Anyone who follows the LTx and LSx boards sees the dyno sheets for the new LS combos making great power with hydraulic cams well in excess of 7000 rpm. Obviously the LSx heads work extremely well compared to the LTx heads, but why are they able to rev so high using hydraulic cams as compared to the LTx engines?

Everyone is so big on using solid lifter cams on the LTx engines for their ability to rev, but why are they apparently unnecessary on the LSx engines?

 

This thread is somewhat similar to the "Hydraulic Lifter Limitations" thread posted here a couple of weeks ago.

Running a roller hydraulic is no stretch. I'm not so sure it's the
camshaft type that's limiting the RPM in the LTx and LSx engines
as much as it would be the tuning of the motor.

The LS1 has slightly more breathing capability which makes the
power come in a little higher because of the increased runner
volumes, etc.

That being said, a ported LT1 with a cam and proper springs, etc
could spin to the 7000 mark just as easily.

I'm not familiar with the need for people selecting mechanical cams on an LT1 for daily driver or street/strip use. We are talking
about a street car LT1 / LS1 correct?

 

Yea, its not really the fact its hyd, its the cylinder heads.

Steve quinn was shifting his OEM rebuild bottom end at 7400 or so with a hyd cam.. and ported stock LT1 heads, but thats cause he wanted to see how fast he could go with a hyd.

in reality (street cars) if you wanna rev high, its crazy not to do a solid roller.

 

Why so?

 

Jordon

You know better than almost anyone else the problems I had with solid lifters. You pulled one motor.

One of the three I’ve had rebuilt because of breaking solid roller lifters while driving on the steet.

I honestly don’t get why you would need a solid roller cam if building powier up higher is in the cylinder heads. Why not just go with bigger volume intakes on heads that are more efficient at higher rpm.

Again…….. the LSx is a clear example of what a broad upper powerband can accomplish. The head, cam and exhaust modded cars are running within 2-3 tenths of what the 427-436 stroker motor cars are on the strip. The obvious secret is winging the suckers up to 7k+ so they never drop down below 5.5k or so.

Again….. knowing all the problems I’ve had with solid rollers, if just adding better flowing heads will get ya here…….. why do solids?

 

A larger, better flowing head will make your cam "act bigger" so depending on your needs you can do good and plenty with a hydraulic. This was one of the things I was contemplating initially but I ended up going hydraulic roller for some of these type of reasons. Once again your ultimate goals have to be kept in mind...

 

I am running a hydraulic cam in my motor and it see's the far side of 7500 rpm on every pass!









8.96@154.82 has seen 159.64 mph

 

Denny-
A lot of LS1 guys are actually running solid stuff now.

However, if you put a good cylinder head on an LT1, you would be able to shift it at 7k or more with a hyd cam.


A lot of things have to be RIGHT for solid lifters to live on the street. course, sometimes **** just "breaks" but I find that most of the time there is a cure.

 

It's possible that this breakage is due to improper lash settings
on a solid cam.

If you don't set a proper lash, or maintain it...clearances get loose
and parts start smashing together.

Just an example of how meticulous some people are with solid cams: my buddy races Top Sportsman and checks his valvetrain
after EVERY pass.

Although the solids can yield more RPM, the hydraulics lend themselves
to self adjusting.

Pros and Cons for a street car tend to lean on hydraulic for most
applications IHMO.

 

I’m not sure why I had so many problems with solid roller lifters. But one thing for sure…….. it had nothing to do with not adjusting them. Hell, I even went out and bought the Reher-Morrison top end book and followed their directions to a T.

Always adjusted them before I raced and usually no more than a month would go buy before I would re-lash them to the spec’s on the cam card. I did this more because I hated noisy lifters than anything else.

After reading the posts, looking at the dyno sheets of the LSx cars, just reading a private e-mail from someone in the know……… I’ve pretty much changed my complete thought process regarding heads/cams. (this is what prompted my post in the beginning)

My currently feeing is it’s better to run larger heads with less cam and forget about solid lifters unless your running a real race motor. This thing about larger ports being lazy may not be all it cracked up to be if you put the proper cam in it.

My vote: Less cam duration – more heads = quick car.

 

right cam + good heads = fast car

you can make 500rwhp or more with a hyd 396 LT1. but you could make 550rw+ with a solid.


or put a blower or turbo on it and make twice as much

 

No argument out of me on the forced induction stuff. No question it works, and works well.

I do however question the fact you automatically gain power from just having solid lifters. Does anyone have actual dyno data testing two equivalent cams with one being hydraulic and one being solid lifter?

Rpm vs rpm differences make no sense to me. Duration is duration and lift is lift. If the engine sees the same…….. It should act the same.

I'd really like to see some objective testing information on this from someone who has a dyno and has tested different cams with the same combo.

 

A good solid lifter camshaft probably has a more aggressive profile than a hydraulic cam with the same lift and duration@.050 specs. The lifter won't collapse under the increased strain of the faster acting ramps. So, even though the 2 cams have the same specs, the solid lifter version will probably have the valve open longer than the hydraulic one. That should make more power. How much? Even the manufacturer probably wouldn't know exact numbers.

 

hehe.......congrats on breakin into the 8's....last time i saw you were at 9.006 or something

 

Denny-
its lobe area from 000 and back to 0000. The solid roller given the same overal duration in degrees, will have MUCH greater lobe area, and there for more air in the engine and more power. Not to mention(normally) less overlap which means better drivability.

You have had bad luck with solids, and I know its not for adjustment.. probably just poor valvetrain setup.

I hardly ever adjusted my rockers.. once break in was done..maybe every 3-4k miles.