street demon2k3

iTrader: (3)

I was looking through a mag. the other day and saw some testing done on COMP Thumpr cams. Upon looking at the specs I was wondering how this cam would work on some stock or mildy ported heads? I've seen how well the Crane227/CC306 work with large splits in duration, but how does this cam stack up granted it can be ground for an LT1?


RPM Operating Range: 1900 to 5600
Cam Grind Number: 283THR7
Duration @ .050'': 227/241
Valve Lift: Intake - .511, Exhaust - .497
Lobe Sep. Angle: 107°

hyperzone

that valve lift going by 1.5 or 1.6 rocker?

EDIT : its on a 1.5rocker. also, heres a link :

283THR7 Cam

SincalT/A

iTrader: (16)

That cam is ground to sound mean hence the thumper name not to make any type of effcient hp.

Razor_Blade

iTrader: (8)

I agree! Unfortunetly, there is a market for that sort of thing.

Puck

iTrader: (17)

Its a "ricer cam". They throw in the valve overlap and exhaust duration for the nice lopey sound, but they lack in lift. It will not only make poor power but run crappy times.

Don't do it!

zlover129

iTrader: (10)

ever heard of rat rods and hot rodders like that? Their not really in the business to go fast just do burnouts and sound great...thats the audience this cam is aimed too. Haha i love how everyone jumped to the ricers for a SBC cam

96capricemgr

iTrader: (1)

Depending on the timing of the valve events these might work with rockers supplying the lift. The 112 off the shelf stuff is compromised for emissions and because people are stupid and buy too much duration as a RULE. On a smallblock Chevy a 106LSA is frequently ideal for power but not manners.

These are aimed at gen 1 stuff which generally for street use runs MUCH less lift than we do, the heads the cars these cams are aimed at are not going to work well at .600" lift, the old muscle car heads SUCK compared to LT1 heads even the old big valve stuff sucks.

The dual plane intake, 1.5 rockers and fairly low compression are all hurting output as compared to the numbers we usually see. It was with aftermarket heads otherwise it would not have done as well.

Not saying these are going to be great just that I think you guys are writting them off too soon and without any real thought or understanding.

Look how low in the rpm band that power is too, some of that is due to the dual plane intake, but just the shift in rpm that an LT1 intake provides would result in a higher hp number.

SincalT/A

iTrader: (16)

The cam in question is not designed to go in (old muscle car headed engines)its hydraulic roller.Unless you consider the mid 80s as a muscle car era.That cam is most likely designed around early vortec heads given the lift specs.I have seen the so called crappy hot cam make the same hp. ,but more torque on vortec headed 350 H.O.(which to start out is rated less power than the zz4).If you notice in the artical the swap to 1.6 rockers netted 16 hp. and 10 tq on the otherwise stock engine.This tells me that the motor was screaming needs more cam.Now we can what if this to death so i will agree to disagree on this subject.Thumpers are a marketing gimmick.I will say i bet they sound good

96capricemgr

iTrader: (1)

Seems to me they are roller RETROFIT cams as in meant for flat tappets blocks to my knowledge ZERO decent heads cam from the factory on a flat tappet block.

They are basically admitting it is a marketing gimmick saying they aimed for sound but still tried to retain power, but my point is they may actually be OK, certainly better choices but IMO people here make worse choices every day of the week.

street demon2k3

iTrader: (3)

What's the difference between the thumpr cam and the cc306 or gm847? They're pretty close in duration but the thumpr cam lacks a little more lift and some more LSA to be right on par with those two. It doesnt sound like it would be that bad compared to other big off shelf cams, but Im wondering how it would perform?

96capricemgr

iTrader: (1)

The huge LSA 112-114, of most off the shelf cams is a BAD thing for power.