I was running one. Now switching to solid roller. They do help control lifter bounce since hydraulic roller lifters are on the heavy side. On my application, they extended theh rpm range by maybe 100-200 rpms. The biggest was it helped control bounce, which in effect does help rpms.
I run a Hydra-rev, I picked up a few hundred RPM out of it (nothing else in the combo changed) but nothing exciting.
Installation is fairly easy *if* your heads are smooth under the valley area and have a center support. If not, you may not be able to run the kit at all or you will have to rig up custom bracing like I had to do with my Dart Pro-1's as they don't have a center support and the plate was flexing. I like to either press-in pins or drill and tap the heads and bolt (use red loctite) the spring plates to the head to keep the plates from "walking" around. If you rely on spring tension alone to hold them in place they'll walk around and may rub the pushrods.
The high-RPM problems with HR cams are caused by two things: the lifters themselves are quite heavy which means you need stiff valvesprings to keep them in line. Unfortunately you can't run tons of valvespring pressure to control the lifter on the lobes because you'll collapse the hydraulic portion. That's where the Hydra-Rev comes in, they apply a bit more pressure to the lifter only (helping to keep them on the cam) while not collapsing the lifter via the pushrod.
You'll see more gains from going to the new beehive springs and Ti retainers/keepers as they save a LOT of weight compared to standard dual-spring setups; best option with an HR is to run the rev-kit and beehives.
Another tip to possibly save you big bucks in the future: make sure you buy the cam ground on a billet core and have the pressed-on iron distributor gear installed (so you can run a long wearing iron gear on the distributor), and run a genuine GM melonized distributor gear. DO NOT RUN THE MSD MELONIZED GEAR. I've had two MSD melonized gears go bad on me with Comp HR's; one was 1/2 eaten up in about 7000 miles and the other completely wore through in 2200 miles which left me stranded and destroyed all the bearings. The reason for the billet core is once you start running decent valvespring pressure plus the pressure from the rev-kit you may very well experience lobe failure of a cast HR cam, the billet cam will not have this problem. Also buy a distributor with a slip-collar so you can properly set the distributor height (which control the gear mesh between the cam gear and the distributor gear.)
I have a set of Comp beehives and Ti keepers/retainers on the shelf in the garage waiting to be installed (along with a new billet HR cam, same grind); I've had them for months now just haven't got around to pulling the engine.
The best piece of advice here is not to go in with false pretenses. Never expect to make a high-winder out of a hydraulic roller. Using beehives and a hydra-rev I would plan on 6500 *max*, and that's an estimate depending on how agressive the lobes are-- you may start floating at 6000, and floating will KILL the springs and lifters in a heartbeat.
If you feel the need to spin higher then either go solid flat tappet or solid roller, and then you have cans of worms to deal with both.
A rev-kit is a MUST HAVE on a street solid roller IMO, as it keeps the rollers in contact with the cam at all times, preventing the wheel from "skidding" on the cam when on the base circle-- this in turn increases lifter life. Also, getting an SR to live and be reliable on the street is dicey, best bet is to buy GOOD rollers with true pressurized pin oiling-- namely Isky Red Zones and even then yank them out every 7500-10K miles for inspection.
Troy
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1969 Chevelle
Old setup: Procharged/intercooled/EFI 353 SBC, TKO, ATS/SPC/Global West suspension, C6 brakes & hydroboost.
In progress: LS2, 3.0 Whipple, T56 Magnum, torque arm & watts link, Wilwood Aero6/4 brakes, Mk60 ABS, Vaporworx, floater 9" rear, etc.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
Hydra rev kit?
Hybrid Mode
