Playing with Desktop Dyno

[FSJ Guy]

I was playing with Desktop Dyno and different cams this weekend. For a 401 motor, I plugged in a 9:1 compression, dual plane intake, headers and stock head flow #s found on the internet. :-/

Someone posted up that they liked one of the Lunati cams. It showed a nice flat torque curve up to 3500-4000 RPM.

I was really impressed with the Lunati until I plugged in the #'s for Edelbrock's Performer Plus cam and it showed very similar numbers. (and much cheaper, too!)

The Lunati showed slightly higher HP numbers (10 HP more at 4500 RPM), but my motor will never see those RPMs. The Performer Plus had ever-so slightly higher HP numbers from 2000-4000 RPM.

The Performer Plus shows slightly higher torque and peaks at lower RPM than the Lunati. (446 ft-lbs at 2500 RPM instead of 434 ft-lbs at 3500 RPM)

It is interesting to see the torque curves for the different cams and how the curves match up to the "claims". Most AMC cams are biased towards high RPM racing applications and the so-called RV cams
aren't terribly impressive.

The image below shows the curves and the numbers, too. (The Lunati is labeled AMC 501.)

The BLUE BOX is next to the maximum torque/HP for each cam. The RED BOX is next to the cam and corresponding # that is the highest for that given RPM. As you can see, the Performer Plus cam is better from 2000 rpm up to just under 4000, where the Lunati takes over.

http://bigscaryjeep.com/burrito/shot1WEB.jpg


I don't expect to get anywhere NEAR these numbers, but am using it more to see what the torque curve is with the difference cams.

[crazydog]

Which Lunati did you use? It would be interesting to see how the Desktop Dyno compares to my actual dyno runs.

[FSJ Guy]

That was the 64501 cam.

[JeepMods]

The heads will struggle to let the HP & torque numbers match that of the desktop dyno... Figure 8% to 10% less from the max numbers on the chart, this will put you pretty close to the actual numbers.

[Heavy_Metal_Thunder_81]

where can i get desktop dyno???

[FSJ Guy]

The heads will struggle to let the HP & torque numbers match that of the desktop dyno... Figure 8% to 10% less from the max numbers on the chart, this will put you pretty close to the actual numbers.

I wasn't expecting them to be anywhere near the computer's numbers. I was just using it to compare between the different cams. If it ends up with more torque than my tired 360, I'll be happy. :rolleyes:

I'm going to see how much it would cost to have some porting done on the heads. It might not be affordable at this point, however. Not a big deal, since I can replace the heads later much more easily than I can replace bottom end stuff.

[FSJ Guy]

where can i get desktop dyno???

Google it. About $50, IIRC.

[Heavy_Metal_Thunder_81]

Oh I thought it was a free program like a tire/gear/mph calculator...bummer...

[Ghinmi]

I wasn't expecting them to be anywhere near the computer's numbers. I was just using it to compare between the different cams. If it ends up with more torque than my tired 360, I'll be happy. :rolleyes:

I'm going to see how much it would cost to have some porting done on the heads. It might not be affordable at this point, however. Not a big deal, since I can replace the heads later much more easily than I can replace bottom end stuff.

I've actually found it to be pretty accurate for the couple of engine builds I've done. The only question is why the low compression? Wiseco has some very nice forged 9.5:1 pistons out now...

[mud89]

By the way desktop dyno and similar fit figures published by Jeep for the 360, and doesn't fit figures published by Jeep for the 401 with the stock cam ??
published Stock cam timing for the 401 seem weird

[JeepMods]

Yup, I have to agree with the compression... bump it up a little... 9.5 to 10.2 and a little port/polish and gasket match and she'll be around those numbers... Imagine 58 to 64cc heads on an AMC that flowed 250 intake and 180 exhaust @ .550" lift.. man we'd be talking

[Ristow]

i like the performer grind. it gets a bad rap for some reason. the one in my 360 pulls hard to well over 5000 rpm.

you can get a performer grind from P.A.W,it'll be an Elgin cam. Elgin supplied/supplies a lot of oem cams.


i have two 8600's. not impressed at all.

[FSJ Guy]

I'm trying to stay with regular octane (85 out her in CO). Can you do that with 9:1 or 9.5:1????

If I need to bore it out, I'll need new pistons anyway....

[Ristow]

my stroker @ a bit over 9.25cr-and rhoads lifters which increase dynamic compression- burns 87 octane fine.

[FSJ Guy]

my stroker @ a bit over 9.25cr-and rhoads lifters which increase dynamic compression- burns 87 octane fine.

Is that regular in your neck of the woods? Here, in CO, 87 is mid-grade.

[JeepMods]

Is that regular in your neck of the woods? Here, in CO, 87 is mid-grade.
How much is 87 over there? Over here in Va it's $2.56 a gallon (as of 2 days ago)

[Ristow]

87 is our regular grade here.

[JeepMods]

Same her... 87 is the low jack.

[FSJ Guy]

87 is our regular grade here.

Thanks. I couldn't remember what elevation you were at. :D

"Regular" varies with elevation.

So you've got a 9:1 compression piston and don't have problems. Good to know. I'll talk to my machinist and see how much more of my money he can take. :D

[Ghinmi]

A lot of it depends on your quench and cam timing. You can ping @ 9:1 on a poorly planned motor or get away with more if you do things right. My last motor was at 9.7:1 and had no problems on 87 (regular here). It never pinged even at 38 degrees timing (didn't make the most power there, but still...)