First Dyno Run

[Tom1]

I was invited to go with a friend to the FordDeiesl.com dyno run up in PA. I Just went to watch. 4 of the ten trucks scheduled for the dyno didn't show so they let me run my truck. Three runs 408. 9 410. 4 409. ? I kept blowing the exhaust hose in two pieces. The runs were done all in 4 gear with a rolling start at around 40mph. Top speed in 4 as measured by the dyno was 109mph. They couldn't hook up to the tach to get the torque reading. If any of you number crunchers know how to figure it out please do so and post it. 17% driveline loss gives me 480. 17 at the flywheel. 410. 4hp at 2550 rpm at 75mph in 4 with 36" tires and a 3:54 gears. I know the speedo is off with the tires but we got the rpm at 75 using David's GPS system on the way home. I also couldn't get full boost on the dyno. I only boosted to 37-38lbs when on the street I go to 45-46lbs on a good hard pull. Thanks for the help.

Tom

I had a great time with the ford guys. There was no brand bashing and I have made some new friends. We are all working for better perfomance for our diesel engines. Look at their site and try to go to one of there events. They are great people and very helpful.

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Smoker
96 2500 4x4 nv4500 3:54 slt 3"body lift 2. 5" suspension by skyjacker 267/75/16 street tires 36/12. 5/16 swampers for mud silencer ring lost 5" pipe borla KN round style filter JRE stage 4 400hp JRE afc spring kit boost and pyro gauges 16 housing pump timed and 3000rpm limit now 4200

 

[DBR]

Tom, congratulations on the dyno numbers. I was curious as to what your Egts were. How did the Ford trucks do? I have to admit that I have been looking at the Ford four doors as Dodge hasn't woke up yet in that department.

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97 SLT 2500, 5sp, 3:54, 255/85/16, US Gear Under-drive, BD Hx40-16cm, BD 370 injectors, TST #10 plate, BD full 4" exhaust, Centerforce Clutch, BD Governor Kit, Rancho 9000's and a few other items with a lot more on the shelve!

 

[Tom1]

My egt's only went up to 1250 to 1300 max. Check out the ford site for the numbers. I know on turned a run of 348hp. David turned a 244 in his truck with a chip. They are going to be posting a graph of all the runs under events and rallies dukes dyno days. I do have a big problem with egt's on the street with my current setup. The dyno just didn't work the truck that hard.

Tom

 

[rich m]

Originally posted by Tom:
. 410. 4hp at 2550 rpm at 75mph in 4 with 36" tires and a 3:54 gears. I know the speedo is off with the tires but we got the rpm at 75 using David's GPS system on the way home.
Tom

Hye tom---400+ is cool---- TQ and HP and RPM are all "married" mathematically to a "constant" of 5,252

I'm ad-libbing, so let's see how the #'s turn out... should be about 850lbft if i put the #'s in the right spots

HP=TQxrpm/5252

410. 4=TQx2550/5252

410. 4x5252=TQx2550

410. 4x5252/2550= TQ

845. 26... =TQ

This torque # should be less than your "peak", which would have happened in the 1500rpm range. If the machine is a Dynojet, and you got a printout, you can use that math formula figure out the torque over as much of the range as was "stable" for graph purposes...

for example, here's a bad-quality image of my graph that I got at Dyno Day here in LV in Nov2K #ad


it shows a wide,flat HP plateau (solid 240 with a 250. x peak) from 75mph all the way to 98mph drumspeed... . the torque calculation was 568lbft @ 75ish and dropped to 450 at 95+... HP was nearly constant... . problem is: he didn't start to "read" the output at a low enough speed to catch and record the HP from 45-55mph where the torque peak should have happened. that will remain a mystery, since there's apparently no formula to extrapolate it... (curve isn't just linear/flat, so we can't just divide here and multiply there to derive it... )

 

[HEMI®Dart]

Tom, Those are Great Dyno numbers. #ad


I am shooting for those kind of numbers this summer.

Rich m,

I have a question. I understand when you say TQ and HP and RPM are all "married" mathematically to a "constant" of 5,252.

But if we built a 340 ci V-8 Chrysler to 410. 4 hp, no way would it produce 845. 26 ft lbs of torque. The 528 ci V-8 Mopar Crate HEMI is rated @ 610 HP & 630 ft. lbs torque.

See what I'm asking? #ad
I'm not that good in math #ad


How do you figure in the mega torque the Cummins makes in your calculations?

UPDATE: I think I may see it now. Peak HP at a lower rpm makes for more torque?

Bill R
94 2500 SLT 4x4 5 Speed, 3. 54 LS, JRE 4" exhaust, Autometer Pyro, Boost & Water temp gauges, Bosch 215 HP injectors, Timing @ 14. 7º, JRE Stage III #4 plate 270/675, AFC spring kit, Scotty Air, Bully Dog Propane Injection, Roadmaster Active Suspension, Optima Red Tops, Geno's Exhaust Blanket, Espar Heater (won it!), Synthetic lubes throughout.



[This message has been edited by HEMI®Dart (edited 01-23-2001). ]

 

[dieselburner]

UPDATE: I think I may see it now. Peak HP at a lower rpm makes for more torque?[/b]


Indeed.

 

[rich m]

To be honest, I "stole" the formula from a different post, so I don't know if the 5252 is a universal constant that works from Poulan all the way to a Terex and beyond, or if the 5252 is a constant that has to do with cylinder count and displacement... I'm thnking its universal, and even a low HP number can still yield a MONDO torque if the rpms are low enough... . engineering/physics guys, where are you to confirm/correct or clarify????

 

[DHRA]

Makes you wonder, I saw a dyno run with a 24v that had 384hp and 1036 torque.
If I calculate that out, I end up with only 1946 RPMs. I now they had her spinning faster than that.

 

[Steve St.Laurent]

That formula is a constant. The reason you can't just use the HP peak to get torque and vice versa is that the HP and torque peaks are at different RPMs.

-Steve