Togo

i was just flipping through their catalog and saw this.......what's it for? think it works? http://www.airflowresearch.com/pages/hydra_rev.htm

MrNuke

It isn't really needed on a typical street motor (especially if it never goes over 6200rpm or so).

However, it does keep the motor out of valve float without having to run a very heavy spring (that can kill hydraulic lifters). It will also give you some extra stability in the valvetrain (not as good as a stud girdle, but not bad) if you rev it too high.

It really comes down to two things: rpm range (higher end) and if you run hydraulic lifters. If you never go over 6000/use solid lifters save your money. If you want to rev it 6500 or beyond and want to use a hydraulic cam to do it, get one. Get a stud girdle and 7/16" studs also for stability.

Togo

so you think the horsepower improvement they boast on their webpage is bogus? it says an additional 100HP at 6200RPM! :eek:

LT4POWR

There was a good article on it in GMHTP magazine. I'll be getting the kit as part of my H&C package this winter.

Those HP#s are marketing :bs

388 SOLid RoLLeR

of course their advertisement is bogus. Arent they all?? Just like the airfoil makes 15 rwhp. Mind you id believe it if the motor made 800 horses but not on a stock motor. If you are revving higher than 6300 its a safety precaution, it maintains the power top end while keepin the valves from tagging a piston. I know some hydraukic motors going 6700 but when those valve springs lose a bit of pressure or the lifters give up the owner is going to spend 20fold the price of a AFR revvkit in rebuilding his motor. Just go to a solid roller. i think hydaulic lifters are sad. :lol:

388 SOLid RoLLeR

A freinds LS1 motor befor eand after solid roller conversion. he has heads and cam already done. its a 382 lS1 stroker

before 388rwhp @ 5800 rpm 351rwhp@6500rpm

after 428rwhp @ 5600rpm 441rwhp @ 6500rpm

i took these off his dyno graphs i have copies of. the solid roller cam has slightly less lift than the hydraulic one, but has more aggresive ramp rates, etc etc. Notice how it makes 40 more horses at around 56-5800 ans still makes more at 6500 while the hydraulic motor died, or is dying. At 6500 it makes 92 more rwhp!! his old redline was 6500, now its 7000. Kinda sad how an entire motor thats built for all out power is limited to the lifters.

black bart

I have been running the afr rev kit for three years one thing that everyone sofar has omitted is that if something happens to valve train like bent pushrod or broken rocker the lifter can't get out of the bore and ruin the block. If you don't mind your engine sounding like a diesel and you want to adjust the valves every few thousand miles real pita use a solid roller but if you want to have a strong engine and not have to tear it apart and adjust valves the hydraulic is what you want

gtsyellow

that's just a typo, they meant to say the airfoil makes 1.5rwhp :jester

bill mcdonald

I was looking into this, since my top end is apart.

One thing I noticed looking at other adds for rev kits were the words something like. due to the improved spring angles (meaning the retainer), it will not cause accelerated wear on the lifters.

Is accelerated wear an issue?

black bart

Bill I can't say how long they last.
I changed my intake in the spring and after two years they looked like new I now have about three years on them. I use the rev kit instead of heavier springs in the head then the lifters won't have to work so hard the spring in the rev kit pushes on the lifter body. I don't turn a lot of rpm but don't want to chance valve float. The limiting factor on my engine is the bottom end just keep turning up the nos until the crank hits the pavement :rolleyes:
Thats why a solid cam would not help me it would only allow more rpm and put more stress on rotating parts with enough cubic inches and a good power adder you don't need a lot of rpms :cheers:

Togo

so what's the general consensus here? the motor is completely NEW and will be a completely forged bottom ended 383 which will be receiving 200-250 of NOS when its all said and done......should i save my money?
my block says it is machined for hydraulic roller, but says nothing about solid roller........and i don't want to tear the thing apart to adjust rockers....so......is this something i want and/or need?

black bart

Go with the hydraulic cam soild is for race use you dont want to be adjusting the valves all the time. You probably don't need a rev kit but that depends on what valve springs you have and what cam and induction system. One of the nice things about nos is you don't need to turn engine destroying rpm to make power as long as the bottom end is strong you can out muscle a high rpm engine and not turn more than 5500 rpm. What cam are you going with what duration and lift.

LT4POWR

Don't get one unless your are running a super high rpm hydraulic roller cam. Otherwise, save your money.

SkarodoM

Rev kits are only there to keep the lifter in the lifterbore in the event that the valves float. They are not there to prevent valve float... think about how it functions ;). There is no band-aid or substitute for having the correct valvespring for your setup & it isnt that hard to get something adequate. The only time I'd actually recommend a rev kit is for roadracers who are banging up and down through the gearbox constantly, and only then b/c theyve got a much higher chance of mechanically overrevving.

-Phil

AquaMetallic94LT1

Keep in mind that you should not run more spring pressure than is needed to prevent valve float at just above max engine rpm. Excessive spring pressure wears the valve train more, takes hp, and wastes fuel.

Lifters don't move as much as the valves and less mechanical advantage on the valves because the valve has the rocker arm ratio as leverage on them. Your money is better spent on titanium retainers and or lighter valves.

Its worth noting that AFR heads have less than adequate valve springs. Their head prep work is not the best either. And....their @#$% valves are offset so the rockers don't sit on the center of the valves.

Call some cam mfrs before you go with a solid roller cam. You'll find that solid roller lifters are for max hp drag cars that get rebuilt often and have new lifters installed fairly often. Solid roller lifters are not designed for street use unfortunately.


[Modified by AquaMetallic94LT1, 11:46 PM 11/20/2002]

black bart

Hydaulic lifters are heavy if you install a rev kit it applys pressure directly on the lifter this allows the use of lighter valve springs. The drawback to useing a heavy vavle spring is the rocker arm ratio means it takes much more power to open the valve and at high rpm the push rods will flex this means less opening of the valve that is why in some cases a rev kit will make more power. Most street engines don't need a rev kit but after reading some of the threads here it is clear that some people don't understand why they help. On a high rpm engine you can control valve float with heavy springs on the valve or lighter spring on the valve and use a rev kit both may float at the same rpm but the heavy spring on the valve causes more valve train wear because of the rocker ratio means it takes much more power to open the valve also if something breaks the rev kit will keep the lifters in the lifter bore. I will say it again most engines on the street don't need a rev kit but for some it is better just depends on what cam and how high your engine will turn. All brands of heads have offset valves on the big port heads it is necessary to get the pushrods to clear the ports that is why they make offset rocker arms.

SkarodoM

Someone PLEASE tell me where t his gross misinformation is coming from... the internet is a dangerous thing :D

Pushrod flex? No, sorry.. incorrect. Solids arent for the street? Better tell GM that.. those fools actually spec'd them stock in engines back in the day...

We're talking hydraulic roller stuff... not reaching full lift b/c of pushrod flex isnt the problem at all. If you arent reaching full theoretical lift (you arent), it's because of plunger movement. There is NO reason to underspring something and slap on a revkit thinking it's going to make up for it. It takes power to compress springs, does it not? So, how do you gain power on something thats correctly setup, by expending extra energy ;). Most people havent, but I have put revkit springs on spring testers, and the ones we've put in 8XXXrpm roadrace engines were only around 20lb at coilbind. Considering lobe lift on the HR's most ppl run are below .350", youre talking maybe 6lb of pressure on the lifter body... figure a 1.6:1 rocker, and that's approximately 3.75lb less at the rollertip, but even then, only at peak lift. As soon as the valves begin to float, you could have a thousand lb of spring pressure on the lifter, but the lifter cant use The Force to pull a pushrod back down into contact with it. That's like having to move a box across a floor, and deciding to put your palm flat against the front of it and pull your palm away, and expecting the box to follow - isnt gonna happen. People will cite that in some instances it helps, sure.. it may help in a few instances, but that is NOT what revkits are for at all. It would only help if you were barely floating the valves and it was altering your IVC and EVC events IMO, and if youre on the edge like that, then you need to fix the problem - improper spring selection or setup. They dont make a cam without making a suitable spring for it, spend your money elsewhere if you're looking for power & don't believe a damned thing in that AFR catalog. :D

Hope that helped.... a little... will probably incite a digital riot by the people duped by magazines however ;)

-Phil

388 SOLid RoLLeR

Allows you to run a lighter spring?? WRONG. Go to the afr site and read where it BOLDY states the rev kit does not allow lighter spring pressures. Again hydraulic rollers suck. so do hydraulic rolelr lifters. Solid Rollers rule.

I constantly hear of people whining of valvetrain adjustments. what kind of parts do you use? billet plastic rockers from pep boys?? no wonder you have to adjust them so often. anyhow, last time i checked theres 4 center bolts in my valve cover keeping them off.... not so hard is it.
:cheers: :cheers: :eek: :cheers: :cheers:

ELEVENS

I had valve float at around 6300 rpm. The rev kit cleared that up completely, now it doesn't miss a beat through 6600 (haven't had it higher than that, yet.... only been driving it for 1 day). Regarding the 100 HP advertising claim, it certainly could be true. What they are probably doing is comparing a motor like mine, where you are measuring HP when the valves are floating, with a rev-kitted motor where the valves are not. I also have a friend with a bone-stock LT-1, w/ a rev kit and a Hot Cam. The motor pulls to 7000rpm clean. Another benifit is if you break a rocker stud or rocker arm, the lifter will stay in the bore, and you won't loose oil pressure and quickly destroy your motor. The downside is they're a PITA to install with the heads on the car. HTH.

LT4POWR

:cheers:
Phil, it's nice to see you on the CorvetteForum. I always enjoying reading your no nonsense replies on the CamaroZ28 forum.