[chiphead]

So lets say I'm comparing two HR street cams from different mfgs. How useful is Hydraulic Intensity parameter to compare between them? I'm assuming the adv duration numbers are both taken at .004".

Cam A is a 219 at .050 with a HI of 51, and Cam B is a 224 at .050 with a HI of 54 on the intake side.

Cam A is 227 at .050 with a HI of 51, and Cam B is a 230 at 050 with a HI of 59 on exhaust side.

Assume .520 Lift and 112 LSA are the same for both. Which is going to make more streetable power 2000-5500 in a 400?

[1968GTO421]

Subscribing, i'll be interested to see what thoughts come out here. (Cam A , to me, looks like a Voodoo cam).

[Stan Weiss]

Originally Posted by chiphead

So lets say I'm comparing two HR street cams from different mfgs. How useful is Hydraulic Intensity parameter to compare between them? I'm assuming the adv duration numbers are both taken at .004".

Cam A is a 219 at .050 with a HI of 51, and Cam B is a 224 at .050 with a HI of 54 on the intake side.

Cam A is 227 at .050 with a HI of 51, and Cam B is a 230 at 050 with a HI of 59 on exhaust side.

Assume .520 Lift and 112 LSA are the same for both. Which is going to make more streetable power 2000-5500 in a 400?

First:
Most of Comp Cams hydraulics are rated @ 0.006" lifter raise.
I believe Crower hydraulics are rated @ 0.004" lifter raise.
I believe UltraDyne hydraulics are rated @ 0.0045" lifter raise.
Anyone know about any of the other cam companies?

I would also look at the 0.200" duration as well.

Stan

[chiphead]

I dont have all that information off hand, only what is avail online. Is it fair to say that the higher the hydraulic intensity, the more aggressive the ramp is above .050" lift?

I'm just trying to avoid noisy ramps that look good on paper but don't actually perform as well. I got burned so bad by the Comp XE cam that I'm scared of any more of their fast-ramp hocum.

[mkpontiac]

From Steve C quoting UD Harold that all of his designs have a hydraulic Intensity of 53.88 degrees at 0.004 tappet lift would this mean that the Voodo advertised duration of the 702 cam for instance would be 219+53.88=272.88 at 0.004" compared to the actual advertised duration of 262 presumably at 0.006"?

[pastry_chef]

Originally Posted by mkpontiac

From Steve C quoting UD Harold that all of his designs have a hydraulic Intensity of 53.88 degrees at 0.004 tappet lift would this mean that the Voodo advertised duration of the 702 cam for instance would be 219+53.88=272.88 at 0.004" compared to the actual advertised duration of 262 presumably at 0.006"?

Could be true. I noted the same posted by Harold Sept 15, 2009.
http://forums.maxperformanceinc.com/...4&postcount=58

Here is a quote about the advertised rating. Might explain why some newer cam cards differ from the adv catalogue values.

Originally Posted by UDHarold
First of all, Lunati/Holley kept the computer and the printouts, so I cannot go back and reference what the actual numbers were.
When the VooDoos were first designed, several Sales Managers and a different owner ago, Lunati decided that they would compete directly with the Xtreme Energy cams at seat duration. I believe the actual ramp height was around .0068"-.0070" high.
The .050s were .050", the .200s were .200", as expected.

[Half-Inch Stud]

The Intensity metric is good.
I have not made that a top-metric because it has been tough enough to get dur/dur and LSA right for low compression.

[pastry_chef]

What cylinder head?

Flow at .400, .500, .600

Rocker Ratio?

Duration at .200 for both cams?

Just a 5500 limit?

The Voodoo line are great.

For what you are looking at the Comp XFI hyd rollers should be great

[mkpontiac]

pastry_chef
It all seems to make sense. I am just trying to make a comparison between cams at 0.004 tappet lift for calculating dynamic compression.
Thanks,

[Steve C.]

A tid bit here for interest only.....

"The Lunati Voodoo cams are not old Ultradyne cams, although as 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 Voodoo's are set by Lunati's former sales manager as far as lift and duration. The shape of the curve is the way I design, the names Ultradyne and Voodoo aren't interchangeable."
Harold Brookshire

Also another fwiw tid bit, Lunati does not have any of Harold's original UltraDyne lobe masters. Some of the cams Lunati sells with the 'same' specs as the old UltraDyne cams are not ground with actual UltraDyne masters. Lunati pirated the UltraDyne masters and made copies before Harold was fired by Lunati. All the original UltraDyne masters were sold to Bullet Racing Cams who also have the rights to the UltraDyne name.


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[Steve C.]

Dynamic Compression Ratio

http://members.uia.net/pkelley2/DynamicCR.html


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[pastry_chef]

Originally Posted by Steve C.

Also another fwiw tid bit, Lunati does not have any of Harold's original UltraDyne lobe masters. Some of the cams Lunati sells with the 'same' specs as the old UltraDyne cams are not ground with actual UltraDyne masters

From the horse's mouth

by UDHarold » Sat Dec 16, 2006 12:49 am
Bullet bought UltraDyne, and got everything that was there when they bought it. They let the CNC machine with the program for making those great roller lifters go back to the CNC company, they didn't want to pay that last $12,500 to pay off the Fadal.
However, before they bought UltraDyne, Lunati made copies of all the masters off the finish masters, the best UltraDyne had.
So Lunati and Bullet both have the UltraDyne masters; only Bullet has the right to call them UltraDynes.

https://www.speed-talk.com/forum/viewtopic.php?t=4793

[BruceWilkie]

Not all fast ramps are noisey. Harold Brookshire prided himself with his designs.(Ultradyne, Bullet and Lunati VooDoo series). That said there are others besides Comp that dont seem to have noise issues. (Though IMO I think some batches of Comp hyd lifters may be more at fault than their lobe designs for being noisey)

Solid lifters can run fairly quiet too and need not be "tight lash" designs. A well designed lash ramp takes the lash up gently. (one of a few reasons I personally wouldnt run solid rollers on a hydraulic roller cam).

[Steve C.]

Keep in mind that many lobe profiles are much slower on the closing side. Relates to this, a hint from the designer of UltraDyne cams & Voodoo lobes........

"I do all my cam designs as unsymmetrical cam designs. Although I design my hydraulics just like I do my roller profiles, The information I will give applies just to my hydraulic flat profiles.
Using Harvey Crane's Hydraulic Intensity formula, ALL my .842" tappet designs have an Hydraulic Intensity of 53.88 degrees. This is the duration at .050" subtracted from the duration at .004", where the SAE has decided that hydraulic durations begin and end.
This Hydraulic Intensity of 53.88 is considered to be very aggressive, yet the cams do not have that 'sewing-machine' sound to them.
The opening side of the cam has a 45.26 degree equivalent Hydraulic Intensity, and the closing side is 62.50 degrees Hydraulic Intensity. The SEATING velocity of the valve is only 37% as fast as the OPENING velocity. This seating velocity is only slightly faster than GM uses on all their engines. At UltraDyne, I have had many hydraulic, as well as solids, go over 100,000 miles on the street. I keep the edge of the tappet about .018" away from the point of contact between the cam and tappet.
That 'sewing-machine' sound is caused by the valves hitting the valve seats too fast. The original High Energy cams, which I designed, produced that sound. I was shutting the valve at .0007"/*, only .0002"/* faster than GM. After hearing about the noise, a little thought made me realise the .0002"/* was only 40% faster than GM.
You do not have to shut the valve faster to keep the charge from getting out.
You have to design the cam so the charge, or inertia ram, is still filling the cylinder when you shut the valve.
Every cam I design, hydraulic, hydraulic roller, solid, solid roller, is designed using the same theory I have used for the past 29 years, and they all make excellent bottom-end torque for their duration."
UDHarold


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[Steve C.]

Side note that might relate to the material I posted by Harold Brookshire. With this statement in mind....

"ASYMMETRICAL refers to a camshaft lobe profile where the opening and closing ramps are not exactly the same. The reason some camshafts are this way is to try to achieve an opening ramp profile that has a high velocity and a closing ramp profile that has a slower velocity. In this way the valve can be set down more "gently" than the rate at which it was first opened."

Now note what Harold stated:

"The opening side of the cam has a 45.26 degree equivalent Hydraulic Intensity, and the closing side is 62.50 degrees Hydraulic Intensity. The SEATING velocity of the valve is only 37% as fast as the OPENING velocity."

I have questioned if maybe he stated it backwards. Or I'm I way off base and interpreted it wrong. Comments from the cam experts ?


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[Steve C.]

And also related, David Vizard's comments here regarding “hydraulic intensity” might be of interest....

http://www.enginebuildermag.com/2006...ifter-failure/


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[pastry_chef]

Assuming 1.65 rocker.
A factory d-port around 240 CFM.

For 5500 RPM

Comp XFI hyd roller
Intake 13080
278 adv dur
228 @ .050
152 @ .200
.360 lobe lift

Intake centerline at 109

[1968GTO421]

Originally Posted by Steve C.

And also related, David Vizard's comments here regarding “hydraulic intensity” might be of interest....

http://www.enginebuildermag.com/2006...ifter-failure/


.

Thanks, Steve. The notes from Harold Brookshire and the Vizard article provide much food for thought on this subject. Speaking from ignorance, I don't know that the OP will find hydraulic intensity outside of the 50*-55* (53.88* per Harold) range to be as useful to him. Cam A sounds like it has the best HI for power , but Cam B would have more gentle ramps if I understand all this correctly. Like you, what do the cam experts say?

[BruceWilkie]

Multi-dimensional and ever moving...the graphic art required to get a visual of all things occuring thru a complete 4 cycles.... even if broke down in 10 degree increments of rotation...would be quite an art feat.
You actually need to graph a running engine with the cam you've chose and be able to record the pressure traces of rising/falling pressures(intake exhaust and cylinder) thru events across 720 degrees combined with a graph of the actual valve lift curves.

I dont think any of us are equipped to do this at home

For me one of the better visuals is putting a head on the drivers side bank and no piston in #1 hole... no head on passenger bank but a piston and rod in # 6(connected to crank of course). Put cam, timing chain, solid lifters etc in so you can actuate the valves, put a degree wheel on and start turning the crank.
Remember that #6 piston motion is same as #1's. Keep in mind what should be occurring if it were actually running and try to visualize increasing and diminishing pressures. As you stop along the way look under and see valves in #1 hole and look at # 6 to see whereabouts the piston would also be in #1.

Alot of work for some insight(but its good). You still need to know when one function is handing off to the next function and be able to consider what would enhace and what would detract at any given point.

Ultimately it all boils down to a set of best compromises for any given application.

[BruceWilkie]

Area under the curve...
Something like the lowly "N" cam(066) could be the start of a fairly high performance cam! BOTH could share the same valve seat time and lobe separation angle and intake centerline. The difference would be in .050" duration and durations beyond the lift of an N cam!

"N" cam is 273/282 duration(at the valve) with .050 cam lift duration 197/206 and valve lift .420/.426 111.5 LSA/107 ICL
Change the lobe and you could get same seat time but .050" cam durations could be upped to 243/252 degrees(or more) with valve lift over .550" . They will NOT idle same or share the same power band. Torque/hp peaks would probably rise 1000 rpm or more depending on rest of combo.

Hmmm a race cam could have 273/282 duration at .050and over .700 lift at the valve same LSA/ICL...thats a bunch of area under the curve, over the curve, and a whole different planet then the cam that came in grandmas Pontiac.