What is the fastest one can consistently and reliably spin an engine with an hydraulic roller lifter valvetrain? What do you have to take into consideration to accomplish this? Assume that this is the primary focal point of the engine.

I would assume that the max RPM would depend very heavily on the valvetrain weight and size of camshaft involved.

Is it possible to determine a valvetrain weight goal? Which weights matter most? Which hydraulic lifters allow more rpm than others?

What sorts of questions should I be asking to determine the targets for valvetrain performance?

Jason

I imagine the valve spring is the most important (not necessarily in weight, but in control of the valvetrain) For weight I imagine the valve weight is the most important followed by the retainer weight. It's hard to give any definitive answers here, for me at least, maybe Bogie can help some more, but I'm just giving places where to put the money at when looking for a max RPM hydraulic valvetrain.

The question of a rev-kit came up a while back, and I'm not sure if it was determined that there were any hydraulic lifter rev-kits available.

If there is a rev-kit available for hydraulic lifters, then the valve springs would have much less weight to deal with. A rev-kit is essentially 16 springs pushing down from the underside of your heads onto the top of the lifters. With a rev-kit and the proper valvetrain installed, your maximum rpm will no longer be determined by your valvetrain, but how good the bottom end of your motor is built.

I sort of doubt anyone makes a hyd. roller rev-kit, as the largest hyd. roller cam you can buy has a power peak rpm in the range that a good valvetrain can keep up with.

If you want to push the rpm limits by adjusting your cam timing, or perhaps having a cam custom ground, then I'd say pay the big bucks for Titanium valves and retainers. That'll save you a couple ounces per... and the valve spring will be better able to control the relatively heavy hyd roller lifter.

Air Flow Research makes a rev-kit for Hyrdraulic roller cam valvetrains. See link below...

http://www.airflowresearch.com/pages/hydra_rev.htm

I would not be surprised if it was designed to fit their heads exclusively.

So I guess a beehive spring with the titanium retainers is as close as I can get as the rumor is titantium valves wear out too quickly for anything outside of high dollar racing.

From the link you provided:

"The easy to install Hydra-Rev Kits come complete with all the components you need and requires no additional machining or modifications when installed on stock or aftermarket cylinder heads"

I have my reservations on their 100hp gains, but as far as your rpm desires, I believe your problems are solved.

Good luck.

You really need to coordinate with your cam manufacturer, especially if your contemplating revs over 6500.

GM has been running hydraulic roller cammed production engines such as the LT1 and 4, the LS1 thru 6 with redlines from 6300 to 6500 for a decade without resorting to titanimum valves nor springs between the bottom of the head and top of lifter.

Ti valves are changing into production stuff. But all are not created equally. Ti has a couple problems it's a bit brittle at elevated temps and it doesn't lube well. This caused problems on competition engines where head distortion through the valve seat caused the valve head to twist to close. This resulted in breakage, a similar fate awaited valves that floated for what ever reason. Stem wear was a problem as well.

Newer alloys of TiAl and SiNi in the mix seems to be overcoming these issues, along with fused carbon stem coatings and other rocket science, these things are moving from race only high buck motors into mom and dads grocery getter bit by bit. They of course have been part of motorcycle lore for a long time, but little engines with little valves are a different problem from cooling and supporting a 2 inch diameter head.

Toyota, Nissan, BMW and others have been sneaking them into some of their engines for a few years now. I suspect thy're also in some domestic production as well. Corvette will be using 'em on the intake for 2006. So if the big guys are willing to put them where their warrantees are, you can bet most of the bugs are getting worked out.

But these are some pretty exotic alloys that may not be reflected in the hot rod market, of if they are, they're mighty expensive. I know that Manley prefers that the NASCAR guys not run more than one race on theirs, but some teams have pushed this to three or four.

Bogie

So it can be achieved, but with special coordination. Ok I can live with that.

The new Z06 is probably the first appllication with a displacement over 6.0L. It would be interesting to see an article that discusses what can be done with Gen I SBCs that mimic/duplicate the results generated from GMs current exploits.

Jason

Okay, I changed my mind and I'm going solid roller. I can't back out because I have already bought the lifters. (Crower severe duty). I also bought the Comp Pro Magnum roller rockers and their stud girdle.

Do I need the rev-kit for 7000rpm?

Thanks,

Okay, I changed my mind and I'm going solid roller. I can't back out because I have already bought the lifters. (Crower severe duty). I also bought the Comp Pro Magnum roller rockers and their stud girdle.

Do I need the rev-kit for 7000rpm?

If properly set up, solid roller won't have any trouble with 7000rpm.  Just be sure your bottom end is up to snuff.

I noticed on that AFR link, that the "100 hp" the rev-kit improved over non rev-kit engine was at 6500, where hyd. rollers would normally start to have trouble. Solid roller lifters aren't nearly as heavy as hyd. rollers, AND there is no worry about 600lb open spring pressures (not uncommon with solid roller) collapsing the hyd. part of the lifter.

If it's a street/ strip car, Crane does sell a "street roller" that has an iron distributor gear on the back of the camshaft, which takes away the need for a bronze distributor gear.  It costs more than a standard solid roller, but if it's a street car, it's worth the peace of mind.

You'll probably end up needing a rev kit for 7000 rpm. The reason is that roller lifters are heavier than flat tappets and put the valve springs under more stress to push everything so the lifter follows the cam contour and the valve closes all while not bending the poor pushrod that's stuck between. The rev kit lightens the load on the valve return spring so a spring of less force can be used. This when backed up through the rocker also reduces the stress on the rocker and the pushrod, since the rev kit is reacting a portion of the working load directly between the engine's structure and the cam follower. So you get a lot less deflection from the rocker and the pushrod. This reduces wear and tear on the bearing points and helps the pushrod to transmit the motion of the cam lobe to the valve.

You'd be astonished at how much the pushrod and rocker deflect at high RPM the result of which is reduced lift over the top of the lobe and when they spring back it can result in the valve being snapped real hard on the seat causing it to bounce if not structurally fail. So reducing the valve spring pressure to what's needed to contol the valve, rocker and pushrod and installing the rev kit springs to manage the lifter is a great asset.

Bogie