Cam Analysis Paralysis
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Billa,
If you wouldn't mind that would be great. Maybe the xe268 vs the xe274 w/my combo? BTW I'm running the XE262 in my Pontiac for about 8 years with no issues. It's doing what it should the car runs 13.8's on street tires with a 9.1 compression 400. I've got no issues with comp.
BTW is it worth looking at Rhodes lifters to try and boost up the vacuum?
If you wouldn't mind that would be great. Maybe the xe268 vs the xe274 w/my combo? BTW I'm running the XE262 in my Pontiac for about 8 years with no issues. It's doing what it should the car runs 13.8's on street tires with a 9.1 compression 400. I've got no issues with comp.
BTW is it worth looking at Rhodes lifters to try and boost up the vacuum?
I kinda stopped doing this on the forum after a while as it got a bit out of hand...but I have models for the engine, heads and cams, so it's pretty quick.IMHO, you're not going to have vacuum issues with that cam - it's just not that radical with that much overlap.
Drifting
Joined: Sep 2010
Posts: 1,412
Likes: 50
From: Laguna Niguel California
Here's another two cents worth. You're off to a good start with changing heads. Go the extra dollars for a hydraulic roller setup. You get more charge volume with a less radical cam and increased reliability. If you don't install a roller setup you'l be asking yourself in a few months, why didn't I do it the best way when I had it apart?
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
Just saw the mention of Rhodes lifters. They do work as advertised, bleeding down lift at low rpm, almost making it seem like you're running two different cam's. The hot rod power boaters like them, but they are very noisy. Even worse than solid, non hydraulic tappets. Crane Hi Intensity lifters bleed down too, although not as much and are quiet. What my street builds are using. Have a set of Rhodes in my basement, and if you open them up, the piston has a groove cut in it. The Cranes just go with a little more internal piston fit clearance.
Thread Starter
Advanced
Joined: May 2008
Posts: 81
Likes: 0
From: Annandale Virginia
Thanks!!!
I'll run them tonight and post - I can do the Voodoo too I kinda stopped doing this on the forum after a while as it got a bit out of hand...but I have models for the engine, heads and cams, so it's pretty quick.
IMHO, you're not going to have vacuum issues with that cam - it's just not that radical with that much overlap.
I kinda stopped doing this on the forum after a while as it got a bit out of hand...but I have models for the engine, heads and cams, so it's pretty quick.IMHO, you're not going to have vacuum issues with that cam - it's just not that radical with that much overlap.
Last edited by 68FireBird; Sep 8, 2011 at 08:55 PM.
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
Two cams with the same lift and opening and closing points will be "scored" identically by Desktop Dyno.
It doesnt consider the shape of the lobes at all. Because of that it will show the same output for a 40 year old cam design as for something very modern.
It doesnt work that way in real life.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Camquest is junk, but DD Advanced does model the lobe to some extent with an acceleration profile. It's certainly not as sophisticated as other more expensive tools - but it certainly does simulate the difference between older cam profiles and modern roller-type profiles.
I generally find that the curve and numbers are within a few percent of what I find on the dyno.
I generally find that the curve and numbers are within a few percent of what I find on the dyno.
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
Camquest is junk, but DD Advanced does model the lobe to some extent with an acceleration profile. It's certainly not as sophisticated as other more expensive tools - but it certainly does simulate the difference between older cam profiles and modern roller-type profiles.
I generally find that the curve and numbers are within a few percent of what I find on the dyno.
I generally find that the curve and numbers are within a few percent of what I find on the dyno.
I have Desktop Dyno on the computer I'm using, but havent played with it in a while.
I opened it up after reading your post, and it obviously does have some ways of estimating ramp rates.
Maybe I was thinking of the original version I had. Oh well, I guess I blew that one.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Used Rhodes lifters on a couple older builds they were auto cars and loved the way they work. They make a roller lifter version of it too from what I understand. Good stuff
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Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Finally :)
I finally had time to do the DDA runs this AM - sorry; been a crazed week. The attached Excel file has the data and an associated graph.
I found the information really, really interesting! The Voodoo cam strongly outperformed the XE268 in TQ through about 4,000 RPM. The XE268 turned the tables on HP at about the same RPM.
The XE 274 gave up significant TQ below 4,000 RPM in exchange for 12 peak HP...IMHO, not the right trade-off unless you're regularly turning to 6K. I would expect a single-plane would show more high-RPM benefits...but with the dual plane the decision IMHO is between the Voodo and the XE268 and dependent on your driving style.
I'll add the caveat that DDA data is as good as the models - no warranty expressed or implied These models are pretty decent, and I'd be pretty comfortable with the comparison and *reasonably* comfortable with the numbers; the HP numbers are usually pretty close, TQ is usually 5%+ optimistic.
<Nomex ON> and ready for the shots to be fired
I found the information really, really interesting! The Voodoo cam strongly outperformed the XE268 in TQ through about 4,000 RPM. The XE268 turned the tables on HP at about the same RPM.
The XE 274 gave up significant TQ below 4,000 RPM in exchange for 12 peak HP...IMHO, not the right trade-off unless you're regularly turning to 6K. I would expect a single-plane would show more high-RPM benefits...but with the dual plane the decision IMHO is between the Voodo and the XE268 and dependent on your driving style.
I'll add the caveat that DDA data is as good as the models - no warranty expressed or implied
These models are pretty decent, and I'd be pretty comfortable with the comparison and *reasonably* comfortable with the numbers; the HP numbers are usually pretty close, TQ is usually 5%+ optimistic.<Nomex ON> and ready for the shots to be fired
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
It's nice to see data plots, but there is some bogus data for the XE274 cam as the lines for HP and torque do not appear to cross at 5252 rpm. Suggest to recheck the numbers, and also, make the colors for torque and HP the same color for each cam.
Thanks
Thanks
Thread Starter
Advanced
Joined: May 2008
Posts: 81
Likes: 0
From: Annandale Virginia
Thanks
Billa, thanks for the DD analysis. Kind of surprised that there isn't more HP with the xe274 cam. That voodoo cam is interesting especially if the car is going to spend most of it's time between 2 and 4 thousand RPM. If you have a minute would you be able to run the voodoo 60103? I wonder if it has the same kind of curve?
Burning Brakes
Joined: Feb 2011
Posts: 849
Likes: 0
From: Woodland California
I finally had time to do the DDA runs this AM - sorry; been a crazed week. The attached Excel file has the data and an associated graph.
I found the information really, really interesting! The Voodoo cam strongly outperformed the XE268 in TQ through about 4,000 RPM. The XE268 turned the tables on HP at about the same RPM.
The XE 274 gave up significant TQ below 4,000 RPM in exchange for 12 peak HP...IMHO, not the right trade-off unless you're regularly turning to 6K. I would expect a single-plane would show more high-RPM benefits...but with the dual plane the decision IMHO is between the Voodo and the XE268 and dependent on your driving style.
I'll add the caveat that DDA data is as good as the models - no warranty expressed or implied These models are pretty decent, and I'd be pretty comfortable with the comparison and *reasonably* comfortable with the numbers; the HP numbers are usually pretty close, TQ is usually 5%+ optimistic.
<Nomex ON> and ready for the shots to be fired
I found the information really, really interesting! The Voodoo cam strongly outperformed the XE268 in TQ through about 4,000 RPM. The XE268 turned the tables on HP at about the same RPM.
The XE 274 gave up significant TQ below 4,000 RPM in exchange for 12 peak HP...IMHO, not the right trade-off unless you're regularly turning to 6K. I would expect a single-plane would show more high-RPM benefits...but with the dual plane the decision IMHO is between the Voodo and the XE268 and dependent on your driving style.
I'll add the caveat that DDA data is as good as the models - no warranty expressed or implied
These models are pretty decent, and I'd be pretty comfortable with the comparison and *reasonably* comfortable with the numbers; the HP numbers are usually pretty close, TQ is usually 5%+ optimistic.<Nomex ON> and ready for the shots to be fired
Does the numbers reflect headers and what size Carb?
Which heads?
Also does anyone know of an artical with the 60102 in a small block?
I too would like to see the 60103 in a chart.
I'd like to see what I'm missing
Thanks so much
Ralph
Last edited by Ralphbf; Sep 12, 2011 at 12:59 AM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The XE 274 would deliver more power with a better intake, I think.
I'll try to run the other Voodoo cam tomorrow or later this week - traveling a bit, so don't have all my "tools" with me
I'll try to run the other Voodoo cam tomorrow or later this week - traveling a bit, so don't have all my "tools" with me
Thread Starter
Advanced
Joined: May 2008
Posts: 81
Likes: 0
From: Annandale Virginia
Thanks
Bill,
Thanks for your help. I assume the combo will make more power with the Performer RPM? I think I'll go ahead and use that. I'm curious to see the results of the Lunati 60103 cam. All set to place my parts order otherwise.
Mike
Thanks for your help. I assume the combo will make more power with the Performer RPM? I think I'll go ahead and use that. I'm curious to see the results of the Lunati 60103 cam. All set to place my parts order otherwise.
Mike