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Comp LSR lobes

General engine tech -- Drag Racing to Circle Track

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turbo camino
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Comp LSR lobes

Post by turbo camino »

5.3L LS

265Lr HR12
Advertised: 265/273
.050: 215/223
Lift: .604"/.610"
L/S 112

That's a bunch of lift for that duration, has me a bit concerned about spring life and general durability. They don't call it a 'truck cam' but that's what I wanna use it for. Thoughts?
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Re: Comp LSR lobes

Post by mt-engines »

turbo camino wrote: Thu Oct 08, 2020 11:32 pm 5.3L LS

265Lr HR12
Advertised: 265/273
.050: 215/223
Lift: .604"/.610"
L/S 112

That's a bunch of lift for that duration, has me a bit concerned about spring life and general durability. They don't call it a 'truck cam' but that's what I wanna use it for. Thoughts?
55mm core 1.7 rocker ratio .355 lobe lift. not a big deal. it will run.
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Re: Comp LSR lobes

Post by turbo camino »

The short seat duration with that much lift is what has me worried, not just the lift alone. With no real data to go on my gut says that's a very aggressive lobe.
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Re: Comp LSR lobes

Post by CGT »

turbo camino wrote: Mon Oct 12, 2020 1:18 pm The short seat duration with that much lift is what has me worried, not just the lift alone. With no real data to go on my gut says that's a very aggressive lobe.
They are in my opinion....and noisy. The LSR-LSL-LXL aren't quite as clattery as some of the previous stuff (XFI-XER, XE) but if its gonna be from Comp, I think the marine, marine high-lift, and HUC lobes are better choices. There is a penalty of some added seat duration, but there definitely quieter and calmer.
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Re: Comp LSR lobes

Post by CamKing »

If you're looking for something to make a lot of low-end power, pull past 5,400rpm, and be easy on the valve train. This is what I would recommend
Cam# LS1, HR65327-67325-114
260/268 @.006"
212/222 @.050"
130/136 @.200"
.327"/.325" Lobe Lift
.556"/.552" Valve Lift
114 LSA
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Re: Comp LSR lobes

Post by turbo camino »

CGT wrote: Mon Oct 12, 2020 1:52 pm They are in my opinion....and noisy. The LSR-LSL-LXL aren't quite as clattery as some of the previous stuff (XFI-XER, XE) but if its gonna be from Comp, I think the marine, marine high-lift, and HUC lobes are better choices. There is a penalty of some added seat duration, but there definitely quieter and calmer.
Thanks. (also, I only just now finally found the lobe catalog on Comp's site... duh)
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Re: Comp LSR lobes

Post by turbo camino »

CamKing wrote: Mon Oct 12, 2020 2:52 pm If you're looking for something to make a lot of low-end power, pull past 5,400rpm, and be easy on the valve train. This is what I would recommend
Cam# LS1, HR65327-67325-114
260/268 @.006"
212/222 @.050"
130/136 @.200"
.327"/.325" Lobe Lift
.556"/.552" Valve Lift
114 LSA
Thank you. Beehive-friendly, I assume?
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Re: Comp LSR lobes

Post by CamKing »

turbo camino wrote: Mon Oct 12, 2020 3:58 pm
CamKing wrote: Mon Oct 12, 2020 2:52 pm If you're looking for something to make a lot of low-end power, pull past 5,400rpm, and be easy on the valve train. This is what I would recommend
Cam# LS1, HR65327-67325-114
260/268 @.006"
212/222 @.050"
130/136 @.200"
.327"/.325" Lobe Lift
.556"/.552" Valve Lift
114 LSA
Thank you. Beehive-friendly, I assume?
Yes, will work great with a number of stock sized, beehive springs.
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Re: Comp LSR lobes

Post by mt-engines »

i have run a number of Comp lobes for LS engines, many customers dont like the noisy valvetrain with some of their lobes. as far as power goes, i havent seen that big of a difference in power going to a milder lobe. But for a racer, 10hp is 10 hp. anytime i go over .600" i end up using double springs. I had just had too many problems in the past with beehives in the .640-700" lift range lasting say more than a season.

That being said, i have used a number of mikes cams, and he's the man. he did an LS cam for me years ago that fixed our valvetrain issues. cam was similar in specs but had no problem going 8000rpm with hydraulic lifters.
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Re: Comp LSR lobes

Post by turbo camino »

Yes, Comp specs a 500 lb/in dual spring (26926) for all the LSR family, even the little baby one. $500 with steel retainers!
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Re: Comp LSR lobes

Post by CGT »

Turbo, If your wanting to keep things budget. Im sure your probably aware of the GMPP LS6 spring kit. They could be had for around 75.00 last time I looked. They work really good if you keep the lobe instensity down and around .560 lift. #12499224
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Re: Comp LSR lobes

Post by turbo camino »

I was actually leaning towards the baby LSR cam and #7228 conical springs, because 'cool'. But breaking parts or replacing springs once a year considerably lessens the cool factor.

If a noisy lobe doesn't do anything other than make noise I don't care, but if the noise is coming from parts getting beat up I'd rather avoid. With the right springs and good pushrods, are there reliability issues with noisy lobes in a daily-driver low maintenance type of application? RPM will not go over 6000, I don't know that a cam that small would want to go much beyond that anyway.
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Re: Comp LSR lobes

Post by CGT »

turbo camino wrote: Tue Oct 13, 2020 9:45 am If a noisy lobe doesn't do anything other than make noise I don't care, but if the noise is coming from parts getting beat up I'd rather avoid. With the right springs and good pushrods, are there reliability issues with noisy lobes in a daily-driver low maintenance type of application? RPM will not go over 6000
There are tons and tons of LS's doing down the street daily with the "noisy" lobes with no issues I suppose, but I just don't know how the noise couldn't indicate that things are getting beat up.

I had a new Trailblazer SS in 2007. 6.0 LS2. I put a cam in it when it had only 2,000 miles on it. It was Comp XFI lobes. 214-220 115 .600ish lift if I remember correctly. I used Comp 26918 springs, good pushrods. It was obnoxious noisy to me...especially considering it was a relatively new, quiet vehicle.

I tried different length pushrods for different preload and couldn't ever get it quieted down. At around 15,000 miles a lifter wheel broke, tore up the block, cam etc. It was hard to tell from the carnage if the cam lobe wore through the heat treat, taking out the lifter, or the other way around. I could have just been unlucky. But I haven't used those kind of lobes in those kind of applications since then. Not saying they don't have their place.
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Re: Comp LSR lobes

Post by Walter R. Malik »

turbo camino wrote: Mon Oct 12, 2020 6:23 pm Yes, Comp specs a 500 lb/in dual spring (26926) for all the LSR family, even the little baby one. $500 with steel retainers!
I use the PAC-1208X, (480 lb./inch), or PAC-1209X, (500 lb./inch), with high .600" or low .700" valve lifts.
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Re: Comp LSR lobes

Post by turbo camino »

Can somebody explain the Comp custom grind format for me? The catalog seems to be missing the part that gives the prefixes for each engine family. I'm able to figure out that CB is BBC and CS is SBC from the examples, but the others are a mystery. I know the core will be 54-000-11 and lobes are 13093 intake & 13172 exhaust. (that's a slightly shorter LSL intake lobe and a supposedly quieter/slower closing LXL exhaust.)
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