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Variable cam timing

vtec uses hydraulicly locked lobes on the cam itself.

As for the cam gear being a wear item and causing piston-valve contact on failure, that would be possibe but easily designed out by only allowing a certain amount of advance and retard. that way if it failed, the car would just run like shit at either the low end or the high end of things.
 
Kudos to c for digging up that great information. It seems the gears
only get made if someone wants 25. I would probably even get a
couple of these if they work as well as advertised. Do we have 25
people that would buy into this?

I see what you mean about what could happen if there was gear
failure. That would be an expensive problem. But, it does sound
like the design is self limiting. Have to see what they are willing
to do at Franco Industries.

Dave 82 242ti
 
If wear issues have been solved, I'd certainly be interested (price dependant of course).

Keep in mind folks, where a new cam is in the same price range, (hopefully we can get it a bit cheaper than $300) and just changes the shape of your torque curve, this little cam gear doesn't change the shape so much as fatten it up across the band. Bang for buck, if this thing works as advertised (and theoretically, it should) it ought to be one of the best mods out there. Apart from increasing boost, there's not much you can do to increase torque across the rpm range like that. I'll take +8ft-lbs from 2500-6000 over +15HP@5000 anyday....

Anyone have a guess as to how it may or may not effect economy?
 
[quote:c1e1c86803]Anyone have a guess as to how it may or may not effect economy?[/quote:c1e1c86803]

I've read that the variable timing increases fuel economy (honda), the only reason I can think is that the variable timing would really only be variable while increasing and decreasing RPM but at constant RPM the gear would be at the ideal timing (if set up correctly). All this is conjecture though. I'll see what I can dig up for real data to back up the increased economy claim.
 
Ok I am stupid the increased fuel economy I was talking about relates to variable valve timing. My mistake. I have not been able to find any information about the fuel economy of the variable cam timing. The two are different.

Here is some info on variable valve timing:
http://www.firewall.ca/VTEC.html

Here is some info on variable cam timing:
You'll need to directly save this one to view it, it is in PDF
http://www-control.eng.cam.ac.uk/aug20/vct_act_control.pdf
 
I dreamed up one of these long ago but thought that there was to much torque required to turn the cam and that would throw of the advance retard mechanism. I am interested in buying one of these.
The IPD adjustable cam timing gear is 6 degrees of retard or advance at the cam, so 12 degrees at the crank,I am fairly sure. So if this on for vw's is rated at 10 degrees I would assume that is at the crank. IPD says that thiers adds 5 foot pounds at one extreme and 7 HP at the other exterme, but with thiers you dont get both. This looks supreme.

-Jack
 
Jack, I kind of agree. Thats my only thing, it would have to be stiff springs to over come just the torque exerted by the belt. That is, unless its dialed in so when cranking over its up against its, for lack of a better word, "Stop" at the advanced end.

Doug
 
doug242ti said:
Jack, I kind of agree. Thats my only thing, it would have to be stiff springs to over come just the torque exerted by the belt.

Doug
Click to expand...

I thought about it to this point and concluded that you would need STIFF springs and heavy centrifical weights and came to the conclusion that it was more than I wanted to attempt.
On my last post I was not logged in, not that I spend much time here, I used to spend a bit of time on the turbobricks site when I was getting my 245 GLTi dialed in. 10 psi "normally" and 15 psi when I push the cigarette lighter in. No it doesn't smoke cigaretts anymore.... it smokes tires.
I would definatley want to buy one of these if they become reality.

-Jack
 
I would also be interested in one of these if we could get
enough people together, and if the reliability issue is raised.
a 10k mile mod isn't worth the money. Did anyone figure out
what it would cost for 25 of them?

Simon Miller
 
Wait a minute here, how would hard cornering effect the weights? Wouldn't that change the timing then? That would suck! And how is it tuneable, I mean, will it actually give more powa? Is the spring rate adjustable?
 
weezilusa said:
Wait a minute here, how would hard cornering effect the weights? Wouldn't that change the timing then? That would suck! And how is it tuneable, I mean, will it actually give more powa? Is the spring rate adjustable?
Click to expand...

The timing shouldn't be affected by the relatively small gforces excerted through cornering, consider they weights are probably feeling many many g's, while the corner might come close to 1 on a really really good car

It might not give more power, but it will make more useable power, so the powerband will be reached faster and hold flat longer

Since we'd probably have to make one from scratch for a volvo, yea it'd be feasible to make the spring rate adjustable
 
What I've always found infuriatingly retarded about those damn f'ing rice magazines and rice ads for rice companies is the claims that cam gears "ADD 8HP!". They don't bother mentioning the "LOSE 10LB FT!" part. Whats nice about this is since it does both, there really is no tradeoff. And yes, like mopareater just said, cornering won't do jack. The idea of cornering affecting the timing while under that massive amount of tension is ridiculous.
 
Someone who is talented enough in the fabrication area to create a few variable timing gears is possibly Gil. Anyone have a connection with him? If we break it down exaclty I don't think he would have much trouble putting together at least the shell of the gear mechanism that could possibly be used w/ our gears modified.
 
I have cadkey 99 and have a decent amount of experience with it. Probably enough to design one of these.
I drafted a design just to get a basic idea of what one of these would look like and could make a scaled draft if wanted. The cam gear I drafted uses two centrifugal weights that move studs attached to the plate attached to the camshaft. I am not a professional engineer but am excited about this project. Does anyone know if it is possible to post a CAD drawing on this forum. It would be nice for people to have a picture to see for reference.
 
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