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VTC cam gear?
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MikeDanger  



Joined: 21 Nov 2002
Posts: 774
Location: Denver

PostPosted: Tue Apr 22, 2014 5:19 pm    Post subject: VTC cam gear? Reply with quote

why cant we adapt one of these for the 924?

http://youtu.be/YjIKUrre4FQ

[/code]
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fiat22turbo  



Joined: 18 Jan 2006
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Location: Portland, OR

PostPosted: Tue Apr 22, 2014 11:22 pm    Post subject: Reply with quote

Nothing new, there was one available for VW/Audi engines back in the day from a company called Franco:

http://www.924board.org/viewtopic.php?t=25531

http://www.924board.org/viewtopic.php?t=8846

http://www.924board.org/viewtopic.php?t=3294

http://www.924board.org/viewtopic.php?t=35547

http://www.924board.org/viewtopic.php?t=2578

The drawback is the stock ignition distributor is driven by the camshaft, so the Franco gear not only changed the cam timing, but the distributor timing which may not be ideal. You can have the stock distirbutor advance re-curved, but moving to a distributorless or a computer controlled distrbutor system would be ideal. As it would allow you to maintain control of the ignition timing separate of the cam timing.

I used the Franco gear I have on my low compression 79 engine with the Integral Stage 2 cam and 45mm ITB's (too big!) and it made a noticeable difference in the torque curve (as it now has one below 3500rpm) and it pulls all the way to 7000rpm. I think with a turbo this little motor would be a lot of fun with the other bolt-ons I've already added.

The thing about the Franco gear that everyone focuses on is the horsepower gains, which is wrong. That isn't the gain it provides, the gain is in the amount of area under the power curve. The larger the area, the faster the car will ultimately be.

Ultimately, the Franco gear was too expensive for the gains, but if you find one for under the cost of a new camshaft, then I'd say it is worth it. With modern short-run manufacturing methods, I could see being able to make these at a more reasonable price point.
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GeorgeV  



Joined: 14 Mar 2010
Posts: 306
Location: Brisbane, Australia

PostPosted: Sun Apr 27, 2014 9:08 pm    Post subject: Reply with quote

fiat22turbo wrote:

The thing about the Franco gear that everyone focuses on is the horsepower gains, which is wrong. That isn't the gain it provides, the gain is in the amount of area under the power curve. The larger the area, the faster the car will ultimately be.

Ultimately, the Franco gear was too expensive for the gains, but if you find one for under the cost of a new camshaft, then I'd say it is worth it. With modern short-run manufacturing methods, I could see being able to make these at a more reasonable price point.

How much do you think it would cost to replicate these gears? Maybe others would be interested in a group buy; I would given what you say it does to to the power curve.
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ideola  



Joined: 01 Oct 2004
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Location: Spring Lake MI

PostPosted: Tue Apr 29, 2014 10:42 pm    Post subject: Reply with quote

GeorgeV wrote:
How much do you think it would cost to replicate these gears? Maybe others would be interested in a group buy; I would given what you say it does to to the power curve.


I looked into this two years ago, and nearly lost my rare and valuable Franco piece in the process.

We were looking into having the unit produced with CNC manufacturing processes. For a short run of 10 units, the cost (to say nothing of room for margin to make it a viable, re-saleable product) would have been something like $400-$500 per unit. There's nothing particularly difficult about replicating the unit, but the setup and programming costs are prohibitive. In the end, the company I was trying to work with went dark on me and it took me a year (and an angry on-site visit) to finally get my sample piece back.

Also, just so you are aware, there is a fundamental weakness in the Franco design that ended up costing Steve Bassington a complete top-end rebuild. The original unit has the front face attach to the main sprocket piece using some inexpensive dowels and cheap bolts. On Steve's car, these sheared off and the timing went kablooey. I have been extremely reluctant to install the old unit I have for this reason. Making the front face as a single CNC-machined piece with bigger, stronger attachment hardware would minimize this weakness.
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MikeDanger  



Joined: 21 Nov 2002
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PostPosted: Wed Apr 30, 2014 6:35 am    Post subject: Reply with quote

Well, I WILL make one, and I can assure you it wont cost more than $300.

As i have looked high and low, theres always a lot of talk of people saying hey were "looking into" getting some made" and no one ever does. Just BS.

I Will do it, as I always do.

I design CNC parts, and have a large number of resources.
These can be made in production for under $200. they arent that complicated. In Fact I have already made few improvements.

I dont have a Franco gear In hand,( would be nice or atleast some detailed pics) but thats not that big of a deal. Some times its better that way, as long the designer gets the concept, some times starting with a blank sheet, can come out with a better products.


Im not really interested in making stuff for sale but if there are some others interested I could probably get them made in the +/- $200 range if I did 6 or more
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tyfighter123  



Joined: 19 Jan 2010
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PostPosted: Wed Apr 30, 2014 12:18 pm    Post subject: Reply with quote

I will be in for one if you can get them made.
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GeorgeV  



Joined: 14 Mar 2010
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Location: Brisbane, Australia

PostPosted: Wed Apr 30, 2014 12:24 pm    Post subject: Reply with quote

tyfighter123 wrote:
I will be in for one if you can get them made.

Me too.
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Eturbo924  



Joined: 09 Nov 2002
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PostPosted: Tue Sep 16, 2014 12:07 am    Post subject: Reply with quote

Get some protos made and dyno a car with one on it. Then with some concrete numbers behind it I am sure you would have many lining up to buy one.
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Shurick  



Joined: 15 May 2005
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PostPosted: Tue Sep 16, 2014 4:26 pm    Post subject: Reply with quote

I will buy one for sure.

By the way, Franco gears for turbo and N/A engines had different advance/retard. If I remember right the gear designed for turbo had advance only with no retard @ high revs.
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fiat22turbo  



Joined: 18 Jan 2006
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PostPosted: Tue Sep 16, 2014 11:35 pm    Post subject: Reply with quote

There are two settings on the gear. One is for -3/+7 or 0/+10 depending on which keyway you chose.

The "crossover" and rate of timing change point could also be tuned by changing the springs use inside the device, much like recurving a mechanical distributor.
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morghen  



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PostPosted: Tue Sep 16, 2014 11:56 pm    Post subject: Reply with quote

When will it be available for purchase?
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tyfighter123  



Joined: 19 Jan 2010
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PostPosted: Tue Oct 28, 2014 6:31 am    Post subject: Reply with quote

Hey Mike, did you ever get these made like you said you would? I am ready to buy one when you have them.

Tyler
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MikeDanger  



Joined: 21 Nov 2002
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PostPosted: Fri Oct 31, 2014 1:14 pm    Post subject: Reply with quote

Not yet, My mom had a medical emergency and the past 4-5 months I really couldnt spend any time on other projects. Im just getting back in gear. but now im much shorter on cash so, that will probably have some effect. Will keep you guys updated.
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Last edited by MikeDanger on Tue Nov 04, 2014 12:49 pm; edited 1 time in total
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MikeDanger  



Joined: 21 Nov 2002
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PostPosted: Tue Nov 04, 2014 12:45 pm    Post subject: Reply with quote

Ok im working on finishing the design.
How many are seriously interested? Ive contacted a couple MFGs Need some sort of firm figure to get pricing.

Ill post up a couple base drawings in a bit.
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MikeDanger  



Joined: 21 Nov 2002
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PostPosted: Tue Nov 04, 2014 12:45 pm    Post subject: Reply with quote

Also can anyone tell me if the "fly weights" are steel or alu in the Franco gear?
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