236/242 @.050 adv 288/294 on a 110 LSA Hyd Roller

OR

250/260 @.050 adv 286/296 on a 112 LSA Solid Roller

Anyone have any expierence with a solid roller like the one above? The application is MiniRamed 383 with 10.5 compression and a manual transmission.

Thanks

Kelvin Mims

 

The hydraulic. Without a doubt. The two degrees of lobe separation angle won't come close to compensating for the difference in duration. Hydraulics are generally "lazier" than solids, also. Valve opening won't be as great at any given number of degrees after opening with hyd as with the solid. Check the timing events. I'm positive you'll see less overlap with the hyd.

RACE ON!!!

 

Ok, then which one should make more power? The problem I'm having is that the lifter seems to pump-up before I hit my HP peak. I need to pull up to 7KRPM at least.

I'm hoping the solid roller acomplishes a few things. First I want it help me rev higher, secondly I hope it frees up a little more power. Do you think I'm heading in the right direction?

Thanks

KM

 

The solid would definitely make more power in an engine that was built to take advantage of it's duration. The greater duration is going to move the HP and torque peaks to higher rpms. The ability to rev higher, then becomes paramount. You'll need an induction system, heads and exhaust that are capable of handling the additional air that the cam and increased rpms will require.

Then we're back to the origional question: Streetability. 250/260 @ .050 is a lot of duration for a "street" motor. Is this a car that you want to be able to say that you drove it on the street, once? Or do you intend to drive it regularly? Generally, solids have more "active" ramps and you will get more out of a solid for a given duration than a hydraulic. A solid with the specs of your hydraulic might be a better choice. What kind of "Rs" are you looking for? It's suprising that a cam co. would grind a cam that had a range higher than the lifters would allow. Could you possibly have other deficencies in the valve train? Springs, maybe? I would consult my cam grinder to see what the power range is supposed to be and what is required to attain those rpms.

RACE ON!!!

 

a solid cam and a solid roller has to be 10 degrees more duration to make up the difference for the 2 cams for example
a hyd at 240 240 at 50 is theorectically larger than a 240 240 solid at 50 because the solid has lash to make up for so a 230 230 hyd is about equal to a 240 240 at 50 solid because of the lash soif you look at those 2 cams they are really close but the solid has a 112 lobe ctr so that would work better in a fuelie car both cams would have about the same rpm ranges but the solid will make about 2-3% more power just by inherirently better ramp design but the hyd will valve float more easily but the hyd has less maintance set it and forget it the solid will need to be checked every few thousand miles ive checked my solid twice in 3500 miles and it hasnt moved so it all boils down to preference :cheers:

 

You need to run a solid lifter or solid roller to consistently run (shift) above 7000 RPM. Most hydraulics will float above 6500-6700 RPM. Once you start floating valves your headed for BIG trouble...read $$$ in repairs. Deen

 

CFI-EFI

I think whats slewing my HP peak way up in the Rev's are the AFR210 heads I have. I'm pretty sure that the AFR springs have degraded some compared to when new. At first I could rev that HYD Roller to 6800-7000 no problem. But after a few trips to the track and a couple of midnight buzzes down the road, it doesn't want to Rev over 6400-6600 now. CompCam tells me it's powerband is to 6200RPM!

Corvette1

Ok so I think I undertstand what you're saying. The solids have to have their lash subtracted from their duration. Makes sense to me, so if a both cams had the same durations, then the solid would act smaller?

Deen

Thanks for the heads up

--------
KM

 

No, No, No, A thousand times NO!. Duration is measured at a certain amout of lift. The common amount, so that cams can be better compared from one grinder to the next, is .050. Once the tappet has moved .050" the lash had BETTER be out of the picture. The lash "take up ramps" are different between hydraulic and solid cams, whether roller or flat tappet. This is why you don't run solid lifters on a hydraulic cam and vice-versa. The solid cam can, and usually does, employ more aggressive acceleration ramps. Look at the two examples you provided. The "advertised" durations are within two degrees of each other. But the solid gets to .050 lift about 15 degrees quicker than the hydraulic. The closer the .050 duration is to the advertised duration, the more aggressive the grind is. A hydraulic lifter will not tolerate the extreme ramps that a solid will. You would be best served if you limit your cam comparisons to the .050 figures. Due to the ramp styles dictated by the different types of lifters, a solid will provide slightly more power AND streetability, for a like amount of .050 duration. That is the reason I suggested, earlier, that maybe you want a solid cam with the duration (@.050) as the hydraulic you are now using. Good luck, and...

RACE ON!!!


[Modified by CFI-EFI, 5:47 PM 11/17/2002]

 

88-406,
I didn't see what kind of headers you have on your web site (I'm guessing 1and3/4" just to fit the head) just wondering if the rest of the exhaust is up to the task?
anyway, hydralic roller lifters are heavier than solid roller's, I see you have a rev kit (that helps) but I don't know of any hyd cam's that are reliable at 7000rpm's.
I think the other cam (solid) is going to be too big for your set up. in order to make the most out of that cam you'll need even bigger head's (220's) and raise the compression (longer duration cam's lower effective compression), it may raise new problem's (fuel line size, injector size and the MAF may limit the power at that point).

If your going to spin it past 6500rpm then you need a solid cam for sure, your 210cc heads are big enough to support good power (maybe not at 7000rpm, but 6500rpm). I think you may need the TPIS #700-701 cam or something simular (242dur @ .050") for the current setup.

 

[QUOTE]Corvette1

Ok so I think I undertstand what you're saying. The solids have to have their lash subtracted from their duration. Makes sense to me, so if a both cams had the same durations, then the solid would act smaller?


I thought that with a solid lifter cam you reduced the lift by the amount of lash and the lash had little impact on the duration. I was told by comp cam that my mild solid roller cam could be used with hydraulics or solid lifters.
Ed

 

A couple of points to consider:

The ".050" lifter lift" specs include the clearance ramps. For example, the 30-30 OEM SHP cam has clearance ramps that top out at .020" on the lobe, so it's 242 @ .050" includes a lot of ramp.

Hydraulic cams have much "shorter" ramps, so the first lesson is that you cannot directly compare the .050" lifter lift numbers of a mechanical lifter with a hydraulic lifter cam.

Also, mechanical lifter cams may not be comparable due to differences in ramp design. Using the 30-30 above, if you measure actual duration at .006" actual valve lift, it's about 272. The Duntov cam is speced at 287 seat to seat and 221 @ .050", but it's actual effective duration measure at .006" actual valve lift is about 270, so the 30-30 inlet lobe very close to the Duntov effective duration, but there's a lot of difference in the detail design.

The bottom line is that the typical cam specs quoted by manufacturers don't mean much when you want to deal with slight differences. The only way I know of to compare cams is to take actual lift-crank angle diagrams, measure actual rocker ratios, and run the number through DD2000 and Engine Analyser.

Duke

 

ED Your right that you subtract the lash from the gross lift to get net lift on a solid.
But Corkvette is right on with the duration. Only I usually consider it about 6-8 degrees.
CFI, think of it, they are both measured at .050" lift, but the solid might have .020" lash, so it is really only .030" into it's lift, where the hyd is really .050" in.

Back to the original post, I would opt for a solid with a little less duration, but keep the 112 lsa. 110 hurts power with an exhaust on less you are running some really short durations. Shoot for a fast intake lobe to get your open high lift open time without all the duration that is bleeding off cyl pressure.

 

When does .050" NOT equal .050"??? The valve may not have moved the .075" (1.50:1 rocker ratio), but if you measure duration at .050" tappet lift, you have to wait until the tappet has moved .050"!!! With the more aggressive acceleration ramps, the solid will overcome the lash in the valve train and pass the hydraulic in valve lift very quickly. Also, don't ignore the take up ramps on the hydrailic lobe. The "lash" that isn't present in the hydraulic system, has to come from somewhere. The lifter...maybe??? Just because it has a hyd lifter, doesn't mean that the valves, rockers, push rods, etc, aren't subject to the same growth due to the expansion caused by heat as their counterparts activated by a solid lifter.

RACE ON!!!

 

The measurment is not .050" at the valve. It is .050lift of the lifter. If you have lash(the air gap or extra clearance) set into the valve train like mechanical systems do, the valve will not move until that lash is taken up. A hyd cam has .000" lash, the valve begins to move as soon as the lifter does.

Let me know if it still doesn't make sense.

 

LT401Vette,
Please re-read my last post. I have addressed the lifter vs valve movement situation. Also, bear in mind that lash is generally set between the tip of the rocker and the valve stem. Because of rocker arm ratio, it only takes .013 tappet movement to take up .020 worth of valve lash. If you take your time with this and my last post, you should understand what I'm saying. If I have left anything out or there is something you don't understand, please ask. Possibly I am making assumptions that I shouldn't.

RACE ON!!!

 

CFI - LT401 is saying why the solid is going to act like a smaller cam. When you degree the solid it's going to read like you say. The motor is going to see it as having less duration like 401 says.

 

Jim the issue is the same. the solid still has to make up that lash. The other thing to look at is the adv duration. The large duration solid cam has about the same adv duration, meaning gthe valve is off the seat about the same amount of time.

 

Ralph, etal,

I respecfully dissagree. Look at the numbers from the origional example.

Looking at the hydraulic intake only, for the present, it takes 26* for the tappet to rise .050 from the advertised duration start. That's 288 adv dur, minus 236 .050 dur, equals 52*. Divide that by 2 (half for opening and half for closing) and you can see it takes 26* for the hydraulic lifter to rise .050". The same calculation yields 18* for the solid. Also bear in mind that the 18* includes the relatively "slow" lash take up ramp. By the time the solid rotates another 8*, to where the hyd tappet has finally reached .050" lift, the solid will be at .100" or more. Even if you assume a linear rate of acceleration, the solid is at .072". Subtract out the .013" travel required to take up our hypothetical .020 valve lash, and the solid is still way ahead of the hydraulic.

Due to the limitations of a hydraulic lifter the rate of acceleration of the lifter of the solid cam is much greater. The area under the lift curve of the solid is much greater than that of the hydraulic.

In my humble opinion, these two cams are miles apart.

RACE ON!!!

 

Wow, this is really becoming an education for me!

Based off of CFI-EFI's last post how does the LSA factor in?

Thanks

KM

 

LSA is a relative measure of overlap - the narrower the LSA the more the relative overlap for the same duration, or as duration is increased at the same LSA overlap is also increased.

Overlap is both a blessing and a curse. It can be very effective at scavenging the cylinder of exhaust gases and initiating the flow of fresh charge, especially when using properly designed headers, IF, and this is VERY IMPORTANT, exhaust back pressure is low and especially if it is effectively zero by the use of open exhaust. Lots of overlap and exhaust back pressure KILL low and mid range torque big time!

Production cars with manifolds and mufflers don't like much overlap. Sixties vintage Special High Performance OEM cams had a fair amount, but it really hurt the low end, and after Chevrolet went overboard on overlap with the 30-30 cam, the followup LT-1 cam cut way back on overlap.

As an example of modern design technology the current LS6 engine has duration at .050" lifter lift of about 204 degrees and an LSA of 117.5 degrees. On the surface these specs look very conservative, but with .550" lift and the relatively free flowing heads, the LS6 maintains excellent volumetric efficiency across a very wide rev range, including the top end and has a specific output better than many DOHC designs.

Duke