Vararam, OBX LTs, MRTv2...dyno results

[cntryman77]

ok, I have a Vararam cold air intake, OBX long tube headers & MRTv2 axle back exhaust...I went for my dyno run today, approximately 80 degrees, 65% humidity..manual transmission, hood open with fans, 93 octane

[Maurdib]

Originally Posted by cntryman77

ok, I have a Vararam cold air intake, OBX long tube headers & MRTv2 axle back exhaust...I went for my dyno run today, approximately 80 degrees, 65% humidity

Forgive my ignorance but does that say 273rwhp?

[cntryman77]

it says 277 with WCF "weather correction factor"

[bmorecam]

Very nicely done!

[cntryman77]

I'll get alink when the dyno shop posts the video

[OOLIE]

Nice. cntryman do you have the cat delete that comes with the OBX or did you leave your cats on

[cntryman77]

no cats

[gahammerle]

Does the Mustang dyno usually have lower numbers than a Dynojet? Or is it the other way around?

[cntryman77]

I think lower...the guy mentioned dynojets are usually 5-10% higher

[cntryman77]

did some more reasearch & it looks like the Mustang dynos are about 12% lower than a dynojet...woohoo 12% of 277 means 312 corrected rwhp...none too shabby...lol

[Beauwulf]

Originally Posted by cntryman77

did some more reasearch & it looks like the Mustang dynos are about 12% lower than a dynojet...woohoo 12% of 277 means 312 corrected rwhp...none too shabby...lol

Basically, you add 30 HP to your corrected number.... 307 then.

[bmorecam]

there's no way you could be pulling over 300rwhp with just VR intake and long tube header. Mustang dyno can be easily setup to read higher or lower. Alot of peoples say that a mustang will read lower but this is not true at all. It all depend on how the op setup their dyno. These days alot of mustang ops setup their dyno to read about the same as dynojet. No one want to go into a dyno shop and get a 20% lower reading especially to a person who really does not understand how a dyno work and operate.

good numbers eitherway tho countryman!

interesting read about dyno specifically dynojet and mustang..

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.

[PoorMansCamaro]

I agree, there's no way you have 300+RWHP. But good numbers

[cntryman77]

wow, I mentioned it as a joke...lol...the 277 is what I'll go by (see my sig) although it was interesting to see the difference discussed in a lot of forums online