3rd gen Engine/Drivetrain Engine/Drivetrain Modification Discussions for 1999-2003 Models Only (BJ chassis)

adjustable cam gears

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Old February-28th-2002, 12:44 PM
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adjustable cam gears

has any one heard about adjustable cam gears yet? i have started this thread at the miata.net forum:

cam gears

my intentions there are to understand the function of the cam sensor so that there is a way around it when i find some gears that will fit. i also put an inquiry in to UnorthodoxRacing to find out thier interest or desire to creat these.
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Old February-28th-2002, 04:56 PM
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I've looked, and there doesn't seem to be anybody making them yet. It's been a pretty dismal aftermarket so far for the gen 3.

I haven't looked into the head yet, but I'd like to know what the pullys look like. Any body know if the configuration of the pullys will support having the hubs cut out and adjusteres put in. It can be an easy job or an impossible one depending on the hub config.

My thought is that adjustable pullys aren't going to do much with factory cams though.
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Old March-1st-2002, 07:19 AM
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i think you would be supprised what you can do with factory cams and adjustable gears, especially on a DOHC engine. my guess would be that there could be 10-15 hp to be had from just adjusting the cams. with the amount of torque our engines produce down low, i would suspect that by increasing the overlap of the cams, the peak power would jump pretty good.

also, for those that are interested, i recieved a note back from UR on producing adjustable gears for the 2.0 liter engine. they said they want 50 pre-orders for thier Ultra Tr gears and 100 for thier Ultra Ts gears. so, let's get buggin' on UR!

(they said thier crank pully for the 2.0 liter would be ready for shipping in 5 weeks, too)
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Old March-1st-2002, 07:37 AM
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Originally posted by njaremka
i think you would be supprised what you can do with factory cams and adjustable gears, especially on a DOHC engine. my guess would be that there could be 10-15 hp to be had from just adjusting the cams. with the amount of torque our engines produce down low, i would suspect that by increasing the overlap of the cams, the peak power would jump pretty good.
Agreed! It is at least worth a shot.


also, for those that are interested, i recieved a note back from UR on producing adjustable gears for the 2.0 liter engine. they said they want 50 pre-orders for thier Ultra Tr gears and 100 for thier Ultra Ts gears. so, let's get buggin' on UR!

(they said thier crank pully for the 2.0 liter would be ready for shipping in 5 weeks, too)
Did they give any prices for those gears, and the pulley? Post that info on the MP3 board, they are more likely to spend the money on the performance parts.

Also, are you aware of any other pulleys that they are planning on making? I'm not a big fan of changing the crank pulley, but some of the other ones I'll change.
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Old March-1st-2002, 07:47 AM
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it was mentioned that the pricing on the gears would be in line with others from that series.
http://www.unorthodoxracing.com/

i went over to post what i had at the mp3 board, but they are in the process of upgrading it and it isn't available at the moment.

there was no mention of accessory pulleys, if that is what you meant. i agree with you on changing out the crank pully, doesn't really sound like a great idea. i would bemore inclined to have an aluminum flywheel installed.
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Old March-1st-2002, 01:28 PM
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I don't know what kind of peak HP or torque gains you would see from adjustable cam gears, but they would certainly let you tune the engines power curve to your application, or liking. In combination with the FS-ZE intake cam for example, you could get the ~10 to 12 HP peak gain from the cam, and use the adjustable cam gears to counter the cams movement of the power curve about 400 to 500 RPM higher in the rev range. Craig purchased a stock gear to send to Bryan Pendelton from the Probetalk forum in the hopes of Bryan getting them produced. Last I heard, Bryan was having trouble finding a source to produce them at a reasonable cost. The 3rd gen Proteges use both a crankshaft position sensor and camshaft position sensor. I believe the crankshaft position sensor is optical and the camshaft sensor is magnetic?
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Old March-1st-2002, 01:40 PM
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if you follow the link i posted in the first post to this thread, there are some links to pictures of cam gears made for a 99+ miata, which happens to also use the cam gear sensor.

this picture:

is of a modification some one did to an earlier model cam gear to accomodate the cam position sensor. (what you don't see is the spacer made for the sensor so it doesn't hit the adjusting screws. follow the link above to see it) this could be done to gears for our car, if there were gears available that would fit our cams. basically, that person modified a machine screw and had it welded in place on a gear made for an earlier miata. i also heard that AEM did a short run of 99+ miata cam gears, but because the interest wasn't high enough, they discontinued them.

does any one know if there are any other model cam gears that will fit our cams that are already in production? does anyone know if the early miata gears will fit our cams?
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Old March-1st-2002, 10:54 PM
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Last I heard from Bryan was that the cam gear project for both Protege and Probe were on halt for now as he could not find a machine shop to do it at a resonable rate. He even got one quote for 1000+ bucks for an initial run of one set for testing. I am going to check with my fathers machine shop here and see if they can do them any cheaper if so then maybe i can get them to cut a deal with Bryan. But the drawings are done and teh specs have been finished so its just a matter of finding a shop to do it at a good rate.
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Old March-2nd-2002, 08:36 AM
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Originally posted by PseudoRealityX


Umm, no. The FS is going to MAYBE pick up 5 hp from just adjusting the oem cams. They simply arent hot enough to suck in enough air at high rpm. Thats why the engine has "midrange", because of its total lack of top end. Adjusting cam gears doesnt usually net any power, it just shifts where the powerband around, and i dont think youre going to see a huge difference.
i was under the impression that dialing in more overlap is good for creating more high end power. am i wrong?
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Old April-5th-2002, 09:19 AM
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I just got some good leads from ZEX on producing these gears. I will hopefully have a quote in the next couple days. . .
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Old April-5th-2002, 10:25 AM
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bryan,

keep us updated!
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Old April-5th-2002, 02:07 PM
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Bryan, thanks for the update. I'm also trying to locate a number for Sunbelt Performance Engines in the Atlanta area. I read that they produced adjustable cam gears for the World Challenge Touring series Protege engines. They'd at least be worthwhile to check out. If you get a chance, would you post an image here of the gear you designed so these guys can see it.
BTW, welcome to the Forum, glad to see you made it over to check us out.
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Old April-5th-2002, 02:48 PM
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Old April-5th-2002, 02:52 PM
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ok, i have to sasy that those look nice, but on the exhaust cam gear there are "nubs" that trigger a sensor. is there anything in your design that would take that into account?
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Old April-5th-2002, 03:52 PM
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I have discussed this with Craig already. I originally designed this for the 1st generation FS found in the 93-97 Probe/MX-6/626. It would make sense to design one gear for both applications, but after I investigated the cam sensor, I decided that I do not want to deal with that at this time. Since the cam position sensor is probably heavily used by the ECU for timing purposes, there is potential for BIG liability issues, that as a small business owner, I do not care to under take at this time. My first priority is to get these basic gears up and operational, and out on the market, and hopefully 6-12 monthes of drive time on them. Before I dive into the more complicated and more expensive gears with the cam sensor "nubs".
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