NewbVetteGuy

I was thinking about the implications of advancing vs. retarding my cam and though "there's got to be someone who's figured out a way of doing this dynamically so that you have better torque and fuel economy on the low end, and more HP at high RPMs"; then I went down the rabbit hole...


It seems like there were a number of attempts at this over the years, but only one option in this line of thinking that stuck around. Anyone know any more about possible solutions here?


Apparently back in the 60's there was a special cam called the "Varicam" that did exactly this -it used a bunch of springs to physically advance the cam timing at rpm -sounds kind of like a distributor's advance mechanism applied to a cam. It was apparently pretty unreliable and the springs broke before too long so it died out because it horrifically destroyed engines.


Then I came across Rhoads lifters- lifters that allow you to run a big cam (hydraulic flat tappet only) and they intentionally bleed down at low RPMs making the lift and duration lower at low RPM so you have good fuel economy and improved torque at low RPM and then from 3000 RPM and up you get high airflow and HP. -Except they're apparently noisy. Crane cams apparently has a less noisy yet less effective version (exact tech in the Rhoads is patented). -These seem like they've been used by lots of people since the 60s, but some think they decrease reliability and that the sound they make is unbearable.


THEN I came across dynamic ratio roller rockers, but I have no idea what happened to them; they seemed like a tech that came out in the last 10 years but dissapeared for some reason; Crane Cams had Radi-ARC and there was a solution called "Hot Rockers"; these are the opposite of the Rhoads lifters in that you run with a smaller than normal CAM to get good torque and fuel economy and then at high RPM the rocker arm increase the ratio in a configurable range between 1.1 and 1.7. I was pretty excited about this solution as you could theoretically use them with a roller cam, but I have no idea what happened to them....




Adam

Gale Banks 80'

As far as the aftermarket its kinda a dead end. Just like ABS Brakes that have been around since the 1980's. Actually the aftermarket has gone the other way, You can buy a late model Engine with Variable Cam Timing and run it with an aftermarket ECM. Since the VCT codes havn't been cracked they use a kit that Locks to Cam in place eliminating the VCT. On modern large Diesel Engines they are doing away with the Cam entirely. Each Valve has a Hydraulic Cylinder and a ECM tells it when to open and close. So to change "Cam" timing is just a matter of typing in a new code. How ever these are very large Engines that Run at 80 RPM.

69427

I've had an idea in my head for variable valve timing for the past twenty years. Small blocks and big blocks are similar enough in design to both use the same type of phase actuator. The slightly complicating factor (actually cost and annoyance factor) is that any cam phasing changes also affect the ignition timing due to the distributor being driven off the cam. But nowadays it's easy enough to get the timing signals off the crank, but that also means extra electronics/software to control the timing, versus just letting the distributor do the timing curve with weights and springs. But what the heck, there's already going to be a small electronics unit to measure RPM and to control a solenoid that changes the cam phasing. Just off the top of my head I can envision any number of present production ECMs (or 80s and 90s ECMs) that have the hardware capability to do this, it's just a matter of either changing the function of some of the outputs and changing the calibration software, or a new software package in a blank ECM.

It would be an interesting engineering experiment (and if I had the time and materials I'd love to try it), but I don't see a lot of interest elsewhere in any volume usage of this capability.

ignatz

Seems like you would first want to prove to yourself that this has a quantifiable improvement. Last engine simulator I played with was years ago and it was fairly primitive. If this were tickling my fancy I would start in simulation land and see what's available.

cv67

Elecronically acutated valves, could program then to open whenever you wanted. Been played with by mfrs for yrs not sure its been perfected

Used to run Rhoads lifters back in the 80s/90s they did what they claimed. Anyone who thinks they are too noisy needs to get out of hot rodding. No worse than a SFT cam if that had a very slight tick at cruise but not a "bad" tick. Didnt seem to pump up quite as quick. If i had a DD that used a HFT cam I may consider them. I think they make or made some in a roller too?

Use to run a Nitrous cam in the high 230ish range would lope fairly good when cold after about 10 min of driving at idle you could hardly hear the cam at all made it more "sleepy"...and easy to drive.

NewbVetteGuy

The phase actuator thing is beyond me but the ecu and ignition timing is easy now.

Even the $999 TBI efi systems offer ignition control and dual sync distributors that know the crank position, right?

They should just be spitting the signal down a bus you could patch into for your controler or use an open efi controller and extend it to control your phase actuator; getting Holley to extend support for something like this would be ideal.

I'm doing holley sniper efi with ignition control this winter and I'd be happy to be a beta tester. 😁

Adam

NewbVetteGuy

I'm not clear on what part of this you think is still just a theory; there's no question in theory or practice what adjusting cam or valve timing does. It been proven for decades. More low end torque, minor fuel economy improvement at low rpm, more stable idle, and greater airflow and therefore more HP at high rpm. There's a reason modern engines can do this.

Cheap aftermarket efi systems with loads of sensors and low latencies are going to make so many cool things possible and cheaper to be integrated into old cars. Standards support and open OR extensible platforms are critical to where this goes. I really hope to see holley produce some efi APIs and ideally an App Store for their efi platform.

Integrating an advanced efi with a touch screen stereo system (with android app support for say Googles car play) could enable incredible solutions today.

Unlock your old cars doors when your cell phone gets in blue tooth range, remote start via cellphone app, hell telling Siri or amazon Alexa to start your car, a cloud dashboard that displays and alerts you to strange engine conditions, shows fuel economy info. Can automatically switch cam timing, inform timing, are, electronic trans shift points, and tc lockup between performance mode and economy mode to give you more power when you want it and more fuel economy when you don't. An aftermarket cylinder deactivation solution is within striking distance for even our old gen 1 SBCs if you've got an aftermarket port efi system; that plus something like the hot rockers solutions could cut both air and fuel to cylinders at cruise.

Sorry huge tangent there but the possibilities are endless right now if this stuff gets opened up.



Adam

ignatz

I am not sure how you got the idea I thought this was a "theory", but you've got the wrong idea on my comment. If I was going to work so hard retrofitting old motors I would want to have some idea in advance what all that work was worth. You use words like "more", "minor", "greater", etc. I am not denigrating your enthusiasm but those are subjective values.

Given the millions of SBC's out there maybe there's business opportunity for hard core enthusiasts, I dunno. I'd start with some "science" as best I could find it, hence the simulator as a cheap way to get some feel for things.

____________
OK, not to be a complete drag on your musing, I got to wondering if anybody else ever asked this specific question and got but one hit, this (with no one replying)

http://forums.hybridz.org/topic/7270...for-gen-i-sbc/

as to newer motors, there's a whole lot of VVT literature, found this as representative

http://www.hotrod.com/articles/hrdp-...formance-test/

The way I read this is improvements are in the under 10% range.

69427

I've always been curious what the performance improvement would be. I often read articles where engine builders will change the cam installed position (versus crank angle position), but I have never seen any A-B tests to see what power/torque is gained/lost/moved in this endeavor. I'm also curious how the idle quality is affected by the cam position change.

NewbVetteGuy

I understand now; yea, I totally misread that and understand what you're saying. Very valid point and more applicable for the majority of people than my take.

I AM pretty enthusiastic about this bringing modern technology and its benefits to old cars thing; I'm fully coming at this from a tech enthusiast perspective so just proving that it CAN be done and the journey is more important than the end result even to me. -I also think the quest for greater dynamic range (more power when you want it; more fuel economy when you don't need more power) is much like the quest for weight reduction and if you always stay conscious of it and focus on a 100 tiny changes and 2 or 3 big ones, you'll get there.



Adam

NewbVetteGuy

Hmm... I need to get a new timing chain and cover and I could get one of those fancy sprockets with the timing indicators etched into the inside and a 2 piece cover and see if the Dynojet dyno in my area would let me do the cheap 3 pulls with a bit of delay in between them such that I could change cam timing between pulls. -Something extreme like -8 degrees and then again at +8 degrees...

I'd be willing to do it "for science". But can't until after November. (Although the air would be nice and cold then.)

I have to think a higher performance engine would show greater differences, though. My little stock L82 with no cat dual exhaust isn't the best test bed to show what's possible...


Adam

NewbVetteGuy

10% is great! I'm surprised it's that much. Reading articles next. 10% for 400hp is 40hp; 10% of 400ft lbs is 40ft lbs. That's an exciting percentage!


Adam

NewbVetteGuy

Wow, I guess I don't need to waste the $75 on the dyno for this anyway. Those results are stupid exciting. Now I REALLY want this... Someone find a way to do this reusing the Gen VI hydraulic phase actuator; the Hot Rod article says it's easy to retrofit the earlier LS motors with the phase actuator and support (probably with an ECM update). All this just makes me want to spend a gazillion dollars to buy an LS motor, but I must be at least partial hipster because that's too cool now for me to do it. ;-)

Hmm... Mastmotorsports solution was/is only for Gen4 LS motors, and it requires using their cam; back in 2008 they were already talking about porting it back to earlier LS engines, I need to track down where that is at least. It also required using their ECM, which makes complete sense as you want this and ignition timing in sync...

The Hot Rod article showed that they DID develop the retrofit for the older LS motors. $245 + the price of a special VVT cam and then you of course need an engine ECU that can do this. The Microsquirt nerds would probably love to build something like this and the ECU would then the cheap. I already need a new CAM and an ECU for EFI is already in the works; another $245 and I'd TOTALLY do this... if it existed for older GEN1 SBCs...

This is so doable. If anyone wants to experiment with my car to get this working and have me pay for it, let me know.

Adam

NewbVetteGuy

Here's CompCams offerings for retrofitting VVT into L92 LS motors; so cool and so wish I had an L92 vs. an L82 right about now...

http://www.compcams.com/WhatsNew/New...yID=-377055714
Here's the PDF. http://www.compcams.com/WhatsNew/Fil...vvtengines.pdf

There's just NO WAY I can swing an LS swap, but this tech is just stupid cool.

Adam

NewbVetteGuy

Obviously variable ratio rockers would be WAAAY simplier and provide some of the same benefits, but it appears that there was a patent issued in 1978 for the tech so I have to wonder if that's why the HotRocker and compcams variable lift rockers dissapeared so silently and quickly...

Stupid patent trolls! (That's who I'm blaming, anyway.)
https://www.google.com/patents/US4182290

Adam

427Hotrod

A Team in the Engine Master's challenge used a Cam-a-Go on a SBC.

http://www.hotrod.com/articles/small...hallenge-2014/

I think the "Cam-in-Cam" concept could work also.

JIM

NewbVetteGuy

Here's another very related and interesting approach to solving the same problem, although honestly I don't think it solves it as well as it doesn't really help at high RPM...
http://www.caranddriver.com/features...system-feature

Adam

NewbVetteGuy

Yea this is ridiculously badass. What are the odds of finding one of these old CAM-A-Go's, though?


Adam

427Hotrod

I remember him talking about it when he was working it out. Seems like it actually messed up during contest and they ended up locking it out. Concept was cool....just needs more development.

You can rock the powerband around some by advancing/retarding the entire cam..but unless cam is way mismatched...it doesn't make a huge difference usually. Of course it depends on what you call an improvement. If you gain a lot of low end because cam was wrong in the first place...you're happy if you never really rev it. Same way if cam is wrong and you're trying to spin it to the moon and don't care about low end. Always a compromise. If it's at least close to right you should be good anyway.

Until you can separate the intake and exhaust lobes, you're not going to get the amazing flexibility of today's top powerplants.

JIM

NewbVetteGuy

Ok, I tracked down the cam-in-cam setup from Mahle Group http://www.mahle.com/mahle/en/news-a...nificantly.jsp

and Mechadyne's "DuoCam" tech that's used in certain versions of the Viper?
https://www.mechadyne-int.com/products/duocam/



Adam