I just got the new hot rod mag and sort of read an article about rhoads variable duration lifters, now availible for hydralic roller cams. They tested them in an ls1 and from what i can remeber(cant find mag) they put in a huge cam and lost lots of low end torque, untill the put in the rhoads lifters. The new lifters made a pretty big jump in torque but lost like 4 hp on the peak, which to me is a good trade off.

Anybody have any experience with these. I was maybe thinking of getting them for the new lt1 motor im building.

Thanks
James

 

They are noisy as hell and from what I heard they suck, very unpredictable and rarely work as stated. That's just hearsay though.

 

I have actually used them a couple times in some pure-stock racers which have a manifold vacuum requirement, went from 16in/mg to 18in/mg and passed tech. They are very picky about oil pressure and valve spring pressure in order to work correctly.

 

I used them in a 355 sbc in my old 84 Camaro with a Comp Cams 280 Magnum cam, stock 700R4 converter, and 2.73 rear gear. They allowed sufficient vaccum for the brakes and I only experienced converter "surge" on the coldest of winter days. 100,000 miles of serious abuse and they were whipped, but I had good luck with them in that engine.