Comp Thumpr cam
03-13-2013, 07:15 PM
#41
Martin, my last paragraph of my post was not dircted at you, but at everyone who instantly replys with no real advice but instead posts "call ________ ", or spreads a false "fact". Someone else suggested a custom cam. Since you were the one suggested, so it only stands to reason that it be you that explains why your cam is more worthy.
I honestly have no problem with you, however if you or anyone alse are "selling" in a post, I expect honest factual replies, as that is how 1 gains respect. I am not acusing you otherwise, but I have read a few crazy sales pitches from others which lead to my little rant
I honestly have no problem with you, however if you or anyone alse are "selling" in a post, I expect honest factual replies, as that is how 1 gains respect. I am not acusing you otherwise, but I have read a few crazy sales pitches from others which lead to my little rant
03-13-2013, 09:42 PM
#42
Well, since this is your thread, I will consider this a green light to move from real world experience with the Thumpr series to a technical discussion.
I will contribute this:
What sets the Thumpr apart from others performance cams of the same operating range:
What Comp cams achieves with the Thumpr is a cam that sounds and acts a lot like a race cam. By keeping the intake duration small and adding in lots of advance, it keeps the RPM range down making it more appropriate for how it will be used in street rods and muscle cars. It is really a cool grind and they hit the mark brilliantly.
What breeds all of the hate on ls1tech for the cam?
In summary, you give up some power for a softer lobes and you give up some midrange and low end power on cathedral port cars that will prefer less duration split for a given application. What you get is a nice little hotrod cam that will make great power with a single plane intake, idle like a race car and wont beat up your valve train.
I will contribute this:
What sets the Thumpr apart from others performance cams of the same operating range:
- Much Larger Exhaust Duration - This creates more valve event overlap (time where both the intake and exhaust valve are open at the same time). Benefits of larger exhaust duration include more high RPM and peak horsepower, a natural love for nitrous if one chooses to use it and of course a rough or hot rod type idle. It also creates an earlier exhaust valve opening which also increase the "Thump" because it releases the exhaust while it is under more pressure. The downside to this is decreased low rpm power and drivability.
- Narrow lobe seperation angle - This too creates more valve event overlap. Benefits of narrower lobe center is typically an increase of peak torque. It generally concentrates the power in a narrower power band. This typically works well with automatic transmission cars with high stall converters. And, of course increases the rough or hot rod idle. It is very important that a car running cams with narrow lobe seperation angles have free flowing exhaust or the benefits will become a liability. Other downsides of narrow LSA cams is poor low speed drivability and a decrease in fuel economy.
- Advanced or earlier intake centerline - Adding more advance has effects on all valve events, but the most important is probably closing the intake valve sooner. By doing this it moves the power band lower in the RPM range. Drag racers have often ran slightly larger cams with more advance to get more peak and midrange power for a given RPM range. They can do this because they do not care about the loss in street manners.
What Comp cams achieves with the Thumpr is a cam that sounds and acts a lot like a race cam. By keeping the intake duration small and adding in lots of advance, it keeps the RPM range down making it more appropriate for how it will be used in street rods and muscle cars. It is really a cool grind and they hit the mark brilliantly.
What breeds all of the hate on ls1tech for the cam?
- It is not a maximum performance cam. One of the differences as Barret pointed out is "soft lobes". It has far less aggressive lobe profile (it does not open and close the valves as fast nor does it have very high lift). This could be a plus for a guy who does not want to worry about valve spring failure or valvetrain stress. A similar grind on aggressive lobes would probably be 10 to 15 HP stronger. On ls1tech, that could mean the difference in being a dyno hero.
- It is not well suited for the long runner EFI LS style intakes. Those long runner intakes prefer wider LSAs combined with later (more retarded LOL) intake valve events. So, of course this type of grind will perform worse for them. Conversely, this type of cam will LOVE a Victor Jr. intake like we carb guys often run.
- The circle jerk of re-idiots. One web hero says it is bad and the parrots take it from there.
In summary, you give up some power for a softer lobes and you give up some midrange and low end power on cathedral port cars that will prefer less duration split for a given application. What you get is a nice little hotrod cam that will make great power with a single plane intake, idle like a race car and wont beat up your valve train.
Last edited by speedtigger; 03-13-2013 at 09:55 PM.
03-14-2013, 03:21 AM
#44
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Well, since this is your thread, I will consider this a green light to move from real world experience with the Thumpr series to a technical discussion.
I will contribute this:
What sets the Thumpr apart from others performance cams of the same operating range:
What Comp cams achieves with the Thumpr is a cam that sounds and acts a lot like a race cam. By keeping the intake duration small and adding in lots of advance, it keeps the RPM range down making it more appropriate for how it will be used in street rods and muscle cars. It is really a cool grind and they hit the mark brilliantly.
What breeds all of the hate on ls1tech for the cam?
In summary, you give up some power for a softer lobes and you give up some midrange and low end power on cathedral port cars that will prefer less duration split for a given application. What you get is a nice little hotrod cam that will make great power with a single plane intake, idle like a race car and wont beat up your valve train.
I will contribute this:
What sets the Thumpr apart from others performance cams of the same operating range:
- Much Larger Exhaust Duration - This creates more valve event overlap (time where both the intake and exhaust valve are open at the same time). Benefits of larger exhaust duration include more high RPM and peak horsepower, a natural love for nitrous if one chooses to use it and of course a rough or hot rod type idle. It also creates an earlier exhaust valve opening which also increase the "Thump" because it releases the exhaust while it is under more pressure. The downside to this is decreased low rpm power and drivability.
- Narrow lobe seperation angle - This too creates more valve event overlap. Benefits of narrower lobe center is typically an increase of peak torque. It generally concentrates the power in a narrower power band. This typically works well with automatic transmission cars with high stall converters. And, of course increases the rough or hot rod idle. It is very important that a car running cams with narrow lobe seperation angles have free flowing exhaust or the benefits will become a liability. Other downsides of narrow LSA cams is poor low speed drivability and a decrease in fuel economy.
- Advanced or earlier intake centerline - Adding more advance has effects on all valve events, but the most important is probably closing the intake valve sooner. By doing this it moves the power band lower in the RPM range. Drag racers have often ran slightly larger cams with more advance to get more peak and midrange power for a given RPM range. They can do this because they do not care about the loss in street manners.
What Comp cams achieves with the Thumpr is a cam that sounds and acts a lot like a race cam. By keeping the intake duration small and adding in lots of advance, it keeps the RPM range down making it more appropriate for how it will be used in street rods and muscle cars. It is really a cool grind and they hit the mark brilliantly.
What breeds all of the hate on ls1tech for the cam?
- It is not a maximum performance cam. One of the differences as Barret pointed out is "soft lobes". It has far less aggressive lobe profile (it does not open and close the valves as fast nor does it have very high lift). This could be a plus for a guy who does not want to worry about valve spring failure or valvetrain stress. A similar grind on aggressive lobes would probably be 10 to 15 HP stronger. On ls1tech, that could mean the difference in being a dyno hero.
- It is not well suited for the long runner EFI LS style intakes. Those long runner intakes prefer wider LSAs combined with later (more retarded LOL) intake valve events. So, of course this type of grind will perform worse for them. Conversely, this type of cam will LOVE a Victor Jr. intake like we carb guys often run.
- The circle jerk of re-idiots. One web hero says it is bad and the parrots take it from there.
In summary, you give up some power for a softer lobes and you give up some midrange and low end power on cathedral port cars that will prefer less duration split for a given application. What you get is a nice little hotrod cam that will make great power with a single plane intake, idle like a race car and wont beat up your valve train.
Thanks for the informative post, this explains this cam better. It looks as though this cam is going to fit the bill for what i am after, make good power, easy on the valvetrain and wallet(heavy springs,etc). I'm not looking for that last 10-15hp, because it will never see the dyno, just don't feel the need to waste money on that to get a "number". Don't need it dyno tuned, well it's a carb, can easily tune that myself.
Thanks to 3Pedals aswell for the "real" world review of the cam, not just saying it isn't good because someone else said so. He actually was in a vehicle that had one installed. I am going with the smaller Thumpr cam, the others did seem to big for the 5.3 to me.
This truck is going to be an auto, 3-3500k stall(not set on this yet) with a 4.10 gear, victor Jr. intake, 1 3/4" headers, dual 2 1/2" exhaust. Cam should work nice for me.
Zones-cam will not be $400, i have a connection to get it for $300(new), so in my case, it really is a budget cam. Just like the forged Wiseco pistons for $400 new, quality pieces at budget price.
Sorry to start such an argument here over a cam, but a spirited discussion is a good thing, no? I looked into custom cams, didn't feel it was what i needed, wasn't looking for that last ounce of horsepower. Like i said earlier, if max effort was what i was after, i wouldn't be starting with a 5.3. With the forged bottom end i am building, cam easy on valvetrain, i should have a fun, reliable motor that makes good power. I'm still learning these LS motors. In all the years i have been hot rodding, i've never used a custom cam, always OTS, made great power. Even my Dad has, and he has many more years than I under his belt racing.
Last edited by Quick Ranger; 03-14-2013 at 03:30 AM.
03-14-2013, 05:11 AM
#45
It honestly has much more to do with the lobes having more overlap at tdc than other faster lobes which have less overlap. More overlap more thump. Less overlap less thump. Simple really. You can do all the things speedtigger mentioned with faster lobes by extending exhaust duration and tightening lobe centers to make it thump more, but what sets the thumper lobes apart is there slower open and close creating more overlap atdc.
That's it.
That's it.
03-14-2013, 08:30 AM
#46
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I had the biggest thumpr in my 5.3l in a 95 z28 with mildly reworked heads. Amd obviously everyone would say "why the hell would you put such a donkey dick cam in a 5.3l?" because it was $100, thats why! Now i never had it on the track, but the seat of the pants feel was strong! That is all. i didnt really car because it was just a cheap engine to finish the ls swap at the time. I have a open header video if anyone wants it
03-14-2013, 09:44 AM
#48
For all the drama this thread turned out pretty good.
I love a happy ending.
BTW, WTF is a nut hugger?
Nevermind. As per urban dictionary
Nut Hugger
N. a socially disadvantaged person who must latch, or hug onto to the nuts of one of his friends to gain acceptance in social setting.
I wish Jon wouldn't have been home schooled because he is such a Nut Hugger when we go out.
I love a happy ending.
BTW, WTF is a nut hugger?
Nevermind. As per urban dictionary
Nut Hugger
N. a socially disadvantaged person who must latch, or hug onto to the nuts of one of his friends to gain acceptance in social setting.
I wish Jon wouldn't have been home schooled because he is such a Nut Hugger when we go out.
03-14-2013, 01:49 PM
#50
I know people use the Thumpers in BBC's allll the time and they all run pretty hard for moderate, hydraulic roller, street engines. Guy at car show with a nice 72 Chevelle had one and I thought it sounded hossy.
The Thumper family of cam's is like the only cam series I have ever seen an ad for on a website or in a magazine from Comp. I don't think Comp would advertise a cam unless they think it works well and has a large market. I mean I don't know what the people at COMP are thinking but, I'm sure no one in that company is starving at night for food and if they were wanting to push a line of cams why would they design a crappy cam and later pick that one?
To me the Thumpers are like the Hotcam or ASA.
The Thumper family of cam's is like the only cam series I have ever seen an ad for on a website or in a magazine from Comp. I don't think Comp would advertise a cam unless they think it works well and has a large market. I mean I don't know what the people at COMP are thinking but, I'm sure no one in that company is starving at night for food and if they were wanting to push a line of cams why would they design a crappy cam and later pick that one?
To me the Thumpers are like the Hotcam or ASA.
Last edited by My6speedZ; 03-14-2013 at 04:03 PM.
03-14-2013, 04:25 PM
#51
Exactly, that is what I would rather use. ASA or Hotcam for me would be fine even on a 112. Not optimal but proven to work great. Like the fact they make the torqer on a 111 LSA though.
Then there is the 2216 edelbrock. Tryin to figure out what I can try one in. Really curious how this 2215 is going to sound. Was 333$ shipped. Just wish it was a dual pattern instead of single.
Then there is the 2216 edelbrock. Tryin to figure out what I can try one in. Really curious how this 2215 is going to sound. Was 333$ shipped. Just wish it was a dual pattern instead of single.
03-14-2013, 07:59 PM
#54
10 Second Club
http://www.summitracing.com/parts/EDL-2215/
03-15-2013, 03:30 AM
#55
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Most likely, it will be awhile. Alot to do on truck before it runs, bodywork/paint, rear end and making the engine fit the chassis, then fabbing headers.
03-15-2013, 06:14 AM
#56
220/224 @ .050 /.510 lift / 111 LSA....would guess a bigger split would have been better ?
http://www.summitracing.com/parts/EDL-2215/
http://www.summitracing.com/parts/EDL-2215/
03-15-2013, 04:28 PM
#57