So everybody say's there is a power difference between the MD and the DJ.
My question is how much? I hit 470 on a MD before my injectors, would I be able to hit 500 on a Dyno jet?

 

yea im also curious how bigg of a diffrence i put 390 on a md i wonder how much id be on a dynojet

 

my tuner has a md he said ill be puttin down 450 but another tuner has a dj he said ill be putting down 500 for sure i sure ther are alot more variables lol

 

Way to many variables to guess. What mods do you have BTW to reach the 470?

 

Ive been checking around also and the "accepted" difference between a md and dj is about 10-12%. The dj might read higher but people have said that a md is more of actual street power.

 

Erik Koenig built 408, stage 1 243's, ms4, ls6 intake, pacesetter headers, ory, ported tb, ud crank pulley, EGR!, that was on stock injectors with the cutouts closed.

http://www.youtube.com/watch?v=P2ihJ...e=channel_page

 

There is no definate percentage or number that you can go by. I bought a H/C motor from a guy that made 463 on a mustang dyno. I dyno'd it in my car on TWO different dynojets and I made 457 and 458. THEN went to a mustang dyno that was supposivly calibrated to read like a dynojet and I made 464 there.

 

Its approximately a 13% difference between a mustang and a dyno jet. 13% of 470 is 61.1 so it would put down 531hp.

 

MOST Dynojets will show 30-40hp more than a Mustang dyno when in the 400hp range. Not all, but most in my experiance. I intend on tuning my new combo on the mustang dyno, then putting her up on the Dynojet for hp bragging rights.

 

You might be able to hit the 500 numbers, but I would expect more around the 480-490 mark. The Ls6 intake, stage 1 heads and cam are working against you in that big of an engine.

 

What exactly makes them read different?
Do they have different absorbers, maybe one shines in certain areas over the other?
Any comparison to a Super Flow or Dyno Dynamics?

 

I have written pages and pages of posts on this topic on various forums. Here's a little write up I did a few weeks ago. . .

DynoJets are inertia dynos, and have been around for years, much longer than any type of load cell dyno. Inertia dyno's work on the principle of the acceleration of a known mass over time. Their rollers are the known mass. Weighing in at over 2500lbs or so. Your car gets strapped down to the machine, and the dyno collects it's data. It is able to calculate horsepower by measuring the acceleration in rpm of the rollers in regards to RPM. This is why gearing can affect the dyno results, more on that in a bit. Now that the dyno has recorded the horsepower curve, it can take the integral of that curve and get the torque curve. Since the dyno’s power calculations are based on the acceleration of mass over time in regards to RPM, gearing is very important. Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).

Now we go to Mustang dyno’s and other loaded dyno’s. Our Mustang MD-1100SE dyno’s rollers weigh 2560lbs. That is the actual mass of the rollers, much like the DynoJet. That’s about where all the similarities end. When we get a car on our dyno, we enter two constants for the dyno’s algorithms. One being the vehicle weight, the other being what’s called “Horsepower At 50mph”. This is a number that represents how much horsepower it takes for the vehicle to push the air to maintain 50mph. This is used as the aerodynamic force. Mustang dyno’s are also equipped with a eddy currant load cell. Think of a magnetic brake from a freight train. This magnetic brake can apply enough resistance to stall a big rig. Off one side of the eddy currant load cell, there is a cantilever with a 5volt reference load sensor (strain gage). As the rollers are spinning this load sensor is measuring the actual torque being applied. So as the rollers spin, the load sensor is measuring the force being applied, sending that information to the dyno computer, taking into account the two constants entered earlier, computing the amount of resistance needed to be applied to the rollers to load the car so that the force of the rollers resistance is as close to the force the car sees on the street. The dyno is then able to calculate the total force being applied to the rollers in torque, and then taking the derivative of that torque curve to arrive at the horsepower curve. Since torque is an actual force of nature, like gravity and electricity, it can be directly measured. Horsepower is an idea that was thought up by man, and cannot be directly measured, only calculated.

I like to state it like this. . . I start by asking how much your car weighs, lets say 3500lbs. Now you take your car and you make a make a WOT rip in your tallest non overdrive gear, how much mass is your engine working against? 3500lbs right? Now you strap your car on a DynoJet and you make a WOT in the same gear, how much mass is your engine working against? 2500lbs right? Now you strap your car on a Mustang dyno, how much mass is your engine working against? 2500lbs. Plus the resistance being applied by the eddy current generator. We’ve seen anywhere for 470lbs of resistance to over 700lbs of resistance as measured in PAU force in the data logs. So which one is more accurate? Well they their both accurate. If a DynoJet dyno says you made 460rwhp, then you made 460rwhp. If a Mustang dyno says you made 460rwhp, you also made 460rwhp. Now which one of those numbers best represents what your car is doing when its on the street. That’s a different question.

The most important thing to remember is that a dyno is a testing tool. If the numbers keep increasing, then you’re doing the right thing. We try to look over at NET gain, instead of Peak HP numbers. A 30rwhp increase is a 30rwhp increase regardless of what dyno it is on.

Now I can address how to calculate the difference between one type of dyno and another. Simply put, you can’t. Because Mustang dyno’s have so many more variables, it’s not a simple percentage difference. We’ve had cars that made 422rwhp on our Dyno, two days later make 458rwhp on a DynoJet the next day. We’ve also had cars that made 550rwhp on our dyno, make 650+rwhp on a DynoJet a few days later at another shops Dyno Day. For instance, my 2002 Z28 with a forged internal LS6 Heads/Cam/Intake, makes 460rwhp on our dyno. I thought that was a little low, since I’ve had cam only LS6 Z06 vettes make 450rwhp. So I overlaid the dyno graphs. Guess what, the PAU force for my car was almost 200lbs more than the C5Z06 that made 450rwhp with cam only. So I entered the weight and horsepower at 50 number for a C5Z06 and did another horsepower rip with my car. The only reason I did that was to compare Apples to Apples. This time my car made 490rwhp, no other changes. Now I don’t go around saying my car made 490rwhp, I say what it actually did with the correct information entered into the computer. It made 460rwhp. Now if I ever get a chance to take it on a DynoJet (which I plan to in the spring), I have no doubts it’ll be over 500rwhp. I know this based on airflow and fuel consumption on the data logs.

But since we’re asked this question constantly we're fairly conservative, and hence tell our customers that the difference is closer to 6-7%, but as you make more power, and the more your car weighs, the difference increases as well. You must remember, Dyno's regardless of the type are tuning tools, and are in no means meant to tell people how fast their car is. Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalactic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coefficient, and you race on a planet called Earth, then use a Mustang Dyno

 

Great thanks for the info!
"Racing on earth!" LOL!

 

I have been to both and saw power difference between all. some dyno's just give the numbers out. I think this is due to the shop wants to make the customer happy,who knows. Ok,I took my first set up to a top shop here on the board.(can't say who because they allways seem to get upset at me,sorry) I have a 01 t.a. m6,small 222 cam,mac headers,off roads,ud pulley,factory ported heads,12 bolt 3.73's.On their dyno jet I got 424hp 407tq. the car ran 12.1@ 114 or 115mph if I remember correct. I then went to another sponsor on this site again dyno jet and got 395hp 380tq with no change between the two jets. With again no changes I went to a mustang dyno at Vector Motorsports and got 370hp 350 tq and almost cryed like a bit*h. Still ran 12.1 at track. All these dynos had no mod changes to them. Why three dynos with no changes. I added n.o.s and wanted it to be checked on the second dyno jet,but n/a mods were the same. I still use the same mustang dyno and have hit near 520hp on my 402ci. my 346ci got a best of 463hp 414tq fully built. hope this helps. mike c.

 

is there a mustang dyno in ga?

 

Wow Either you have done you're homework or you are a really good BS'er.
Thanks That is for the most part what I was looking for.
Brandon

 

If this was at Tom's, I have been on his MD dyno a number of times with a couple of different setups. I have found his dyno reads almost identical to two dynojets up here.

 

Thats food for thought??? I wonder if you tune for one or the other, youll end up faster?????

 

Ya it was at toms. I know I could hit 500 on a dynojet with the cutouts open. When I ran at Toms I still had the second cycle of break in conventional oil in it also and about 4 hours on the new block. Aren't you up North? not to many of you guys come to vancouver.

 

point me to the nearest dynojet!