I've got this debate with my nephew who is attending an automotive tech. school. He said his professor stated that auto manufactures started using roller cams for emission purposes and not necessarily for performance. I said that they started using them because of the benefit of a steeper cam lobe opens the valve quicker and still retain a good lobe sep. for a smooth idle. Is he right? Do I owe him a beer? Man I hate it when these young guys put me in my place.

 

Roller cams first appeared in the Ford motors around the mid-late '80s, at that time these motors all employed EGR and air injection systems regardless what type cam they got. The roller cams certainly reduces friction in the rotating assembly so there is an efficiency gain, but the early roller cams were close copies of the flat tappet cams and produced nearly identical power, so it doesn't appear that they tried to get more performance from the motors with the change to roller cams. It aslo doesn't appear that these cams significanly improved emissions, it wasn't until OBD-2 control systems were introduced in the mid '90s that they were able to do away with the smog equipment and still achieve emissions targets.

 

Your nephew owes YOU a beer, bro. If he doesn't believe "The Professor", oh well....ups and downs of high-performance valvetrains, The | National Dragster | Find Articles at BNET.com. And have him tell HIS "professor" to go back to teaching home-ec.


Pete

 

i would tend to think that the manufacturers did it more for fuel economy purposes than anything else, with a side benefit of being a performance gain. the roller cam produces less friction, which leads to less hp loss to turn the cam, which leads to better fuel economy which also leads to better performance.
people still wanted their high performance engines in their small cars but also still wanted 25+mpg from the same engine. fuel injection is one answer, overdrive transmissions is another way and reducing internal friction losses is another. another reason manufacturers are going to low tension rings and smaller and more compact engines and overhead cams. most engines waste a lot of energy through friciton losses. the more you can reduce friction losses, the more efficient the motor is. that is one reason that a lot of the new small engines are producing comparable hp figures to the old V8's with twice the fuel efficincy of the old motors.
with the gov't mandating min mileage figures and one of your most popular selling cars having a thirsty V8 under the hood, Ford really had no choice but to make the engine as efficient as it could with what it had to work with.

my 2 cents on roller cams.

rgds
mike

 

Roller cams don't have the same break-in procedure as flat tappet cams either. Maybe it saved some money on warranty work or break-in time on the dynos.

 

Go buy your nephew a beer. I have to agree with Paul on this one and especially since it was phrased "not necessarilly for performance". The performance aspect was a side effect, IMO.

 

I think the only reason chevy went with a roller cam was to get away from rounded lobe problem.

 

Unless someone from one of the engine manufactures says something on this thread I think you both owe eachother a beer. By reducing friction and break-in issues you gain performance and better mpg which equal better emissions. My guess is rollers have long been on the drawing boards but it took more modern tooling to be able to mass produce a cost effective and reliable roller lifter/cam.

 

I go with fuel economy. I have had both roller and non-roller motors in foxstangs. On the dyno there may have been 10HP difference between them. I think if they did it for performance it would have been done with a hotter cam than the one they used.

 

The Japanese developed steel hardening techniques over 1300 years ago, so theres no excuse for the crap GM produced then and continues to produce today.