R&M Racing BMW M20 Adjustable Camshaft Gear

[nando]

well without bringing this thread too far off topic, it's a 2.8 M20 with a Schrick 284/272

and now with an RM Racing adjustable cam gear. ;)

[briansjacobs]

im 2.8 288/288, with that 284/272 and the RM ACG (see back on topic) you should have great low end, I imagine power will fall off at 6000 as mine does. I will expect as mine is not on the street at all my compression is a bit higher than yours at 10.5:1, the car will go to 7000 rpm (more like 6800) but the power is gone by 6300 and you must shift so you will likely never see past 6000 other than 5th.

With this low revving motor is was almost a waste to install the billet rockers, but I broke so many in the past I was scared not to.

[nando]

My power actually peaks at nearly 6500 - I originally had the limit at 7200, but after the cam gear installation it felt like it was still pulling, so I bumped it up to 7500. My exhaust may have something to do with the shape of my powerband, and I've seen a lot of variation with the same cams. a 288 should be able to make power to 7000-7500 easily, but you have to design the whole engine that way. My CR isn't much lower either, 10:1.

No billet rockers here. Just inspected Febi's and new stock springs. The head has about 35k on it now. if I were to do it again I'd go with HD springs and IE HD rockers for extra safety. having the deep valve pockets of the MM pistons probably helps - even if I completely float a valve, or break a timing belt, I won't damage the valves or rockers.

[briansjacobs]

with my compression the engine is starving for air, I need to bore the throttle body if I want any more power. My thought process has been with the car being race only I am happy to keep the revs down so long as I make good power down low, that is where the ACG has helped, but mostly I tune for AFR not peak power. I quit counting after 6 hours on the dyno. AFR is perfect from 2500 to 6500. With 3000 rpm of power band, it is damn good on the track. At Homestead it is able to do times in 1:35's maybe a little better next time out. That is mid pack at a current Grand AM ST race!

[nando]

I want to try advancing the gear and see what happens to bottom end torque. Of course the widest powerband is most desireable, but being stuck with 4.10s (or 3.91s at best), it's advantageous to me to have peak power further up, so I may just leave it. With the same gearing and a stock motor, I was on the limiter a LOT, which can't be good for anything. Being able to hold out a gear is a good thing. :)

[briansjacobs]

as far as the rocker arms go I would stick with stock, Febi or VAC. I have used aftermarket rockers and they did not work. Literally lasted 3 hours on the track! I would prefer not to name names, but I will say they were great about returning my money when I showed them they did not work, I believe we tried two sets before they just refunded me. So far the VAC ones are working great with about 5 hours on them.

My understanding the stock ones are good to 7000

[Luis325]

do i have to change anything when installing it?
Does it come setup in the stock placement?

I ask because im installing it but dont want to play with it yet untill I tune the car with my war chip in the dyno first.

[briansjacobs]

just put it on as you would your factory gear, when you want to adjust on the dyno just loosen the 4 keys and turn then tighten, another pull, repeat till perfect.

[r-mracing]

do i have to change anything when installing it?
Does it come setup in the stock placement?

I ask because im installing it but dont want to play with it yet untill I tune the car with my war chip in the dyno first.

The only thing, stock gear has a "plastic" piece that goes between the stock gear and the bolt. Ditch this plastic part, as you will find out that it doesn't fit the new gear. Other then that, its basically same as a stock gear install.

[Luis325]

Cool
Thanks
Just got mine yesterday, should be installed on saturday.

[r-mracing]

Cool
Thanks
Just got mine yesterday, should be installed on saturday.

So how did it go luis?

[Luis325]

Its still sitting in the box... LOL
Finished installing my swaybars and brakes and didnt have time to install it...
Should be on this weekend.
Ill let you know!

[Luis325]

Installed it finally!
Really easy to install!
Car runs great!
I have to start playing with it now.
I put it 2degrees advanced and the car really wakes up after 3,500 to 7,000.

[r-mracing]

Glad to hear you are happy with it luis! Keep us updated! :)

[nando]

Installed it finally!
Really easy to install!
Car runs great!
I have to start playing with it now.
I put it 2degrees advanced and the car really wakes up after 3,500 to 7,000.

did you find 0 degrees first? because advancing the cam will bring your powerband into the lower RPMs, retarding it would bring it into the higher RPM. I just set mine to 0 to start since I haven't degreed the cam yet, and I think it's a tad retarded as my 7k+ range really woke up.