Composite Flat Tappets

[SFfiredog]

Ant,
I have used a few sets of Jesel "dog bone" lifters. One nice thing about NASCAR is the abundance of hardly used parts available on the internet. I bought a $1800.00 set of lifters with just dyno time on them for $380.00! The lifters are like jewels. So far they are working well but they are all in race engines so I can't positively report on their "street credentials" but they sure seem to be one of the best on the market.
I would speculate that the composite lifters would be comparable in horsepower to the rollers; maybe 15 to 20 hp less. The main reason being the fact that a solid or roller cam that is ground for a street car using these lifters would be pretty similar. The specs and power the cam could make is limited by the desire for reliability and drivablility in a street engine.
One thing about roller cams that can be a detriment on the street is valve springs.
Roller cam springs are getting better every day but they still need to be replaced at regular intervals especially on the street. THe springs need to stay cool in order to live. NASCAR and road race engines use misting spray bars in the valve covers to cool the springs.
This isn't a problem on these engines because they all run dry-sump oiling systems to evacuate the hot oil from the valve covers.
I have to go but I'll post some more info tomorrow.
--Mike