Why dont we have degreeable cam gears for the exhaust cams?

Before ppl get smart and try to burn me with the "CUZ WE HAVE VVTi" thing, that only degrees the intake cam on our cars, the exhaust cam is driven straight from the timing chain by an unadjustable gear.

Now ive seen FI engines benefit fairly well useable torque-wise from about 6* retard of the exhaust cam, and usually about 10* gives you the best spool, and for those with bigger duration cams, you can greatly smooth idle by advancing the exhaust cam a couple of degrees.

Plus theyre not an ultra difficult part to make, nor would they be that expensive.

So yeah, why dont we have them?

 

good question any answers

 

no answers...

because toyota didn't start adding it until the new dual-vvti engines.
(new.. in being a smaller 4 cylinder engine)
why? because there's more than just mechanics and hardware.

and the 2AZ-FE design has already proven itself pretty damn reliable..

you want dual-vvti? buy a xD.

 

^^ Very good point(s) there Squal....

Personally I'd rather have a power plant that has been tested and has a pretty reliable track record then being the guinea pig with my hard earned dollars at stake. Unless I had more extra dollars to spare... lol

- to the thread starter... not shooting down your idea... but I've gotta side with Squal on this one.

 

Dual VVT-i has only been out since the GR series motor was introduced and that was back in 2002 and only available on the V6. It didn't hit the 4 cyl engine until a new replacement engine for the ZZ series was develop which was 3 years ago.

The AZ series dates back to early 2000 and VVT-i was introduces as early as the early 90s.

Beside, Toyota already discontinue production of the AZ series motor and moved on to the AR series motor that does have Dual VVT-i. It's only a matter of time that the transition from the AZ to AR will be finished.

 

SOMEONE TOTALLY CHANGED THE TITLE OF THIS THREAD! I didnt mean dual vvti, i understand that it was a development and generation of engine issue. I just mean why havent any aftermarket manufacturers made a degreeable sprocket for those with aftermarket cams? like so...


Thanks Squalllheart for the clarifying edit but my question was a little different. And god no, no xD for me. Just a properly degreed exhaust cam for some more torque would be nice =)

 

it may be from having the chain instead of exposed belt.

 

i said that.. because i dunno how the car's ecu will like anything aftermarket for the exhaust cams