"The Mustang MD250 dyno is a true loading dyno, because it uses an inertia weight as well as an eddy current motor that is attached to the rollers. This eddy current motor creates a drag on the shaft by way of electricity that causes a magnetic field to try and overcome the torque going through the roller shafts. This current is controlled by software that is always trying to simulate load as if the car is driving in real world conditions. The real benefit from the loading dyno is the ability to maintain a load that allows a tuner to properly go through a fuel map or ignition map and tune the chip for optimum horsepower and torque. It has the ability to also simulate the IM240 emissions test as required in some states. It can check 1/4 mile times as well as times for 0-60 MPH and 0-100 MPH. It can also be used for road testing and simulation for drivability problems. As a result of the loading capability, the dyno numbers from a mustang dyno will come out lower than the inertia (dynojet) dyno."[/align][/align]With that out of the way, I put down 250RWHP and 330TQ, not exactly what I was expecting. But I'm not going to say I'm unhappy! I know that most vehicles are losing~20% due to drivetrain, and the mustang dyno's post numbers another ~10% less than the dynojet dyno's. So I expected the HP to be a little higer and the torque to be a little lower. [/align][/align]Stock these motors are rated for 340HP and 390TQ, so I didn't lose much TQ, but lost a lot of HP. [/align][/align]I am going to go back and do some more runs on the mustang dyno, and then maybe find a dynojet in the area for comparison.[/align][/align]The smart-tach wasn't working when I made my dyno run, so they invited me back next week to try and post some better numbers.[/align][/align][/align]The automatic transmission made things kind of a pain in the butt.[/align][/align]

 

I believe the stock Ram Hemi is rated 345 hp and 375 lb/ft of torque. Even then, I believe it is understood thatthe hp ratingis a little generous.

I think the Hemi in either the Chrysler 300or Dodge Charger is the one tuned to 330 hp and 390 lb/ft of torque.

 

Yeah, kinda funny they got it backwards and gave the trucks more hp and the cars more torque....

 

just a question but I know me when I think high performance engine I like having a standard tranny mated to the engine. why doesn't dodge offer a stick shift for the hemi. I'd still rather have the hemi since the mileage imo isn't too bad and the 4.7 doesnt do much better but it just seems more logical to have a manual

 

Hey Rob, a question for you.

I've never done a dyno run before, you said "automatic transmission makes it a pain". How exactly does the dyno run go that makes that a pain? (just curious!)

Thanks

 

As a guy who has made well over 100 runs on a dyno, I can tell you that it makes no difference if your an auto or a manual, if you know what your doing. In a manual, you put it in 4th, get up to @ 1000 rpm, and then make your pull to redline. In an auto, its no different. You get to a speed fast enough in THIRD gear (or whichever is your 1:1 ratio) to keep the transmission from downshifting. Usually, its @ 2000 rpm (above your stock stall speed in the converter) in most stock vehicles. Then you can make your pull, staying in one gear, and get a solid chart. Of course, when you upgrade your converter to say a 2800, your run most now start at 3000 rpm to keep it from downshifting to another gear.

When you redo your dyno, take my advice and you will see a HUGE improvement in your numbers. And by my math, a manual loses 15% and an auto loses 18-22%. So if you are rated at 345 at the motor, you should be making 269 on the low end and 283 on the high end.

 

when you do a dyno run, to get the most accurate numbers the run has to be done in a direct drive, usually 3rd gear. if the run isnt done in a direct drive gear then the numbers will be higher because of the torque being multiplied by the trans. having an automatic makes it harder because you cant always keep it in a direct drive gear. hope that answers your question

 

Yeah, the problem was trying to keep it in one gear. The first run we calibrated the Dyno @ 3100rpms and I had the truck in second gear @ 70km/h because pretty much anything lower than that, and the truck would downshift into first gear and ruin the run. There's no way I'd be able to get it into 3rd gear and stay there.[/align][/align]

 

sure there is. When I had my 98 camaro, I would have to be @ 80mph in third just to be at a high enough rpm so it wouldnt downshift. Dont be scared brutha!

 

rob, i'm puttin my truck on the dyno sometime this week during class so if i get something figured out how to keep it in 3rd i'll repost it and let ya know