[Steve C.]

Recently there was a discussion here about using a hydraulic flat tappet cam with short seat timing verses one with additional seat timing in conjunction with a 400 engine using iron heads with a lower 9:1 compression. Both cams with the same or similar .050 duration and the same lobe separation.

For interest here are simulation results for the Crower 60242 cam with 280/286 advertised duration and the Lunati Voodoo 10510702 cam with 262/268 advertised duration. The Crower has 221 at .050 and the Voodoo has 219 at .050. Both cams with 112 lobe separation and input for both was 4 degrees advanced. Both cams with a 1.5 rocker arm ratio.

The computer program was the Dynomation-6 Professional Series Engine Dyno Simulation. No attempt was made for a comparison involving any specific known engine combination. Those that have used various programs know we don't want to look at the values xxx HP or xxx TQ literally, they may be off a bit there. But they are good at showing "trends" when comparing one part or spec to another. With that in mind, note no attempt was made to evaluate if these particular cams or the static compression ratio were optimum for the specific 'engine' input . The simulation was done for interest only to determine approximate flywheel power with the lower compression ratio. This was done with a improved program, knowing that different programs have changed much over years ago with better predicted results.

Input in short:

400 cid / 6.625 rod
Factory d-port cylinder heads / ported
9:1 compression ratio
2.110 / 1.770 valves
Intake flow- 267 cfm at 0.550" lift (28")
Exhaust flow- 218 cfm at 0.550" lift (28")
Dual-plane intake / overall induction flow 800 cfm
1.750" diameter headers

Crower cam:

RPM Power Torque
(rpm) (HP) (LB-FT)
2000 166.8 438
2250 196.1 455.9
2500 225.2 473.1
2750 255.4 486.7
3000 284.9 498.7
3250 312.2 504.1
3500 339.2 508.9
3750 360.5 505
4000 377.8 496
4250 392.1 484.5
4500 384.1 448.3
4750 387.1 428.2
5000 386.9 406.3
5250 380.5 380.9
5500 371.4 354.6


Voodoo cam:

RPM Power Torque
(rpm) (HP) (LB-FT)
2000 176.5 463.5
2250 206.8 481
2500 236.7 497.2
2750 267.2 509.2
3000 296.6 519.3
3250 324.4 523.8
3500 351.8 527.9
3750 372.9 522.6
4000 389.9 512
4250 403.1 498.1
4500 394.4 460.4
4750 397.9 440.1
5000 397.4 417.4
5250 390.9 391.3
5500 382.5 365.3




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[Jay S]

Steve what inputs does that program use for inputs on the cam specs?

Game #1

262 1......60242 0
Jay

[ponchjoe]

Thanks for starting this Steve, subscribed to learn.
Special request if you’re taking them, 60919 and 704 in a 9.5 comp iron headed 455

[pastry_chef]

Originally Posted by Jay S

what inputs does that program use for inputs on the cam specs?

Two options noted in their manual are "10 point data" or cam file (camDR, CamProPlus, S96 etc)

10 data points that Dynomation6 uses to extrapolate a full valve-motion curve (in effect, a new profile data set) that establishes valve lift at each crank degree during the simulation process. The 10 points used are:
IVO. IVC, EVO and EVC at both 0.006-in valve and 0.050-in lobe lift points...that’s 8 data points...plus the maximum lift for each lobe.

[72LuxuryLeMansLa.]

Do we need a separate Thread or can you post what the results would be at 10:1scr?

[Jay S]

I read a old posting by UDharold that he thought lunati rated the voodoo cams at .0065 to .007. I was curious if there is a computer file somewhere that allowed for the strange seat specs and the unnusual symmetry of those profiles.

Everyone has there own methods and ideas on figuring what cam is best. I usually calculate dynamic compression for my engines using .006 lift. I know other use higher dcr numbers, but at my altitude (1000ft), it seems to take a minimum of 7 (using the Wallace dcr calculator) to make power and after 7.5 I start to get detonation on pump gas here. The crower has about 6.9 dcr and the lunati around 7.3 dcr. (No altitude adjustments).....I would expect the lunati to have more power with similar .050, ls, and lift. Once the compression rises to close to 7.5 on the crower it would be my choice.

The 7.0 to 7.5 dcr is only what I use for hydrualic flat tappet profiles with cast iron heads. Just guidelines I use. The performance engines I have built with hot cams that the dcr fell much below upper 6’s dcr don’t seem to run great anywhere.
Jay

[Rick Jones]

Great info Steve C. Thanks for sharing! Would you be able to run the same simulation with the Crower 60916 and the Summit 2801?

Thanks, Rick

[Steve C.]

Although there are caveats involved, this material from a website involving cam theory:

In short.... If the cams being compared rate the advertised duration at the same lift, the cam with the shorter advertised duration compared to the 0.050” duration should be the cam with the more aggressive ramps. If it results in stable valve motion, the more aggressive cam will give better vacuum, better responsiveness, and a broader torque range, along with other improvements in driveability. Aggressive ramps allow the valve to reach maximum velocity sooner, allowing more area for a given duration.

Knowing this my sole purpose of this endeavor was to satisfy my curiosity using a computer simulation regarding seat timing in relation to the .050" duration and in conjunction with the lower static compression ratio. Then share that information. My Performance Trends Engine Analyzer program is no longer working therefore I reached out to to someone I knew that used that program. He suggested the use of his Dynomation-6 Professional Series Engine Dyno Simulation instead of the EA program.

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[se428bandit]

Originally Posted by ponchjoe

Thanks for starting this Steve, subscribed to learn.
Special request if you’re taking them, 60919 and 704 in a 9.5 comp iron headed 455

I would also like to see that.

[Jay S]

.006 specs
Lunati 702. 267*int 274*exh (guess no cam card)
Summit 2801 272*int 282* exh ( from cam card)
Crower 60916 278* int 289* exh (advertised)
Summit 2802. 282* int 292*exh (from cam card)
Lunati 704 281*int 288* exh (from cam card)
Crower 60919 286*int 292* (measured estimate)

Seat timings are closer when using same specs

[pastry_chef]

Originally Posted by Jay S

.006 specs
Lunati 702. 267*int 274*exh (guess no cam card)
Summit 2801 272*int 282* exh ( from cam card)
Crower 60916 278* int 289* exh (advertised)
Summit 2802. 282* int 292*exh (from cam card)
Lunati 704 281*int 288* exh (from cam card)
Crower 60919 286*int 292* (measured estimate)

Interesting, thanks.

[Steve C.]

Stated- "I read a old posting by UDharold that he thought lunati rated the voodoo cams at .0065 to .007. "

I called Lunati Tech today and asked about that very subject. I was told it is true Harold's original Voodoo designs were rated closer to .007" tappet lift. But since then Lunati has changed their grinding process and they are now rated at .006" tappet lift for the seat-to-seat duration.

I'm currently waiting on a phone call from Louis the head cam designer at Crower on this subject as well. In the past I have been told by their tech department two different answers, .005" tappet lift and .006" tappet lift.

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[Jay S]

I noticed they don’t have the 281/289 listed on the new online cam cards, just 276/284...maybe I missed the memo.....

Was there “original voodoo’s” when lunati first released them versus what we run now? Harold mentions a sales manager set the specs on the lift, duration, etc, but the designs where his...I think I even notice your name were he mentioned that, I think it was on pontiac zone...thanks Steve C.

[Steve C.]

I feel confident Paul Carter (gtofreek) knows more about Voodoo cams than anyone who posts here. And if interested in more information call Lunati, and if he is still there, ask for Steve Slavik who worked with Harold Brookshire at UltraDyne for 13 years.


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[Steve C.]

Jay S

I suspect this might be the old post Harold Brookshire made that you referred to in your post above. This was back in 2008 when I was unaware the UltraDyne designs were different than the Voodoo designs.

"Hello, everyone, I am UDHarold, former owner/designer of UltraDyne Racing Cams, and the designer of the Lunati VooDoo series. In fact, so far in 2008 I have designed new solid lifter VooDoo cams for the SBC, BBC, SBF, and BBF.
I hope to have finished this week the solids for the Chryslers, and their .904" tappet.
The Lunati VooDoo cams are NOT old UltraDyne cams, allthough as the designer of both there are certain similarities: Both are unsymmetrical, with aggressive opening sides and gentle seating ramps(to control seating noise).
The specs on the original VooDoos were set by Lunati's former Sales Manager, as far as lift/duration, etc. The shape of the curve is the way I design, and the 2 names of UltraDune and VooDoo are not interchangable. UltraDynes are made by Bullet---Tim worked for me for 21 years---and the VooDoos are made by Lunati, where Steve works, and he worked for me 13 years. My former shop foreman, who made all of UltraDyne's models and masters, etc, is the cam shop foreman at Lunati. He worked for me for 19 years. He is also in charge of Lunati's Landis CNC cam grinder. I work simultaneously for Lunati and for Custom Camshaft Company, of Martinsville, VA. CCC is an engine development company for Dodge, and a long-time NASCAR engine builder. They have a Landis 3L CNC cam grinder, where I make most of my custom roller cams.
If anyone has any questions on cam theory or cam manufacture, I will be glad to answer them on this forum. I am an Old Codger, 67, so bear with me if I am a little slow. I also am on Team Chevelle and Speed Talks, as well as several political groups and some military groups. I spend a LOT of time on the Internet. Paul from Koerner Engineering told me of your group, and I'm glad to be here"

UDHarold




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[gtofreek]

We sure miss Harold.

[Cliff R]

Steve, when you get time can you run dyno sims on this engine:

463cid
250cfm #96 "D" port heads
RPM intake
850cfm carb
.039" quench
9.3 to 1 compression

1st cam Comp Cams XR276HR with the ICL @ 106

2nd cam custom ground Comp HR cam "OldFaithful clone": 289/308 @.006", 236/245 @ .050", .381" lobes on a 114LSA ICL @ 110

1.65 rockers used on both cams....tks.....Cliff

[Jay S]

Yes you found it. Love his posts, always worth reading

[Steve C.]

Cliff,
Again my sole purpose of this was only to satisfy my curiosity using a computer simulation regarding seat-to-seat timing in relation to the .050" duration in conjunction with a lower static compression ratio. And with the same or similar .050" duration numbers and same lobe separation. Then share that information.


http://forums.maxperformanceinc.com/...6&d=1527195972




.

[gtofreek]

Here's a snap shot of the dyno screen from a 467 we did with 670 heads that were ported to 260CFM, and 9.5:1 compression, with RA exhaust manifolds with 2.5" pipe, iron Q-jet intake, and Q-jet. It had 1.65:1 rockers, and ran on 91 pump gas. It had a Voodoo HR cam with 239°/243° @ .050", ground on a 112° LSA, installed on a 106° ICL. It peaked at 580 Ft. Lbs., and 522 HP.