This goes out to all of you that already know what I'm putting together.

Now since the SuperRam as opposed to the MiniRam is more of a "middle RPM happy" intake, should I even bother?

I would like to try and keep the flattest possible hp/torque curve all the way up to the shift. I think we've all agreed that I'll be shifting in the 6000 RPM range, and Craig has burned my chip to cut fuel at 6600 and turn it back on at 6550.

Would a rev kit help me keep the HP figures up during these higher RPM times? Or am I wasting another $200 or whatever they cost?

Remember.... the more bulletproof I can make it, the better.

Thanks!!

 

The rev kit is supposed to help keep the valvetrain stable, so I'd suspect that it would help from 5000 rpm on up. I'm putting in the LPE 219 cam soon also, and plan on getting a rev kit myself, and shifting around 6000. The rev kit should let you shift a couple hundred rpm higher, you'd think.

Question is, are all the aftermarket rev kits the same? I've seen them from $50-$150 bucks. Moroso and a lot of other companies in the Summit catalog make rev kits much cheaper than the AFR kit. Has anybody used these kits, and is there a difference? Thanks.

 

Scorp, 89gta383: I think you got to ask yourself what are my priorities! Yes a Rev Kit will push you RPM limit a little higher before valve float, but at what cost? You guy's are talking about an induction system & cam which fall flat on their faces after 5800RPM's. Don't get me wrong, what they do in their window of operation is very good, and I have purchased both the S/R and the 219 cam for my 383.

Back to the HydraRev type device, you will notice that every advertised Dyno curve shows testing starting at 4500RPM's or higher. There's a reason why, because at lower engine speeds they have no benefit to the valve cycle event. What they do produce is more friction, which causes a small loss (5-10Hp) of low to mid range Hp/Tq -Doh!

So if you plan on using the car for 80% track time, than yes get the Rev Kit. If you plan on driving the car 80% of the time on the street- NO! If it were me, I'd spend the money on a set of quality springs like K-Motion, Isky H-Alloys or Comp Cams.
Just my 2-cents.
Chris

 

A rev kit is a band-aid for a poorly mathced cam and valvetrain. The right springs and good lifters make a rev kit useless.

 

Hey Scorp, I have an AFR Hydra-Rev kit in my car. My setup is in my signature. I only paid $100for mine so it wasn't a big deal, but the main reason why I got it was because I have a T-56 6-speed, and I wanted the extra insurance if I missed a shift. I've had it in the car now for 2 years, and it works well. I haven't noticed any losses with it, and you don't even know it's there once installed. I will be switching to a HIGH RPM setup soon, so it will really be to my benifit them. You have a STICK also, so you make the call. It is a ROYAL PITA to INSTALL THOUGH!!!!!. HTH's

 

Scorp,

Unless you plan on taking this to some high RPM's, I wouldn't bother. Although I kinda disagree with Aaron, I wouldn't say it's a bandaid, more of an insurance. But if your RPM's are staying reasonable, you should be just fine, if you match the springs to the cam.

 

Yep.... the springs are matched to the cam. Exact same cam/spring/retainer setup that LPE uses in their 383s.

I might go ahead and get one just as extra insurance. I don't mind parasitic loss of 5-10 hp (if thats true), it isn't a big deal. I dunno, haven't decided yet. If I get into road racing with the car and am holding it higher up in the RPM range, I'd feel a little safer.

 

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:[/color]<HR><font face="Verdana, Arial" size="2">

A rev kit is a band-aid for a poorly mathced cam and valvetrain. The right springs and good lifters make a rev kit useless.

[/color][/QUOTE]

Aaron...YOU CAN NOT BE MORE WRONG!!!


You have to know the physics here. There are a few important facts:

1. He is using HYDRAULIC ROLLER LIFTERS!
2. HYDRAULIC ROLLER LIFTERS ARE VERY HEAVY!

If you put sufficient spring on the valves to prevent valve float at 6000 RPM's on a hydraulic roller lifter motor, you will cause lifter plunger bleed down at high rpms, starting around 4500 RPM.
That is a PROVEN FACT, whether you take my word for it or not.

Due to this process of roller lifter plunger bleed down, the lifter body will not fully track the cam lobe...meaning the opening ramp of the lobe will be beat to hell by the lifter wheel...any you won't notice it because the valves are not floating.

In fact the only symptom you get is a high RPM nose over in power ( you will likely blame that on intake or head design problems instead of really knowing what you are talking about... ) and the cam/lifter will wear excessively or even break.

The rev kit basically removes the lifter body/wheel weight from the plunger. This keeps excess pressure off the plunger and keeps the lifter glued to the cam.


So Scorp508...as was stated by RU4L98...it's only worth it if you think you are going to run in high RPM's. ( I'm betting you will )

 

I've heard it before, but I go by what I've seen - 7200+ rpm out of 350s and 400s with hydraulic cams and no power loss up high with no rev kit. People see TPISs ads with the big hp gains with the rev kit and assume it's god's gift. If it were, there'd be a lot more people running it.

 

my shop does a lot of dyno work. they said they will usually see float around 6200-6300 with an aggressive hyd roller. if they run heavy seat pressures (in the neighborhood of 140lbs) they can hold it off a few hundred rpms. And rev kits will add 100-200 rpms. I asked him how stockers can rev to 7000+ with hyd cams...he said run high pressure springs, special lifters and a bunch of other tricks.

I tipically shift my car at 5800, but it will peak at 400-500 rpms higher...so around 6300. i've never noticed float and the machinist said there was no sign of float in my valve train. i don't have a rev kit, but it might be good insurance. Keep in mind that 5800 is probably as high as you want to shift with the SR/219 combo (probably less with a more cubes), so you wont be over 6000 rpms very much.

 

How about using titanium retainers? I would assume that the reduction in weight might give Scorp the "insurance" he's looking for without going to the rev kit. I read somewhere you can get an extra 100-200 rpms with them.

 

Already got em'. [img]http]//www.corvetteforum.cc/ubb/smile.gif[/img] They were like $140 or something like that.

 

If you notice power falling at 6300 RPM...it is rolling off much before that. Thats where the rev kit helps.

I saw the PHR ( or maybe even was CarCraft or superchevy ) article in 95 that dyno tested a stock hyd roller engine without and with the rev kit. The difference was astounding. Almost 20 HP at 6000 RPM...this was on a STOCK engine.

They also proved that using a higher seat pressure valve spring without the rev kit causes the lifter plunger bleed down.

I'm not making it up, and I have used rev kits myself ( I even have one sitting on my bench right now ). BTW: My rev kits cost $65.00 from a circle track claimer engine parts supplier. I think modifying the lifter /spring seat to fit hydraulic roller lifters is a LOT cheaper than the $300 hydra rev kits you see in magazines.

I think $65.00 is definitely worth 20 or more horsepower also.

 

BBA or anybody,

How can I tell if I have float problems ? I currently make Peak HP at 5600 rpm and shift at approxmiately 6000 rpm.... it seems to make power into the shift and through it, but if there is power to be found with a rev kit... especially 20 HP... I'm buying a rev kit tomorrow.

Tell me more, I'm valvetrain challenged.

thanks
Beach

 

Beach look for pounded valvetrain parts, particularly the keepers. I think Phil sent us some pictures of his keepers after a bout of valve. also look at the tops of the valves, rockers, etc. However minor valve float at the top of the rpm range may be difficult to detect.

 

Scorp508,
I think you are overestimating the useable RPM range of a 350 with the SR. I have run this combo for years and have found that 5600 on my shift lite seems to yield the best power. If you assume that by the time the shift is made, you are at 5900 RPM, this still does not seem like the RPM that you were describing. I think the rev kits are a great addition to high RPM motor (if you are experiencing valve float). Follow Ralph's description on what valve float looks like. Fortunately, I have not had this issue with the Corvette, but I had an issue many years ago with a roller cam Ford ('66 Mustang) at 8800 RPM.

I like many others have run n.a. in the 11's for many years. Some time back, I added a blower, but still kept the 5600 pill (6000 in the MSD). Times decreased slightly, MPH increased dramatically, 60' times increased dramatically.

BTW, I did not use a rev kit on my new 408 ci motor that I am currently installing, as I have stepped up to the SR cam. Machinist and CC felt like 6500 RPM did not warrant it. Spring pressure is 325 closed, 7xx open. The old HR ran 135 psi closed, 390 psi open.

Just my thoughts on the subject.
Aaron

 

When I ran my first HR motor, I did a freshen up build about a year later...I couldn't even get the valves out of the head! The tips were so beat up I had to file them round again just to dissassemble.

I used lash caps next time, with a rev kit and never had a beatup valve tip again.