thumpr 291 vs. t-rex cam????

**Steve's LS1** · 02-24-2011, 07:46 PM

ok ive been looking around for a cam for my 98 camaro. and ive narrowed it down to these 2, tell me what you prefer and why. hear are the cam specs.

Thumpr 291: 291/311 - .573/.558 -109 lsa

T-Rex: 242/248 - .608/.612 - 110 lsa

**zmg00camaross** · 02-24-2011, 08:22 PM

The Trex cam is prove itself some many times in the cam only records its hard to beat what you know is going to work. Of cours if you have enough gear/ stall if auto. The other cam have no info and the numbers dont stack up to me, The duration seems wrong.

**Steve's LS1** · 02-24-2011, 08:35 PM

Originally Posted by zmg00camaross

The Trex cam is prove itself some many times in the cam only records its hard to beat what you know is going to work. Of cours if you have enough gear/ stall if auto. The other cam have no info and the numbers dont stack up to me, The duration seems wrong.

i've been leaning to the T-Rex. ive heard alot about it mostly positive. and i dont kno much bout ls1's since this is my first and all. the cars 6spd so no stall worries. and its got 456s for it but not installed yet. heres the link to the Thumpr cam...

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

**Spaz** · 02-25-2011, 05:31 AM

that thumper seems to be geared more at lrge cube engines...

**Firebirdjones** · 02-25-2011, 12:12 PM

I run one of the thumpers in a gen 1 engine.

They are actually designed for anything 300 cubes and up, with 3 different versions they make. (thumper, mutha thumper, and big mutha thumper).

I run the middle version (mutha thumper) in a 406. But for the carbed applications they tighten up the LSA even more (2 degrees) and grind another degree of advance in.

The one that Steve has posted up there is for a fuel injection application and is a little tamer. Also those duration numbers are the advertised numbers,,,so they can't be compared to the T-rex which is showing .050 duration numbers.
The actual .050 numbers for that thumper listed is 235/249 which is exactly what I'm running.

Just a heads up that may help you decide. If you are going for all out performance and HP numbers the T-rex is designed for that.

The thumper series of cams are based off of roundy-round dirt track racing cams that make power early on and awsome mid range to come out of the corners hard. They make an extremely flat torque curve that comes in early but these cams usually peak around 6,000 rpm and they are done. They aren't big HP cams.
I can tell you I love mine in the 406. It dyno'd at 440 HP on pump gas with a more conventional 230/240 at .050 cam with .520 lift on a 110 lsa. I swapped to the mutha thumper recently (235/249 with .489/.476 lift on a 107 lsa) No dyno numbers but that's not what I was after. I can tell the engine is much more responsive lower end, and makes more mid range power than before (just seat of the pants) The cam is supposed to peak at 6100,,,but I shift at 57-5800 anyway. It's a blast on the street and thumps nicely at 1,000 rpms. I can idle it down to about 700 fine, but even at 1,000 this thing idles with about 6-7 inches of vacuum.

**Steve's LS1** · 02-25-2011, 05:02 PM

Originally Posted by Firebirdjones

I run one of the thumpers in a gen 1 engine.

They are actually designed for anything 300 cubes and up, with 3 different versions they make. (thumper, mutha thumper, and big mutha thumper).

I run the middle version (mutha thumper) in a 406. But for the carbed applications they tighten up the LSA even more (2 degrees) and grind another degree of advance in.

The one that Steve has posted up there is for a fuel injection application and is a little tamer. Also those duration numbers are the advertised numbers,,,so they can't be compared to the T-rex which is showing .050 duration numbers.
The actual .050 numbers for that thumper listed is 235/249 which is exactly what I'm running.

Just a heads up that may help you decide. If you are going for all out performance and HP numbers the T-rex is designed for that.

The thumper series of cams are based off of roundy-round dirt track racing cams that make power early on and awsome mid range to come out of the corners hard. They make an extremely flat torque curve that comes in early but these cams usually peak around 6,000 rpm and they are done. They aren't big HP cams.
I can tell you I love mine in the 406. It dyno'd at 440 HP on pump gas with a more conventional 230/240 at .050 cam with .520 lift on a 110 lsa. I swapped to the mutha thumper recently (235/249 with .489/.476 lift on a 107 lsa) No dyno numbers but that's not what I was after. I can tell the engine is much more responsive lower end, and makes more mid range power than before (just seat of the pants) The cam is supposed to peak at 6100,,,but I shift at 57-5800 anyway. It's a blast on the street and thumps nicely at 1,000 rpms. I can idle it down to about 700 fine, but even at 1,000 this thing idles with about 6-7 inches of vacuum.

well im just looking to get into low 12s. then im done. thats fast enough. the car has long tube headers with a custom 3" exhaust. and i have 456s that i havent got around to puttin in yet. i ran 3 times at the track and the slowest was a 13.49, 13.10, and i 13.04 on street tires. which spun a bit on take off. so im just looking for a cam i can slide in that will give it a nice sound at idle and hopefully get me in the low 12s