aaronz28

Hey gang,

i was wondering if anyone would be interested in running a cam comparison. I did it using desktop dyno, but wanted to check my calculations.

test mule is a 64-65 SHP 327. stock fuelly heads (perhaps a bit of bowl blendig) stock 2.5 ramshorns etc.

i did a run with the LT-1 cam, and want to compare it to
Lunati's 401A6Lun (although on a 112 LSA) as opposed to the 110 it comes stock.

those specs are 243-251 @.050 with .518-.530 lift with .026 lash. 112 LSA.

My runs showed that the LT-1 made 1 more ft/lb peak and maintained about 5-13 more ft/lb than the lunati from 2000 up to peak torque which was at 4500 rpm. The Lunati made 21 more peak hp at 6000 rpm . The Lunati passed the LT-1 cam in HP at 4500rpm and at 6500- 7000 rpm it was making 27-35 more HP.

They both build torque at about the same rate, but by the time the Torque falls off, the Lunati is ahead 15 HP and torque falls at a slower rate while HP is gaining.

THis would seem that the Lunati Cam is the better all around performer, and before I go to that, I'd like to make sure that my results are somewhat accurate.

Lunati maintains that their ramps being more agressive would sustain a more responsive motor and build more lowspeed torque than the "old" Lt-1... I know that this is a highly debated topic, but I'm wondering if there is any merit to the discussion that more agressive ramps and less seat duration actually build better power.

anyone care to run these numbers to see if mine are accurate?

Thanks

Aaron

aaronz28

no takers,

i thought for sure someone would want to see if these results are accurate.

kidvette

Wait a while SWC DUKE will have something to say.He is very familiar with the LT 1 cam.
I am also looking for a cam that delivers LT 1 performance numbers with hydraulic lifters.

SWCDuke

"I am also looking for a cam that delivers LT 1 performance numbers with hydraulic lifters."

You'd be about as successful looking for the proverbial pot of gold at the end of a rainbow!

There are NO hydraulic cams that offer the full performance of a good mechanical lifter cam because mechanical lifter cams offer at least 500 more useable revs.

Most overlook or don't seem to be able to comprehend this critical point.

The best hydraulic cam for good street performance and OE valvetrain reliability in a 327 is the OE L-79 cam. Its average torque/power output is nearly the same from 2000-6000 as the LT-1 cam, but the LT-1 cam keeps going for for another 500-1000 revs after the L-79 cam power falls off a cliff or the lifters pump up.

If you shift each at the recommended redline the gearbox ratios will result in about a 1500 rev drop, so the L-79 range is 4500-6000, and the LT-1 range is 5000-6500. What counts for maximum performance acceleration is the AVERAGE power in their respective rev ranges, and the LT-1 cam's average in its maximum rev range is higher than the L-79 in its maximum rev range - much higher than their comparative peak power values would indicate.

It's possible to extend the L-79 cam rev range to 6500, and likewise, the LT-1 can provide useable power to 7200, so you end up with the same result.

And as I've said countless times before, the key to achieving maximum high rev power is working the heads. There's no "magic cam" that will make up for the somewhat restrictive OE machined heads without killing the low end torque, but working the heads will get the most top end power out of the L-79 and LT-1 cams, both of which will maintain decent low end torque because they DON'T have excess overlap.

Most after market cams - even those with less effective duration have TOO MUCH OVERLAP!

Too much overlap in the presense of exhaust backpressure with either headers or manifolds (even the Corvette's 2.5" exhaust system's modest 3 psi with a good SHP 327) KILLS the low end torque without improving top end power, so you end up with a poor torque bandwidth soggy dog.

If you don't comprehend this physics, you're likely not going to make a good cam choice, and for this reason if you don't use a simulation program that allows you to model the street exhaust system, the results can be misleading, which is worse than worthless.

That's why the only simulation program I now use and recommend is Engine Analyzer.

Duke

Corbrastang

I hope to soon disprove the theory that the original L-79 cam is still the best hydraulic cam on the market. i put that cam in my fathers car-fun, but not too much excitement.
I'm putting Voodoo part number 60103 in my 65 327
I would like to believe that 40 years later technology has allowed us to produce something better.

How do you get 6500rpm out of the L79 cam??

I agree with working the heads- there is no substitute for the power you can get from the heads.

aaronz28

i certainly am not looking for a fight here, but with the time spent on running the LT-1 and 30-30 cam through the engine simulators, be it desktop dyno or Engine Analyzer, I can't believe that it would be that difficult to do the comparison with a different cam.

i would agree than on entirely stock valve train, aftermarket cams are risky. But most valve train rebulds include springs that can handle higher pressures over the long haul and stainless valves. Steel rollertip rockers, guideplates, and good pushrods, will ensure that aftermarket cams go 100k or better. I've done it with a Compcams 292h. That cam went 122k on a 350 that I ran everyday for 6 years in a dailydriver camaro. When I finally tore the motor down, the valvetrain looked perfect. So I'm not sure that reliability is an issue anymore.

I agree that 40 years worth of research must have produced some favorable results in street applications. I also ran a 268h Comp cam in a 428 motor in my 1970 Pontiac GTO for like 80k miles on pump gas and that thing would run 13 flat all day long, driving to and from the track.

So, while I'd like to believe that the OE high performace cams are the best out there, i"m still gonna look for more.

This 401A6LUN that I am referring to has very similiar duration figures at .050 to the LT-1 and it was designed for Restricted class with 2bbls and manifolds, but that was on a 106LSA. I'm not that crazy, I'd run it on a 112 which is why I'd like to see a simulation of it comparing it to the LT-1 for fun's sake.

Aaron

kidvette

Ive also read articles that some aftermarket hyd roller cams can have aggressive profiles without excessive valve overlap do to modern technology.
But like SWC said I guess a eng anylizer will tell for sure.
Keep us posted Cobrastang

AZDoug

I have the L-46 cam which is very similar.

To get up to 7K RPM on that cam, you need new OE valve springs (under 5K miles on them, or not decades old),and when you adjust the lifters, back each lifter off until it just starts to clatter (make a cut out valve cover oil catch,a nd use rocker arm clips to avoid being soaked with oil),a nd then once you reach clatter, stop,and tighten the rocker arm nut down 1/8 turn, no less,and not more than 1/4 turn.

My Factory short block motor which came with a L-46 cam in 1976, will spin past 7K with new valve springs; now, I may only get 6500 RPM before the valves float, until I change the springs again as they have ~4K miles on them.

Doug

ghostrider20

Why are so many people gun shy of the Solid Cams?

Lifter adjustmets are really a non issue. In the 6 years I have owned my car I have done it once a year, and ther are never off more then a few thou, and that is one or two. And I do alot of driving.

Mark

Corbrastang

I personally just dont care for the chatter and if todays technology allows me to avoid messing with hot valves and a feeler gauge and illiminates the noise then i'm going to take full advantage of it.

ghostrider20

Duke and JohnZ worked out a Cold Lash setting for the 30-30 / LT-1 so you can do them with the engine cold, and not running. Very precise, and no clang or clatter. There is matalic noise with solid cams, but I love that sound.

Mark

AZDoug

Not gun shy, lazy.

Easy and quick to adjust the (hydraulics) lash once as described, and never have to fuss with it again until valve spring change time.

perhaps if it was still a semi-accepted past time to street race, or if I had more time to spend leaning over a car fender or if I wasn't so old my back didn't hurt from leaning over car fenders too long, I would do a solid lifter cam.

Doug

Donny Brass

I would recommend talking to Scotty Brown at Straight Line Performance 517-381-8801.

He is a custom grinder who is verywell respected for his work.

Corbrastang

Just dont buy a custom grind from compcams. They gave me a horrible custom grind a few years ago-no power at all.