Voodoo vs thumpr

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Stewie1977

Stewie1977

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Hi guys, hope this one hasn't been covered, couldn't seem to find it anywhere. So after the advice I received in my last post about my 390 build I started looking at other cam options. I'm building a 390 stroker (318 block, 4.00 mp crank, forged flat tops, aiming for 10:1, 360 "J" heads with 2.02/1.6 valves, PRW alloy 1.5 roller rockers, heads will flow around the 250, eddy air gap, 750 eddy carb & block huggers. These are parts I either have or have to run to fit my Aussie A body). I'm now considering one of two cams. The comp mutha thumpr or the lunati voodoo. The comp is 235@50 in, 249@50 exh & lift is .497 in & .483 exh. Las is 107.
The lunati is 234/242 @ 50, 513/533 lift & 110 lsa. My question is what differences am I likely to notice between the 2 ? Trans is a 904 with manual VB & has a LSD with 3.27. Looking at a 2800-3200 stall. Any advise would be much appreciated. I'm not looking at a regular strip car but the odd run will be on the cards. Anyone know if there would be much difference in hp ? Thanks
 
The Lunati will make better power and have a flatter torque curve.
 
The Comp thumper series are designed to give it a racier idle. I personally prefer a cam based on power output, rather than a rough idle, but that's just my opinion
 
You're a little light in the gearing department, but for what you have, and if the exhaust side of the head is up to speed, I'd seriously look at this XE275HL Comp grind.....http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=631&sb=0


Keep in mind I will never go against a "OU812" recommendation, Brian is one of the best. I just thought I'd throw this "off the shelf" grind out there for discussion...
 
Just for kicks I ran it on desktop dyno and it is the opposite of what I thought. The Thumpr wins out. More bottom end torque and a flatter torque curve. You wouldda figured with the 110 LSA, the Lunasty wouldda won.....that said the difference was not tremendous. Either cam would have a similar effect.
 
Thanks very much for that RustyRatRod. That's exactly why I wanted to know. That has made the decision for me. Looks like I'll go with the comp. I thought the extra lift might help a little but because it's mainly street the mor torque down low the better. Thanks again
 
You've got the cubes and the cyl head setup, why not take advantage if the higher lift and the fact that the Voodoo is ground to take advantage of the .904 lifter diameter which in turn means faster more aggressive ramp rates. The Thumpr's are/where designed to sound choppy, not with small block mopar performance in mind first and foremost. I've read on more than one occasion disappointing results including low vacuum, reduced cyl pressure and crappy low end torque all as a result. I'd pick Lunati hands down but that's just me. There's way more than meets the eye in cam design. I would read and research some more. I think you'll find the Voodoo to be the better choice!

Google Harold Brookshire

Also a good read here...

http://www.corvetteforum.com/forums/c3-tech-performance/2155901-voodoo-cam-or-thumper-cam.html
 
...or atleast consider the Hughes Whiplash cam too. That's what I'm running in my 360 and it degree'd in perfectly and really "Thumps" no pun intended! Gonzo low end torque and great vacuum and Cyl pressure! Sounds bad to the bone too.
 
I ran them on Desktop dyno also just to see what it said and I came up with a much different ending. The Lunati had 29 lbs ft more torque at 2500, 26 lbs. ft more torque at peak (3500). Horsepower was real close with the Lunati winning by 2 hp at 5500 rpm (peak). After HP peak the Thumper started pulling harder and at was 18 hp better at 6000.

The problem with desktop dyno is unless you have every figure inputted exactly correct (actual head flow is a huge factor) it can be way off. IMO it's hard to say who's desktop dyno figures are the closest, mine or Rob's. I found a head file of a set of ported J heads that peaked at 256 cfm intake flow and used them since the OP didn't give exact #'s, just that they'd flow around 250. And since Desktop dyno doesn't have the option for shorty headers I used the stock HP manifold option.
 
Bugger all difference in my opinion.
I ran a calculation with engine analyzer pro for a direct comparison between the two camshafts and the results predict the lunati to have about 4-7hp more through the entire rev range of 2000-6500rpm and also about 1.5" inches more vacuum at idle.

Of course this is only based on the cam numbers given and doesn't take into account the camshaft's overall shape. there are a lot more than just three points of reference to a cam lobe!

Both cams made 365-370 peak hp @5000RPM and 455-460tq at 4000RPM.
I would take this with a grain of salt and consider both camshafts to have relatively equal potential to make power. I would however agree that the lunati should theoretically give a smoother idle.

The simulation was based on the following

Ported J head flow numbers are from an old carcraft article from 2002.
10:1 comp
Simulated "race dual plane" manifold. no crossover. 750CFM throttle.
1-5/8" short tube exhausts with 18" primaries and a 6" collector. (block huggers)
Simulated typical oil windage.
Water brake dyno
coolant @ 165 degrees Fahrenheit
This simulation was for SAE air temp and barometric pressure figures and also had waterpump and a steel radiator fan installed.

Based on my own limited real world experience with ported J heads. I would consider this to be a relatively accurate power level, some people seem to get huge numbers from factory iron heads (400+) but in my opinion If you are intending on making more horsepower than this then it may be worth seriously considering a set of aftermarket cylinder heads.

Just my opinion. Hope this helps.
 
frosty_the_punk said:
Bugger all difference in my opinion.
I ran a calculation with engine analyzer pro for a direct comparison between the two camshafts and the results predict the lunati to have about 4-7hp more through the entire rev range of 2000-6500rpm and also about 1.5" inches more vacuum at idle.

Of course this is only based on the cam numbers given and doesn't take into account the camshaft's overall shape. there are a lot more than just three points of reference to a cam lobe!

Both cams made 365-370 peak hp @5000RPM and 455-460tq at 4000RPM.
I would take this with a grain of salt and consider both camshafts to have relatively equal potential to make power. I would however agree that the lunati should theoretically give a smoother idle.

The simulation was based on the following


Ported J head flow numbers are from an old carcraft article from 2002.
10:1 comp
Simulated "race dual plane" manifold. no crossover. 750CFM throttle.
1-5/8" short tube exhausts with 18" primaries and a 6" collector. (block huggers)
Simulated typical oil windage.
Water brake dyno
coolant @ 165 degrees Fahrenheit
This simulation was for SAE air temp and barometric pressure figures and also had waterpump and a steel radiator fan installed.

Based on my own limited real world experience with ported J heads. I would consider this to be a relatively accurate power level, some people seem to get huge numbers from factory iron heads (400+) but in my opinion If you are intending on making more horsepower than this then it may be worth seriously considering a set of aftermarket cylinder heads.

Just my opinion. Hope this helps.
Click to expand...


Thanks frosty. Wow that's a little disappointing as I was hoping to be up over the 400 mark. Guess I may have to rethink the whole build if that's all I'm looking at getting
 
Work on that head airflow..... Find a way to get that intake airflow 250 c.f.m. on up,should be at least 425 assembled correctly. Engine simulation programs need accurate airflow specs, to even come close. Both cams are good,I would hold off until you have actual head airflow & real assembled/ measured compression specs.
My .02....
 
My simulation was for a freshly built (tight) motor on a water brake dyno (typically reads low) with all accessories (as it would be in a car), factory windage and at a coolant temp that is going to work in an aussie summer.

It also was assuming a very mild cam ramp rate (neither of them are really optimized for the chrysler lifter, despite advertising guff) and also the cheap swill that passes for fuel over here.

Also block huggers are a big no-no for performance. there's at least 15hp in going to full length extractors/headers alone

basically a worst case scenario in many ways.

I could change these specifications and make it simulate 405-415hp. but it seems that everyone who's ever read a magazine seems to believe that their motor will definitely top 400hp. Many are disappointed...

I strongly believe a person could literally have two "mild" motors such as this one assembled using the same parts, and the same person doing the port work on both and one might produce as much as 15% more output because of small attention to detail in things like minimizing frictional losses, optimizing oiling in specific places, casting flash/core shift and the quality of the machining on some specific parts.

But yes, if you know what you're doing 400 and beyond is definitely possible with ported Iron heads.

To the original question. I don't believe there's going to be a heck of a lot of difference between the two camshafts. If i had to pick I'd be looking at the lunati.
 
frosty_the_punk said:
My simulation was for a freshly built (tight) motor on a water brake dyno (typically reads low) with all accessories (as it would be in a car), factory windage and at a coolant temp that is going to work in an aussie summer.

It also was assuming a very mild cam ramp rate (neither of them are really optimized for the chrysler lifter, despite advertising guff) and also the cheap swill that passes for fuel over here.

Also block huggers are a big no-no for performance. there's at least 15hp in going to full length extractors/headers alone

basically a worst case scenario in many ways.

I could change these specifications and make it simulate 405-415hp. but it seems that everyone who's ever read a magazine seems to believe that their motor will definitely top 400hp. Many are disappointed...

I strongly believe a person could literally have two "mild" motors such as this one assembled using the same parts, and the same person doing the port work on both and one might produce as much as 15% more output because of small attention to detail in things like minimizing frictional losses, optimizing oiling in specific places, casting flash/core shift and the quality of the machining on some specific parts.

But yes, if you know what you're doing 400 and beyond is definitely possible with ported Iron heads.

To the original question. I don't believe there's going to be a heck of a lot of difference between the two camshafts. If i had to pick I'd be looking at the lunati.
Click to expand...

Good info.. Neither can qualifies as "a mild street cam" , in the world ,I know. Both are aggressive as hell, on the ramps. A Comp 268 would qualify as mild at 268 Advertise/[email protected]/.460 lift. Good airflow let's you pull that big cam timing back,& possibly widen ,those lobe centers. Street ability is a scary thing.
 
All I did was put them each in a file labeled "360 test mule". It's a 9.3 360 .030 over with stock heads and valves, small tube headers and mufflers. No port work, no nuthin and with a 670 Street Avenger.

Really guys, those cams are very close, regardless of what any real or simulated dyno says. Once again, here we are splittin hairs over an engine that'll probably never push the envelope of either cam we're discussing, so it makes no difference. Pick one and GO.
 
frosty_the_punk said:
My simulation was for a freshly built (tight) motor on a water brake dyno (typically reads low) with all accessories (as it would be in a car), factory windage and at a coolant temp that is going to work in an aussie summer.

It also was assuming a very mild cam ramp rate (neither of them are really optimized for the chrysler lifter, despite advertising guff) and also the cheap swill that passes for fuel over here.

Also block huggers are a big no-no for performance. there's at least 15hp in going to full length extractors/headers alone

basically a worst case scenario in many ways.

I could change these specifications and make it simulate 405-415hp. but it seems that everyone who's ever read a magazine seems to believe that their motor will definitely top 400hp. Many are disappointed...

I strongly believe a person could literally have two "mild" motors such as this one assembled using the same parts, and the same person doing the port work on both and one might produce as much as 15% more output because of small attention to detail in things like minimizing frictional losses, optimizing oiling in specific places, casting flash/core shift and the quality of the machining on some specific parts.

But yes, if you know what you're doing 400 and beyond is definitely possible with ported Iron heads.

To the original question. I don't believe there's going to be a heck of a lot of difference between the two camshafts. If i had to pick I'd be looking at the lunati.
Click to expand...


Thanks again Frosty. At least what you have given me is a real world sim for our conditions. Will maybe even be a little less up here in Qld. After a heap more researh I've decided I'll probably go for the Lunati, even if it just means a little more vacum. I'm running the block huggers because as you would know, off the shelf extractors for a VC is non existant. I can get huggers for around $250, where the cheapest I've been quoted for a set of custom headers is around $1500. Big difference. What set up are you running in your VC ? Engine combo ?
Rusty ratrod your right, it is splitting hairs & I doubt it ever will be pushed to the limit. I'm looking at running a Mallory or similar electronic set up with a rev limiter, which will be set well under what the engine will handle for regular street use. I guess I'm just trying to get the best bang for my bucks, have a fun car on the street & not be too ashamed to take to Mopar Sunday & put it down the 1/4.
 
Good general street cams are ones with around .500 lift, 230 sumffin duration @ .050 and lobe separations to match whatever driving manners you want. Wide LSA usually = flatter torque curve, a little more bottom end response, more vacuum signal and smoother idle with better street manners. Narrow LSA usually = a more peaky torque curve, a little less bottom end in favor of a little more on top, less vacuum signal and a rougher idle. Other than those ground rules, any modern grind will do about the same as any other. There's not a magic cam out there that'll suddenly shake out 50-75 more HP than all the others. That's why I always say pick one and go.
 
I have the lunati cam in the 340 in my Duster. I haven't run it on a dyno yet, it was built in hopes of being in the low to mid 400's for hp.

Here are the specs...

'68 340
.060" over with KB 243 hyper pistons, .018" over the deck, ~9.8:1
Forged crank, stock 340 rods resized with ARP bolts
308 heads, 2.02/1.60 valve, 65 cc's chambers, stage II ported and flowing 264 cfm at .500"
Lunati 60404 Hydraulic cam, .513/.533", 276/284 advertised duration
Doug's headers, 2.5" dual exhaust
Stock electronic dizzy with modified curve, 20* initial timing, 34* all in mechanical
Edelbrock RPM Air Gap
Holley 770cfm Street Avenger (couldn't get it to idle with a 670)

Idle is pretty choppy, I keep it set around 900 rpm. Vacuum at that setting is around 10mmHG.

Short video at idle and short revs, this is with Summit Turbo mufflers, I've since upgraded to welded dynomax ultra flow's. Lunati rocks!

[ame]http://youtu.be/C_P8H2aLYPU[/ame]
 
That sounds freakin awesome !!! That's pretty much what I'm after, although I guess it'll sound a little less angry in the 390 stroker & give a little more vacum. My specs are pretty similar to yours except the heads. I'm running J heads, mainly because I have a set already & I started porting them. Money is a little tight so maybe eventually I'll upgrade to a set of eddys, but for now the old irons will do. I'm pretty sold on the Lunati now so I'm going to go with it. Great street manners aren't a high prority as it'll probably only be driven on weekends or to the odd show.
 
OldmanRick said:
You're a little light in the gearing department, but for what you have, and if the exhaust side of the head is up to speed, I'd seriously look at this XE275HL Comp grind.....http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=631&sb=0...
Click to expand...


RRR is right about how close these cams perform on the street, but I still like my choice. Sounds good, less overlap :D:D:D.

Not my car, but a you tube of the sound....... [ame="https://www.youtube.com/watch?v=DbaR0CuWG4g"]Dart Sport 360 XE275XL Comp Cams Idle - YouTube[/ame]
 
Stewie1977 said:
Thanks again Frosty. At least what you have given me is a real world sim for our conditions. Will maybe even be a little less up here in Qld. After a heap more researh I've decided I'll probably go for the Lunati, even if it just means a little more vacum. I'm running the block huggers because as you would know, off the shelf extractors for a VC is non existant. I can get huggers for around $250, where the cheapest I've been quoted for a set of custom headers is around $1500. Big difference. What set up are you running in your VC ? Engine combo ?
Rusty ratrod your right, it is splitting hairs & I doubt it ever will be pushed to the limit. I'm looking at running a Mallory or similar electronic set up with a rev limiter, which will be set well under what the engine will handle for regular street use. I guess I'm just trying to get the best bang for my bucks, have a fun car on the street & not be too ashamed to take to Mopar Sunday & put it down the 1/4.
Click to expand...

I hear you on the headers.

I was lucky enough to snag a set of custom 1-3/4" 4 into 1 pipes off moparmarket about 6 years ago which were a work of art until i went to fit them and had to cut them up to make them fit anyhow. now they have my ugly MIG welds all over them lol.

block huggers for a VC. there's only one set that will actually fit a vc without cutting them up and even then the outlet is in a pretty bad position. You can buy the right hand side x2 on summit. but in my opinion these probably aren't going to be a heck of a lot better than cast manifolds.

(ebay block huggers come out too wide and will almost definitely snag on the inner RH guard)

http://www.summitracing.com/int/parts/hed-78500rso/overview/ (no longer available?)
http://www.summitracing.com/int/parts/hed-78500/overview/

If it were me, I would use cast iron manifolds and if/when you want to step up to some headers you could invest in a set of these and build them yourself in your own time (and lots of it).

http://www.summitracing.com/int/parts/evt-1750basic/overview/

It all depends on how fast you wanna go. The beautiful thing about using the above system is you can actually test how easy/hard a design is to remove/refit before you even cut a single piece of tube.

When I build my next mopar. I'm keen as knives to build a GOOD set of custom headers that ACTUALLY FIT and oxy weld the whole lot. lol.
 
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