So I've been in the LS game since 2017 myself, but I grew up with my dad working on his LQ4 2500 truck. Pat G Specced EPS Cam, FAST LSXRT, Headers, etc.

Now back in the day with few exceptions (MS4 comes to mind) Most cams were in the .580-.620 range on lift. And with a modern dual spring, like the BTR .660s that's about 373-388lbs of open pressure.
Now in modern times, it seems most cams are getting up there in lift, all the GPI cams are .646/.637 and even BTR the Stage 1 v2 is .615/.636 with the Stage 3 and 4s being .636/.636.
I have no doubt about the stability of the GPX lobes or the BTR lobes and no one is gonna argue that stability is the main thing with valvetrain reliability.
My question with this is the pressure with a BTR .660 would be 394-397lbs with the lift of those cams. Is that in of itself not a little harder on valvetrain? What about valve tip wear?

Even Brian Tooley himself said he'd use .630 as his breaking point in post #14. Now he goes over that.
https://ls1tech.com/forums/generatio...m_content=post

Obviously, that post was 13 years ago. So things change with lobe design and such, just curious if anyone has any input, why cams now have more lift than we used to run?

Are you an old head that won't run over .620 lift or so? Or do you run big lift with the stock rockers?

Personally my engine has .627 on both lobes. Cam Motion XA lobes, nothing fancy. My old LS1 had .619/.606.
I got one close friend with a GPI SS3 in his LS1 and another friend with a Cam Motion cam that's .600 lift on both lobes.

Discuss

 

OK, the large cam lobe is easier on the Valve Train AND Camsfaft!
Lance

 

Large=higher lift? or higher duration?

 

I do state that I believe these new lobes are stable on parts and that ultimately is most important for reliability. But that doesn't mean the valve train isn't seeing a little more pressure due to the extra lift. Spring open pressure is one of many variables to valvetrain reliability. Moreover, the stock rockers scrub worse and worse as lift goes up, why are we suddenly okay with this now, but weren't 15 years ago?
I'm not tryna argue, just making observations and want to learn and discuss

 

Talking strictly about stock rockers here, my personal cutoff is .625” lift. Once you get higher than that, the rocker pad gets compromised on the valve tip, and the north/south scrub effect magnifies itself greatly. I’ve seen guys go higher, sure, but reliability goes down significantly. The extra spring pressure required is harder on lifters, pushrods, and cam bearings.

 

A lot of Cam Motions stuff stops at about .621. At least for Hydraulic stuff. They have some Nitrous and Single plane stuff that gets to .646. But all their street stuff is .621 or lower.

I do find it interesting that the Morel 7717, that I see commonly used recommends no more than .360 cam lift (.612 with a 1.7 Rocker) and people have definitely ran the new BTR stuff with .636 lift with them. Those lifters also recommend 380lbs of open pressure or lower, and with BTR .660 springs that 394lbs.

 

As others have said here and before anything over .550-.570 without supporting upgrades is not helpful but harmful. Need bigger springs, upgrade rockers, heavier pushrods needing even heavier springs lol. Going over that lift without ported heads and roller tip rockers is also useless imo. But if you’re building a drag only car or to Bonneville salt flats I personally don’t see much benefit in going over .620 ish lift. Even with newer cam lobes there’s only so much they can do and the ramps just get too aggressive and valve train life goes down quickly.

 

Very little of what you say is accurate. There is huge benefit to lift, but I side with Chev70elle that there is a limit on the stock rocker. .600-.620 lift in a daily on a good beehive is no big deal, been done a million times. I ran a Lingenfelter GT11 cam . 635/.644 lift for 49k miles w/ 4.10 gears at 90mph daily and was great till it ate a lifter. Still think the dual . 660 springs had something to do with it. New combo, ws6store 231/234 THAK cam . 640/.600 cam on a PAC 1276 beehive w/ Johnson drop ins. Let's party 🤘

 

BTR cams are running more lift now because Brian invested in a spintron so he could accurately examine the cam profiles and see what worked and how.

 

Best investment he ever made. The new stuff makes power and from the few engines I've heard, they are very quiet valvetrain wise.

There is that part of me that thinks it's how the market shifted with the car culture of today. Power is the goal after all, if the valve tips are worn after 50k miles is it really that big of a deal to most?
Very few people I've met recently actually keep a car around. I've had mine 8 years, it's actually my first car; but a lot of people now, buy a car, mod it, run it for a few months and then sell it.

 

What did I say that’s inaccurate? Stock head’s don’t take advantage of lift over .570 without porting. Any time you increase spring pressure you have higher wear on cam and bearings, too much lift on stock rockers cause both more wear, potential valve and/ or rocker damage. Increasing the need for trunnion upgrades. You even prove my point and disprove yourself by saying you had lifter failure. As I said lift does have benefits but without supporting parts and goals you’re just throwing cash out the window for little to no gains where you could have spent in better things. But show me data and ACTUAL HP/Torque “HUGE” gains by going with a cam with huge lift vs lower lift on a daily driver. Add a few deg of duration or play with LSA on the lower lift cam and have a far better valvetrain life with far better lobe ramps. And as I also pointed out that a max effort drag engine would benefit BUT not a daily driver please explain why you think that almost all I said was wrong while you are proving me correct.

 

Well if it didn't help power, cam companies wouldn't sell them. No doubt the extra lift puts extra stress on the whole valvetrain. The true benefit of lift is you spend more time in the mid-lift. The peak lift isn't what gets the gains.

Example
225/239 .561/.561
That .561 is the peak if only happens for a few degrees
225/239 .629/.629
The duration of this cam at .561 lift is much greater because the lifter is still rising on the cam lobe.

I do have a friend with a baby cam. 216/224 .550/.550 111+2 and some LS6 springs. No other supporting mods, and that car is beaten on and has 175k miles on it. And it's got about 60k on the cam swap. Valve covers haven't been off since. I mean he drives it 25k miles a year easily. So I do buy into the low lift cam market for true daily like reliability.

I'd love to see a test of it. I've seen .480 vs .550 lift from Richard Holdener that showed about 7hp of peak difference, but the curve wasn't much different. American Heritage did one comparing I think .686 to .624ish and it showed a decent difference in power, but that's on a 442 Stroker LS7 and most guys aren't looking at .686 lift cams.
To me the real test would be something like the two cams I did above. One with LS6 springs, and the other with a typical dual spring. If it was less than 10hp, I'd say it's drivers choice, but any more and I'd almost always do it unless that person simply doesn't want to spend cash, which is valid.

 

I was the person who created the "spintron" for Bruce Crower AND I synced a STROBE Light
to the cam speed.
We were ABLE to then watch rocker arm, valve, Valve Spring in ACTION
Crower cams, Reed Oliver, was the first to report to me about Valve Spring Bounce on the SEAT.
This is ONE REASON Dave Crower sold me camshafts at COST!

 

Every cam (actually almost every part) in an engine is a compromise. Do you want longevity, good idle, max hp or max torque. Is adding a name like stage 3.5 real ? Or like Truck Norris, Camzilla, Chopracura just a marketing scam. Does hiding your cam specs actually keep China from getting the specs? 23X/24X dur. .58X/.59X lift. Hell no 5 minutes on cam doctor would give them that but it makes YOU think they have a secret ingredient that others can’t copy while in reality they are only hurting the ACTUAL CONSUMERS. It’s all about $$$ and compromises. Call many cam companies and get multiple cam advice. Now I know many will try giving best advice that they can but just a slightly different chat can vastly change advice. And actually most people don’t actually say what they really want. An example is if you say you want an LS to go off-road but don’t say rock crawling vs soft sand or you want a 600+ hp n/a Camaro but don’t mention you want to not touch the engine for 100k + miles or it will be driven daily and raced 3 times in a year your cam advice will be far from accurate.

 

FWIW, I've been at 0.650" lift on stock rockers for well over 40K miles, everything is fine. I did have a 1206X dual in there for a long time. The other year, I swapped over to the 1276X just to lighten things up and get real world data on a beehive with 0.650" lift in a street car.

 

Most annoying thing about tryna help people with their builds is them not being honest with how they're gonna use the car. I Called up 4 companies about my cam and even emailed Richard Holdener the specs of all of them and he helped me decide. Went with the smallest cam because I prefer to get everything else dialed in and right as can be, then run the smallest cam to achieve the goals I want. And it's how I recommend stuff to all my buddies when they ask for advice.

That's good to hear about 40k miles at 0.650" lift. Makes me wish maybe I would've gone that high! Lol

 

And we're only finding this out now. Any more secrets you want to spill?

 

This is without a doubt THE BIGGEST FALLACY in our hobby.

Companies SELL stuff that ... is a waste, in whatever ways (think, drilled brake rotors) ... because CUSTOMERS DEMAND THEM. I don't think anyone who hasn't been inside the industry, or in some similar one (almost any hobby that involves competition but isn't "professional" is like this), has ANY IDEA how prevalent this is. Cams are no different from any other hot-rod part in this respect. Maybe even more so.

Non-professional (read: gullible) people somehow get into their heads some random notion about "all the fast cars have [fill in the blank]" and then they JUST GOTTA have that. Often it doesn't matter that technology has moved on and made the "feature" irrelevant (drilled brake rotors), or that it applied to one type of engine or one high-profile class (Super Stock used to be like that), or whatever else; without physical measured proof, like dyno numbers or failure mode analysis, The Myths And Legends live on and cost hobbyists their hard-earned cash.

With cams, the "high lift" thing has taken on a life of its own. The reality is, opening the valve further increases power IF AND ONLY IF the valve is The Bottleneck to the flow. What a "high lift" cam DOES do however, is usually, open the valve a little bit more all the way throughout the whole lift cycle, than an otherwise identical lower lift one; thus, at points other than peak lift, a "high lift" cam CAN increase power, as seen by the naked eye. Butt it's NOT because of the higher peak lift, it's because of the steeper ramps. IOW, it is often entirely possible, especially with stock heads wherein something other than the valve lift is the limit to their flow, to design a cam with some lower peak lift which gives better compatibility with other parts, by making the ramps steeper. Used to be called "major intensity", not sure if it still is.

The "ideal" lobe curve is one where ALL the derivatives of ALL the parts of the curve have the same value wherever the curve changes. For example, from the slow opening ramp to the faster part of the ramp, then where the ramp nears peak and slow down, then when that "over the nose" curve meets the closing ramp, and so on. A cam lobe has at least 5 curves that need to meet like that, and depending on how **** the designer is, may have MANY MANY more than that. Furthermore, the ramp on the opening side might want to be different from that on the closing side (and usually is these days), to get the best performance. This is MUCH harder to accomplish than it sounds like. The "derivative" of something is the rate of change of that thing, literally the slope of the curve; like rise and run in a roof. The first derivative of lobe lift is the velocity of the lifter; the 2nd derivative of lift is the acceleration (1st derivative of the velocity); higher derivatives are called "snap" "crackle" and "pop". "Snap" is the rate of change in acceleration (think, the difference between smoothly pressing on the gas pedal vs stomping on it like it's a cockroach), "crackle" is the rate of change of "snap", etc. Derivatives beyond that don't have colloquial names that I'm aware of. The math can give you a design, then the Spintron displays it for you in real life in real time on real parts, where you get to see how it works. Sometimes there are factors the math described above can't account for, that render a promising design ineffective; parts bending, castings deflecting, resonances, and so on, i.e. assumptions you might make about things peripheral to your design, that simply aren't true, appear. Very humbling in any field where computer simulation is used.

I also did the thing with a Strobotac back in the 70s when I worked in a test eqpt lab and had friends & family who worked at a major cam mfr, and I could occasionally "borrow" a Strobotac for a day or 2. We didn't have a Spintron then, not sure the idea had been thought of yet, so we just looked at stuff on running engines. Believe me, it was HUMILIATING sometimes. The model with a microphone, that you could sync to vibrations or whatever of the rotating thing, was THE COOLEST.

I used to occasionally build motors for people in the class that had to have what they called a "stocker" cam ... that rule was, int lift could not exceed .390", and exh .410". (the old stock SBC "929" cam) All other parameters were open, including solid lifters, so I don't think anybody ran hydraulics in that one. You'd be AMAZED at what you can get out of an engine with that little lift, if the ramps are steep enough, and with enough valve spring push rod and rocker. Another class I had to work with once in awhile was the 1.25" spring class: in that one, you could run any cam you wanted, your springs just couldn't exceed 1.25" OD. Again, AMAZING what a hard upper limit to cam profiles that was. This was before beehives of course.

Oh well, I digress. The point is, "peak lift" is NOT the be-all end-all number to evaluate a cam with, any more than any other ONE number; and that's why we don't all run cams with the highest "peak lift" we can buy. Sometimes, other things about a cam design matter more than that.

 

I didn't say that meaning everything in our hobby, there's people still buying air foils for LT1s. But I would assume Brian ended up at the lift he has on his lobes because they simply are a good compromise between power and reliability. So I think it's safe to assume, he wouldn't have chosen the extra lift over his old stuff if it didn't make more power.

And this isn't a thread about picking a cam with more lift. I willingly chose less lift. Nobody said it was the be all end all, I even say that. Stability of valvetrain is important, most important really. I did also say that peak lift isn't the whole story, the lobe has more duration at a given lift point when the peak lift is higher; because you're reaching more lift in the same duration (at 0.050") you end up with more duration at say 0.400" lift. You're only at that peak for literally and instant. And you're right you can have some crazy looking lobes in those class rules stuff. Powell Machine has done some videos on that I believe.

 

Upgraded trunnions or stock trunnions?