HP difference between flat tappet and roller lifters

QuantumMotorsports · 07-07-2003, 01:11 PM

You guys think there would be any horse power difference between flat tappet and roller lifters? I know you'd have to change cams, but assuming you had a cam that was the same lift and duration? I'm running a set of flat tappet hydraulic lifters in my 306 because it's a '76 block (non roller) Just wondering what you guys think. Also, what's the best set of roller rocker arms that mount on the stock heads without modification to the head?

Stang_ROTY · 07-07-2003, 01:52 PM

I don't know about just lifters but I was told by several tech's at Comp Cams that I could of expected a 5-10% increase in HP by going full roller in my '69 block. Good luck!

UglyFast88 · 07-07-2003, 02:00 PM

Speaking of, I was just looking at the Rhoads variable lifters.

Anyone run these or know anyone who does?

See tech here

Curious...

tarmon8r · 07-07-2003, 11:05 PM

Roller lifters allow a more aggressive profiles, faster ramp speeds so the valve gets to maximum lift sooner, within the same specs as a flat tappet cam. Rhodes lifter "bleed off" some of your cam at low rpms, for example: if you had a real aggressive cam, with lots of overlap and poor bottom end performance, rhoades lifters will make the motor think its a smaller cam at lower rpms and give back some torque in the process, by not pumping up until a certain rpm and "digesting" that overlap, thus reducing bleed off of having the exhaust and intake valves open at the same time as long and there by giving you more cylinder pressure for better throttle response and bottom end torque . and then give you back your more aggresive profiles on the top end when they do pump up. they are usually a little noisy. But your only talking about a minimal amount of impact rhoades lifters can have on a cam.

UglyFast88 · 07-08-2003, 08:26 AM

Interesting info.

Thanks for the reply!

07-07-2003, 01:11 PM	#1
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	HP difference between flat tappet and roller lifters You guys think there would be any horse power difference between flat tappet and roller lifters? I know you'd have to change cams, but assuming you had a cam that was the same lift and duration? I'm running a set of flat tappet hydraulic lifters in my 306 because it's a '76 block (non roller) Just wondering what you guys think. Also, what's the best set of roller rocker arms that mount on the stock heads without modification to the head? __________________ Michael Black QuantumMotorsports Norman, OK 1984 LX Hatch 306 w/ TRW forged flat toppers, Comp Cams Magnum 292H, GT40P heads w/ 3 angle valve job, .550 lift springs, Angus Racing Roller Rockers, Weiand Stealth Intake, Holley 4150 650cfm carb, MAC 1 5/8 Long Tubes, Single Chamber Flowmasters, 91' T5 w/ Pro 5.0 shifter, Turbo Coupe 8.8 Rear w/ 3.55 gears, QA1 Motorsports tubular K member, no interior except steering wheel and seat. Coming soon: 6 or 8 point cage, Fuel Cell, Weld Draglites

07-07-2003, 01:52 PM	#2
Stang_ROTY Registered Member Join Date: Feb 2001 Location: Berkshire County - Massachusetts Posts: 735	I don't know about just lifters but I was told by several tech's at Comp Cams that I could of expected a 5-10% increase in HP by going full roller in my '69 block. Good luck! __________________ Red 1993 GT Street Machine Best E.T. - 12.41/Best MPH = 108 Engine is a 1969 351 block w/393 stroker kit. Dynamic Roller Myte C4, 8 pt cage. Edlebrock Performer heads and Victor Jr. EFI, FRPP 30lb injectors & Cartech fuel system. MSD ignition. Sothside Machine bars & Sub-frames, adj. upper's, 3.73's, Koni rear shocks, much more

07-07-2003, 02:00 PM	#3
UglyFast88 Registered Member Join Date: Apr 2002 Location: Fordland Posts: 117	Speaking of, I was just looking at the Rhoads variable lifters. Anyone run these or know anyone who does? See tech here Curious... __________________ '88 Speed Density LX 1998 Explorer motor 1.7 Roller Rockers GT-40 lower ported & polished Cobra upper intake MAC CAI Aluminum Pullies FRPP P-Shortys Cop car cam (to insult) Competition Engineering F/R adjustables Flowmasters New black carpet and... '84 Racin' Tempo seats! Cars' best run in 2002 with stock 150,000 mile 302 with pullies, exhaust and roller rockers only... 13.27 at 101.5 mph

07-07-2003, 11:05 PM	#4
tarmon8r Registered Member Join Date: Jun 2002 Location: manassas, va Posts: 186	Roller lifters allow a more aggressive profiles, faster ramp speeds so the valve gets to maximum lift sooner, within the same specs as a flat tappet cam. Rhodes lifter "bleed off" some of your cam at low rpms, for example: if you had a real aggressive cam, with lots of overlap and poor bottom end performance, rhoades lifters will make the motor think its a smaller cam at lower rpms and give back some torque in the process, by not pumping up until a certain rpm and "digesting" that overlap, thus reducing bleed off of having the exhaust and intake valves open at the same time as long and there by giving you more cylinder pressure for better throttle response and bottom end torque . and then give you back your more aggresive profiles on the top end when they do pump up. they are usually a little noisy. But your only talking about a minimal amount of impact rhoades lifters can have on a cam. __________________ 1983 mustang, 393 cubic inch stroker small block, victor jr heads and intake, gold race 1.6 roller rockers. comp cam 304, 244@ .050. .576" hydralic retro roller cam,lunati rods. block was o-ringed,10:1 forged pistons, speed pro fit fit rings, clevite bearings,msd distributor and igniton,be cool huge radiator, black lite electric fan, march underdrive pulleys, mildon deep sump oil pan, mac 1 3.4" long tube headers, 3" dr gas x-pipe and mac exhaust,ARP bolts. car weighs 2900 lbs w/out driver, sub frames, weld wheels, mickey thompson sportsman pro 26 x 10.5 x 15's,#8 fuel line steel braided

07-08-2003, 08:26 AM	#5
UglyFast88 Registered Member Join Date: Apr 2002 Location: Fordland Posts: 117	Interesting info. Thanks for the reply! __________________ '88 Speed Density LX 1998 Explorer motor 1.7 Roller Rockers GT-40 lower ported & polished Cobra upper intake MAC CAI Aluminum Pullies FRPP P-Shortys Cop car cam (to insult) Competition Engineering F/R adjustables Flowmasters New black carpet and... '84 Racin' Tempo seats! Cars' best run in 2002 with stock 150,000 mile 302 with pullies, exhaust and roller rockers only... 13.27 at 101.5 mph