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 Rhoads vmax at cruising speeds
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Corncob2061
Cochise

USA
446 Posts

Posted - 23 Jul 2018 :  11:23:45 AM  Show Profile  Reply with Quote
I recently took some time to figure what the cams specs of a crower 60919 and a melling 041 cam specs might look at cruising speeds or from 2500 rpm using Rhoads vmax race lifters. The numbers are just ball park but I thought some other folks running similar combos might be interested. I took time and mapped the lobes of both cams and worked backwards to get some specs. I just checked the intake lobes but here is the info I found.

Crower 60919 at .006 tappet lift measured 286* and 231@ .050
Melling 041 at .006 tappet lift measured 292* and 231 @. 050

Mapping the lobes and using .02 lash setting with 1.65 rockers at 2500 rpm this is approximately what I calculated the engine cam specs changing too.

Crower 60919 at a 2500 rpm 272.5* @ 006. 227*@.050
Melling 041 at 2500 rpm 276* @ .006. 227* .050

The melling lost 2.5 more degrees seat timing with the same lash setting at 2500rpm.

In an automatic car with a 2500 rpm converter the engine should never see much of a load below those rpms. Four speed car though I can see maybe some detonation issues coming into play effecting the cam that much or more below 2500 if it was lugged down.

These are just rough estimates. But if interested in this type of things feel free to chime in. Some other things that I can see being of I interest on this is setting the timing curve to utilize the changes. Also if theses two cams had a 2.5 degrees increase with the slower ramp going from 292 to 286, how about going the other way, for example a comp xe 274 has 274 .006 seat and 230 at .050. Looks to me like 7 to 8 degrees less effect at the seat comparing a fast ramp cam with 1.5s to the big seat timing cams with 1.65s.
Compare the specs of a XE274 no Rhoads to with Rhoads set at .02 @ 2500 rpm

XE 274. 274 230
60919. 272 227
041. 276 227

If you see this is off some where let me know I will dial it in
Jay



Edited by - Corncob2061 on 23 Jul 2018 12:01:26 PM

Steve C.
Chief PONTIAC

1993 Posts

Posted - 23 Jul 2018 :  2:01:00 PM  Show Profile  Reply with Quote
How many degrees duration delivered 'at the valve' under running conditions ?

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Corncob2061
Cochise

USA
446 Posts

Posted - 23 Jul 2018 :  4:37:13 PM  Show Profile  Reply with Quote
Most the numbers above are for .009 at the valve. The 1.65 rocker arms looking at the lifts and durations every .001 it appears that the 1.65 rockers add about 2 degrees maybe 3 at the most.
XE 274. 1.5 .009 at the valve 274. 230 at .050
60919. 1.65 .009 @ 274-275 and 229-230 at .050. Goes to 288-289 at .009 and .050 to 233-234 fully stroked
041. 1.65 .009 @ valve 278-279 and 229-230@ .050 Goes to 294-295 at .009 to 233-234 fully stroked





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Steve C.
Chief PONTIAC

1993 Posts

Posted - 23 Jul 2018 :  5:42:10 PM  Show Profile  Reply with Quote
Interesting tid bit. Not intake, but the Comp XE flat tappet exhaust lobe 5203 rated 230 at .050" when measured static with a 1.5 rocker ratio has 244 degrees duration 'at the valve' at .050" lift (in theory). However when measured on a Spintron machine under running conditions it had 241 degrees duration. Like a shock absorber, the lifter"gives" a little as you load it.

Edited by - Steve C. on 23 Jul 2018 5:52:14 PM
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Corncob2061
Cochise

USA
446 Posts

Posted - 23 Jul 2018 :  11:56:32 PM  Show Profile  Reply with Quote
I have read that compcams has some very very state of the art spinatrons. I always thought comp came fairly close to their advertised ratings usually slightly higher. 244 on a 230 lobe seems off quite a bit from adv specs for the xe268 exhuast profile, maybe I am not following you right on that. I have a friend running a xe 268 in a 455 with 260 cfm heads, it is runs hard to 5000. But it hits a wall when it gets there.

Loosing 3 degrees from the hydrualic cusion sounds very reasonable for a hydrualic lifter. I imagine that can vary some just based on the viscosity of the oil.



Edited by - Corncob2061 on 24 Jul 2018 12:14:37 AM
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Steve C.
Chief PONTIAC

1993 Posts

Posted - 24 Jul 2018 :  08:00:46 AM  Show Profile  Reply with Quote
Here are numbers thru the lift curve for the Comp XE Hydraulic roller lobe number 3315 rated 230 at .050". Shown is the lift point, tappet duration, and the duration measured at the valve (not running) based on a 1.5 rocker ratio:

0.006" 282 288
0.020" 257 266
0.050" 230 243
0.200" 151 185
0.400" --- 109

This lobe under running conditions at .050" tappet lift had 240 degrees duration measured 'at the valve'. Very similar to the hyd flat tappet lobe at .050" lift. But important to note is the fact that the hydraulic roller lobe has more lobe lift than the hydraulic flat tappet lobe and measured thru the entire lift curve it has 7 percent more area than the hydraulic flat tappet lobe.

They did the same thing for Comp XE solid roller lobe number 4873 rated 236 degrees at .050" lift. Note, it has six additional degrees duration at .050" lift than the hydraulic roller lobe above. Tested on the Spintron machine with the same 1.5 ratio under running conditions, and taking into account for 0.016" valve lash, they measured the amount of duration delivered 'at the valve' at .050" tappet lift and it had 241 degrees. One degree more duration than the hydraulic roller lobe at .050" and the same amount as the hydraulic flat tappet lobe previously mentioned at .050".

But again the sold roller lobe has even more lobe lift than the hydraulic roller lobe and thru the entire lift curve it has 15 percent more area than hydraulic flat tappet lobe. With this the 'bigger' solid roller will potentially make more power. That said, keep in mind the additional 6 degrees duration of the solid roller will likely raise or shift the torque curve and power curve upward some. Peak torque rpm and peak power rpm will be a bit higher. And don't forget that in real life all this is in theory, keep in mind pushrod flex, spring pressures, rocker arm flex, lash on the solid tappet and the 'give' of a hyd tappet under running conditions, etc all effect the net lift of a cam. And also as you increase the rocker arm ratio it has it's effects on increasing effective duration and intensity 'at the valve'.


Edited by - Steve C. on 24 Jul 2018 08:07:30 AM
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Steve C.
Chief PONTIAC

1993 Posts

Posted - 24 Jul 2018 :  11:57:59 AM  Show Profile  Reply with Quote
"You check a cam at .050" because it's easier to check there, and that's the only reason. At seat, the valve is moving slowly, so if you thought you were checking at .012", but were at .011" you'd be around 4 degrees off. IF you think you're checking at .050", but were really at .049", you'd be about 1/2 a degree off."

Mike Jones
Jones Cam Designs
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Corncob2061
Cochise

USA
446 Posts

Posted - 24 Jul 2018 :  2:13:21 PM  Show Profile  Reply with Quote
The .020 lash setting on the Rhoads appears to have the valve opening past the slow part of the ramp. The crower starts to have 1 degree change per .001 tappet increment after .008, 041 hits that point at .010 tappet lift. Both are easy to measure after those points, a lot like measuring at .050. I will post the numbers, they certainly are not spinatron numbers but you can see trends. Jones is right on with with what he mentions about seat timing varying.
Jay

Edited by - Corncob2061 on 24 Jul 2018 2:56:58 PM
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Corncob2061
Cochise

USA
446 Posts

Posted - 16 Mar 2019 :  02:05:10 AM  Show Profile  Reply with Quote
I never got around to posting the duration numbers for the cams I checked. Not really sure what the best way to do it would have been, a lot of numbers to decipher. But to further comment on this topic, I will post some more info, from checking another crower 60919 and a compcams XE 268. So we have measure 2 different crower 60919s, and melling 041, exhuast profile of the XE 268, which is the 5203 compcams profile that Steve mentioned, a magnum profile. Then the intake profile of a comp XE 268.

We looked into how long it took each profile to get to 1 degree per .001 lift. Which seems to be when about when the lash ramp is done and the profile really gets aggressive.

This is the order on the opening side of the lobes

Melling 041. Hit 1 degree per .001 at .010 tappet lift
Crower 60919 intake 1 degree per .001 lift at .008 tappet
Compcams 280 magnum 1 degree per .001 lift at .005
Compcams XE 268 hit 1 degree per .001 at .004 lift.

This is note worthy becuase the sooner the profiles hit 1 degree per .001 lift. The less duration Rhoads Lifter take off. The rhoads can take huge amounts of duration off the 041 compared to the XE profile.

Going from .004 tappet (SAE .006 at valve) to .006 tappet the melling 041 changed 11 degrees overall valve timing, The Crower 60919 changed about the same. The XE 268 intake changed about 7 degrees over all on the intake, slightly more on the and the exhaust, around 8. That is a pretty big difference from 11 to 7. The Rhoads would not effect the XE much, the ramps are fast.

After a conversation with Rhoads, and in the spirit of experimenting. I also checked a Ultadyne 280 solid profile to see if it would be a canidate for a solid lifter vmax conversion for racing. So we checked the UD 280 at .006 tappet, and the duration at .020 lash (where it is rated at) plus .006 tappet (.0193 total at tappet) to see the difference.

The UD280 ran 282 at .0193, at .006 it has 316 of seat duration. lol, huge change.

Then I checked a compcams MA283 profile rated with very similar seat timings. At .0193 it had 281 overall duration. But at .006 it had just 301 overall duration, which is only 3 degrees more seat timing than a XE hydrualic profile 2619 with close to the same specs, but in hydrualic. So with the Rhoads vmaxs the engine would see the full .050 duration, not .050 less the lash, and not change the seat timing that much.

So compare how much gentler the Ultradynd cam is on the valve terrain.

Ultadyne 280, 247 at .050, measure 282 at .0193 tappet lift (.020/1.5+.006=.0193) 316 at at .006

Compcams 2616, MA283 solid profile, 256 at .050, 281 at .0193 (measured), compcams rated at 283 at .020, 164 at .2, as a solid lifter cam.

But if you put hydrualic lifters on it, it would be 301 at .006, 256 at .050, 164 at .2 with .510 lift

The XE 5419 hydrualic profile advertised has 298 at .006, 254 at .050, 166 at .2 with .507 overall lift. Almost identical to the solid max area cam if the max area has hydrualic lifter on it.

Thought it was interesting how different UD 280 versus MA 283 are, and close to the same MA283 vs XE 5419 cam designs appear to be. Jay

http://www.compcams.com/Technical/Catalogs/CamLobeMasterCatalog.pdf






Edited by - Corncob2061 on 16 Mar 2019 09:57:22 AM
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Corncob2061
Cochise

USA
446 Posts

Posted - 16 Mar 2019 :  02:50:25 AM  Show Profile  Reply with Quote
quote:
Originally posted by Steve C.

Interesting tid bit. Not intake, but the Comp XE flat tappet exhaust lobe 5203 rated 230 at .050" when measured static with a 1.5 rocker ratio has 244 degrees duration 'at the valve' at .050" lift (in theory). However when measured on a Spintron machine under running conditions it had 241 degrees duration. Like a shock absorber, the lifter"gives" a little as you load it.



I miss understood this earlier. I should have read it more carefully, the 244 is a the valve, 230 multiplied by the 1.5 rocker ratio, and the 241 is the loss do to the hydrualic cusion. I have seen a couple people say that the vmaxs do not seem to have as much of hydrualic cusion and act closer to a solid cam. But only a spinatron would show if that was actually true. Jay
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Corncob2061
Cochise

USA
446 Posts

Posted - 16 Mar 2019 :  11:51:28 AM  Show Profile  Reply with Quote
Melling 041, 231 at .050 tappet

.001. 320
.002. 313
.004. 302 (SAE rating is 303) my measurement are with in 1 degree here
.006. 291. (Compcams rates it at 292)
.008. 285
.010. 279
.012. 275
At a lash setting of .020, if the vmax lifters are at half stroke, the engine would be seeing the cam as around 275 degrees duration

Compcams 280 magnum, 230 at .050 tappet (5203)
.001. 309.
.002. 306. Assymetric (Pan) 4 degrees longer on the closing from .001 to .002
.004. 288. Pan=2.4 degrees longer on the closing from .002 to .004
.006. 280 Pan= 2
.008. 277. Pan= 1
.010. 273
.012 269
Rhoads would see 269 at the same lash setting. With the Rhoads it also sees the cam as symmetrical on this profile. By the time the lifter takes out the lash, the assymetric closing side of the ramp is gone. The Rhoads take more duration off the closing side than the opening side.





Edited by - Corncob2061 on 16 Mar 2019 6:52:48 PM
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Steve C.
Chief PONTIAC

1993 Posts

Posted - 16 Mar 2019 :  12:38:15 PM  Show Profile  Reply with Quote
It was about 1990 that we first started messing with cams in my factory 400 engine, first and very briefly the Comp 268H cam. Soon yanked that out for the Comp Magnum 280H Jay mentions here. Back then many were stating the 280H was a symmetrical design, meaning both sides are exactly the same. Not so. I had a detailed print out provided by Comp that had full specs on it and it indicated the small difference in opening and closing rates.

.
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Corncob2061
Cochise

USA
446 Posts

Posted - 16 Mar 2019 :  7:35:04 PM  Show Profile  Reply with Quote
I was actually pretty impressed by the magnum profile. I was expecting it to be lazy. It really was not, plus it was more assymetric than I listed, due to rounding.

There has been some debate on what the rhoads vmaxs do to the dynamic compression on a engine. Or, if you can care less about dynamic compression, some have suggested they build to much cylinder pressure. Last week we tested those theories.

We installed crower 60919 in a 9.7compression 462 pontiac with a 4 speed behind it. We measured the cam specs in .001 increments all the way to .050, open and close. Proceeded to set the vmax lifters at .028 lash. Then went for a test drive. At 600 rpm, it idled like a stock cam. No lope at all. We drove it around, putting around making the engine lug. It picked up the load, just as though it had a tiny cam in it. Took it out to the highway, punch it and the engine shot up to 6k blazing the tires. Started in third, lugging it, then accelerated to 5000. No issues at all.

Looking at the map we made of the cam, this is the equivement cam specs at .006 the engine would have been seeing.
At idle, at .006. 251*
Half way between full stroke and idle, 263* at .006, probably around 2500 rpm.

Then we came back, tighten the lash to .015. Now the engine lopes some, lifters were a lot quieter. Then had to adjust the idle up some, to make up for the reversion cause by the engine seeing a bigger cam at idle. Still has plenty of torque, not as snappy at the bottom end.

Thought I would mention this for the people that are concerned out about rhoads causing detonation issues. On this combo, we certainly did not see any issues, and we went looking for them. The tunability gives them a lot of versality. Some time we will crank them all the way down to .005 just for comparison. Jay




Edited by - Corncob2061 on 16 Mar 2019 7:37:18 PM
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Steve C.
Chief PONTIAC

1993 Posts

Posted - 16 Mar 2019 :  11:45:44 PM  Show Profile  Reply with Quote
As this material from Harold Brookshire suggests he did the Comp High Energy Hydraulics, but also he was involved with the Magnum lobes.

He writes this well read tid bit....

"Although I have done only a few Buick cams, I have done an awful lot of Pontiacs and Oldsmobiles. Jim Butler, famed Pontiac engine builder, was my largest buyer of camshafts at UltraDyne, doing over $65,000 a year. He thought they worked very well, until the Recession of 2000 left us with an inability to keep him supplied.
As was said, 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.


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