Adjustable CAM Gears, Who uses them, do and donts

[j_magers]

I would like to start a topic on Adjustable CAM gears. Did a search and there is nothing on this topic, however it is one of the most important "tuning" techniques out there.

Lobe Separation Angle, very important for dual CAM users.

Advancing intake and retarding exhaust etc...impact your car and the dyno curve more than anything out there. When you can move the whole curve 200-800 rpms to the left on the chart, thats pretty significant.

Got a big turbo that takes along time to spool up and you can move your power to the lower end of the power curve will help until the turbo spools and gives you the high end power.

All of you advanced tuners out there, lets here from you.

 

[j_magers]

Good article in DSPORT mag december issue.

 

[tubbie]

Good article in DSPORT mag december issue.

Want to scan it and post it up?

 

[GrimJack]

I've seen tons of people with these... and they are all, without exception, set to zero angle.

 

[rakkasan]

I've seen tons of people with these... and they are all, without exception, set to zero angle.

Exactly, 98% that have them aren't using them for what they were designed for. Nothing but show.

 

[IJ.]

whoo hoo I'm a 2% er

 

[j_magers]

IJ, have you tried different combinations?

 

[IJ.]

Jay: Not yet I'll dial them in to the timing tag for the break in period then once that's done I'll play on the dyno and see what happens!

 

[GrimJack]

whoo hoo I'm a 2% er

No you're not! It only counts if your engine runs!

 

[IJ.]

ROFLMAO ya almost made muffin come out my nose!!

 

[rakkasan]

No you're not! It only counts if your engine runs!

LOL, but they do look pretty:biglaugh:

 

[IJ.]

Damn I've been busted I only bought em cos they're blue and match my interior !

 

[j_magers]

In the article they advanced the intake 4 degrees and got peak torque 200 rpms earlier, they tried advancing 7 degrees and heard some rod knock so they backed it off. I was hoping someone had some numbers for the 7MGTE's.

 

[IJ.]

Jay: The biggest bonus for me will be being able to open the lobe centres without changing cams like in my old V8 days!

My cams aren't huge so being able to shift the band around some will be nice.

 

[j_magers]

"opening the lobe centers", you just explained lobe separation angle to anyone that was guessing. The angle between the lobe centers makes LSA, which can you can use to reduce valve overlap, open or close valves earlier etc. in return you get more power and torque.

 

[IJ.]

As well as drops EGT's a bit on overrun!

Old School used to be 106 degree centres then add a turbo and you open em up to 112>114 ish to stop pumping raw fuel into the exhaust manifold on overrun! (Brings cylinder pressures up quite a bit as well per the knock your article reported)

Lunch is over back to the shed cya later guys!

 

[j_magers]

Good to see a discussion on here that is going to help tune our cars, instead of the damn "which Spark Plugs to buy" threads. I fricking hate them albiet Iam new to the 7M myself, I have worked some engines in my day and dont need help buying spark plugs.

 

[mkIIIman089]

^ very true...

On the cam gear discussion. Would it be wise, since my head has been milled and a stock gasket replaced, to get a set of adjustable gears and set the cams back to factory specs according on lining up the TDC marks? Would it effect my reliability or performance in any way?

 

[j_magers]

Before you do anything with the cam or gears, ensure your valve clearance is good and check the clearance on your valve buckets and shims. Basically, get it to a baseline and then start playing with it. Also, its not going to change a huge difference but when you start getting up there in power/hp it will start to make a difference when you see the power early/later etc.

 

[j_magers]

BTW, Iam no expert on tuning cam gears but know enough to be dangerous. Hope there are some experts (or self-proclaimed experts) on here that have some experience with the 7M and tuning the cams.