Variable Cam Timing for SB V8s

[Ron Earp]

Does anyone know if there is an aftermarket supplier for a system that can vary cam timing for domestic SB V8s? Seems to me this would certainly be a marketable product and doable. Sure, you can't have independant control over intake and exhaust timing like is current tech on DOHC motors all over the world, but being able to advance and retard the cam timing would be worthwhile.

Seems an oil pressured valving technique would be useful and could retro fit onto a SB with modified front waterpump and front cover housing. Gains wouldn't be tremendous but they wouldn't be anything to sneeze at either.

I read tale some time ago of GM building some "dual cam in block" SBs for evaluation and the article mentioned one of the goals was to incorporate independent cam timing for intake and exhaust.

[Steve Toner]

Do Rhoads lifters count? [img]/ubbthreads/images/graemlins/smile.gif[/img]

[roaldin]

Have you seen web page ?

Tim.

[Kevin M]

Tim,

Do you have any experience with these people? It looks like it should work, although it only changes lift and not overlap so it won’t do the same things as a DOHC system like BMW’s Vanos which changes overlap or Honda’s V-Tec which changes both.

It would be very interesting to hear from someone with actual experience with this.

Kevin

[Mark Worthington]

Interesting. It seems like the steel components would add more inertial mass to the valvetrain, so I wouldn't expect it's a very good solution for high-revving engines.

[roaldin]

[ QUOTE ]
Do you have any experience with these people?

[/ QUOTE ]

No. I found it while researching something else.

Tim.

[roaldin]

I'd expect it to affect "effective" valve timing simply because the valve would accelerate past shrouding etc faster ("sooner" on the way up, and "later" on the way down). "Off the seat" or "advertised" timing info' shouldn't be taken too seriously anyway, it starts getting interesting from about 50 thou' on.

As for weight/mass/inertia I have no idea although it's placement seems to be likely to cause less problems than the same mass added to the pushrod or valve for instance.

Tolerances etc worried me when I looked at it but I quite like the idea as an example of creative thinking.

Sorry about the tongue twister at the start. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Tim.

[Lee]

Shouldn't add anything to the inertial mass of the valve train. The heavy looking shaft is fixed most of the time. The only things moving is the usual rocker, valve pushrod etc, so its just the additional weight of the rocker over the weight of a conventional rocker if any.

Looks like quite a neat idea, but who has one??? Is it like the 4 valve arao head, which everyone says looks neat, but no-one has ever seen one in daily use.

[roaldin]

Slightly off topic (not too far a digression I hope), checkout Coates .

I wouldn't mind trying such a setup in a 40.
They have done a small block Ford as a development exercise apparently. I have contacted them about another project and development cost is through the roof unfortunately.

Have a look in the photos section for a couple of nice pic's.

Tim.

[jimbo]

This is a terrific idea and I hope they can make it work. It is elegantly simple, which may be the hallmark of genius. They do not have engines for sale; I wish they did, I would seriously consider one for my GT40. Never mind originality- volumetric efficiency of that order could make a SB Ford eat a big block anything.

[Bill Hara]

Here is another similar rotating valve system from the UK called Roton. Do you think this is the way of the future??

link: http://www.roton-engines.com/

Regards
Bill.

[Bill Bayard]

That is cool! It takes in and exhausts air like a two stroke,via ports instead of valves. Fewer moving parts! If built with the right parts, I'll bet that you could spin one of these babies up to some serious RPMs! Check out the flow chart! That's a huge increase over current valvetrain technology. I'd love to see some horsepower numbers!

[John]

That looks awesome! Great idea.

Pros not discussed on their website... - because there is no standard valve, you have no piston to valve clearance issues. Thus, you can run a tighter quench area without having to worry about valve interference. Also yes, the RPM potential is huge!

Questions though... I am curious about how this design would effect the swirl effect in the combustion chamber which functions to keep the fuel/air mixed well? Seems to me like the flow would be so smooth that there might be the tendancy for there to be less swirl.

Also, they don't go into the sealing mechanism on the website, but it seems to me that the shafts would be held in place by something similar to camshaft bearings. However, it strikes me that it would be difficult to get any oil flow to the area right around the cut-out valve.

Also, where did you find flow numbers? I just found one chart of lift numbers, but no CFM numbers.

I'd be interested in hearing more about it!

John

[John]

Well, I looked into the Roton Engines thing a bit more online. Seems that they've been around for years and have never really gotten it working.

Problems seem to be related to sealing the shaft to keep compression in the cylinder during the compression stroke.

Oh well, seemed neat anyway.

John

[roaldin]

The Coates system uses ceramics. I believe it uses cylinder pressure to "push" a ceramic seal against the valveshaft.
If memory serves me correctly I had some information that included a Ford smallblock that had some numbers. I'll see if I can dig it up.
The use of ceramics also solved lubrication problems (apparently).
I had some cursory discussions with them about a project I was interested in doing, but they put development costs at about US$500000 for any new system. This put me off a tad. [img]/ubbthreads/images/graemlins/smile.gif[/img]
They are also VERY protective of their design. Their first email to me left me feeling that they were impressing upon me the understanding that they wouldn't be impressed if I was trying to develop a similar system.

Tim.