Cam Gears Jackhammer/GZP style

[thor'svr4]

Ok so ive been looking to purchase a set of the Cam Gears for a while now but had a few concerns. Obviously we've all seen the dyno results so its known that these do work and do increase power through out the power band. However, it was brought up that on a 91-92 car with a CAS the cam gears would advance ignition timing slightly (~2 degrees) which could be the cause for the increase in performance. my problem is that i'm already battling knock due to running a higher compression ratio. Im about to go back to Pampena motorsports for another dyno tune and was debating if i should pick up a set of cam gears. One thing that really stuck with me was

ray believes the cam gears hurt it, i'm really curious to see what other folks' torque curves look like in particular.

Now i know Ray knows his shit, so as far as i'm concerned whenever Ray gives anyone advice they should listen to him. But two of the highest HP 13T pump gas cars are running the cam gears. Chansigril made 458whp and someone else made 460ish but i cant remember who it was.

So far my major mods are:

forged bottom end with 8.5:1 pistons and decked heads (so maybe 8.6-8.8:1 compression ratio)
WRX 13T's
550's with a hotwired walbro 250lph
FMIC
MAFT & Apexi Neo for fine tuning
AEM W/M injection (new haven't been dynoed with the w/m yet)

my first time on the dyno back in 2010 was with 8:1 comp ratio and the car made 418whp at 18psi. the car never had any knock and the only reason ray didnt keep increasing the boost is because the stock bottom end had ~160k on it and the oil pressure was a little lower than expected.

after rebuilding the bottom end and bumping the compression a little i went back for another dyno tune and the car could only get 408whp at 16psi. however it struggled with avoiding knock and ended up with a fairly rich afr.

this time i will be going back with the same mods except i've added a 3"DP, maximal high flow cat, some W/M inj to help out with the knock, and possibly some cam gears.

So far these are the only two threads ive seen on the cam gears
http://www.3sgto.org/f54/gzp-perform...ears-8303.html

http://www.3sgto.org/f2/13t-dyno-she...read-8424.html

Does anyone know for sure how the cam gears make more power? is it through the physical cam timing shift or by advancing timing? Also do people re-time there cars after they install the cam gears?

[stealthee]

I thought it was 93+ cars that the worry about timing advance was the issue? You can adjust the ignition timing on a 91-92 with the CAS.

[futurevr4man]

what do you mean by "re-time" the car? you have to take the timing stuff all apart to put on the cam gears anyhow

[thor'svr4]

By re-time i mean to check the base ignition timing with a timing light according to the procedure on Stealth316. From what i understand if the car was running 5 degrees BTDC base ignition timing before installing these cam gears, it will be running 7 degrees BTDC base ignition timing after the proper install of the cam gears. Someone could easily put a timing light on there car and adjust the CAS until they were back to 5 degrees BTDC, but so far no-one who has had dyno results has done this. so as far as i know, everyone whose posted dyno results of the cam gears has simply shown that advancing the timing made more power...

Thinking out loud here, with the cam gears dropped in, are you re-syncing base timing? I wonder if the "gains across the board" are due to the base timing shift? Thought would be that the cas sensor is spun as the cams are spun to align with the new mark, this changing base timing.

I wonder what the effect would be on a 2g car?

When we had done the cam gears we had the ecu crap out which was throwing a CEL for a cas. So, it was replaced only to find that the ecu was bad. I'll be getting our other stealth together within the next couple of weeks to try to get more back to back numbers. These initial numbers were done on a car we have for sale, so I really don't want to go tinkering in that thing anymore... but you do make a valid point.

Installing these gears with no other change will advance the ign. timing 2 deg. on a 1st gen, and make no change at all on a 2nd gen.

Edit: Make that 91-92, and 93+... Just so I don't get dogpiled by generational correctness.

[futurevr4man]

ah, i see. i will keep an eye on this thread as well, because i am curious what kind of information will come out of the woodwork. i have no experience with the gears

[CoopKill]

I thought that at least with the GZP set he rotates the timing ring thing as well for 1st gens. I could be wrong, but I thought I read that somewhere in one of his threads on them.

[GTOJOE]

Also remembered reading about this issue and wondered if anything ever came of it. Need back to back dyno tests on on a 2nd gen car. GZP's test was only on a 91.

[BaadVR4]

The cam gear change moves the camshafts in relation to the gears and, thus, in relation to the crankshaft. In the First gen cars, that means the CAS is moved; in second gen cars, the cam angle sensor blade (which is mounted on the rear exhaust cam) is moved.

I'm not knowledgeable enough to know how moving the cam angle sensor blade and keeping the crank angle sensor the same will affect engine timing for the second gen. Someone else surely knows?

[CoopKill]

Yes that is it, I looked at my 2nd gen set, and he rotates the blades on them. So not sure what can be done on first gen, carry on...

[Roybatty]

http://www.miata.net/garage/KnowYourCar/S10_Timing.html
Not specific to 3s, but good info read.
Sent from garage