A pair of 107's Samson (M120 V12) and Delilah (Stock) on the Dyno

[Roncallo]

Dyno Day at Forced Induction Motorsports South Windsor CT. For $50 each car I did them both.

Delilah up first 183RWHP 238 ft-lb
Samson up second 347RWHP 338 ft-Lb.

Delilah
Mercedes 560SL Delilah Dyno Run - YouTube

Samson
P3240068 - YouTube

[ericdee]

Thanks for sharing good to know.

[MAG58]

Do you happen to know what the RPM's for each were?

[Roncallo]

I don't have RPM. My guess is its too hard to plot against RPM with the car running through gears. It also looks like he never got into 4th gear in either car since I know these cars don't shift into 4th until about 125 MPH at WOT. I should be able to back out RPM with both HP and Torque know. I will try to re-plot by hand.

[mespe]

36 seconds to get to 110 mph on a dyno?

[Roncallo]

Originally Posted by MAG58

Do you happen to know what the RPM's for each were?

I re posted the pictures with RPM derived based on transmission and diff ratios. It is assumed both vehicles are in 3rd gear for the majority of the run as no other gear would make sense.

For Samson

Tire Rev/Mile 836
Final Drive = 2.65
Trans Gear Ratio 3.59 2.19 1.41 1 0.83
Overall Gear Ratio = 9.5135 5.8035 3.7365 2.65 2.1995
Engine RPM/Mile = 7953.286 4851.726 3123.714 2215.4 1838.782

RPM
MPH 1st 2nd 3rd 4th 5th
50 6628 4043 2603 1846 1532
55 7291 4447 2863 2031 1686
60 7953 4852 3124 2215 1839
65 8616 5256 3384 2400 1992
70 9279 5660 3644 2585 2145
75 9942 6065 3905 2769 2298
80 10604 6469 4165 2954 2452
85 11267 6873 4425 3138 2605
90 11930 7278 4686 3323 2758
95 12593 7682 4946 3508 2911
100 13255 8086 5206 3692 3065
105 13918 8491 5466 3877 3218
110 14581 8895 5727 4062 3371
120 15907 9703 6247 4431 3678
130 17232 10512 6768 4800 3984
140 18558 11321 7289 5169 4290
150 19883 12129 7809 5539 4597
160 21209 12938 8330 5908 4903
170 22534 13747 8851 6277 5210
180 23860 14555 9371 6646 5516
185 24523 14959 9631 6831 5670

For Delilah

Tire Rev/Mile 820
Final Drive = 2.47
Trans Gear Ratio 3.68 2.41 1.44 1
Overall Gear Ratio = 9.0896 5.9527 3.5568 2.47
Engine RPM/Mile = 7453.472 4881.214 2916.576 2025.4

RPM
MPH 1st 2nd 3rd 4th
50 6211 4068 2430 1688
55 6832 4474 2674 1857
60 7453 4881 2917 2025
65 8075 5288 3160 2194
70 8696 5695 3403 2363
75 9317 6102 3646 2532
80 9938 6508 3889 2701
85 10559 6915 4132 2869
90 11180 7322 4375 3038
95 11801 7729 4618 3207
100 12422 8135 4861 3376
105 13044 8542 5104 3544
110 13665 8949 5347 3713
120 14907 9762 5833 4051
130 16149 10576 6319 4388
140 17391 11389 6805 4726
150 18634 12203 7291 5064
160 19876 13017 7778 5401
170 21118 13830 8264 5739
180 22360 14644 8750 6076
185 22982 15050 8993 6245

[mender]

Sorry to drag up an old thread but there's an easier way to figure out the rpm.

Torque and hp curves cross at 5252 rpm, which is about 96 mph on the Samson chart. Peak hp was at about 102 mph or 5600 rpm.

[Roncallo]

Originally Posted by mender

Sorry to drag up an old thread but there's an easier way to figure out the rpm.

Torque and hp curves cross at 5252 rpm, which is about 96 mph on the Samson chart. Peak hp was at about 102 mph or 5600 rpm.

That assumes you know the power curves already and only gives you 1 point.

[mender]

Horsepower is calculated from torque and rpm, which means that the curves cross at 5252 rpm on every dyno sheet as long as you're using imperial units. https://www.motorauthority.com/news/1115177_why-do-horsepower-and-torque-cross-at-5252-rpm

No assumptions about any curves needed. Now that you have one accurate point, you can use that to get a correction factor.

[mender]

With 5252 rpm coming at what looks like a dyno reading of 96.25 mph, 100 mph would be about 5450, so about 4.8% more than your calculation.

Again, it looks like your peak hp was at 102 mph or 5,560 rpm. Factory peak was at 5200 rpm.

Thanks for posting the results, nice to see what the M120 can make at the wheels.

[mender]

Originally Posted by Roncallo

That assumes you know the power curves already and only gives you 1 point.

No assumptions, just math. With imperial units, they always cross at 5252 rpm.

A single HP is 33,000 pounds moved 1 foot in 1 minute. One lb of force acting on a one foot lever would travel ~6.283ft (the circumference of a 1 foot radius circle) for each revolution.

33,000/6.283 = 5252

Edit: sorry about the extra post, the first one finally showed up, so this is the short form of that one.

[Roncallo]

Originally Posted by mender

Horsepower is calculated from torque and rpm, which means that the curves cross at 5252 rpm on every dyno sheet as long as you're using imperial units. https://www.motorauthority.com/news/1115177_why-do-horsepower-and-torque-cross-at-5252-rpm

No assumptions about any curves needed. Now that you have one accurate point, you can use that to get a correction factor.

Never knew that. Thanks

[mender]

No problem.

I do a lot of engine testing on engine dynos (race engine shop) and lately have compared the test numbers from engine dyno to chassis dyno for curious customers. For the race engines I only use the engine dyno results to see how things compare year to year.

Some chassis dynos use a tach feed to get accurate rpm numbers for the graph but others just use a mph number like yours. The 5252 crossover is a useful signpost for backing good numbers out of those dyno results.

The engine dyno results I get are corrected to STP (I'm at 3200 ft ASL) and not all chassis dynos are, adding one more difference to be accounted for if they are just giving the raw dyno results.

Again, thanks for posting the numbers and your build! Wish I could have been there when you popped the hood for your naysayer!

[Roncallo]

Where are you located. I might need a dyno in the near future.

I have been toying with the idea of starting a local club of people operating a dyno shop. Sort of like what I used to do with airplanes. We had 30 members owned and operated 2 planes.

I wouldn't mind setting up a place with a hub dyno and an engine dyno.

[mender]

I'm in Alberta, Canada, so it would be quite a drive for you.