gkull

It has been done for many years in race motors. A computer controlled setup without a cam. air or electric solenoid valve actuation.

But for us poor people Rhoads lifts were an begining and I bought the Crane Hi- intensity lifters.

My question during the 10+ years of using them was that the bleed off rate was set. so at lower rpm and less oil pressure that they would have less lift and duration (Supposedly) Motors have different oil pressures. Change the oil weight, temp of the motor, or type of oil pump and this bleed off lifter might never give full lift or have full lift all the time.

cv67

dont waste your time or dyno money
Get the right cam or even close youll be fine
some overthink on stuff start advancing retarding etc on a new build and never knew what it would do "straight up".

Patent trolls, yes agree. So many do nothing wiht the product or even the concept they just wait and want $. Stopped a few endeavours.

NewbVetteGuy

I don't fully understand it but this seems at least marginally relevant:

http://www.greencarcongress.com/2007...impulse-a.html

For those who were saying that the advantages of cam phase shifting / dynamic cam timing changes probably aren't "worth it" with a single cam and that the significant benefits come when you can control the intake timing and exhaust timing independently; this seems like a good solution to enable cam phase shifting to focus on exhaust valves and these per intake-port "air impulse valves"to focus on the intake independently. (Think throttle body per cylinder and one that works really rapidly so that it can maximize the pulses of the inbound air to both stuff more air into the cylinders AND to keep air velocity up.)

It shows 10 -23% increase in torque (depending where you are in the range; but it helps the most at low RPM which is AWESOME) and a 4-9% increase in fuel economy; obviously it is only relevant / useful if you already have some sort of VVT. What the heck an intake would look like that uses this, I'm not sure...


Adam

NewbVetteGuy

So what did you think about the Crane Hi-intensity lifters vs. the Rhoads? (I've heard internet rumors that the Crane doesn't work quite as well.)

I'm glad you added the comment about each of these lifters requiring the oil pressures to be within an ideal window to work properly; I was starting to get that impression, but as long as you plan for it and use the appropriate weight oil and oil pump it seems like you could definitely get it in the right range.


I think if I'm going to do ANYTHING in this vein it's going to be either the Rhoads lifters or the Crane Hi-intensity lifters OR if I can find a set of the variable ratio rockers, I'd LOOOOVE to go that route, but I'm pretty sure I'm going to have to wait it out and setup Craigslist alerts because it seems like they were all pulled from the shelves so it's just waiting for someone to sell a used set to find a set that's been laying around. I'd rather go with just a normal roller cam and retrofit roller lifters and then get the dynamic ratio roller rockers; ESPECIALLY if you can lock down the ratio range. (I'd love to find a set that can be set between like 1.4-1.7. (then play around with the intake and exhaust rates on a dyno to dial in what my engine likes and just leave them in that range forever).

The cam phase shifting is super cool but I didn't realize just how unavailable the tech really is to our engines and how much risk there is in such a thing (screw it up and heads crash into valves and you cause massive destruction). The risk is high and the reward is pretty low, even though the geek factor is really high.



Adam

NewbVetteGuy

Yea, that's the dream. Cams seem really outdated. If we could get reliability with "digital" valve timing (that actually works up to 7,000 or 8,000 RPM) it would be a near holy grail.

Infinitely configurable intake and exhaust lift and duration and timing.

-Such a system with an autolearning algorithm like current self-learning EFI systems would be PERFECT for being retrofit into any combination with an initial setup wizard to get it in the ball park and to ensure that it doesn't go past a safe point and cause the cylinders to crash into the valves.

Although in an ideal world, I think the autolearning algorithm would need torque and HP inputs in the feedback loop. -Install system, drive to a wheel dyno in "safety mode" and then give it the torque and HP data feed from the dyno and let it run through some simulated acceleration scenarios while tweaking the exhaust and intake durations lifts, and timing until it gets in the compromise sweet spot; or compromise sweet range if using dynamic cam timing / phase adjustment.

(A car that can self-tune itself for torque and total HP on an engine dyno and save this to a "performance" profile and then self-tune for fuel economy and save that to an "eco" profile just makes me giddy. I can't wait for an artificial intelligence overload to tune my car for me--- hmm.. This is actually a good use for a cloud service; you'd need something like a bluetooth or wifi OBD / can bus reader thingy that could just take the data generated by the different tests from the EFI system and dyno and just live upload it to the cloud, apply purpose-built machine learning algorithm and send the results back down to the EFI in terms of config files. It would then be pretty easy peasy to make different profiles for different EFIs/ECMs and different dynos.) --It could also radically reduce the cost of a "tune" as you've got AI doing it. The humans are just needed to physically plug it in and put the car safely on the dyno... (as long as no one gives the dyno or efi a high powered laser or rockets, humanity is still safe!) ;-)




Adam

NewbVetteGuy

Jim, I looked at the Cam-in-Cam and they only make it for overhead cams right now, right? -It also looks like they only sell direct to OEMs and aren't focusing on any sort of direct-to-consumers / retrofit option.

Couldn't, at least theoretically the CAM-in-CAM solution change the intake and exhaust timing events separately? (it looks like the exhaust lobes are fixed but if you had CAM-in-CAM+hydraulic phase actuated timing adjustments which would move the WHOLE CAM the combination of the two technologies could even for a a cam-in-block engine allow you to change both intake and exhaust timing? ---A shame there's so much proprietary technology and cross-patent licensing that would be required to make such a thing possible.




Adam

NewbVetteGuy

This whole thread just makes me want to turn my engine into a giant science experiment, for the record. I'm posting this here so when I destroy my engine several months in the future I can blame everyone in this thread for putting all these ideas in my head! lol! ;-)


Adam

427Hotrod

I ran the Rhoads lifters years ago in a big block. I hated them. They were relatively quiet when oil was cold...but as it warmed up and they started to bleed off they were ungodly noisy. I tried adjusting them every way I could and they just made racket. Now that wasn't all bad really because I was using them in an ugly brown Nova as a street racer. It sounded like it was going to either fall apart or blow up at any second...so it helped get races. It was a fairly hot Cam Dynamics hyd cam....but I couldn't tell any real improvement in idle quality or low end power.

Definitely noisier than any solid lifter cam I ever ran...so I went back to solid lifter cams. They allow you to easily vary lash on intake/exhaust to change characteristics.

JIM

NewbVetteGuy

So if any CF member wins the lotto and stumbles across this thread and decides that they want to fund a grand science experiment, please PM me and we'll work out how you can buy me one of these: ;-)


http://sturmanindustries.com/Solutio...2/Default.aspx


Adam

Haggisbash

Does the C3 differential share any parts with other GM differentials? Reason I ask is that where I live Corvette differentials are hard to come by and I never see parts for them advertised so I'm looking big $$ to import the parts for a rebuild.

The Money Pit

I'm still waiting on the "flux capacitor" to be developed......or how about "warp drive"....

You laugh, .. but years ago when Captain Kirk was using a flip phone to talk to the Enterprise,....cell phones weren't even a glimmer on the horizon...and now everyone has one.

v2racing

There used to be a centrifugal weighted cam sprocket in the 60's and 70's called Vari-Cam. You could adjust the degrees of cam timing retard and the RPM through which it retarded timing. Problem was it retarded the distributor timing at the same time because of cam driven distributor. It wouldn't be a problem with a modern crank trigger ignition though.

Mike

69427

I've always had good luck with Crane cams, so I tried a set of their high intensity lifters several years ago. I pretty much had the same experience as you describe above: lots of valvetrain noise, and no perceptible improvement in idle quality. I eventually just pulled them out and put the regular lifters in. It was just a time and money wasting experience for me.

427Hotrod

The one thing Hyd lifters can do well is be quiet. That is their intended purpose and to make up for valvetrain wear over time. Everytime folks try to make them do what solids can do, they become compromised. The high bleed down lifters just have either sloppy clearances or grooves in the plunger to allow oil to bleed off and let the plungers collapse at low speed/pressure. Now you've got clearance to take up without the clearance ramps on the lobe that a solid lifter cam is designed with.

I suppose there were applications where they worked OK...but to me it just didn't work out. Wish I had thought all of that out before I bought them! Live and learn...I was young and dumb.....

JIM

cv67

Remember those Rhoads had to be adjusted just right if they were off even some the valves wouldnt close and itwouldnt start.
Oh well guess Igot lucky. Helped reel in a few races, people thouhgt I had noise 302 with a little cam (85 5.0) 460 C6 stall 100 shot 4.10 Sucker would fishtail at 90 with M/T 10" slicks on it.

69427

BTDT

NewbVetteGuy

That seems to be a weird (and by that I mean incorrect) interpretation of history. As far as I can tell hydraulic lifters were created to create a more user-friendly cam /lifter tech that didn't require periodic valve lash adjustments; reduced noise is a side effect.

Valvetrain wear I'm not so sure about; but that's definitely a point of roller cams in either mechanical or hydraulic.


The old (getting REALLY old and this point) statement that roller cams can't deal with high rpms or sharp ramps just isn't true, although quite the opposite IS true of flat tappets when you talk about sharp ramps (wiping lobes)- which is flat tappets trying to do what roller cams were meant to do.


From Chris Straub just 2 short months ago: "The ultra pro hydraulic roller lifter from Morel in conjunction with a well thought out valve train are stable at 7500+ rpm and will make power. In an LS platform with light valve train and a 55MM core the lifters have been north of 8000 rpm.

My point is if you are wanting to make power in the higher rpm range a quality lifter is all you need."


I also just today read an article (from HotRod so normally I'd beware the results depending upon who the sponsor is, but in this case both cams were provided by CompCams) that showed an equivalent mechanical roller vs a hydraulic roller and they both had near identical results with power peaking at the same RPM.

I also noticed by looking at some of the really high RPM spinning hydraulic roller cams that lifter tolerances are a critical part of this equation to supporting higher RPMs and all this is making me think very quickly that the Rhoads lifters really have no hope of doing what they say that they can do (both bleed down to reduce duration and lift at low RPMs to increase torque -AND still spin up to high RPMs without float); theoretically one should be possible and not the other.

I'm also starting to see why rev kits seem to be slowly going the way of the dodo if high quality lifters with very accurate tolerances can spin to high RPMs, you don't need them to spin high RPMs and their only benefit would be reduced wear which makes their cost pretty high for what you get.


I think I'm slowly getting sold on definitely spending the money for hydraulic retrofit rollers (and high quality ones at that) and high-quality 1.5 RR roller rockers. I'd still love to find a dynamic ratio roller rocker or super amazing phase shifting cam timing solution to help limit choosing a "compromise" cam, but I think I'm going to have to pass on the Rhoads. Especially since comparative dyno results seem literally impossible to find and if that isn't fishy, I don't think anything is.


I'm afraid it's going to have to be my budget that is flexible on this build...

NewbVetteGuy

Read back to the 1st page of the thread; covered. That wasn't even the worst part of the Vari-Cam -when the not very reliable spring that made it all work broke it caused catastrophic engine failures. --A guy who worked at Var-Cam until they got bought out and then closed is on the Jalopy forums and there's a ton of information on the Vari-cam there including pictures of it and the original manuals and other materials over there if interested.

Read this to see the coolest thing in the whole thread: http://www.hotrod.com/articles/small...hallenge-2014/ Guy took a 1960s variable phase cam timing system that no longer exists and that used to use two pull handles to advance and retard the cam while driving and adapted it with custom code to an ECU that controlled the whole thing and took second with a BEAST of a huge SBC in Engine Masters a few years ago.


Adam

NewbVetteGuy

Here's an off-the-shelf variable cam phaser from Delphi.
http://delphi.com/manufacturers/auto...valvetrain/vcp

If I'm not mistaken, this is exactly the part that would be required for someone to build a retrofit for GEN1 SBCs. (Unless you stumble upon a 1960s Cam-A-Go on CL/EBAY.)

-Now we just need someone to do it AND build the code for an EFI or stand-alone ECM.


Adam

GUSTO14

Actually two of the most successful engines that addressed the idea of having more than one cam profile available were the Corvette ZR1 and the Taurus SHO. Their systems didn't rely on hydraulics as much as they did on their PCM to activate a second set of injectors and throttle plates to open a second set of intake ports. Both were unfortunately short lived, but both produced significant power increases while offering substantial fuel economy when desired.

I installed a set of Rhoads lifters on a SBF (302) I built for a Mustang in the 70's. The cam was hydraulic, but had a profile similar to the Ford 271 hp solid from the 60's. It pulled hard from about 3000 rpm to well past 6000 rpm. The engine idled at 800 rpm, had a nice lope to it and when driven normally, it got better than 18mpg even though it had 3:90 gears. Back then I considered it having my cake and eating it too... The lifters were just noisy enough that many thought it had solid lifters.

Good luck... GUSTO