't know if Comp has turned conservative this time out or not.
Good luck with the 918s, I'm having double springs put in my ARE heads.
Good luck with the 918s, I'm having double springs put in my ARE heads.
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From: Orlando, FL
Re: Why not 918s with certain XE-R lobes? Comp sent me a fax of all the XE and XE-R lobes. I have converted it to .JPG. These aren't on the website yet. If anyone would like it e-mail me and I will send it to you.
Tim
Tim
Re: Why not 918s with certain XE-R lobes? [quote]Originally posted by TimZ28:
<strong>Comp sent me a fax of all the XE and XE-R lobes. I have converted it to .JPG. These aren't on the website yet. If anyone would like it e-mail me and I will send it to you.
Tim</strong><hr></blockquote>
You've got mail....
<strong>Comp sent me a fax of all the XE and XE-R lobes. I have converted it to .JPG. These aren't on the website yet. If anyone would like it e-mail me and I will send it to you.
Tim</strong><hr></blockquote>
You've got mail....
Re: Why not 918s with certain XE-R lobes? 
D(irecto)r Pepper
Joined: Nov 2001
Posts: 1,952
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From: Houston Raceway Park...in TEXAS.
Re: Why not 918s with certain XE-R lobes? Tim excellent info. Thanks for taking the time to post it.
My one question is to ask, is why you think the cam will peak at 6000 rpm?
I would bet it to be much higher than that... 6500 or so... maybe a good bit higher. Even with the stock heads.
Again... that was some EXCELLENT info.
BTW, I have seen no reason to go as big as a 228/228 on a stock cubed LS1. Then again... I'm pretty conservative when it comes to cams. (were talking duration here)
I would recommed the XE- Hammer style lobes for most racers. I would only recommend the XE-R Lobes for the most avid racers. I would seriously recommend TOP NOTCH springs for the XE-R lobes. They are pretty dog gone steep/aggressive. But to get the idle of a much smaller cam and the performance of a BIG cam. I gotta admit that if you can pay the admission fee (springs) then they (The XE-R's) are well worth it.
BTW, I like the looks of those Crane Duals too.
Just my 2 cents. And good luck with the new motor.
My one question is to ask, is why you think the cam will peak at 6000 rpm?
I would bet it to be much higher than that... 6500 or so... maybe a good bit higher. Even with the stock heads.
Again... that was some EXCELLENT info.
BTW, I have seen no reason to go as big as a 228/228 on a stock cubed LS1. Then again... I'm pretty conservative when it comes to cams. (were talking duration here)
I would recommed the XE- Hammer style lobes for most racers. I would only recommend the XE-R Lobes for the most avid racers. I would seriously recommend TOP NOTCH springs for the XE-R lobes. They are pretty dog gone steep/aggressive. But to get the idle of a much smaller cam and the performance of a BIG cam. I gotta admit that if you can pay the admission fee (springs) then they (The XE-R's) are well worth it.
BTW, I like the looks of those Crane Duals too.
Just my 2 cents. And good luck with the new motor.
Re: Why not 918s with certain XE-R lobes? John I have those Crane duals.. I am still waiting for some b4 and after cam swaps with the XE-R.. I have the valvetrain, just need to know if the swap is going to be worth it.. Power under the curve is what I am looking for..
