Has anyone considered trying to contact manufacturers (Harland Sharp, Comp Cams, SLP/Yella Terra, etc...) about creating high-ratio full roller rockers for the 2.4L VVT motor? I think that with the VVT, significant gains can be had by increasing the lift.

...just a thought to ponder.

 

DOHC = no rocker arms

 

OK, then how does one increase the lift in our motors and retain driveability? (sorry used to "old-fashioned" push-rod motors)

Thanks for straightening me out

 

the only way i know of is bigger cams.

the cam pushes the valves directly

 

i wonder if the cams for the 2.0/2.2 would work for the 2.4? vvt is there but i dont know if that matters at all with the cam being used

 

Actually, not true in an Ecotec. There are in fact roller rockers in the head. The arrangement is a little different then you might be used to however, and changing them won't change lift. Higher lift cams are the only way to do that, and you can't do that with stock springs. You have to change to higher rate springs first, other wise you will get coil bind.

Anyway, there are hydraulic lifters in the Ecotec head. They lift against one end of the rocker, which levers against the cam lobe next, and then the valve stem. They free float in position. Nothing holds them in except for those three parts.

 

Bowden!?1

 

Yes Chris?

I picked up a SS 2.4L for a daily driver....the Prix is in storage right now.

Glad to see you are getting involved with the Cobalt market, old friend.

 

w00t! Those are fun little cars!!! It's not an auto is it? hehe

 

Yep, it's an auto.

I can drive a stick, no problem. In fact, I test drove one...lots of fun.

But, it would be a pain in the ass for stop and go highway driving.

I can always slap a shift kit in it in the future if I desire.

How's the Goat running? Been to the track lately with it?

We need to have another binge drinking session at Dave's this spring and get caught up on old times

 

Well technically it IS possible to increase your lift, using different roller followers on the ECOTEC.
The stock followers have a rocker ratio of 1.688:1
Some of the aftermarket pieces (like the Jessels for instance) have a ratio of 1.700:1

So if you had a pure lobe lift of 0.250 with stock RFs your net lift at the valve would be 0.422"
But with the Jessels .0250" of lobe lift results in 0.425"
This is a small but significant increase in lift and very important in terms of valve>piston clearance
Regards
WopOnTour