mustang51js

i read a couple times that a dynojet dyno doesnt give the best hp ratings, if this is true and my last dyno was a dynojet and came out with 420rwhp. Does this mean my actual rwhp is lower and i could go a little more on the stock block.

97gold

yeah thats at the rear unless u had a engine dyno and from what iheard 420 is about far as u wanna go eith a stock block

massmustang02

Any higher and I think you'd be playing with fire. 100 or 125 shot?

mustang51js

no nitrous, just the vortech,i thought that some people said the dynojet is like 20 hp less that the other type of dyno(cant think of the name) which would mean i might go up another 20hp and then be at the max,i am going to leave it where it is but if this is true about the dyno jet it takes a little off the motor being maxed out.

mrtstang

Regardless of the dyno, 420 on a dynojet is about the max for a stock internals 2 valve. I wouldn't go any higher.

I do believe dynojets read a little higher than a Mustang dyno. Your rwhp is just a measurement of whatever formula that particular dyno uses. With that said, is a dynojet a true indicator of rwhp??? I don't know for sure. I'm guessing it depends on who you ask.

cliffyk

There is no dynamometer system that is sufficiently accurate that you should start flirting with running within 10% to 15% of engine component failure levels.

As far as inertial dyno (DynoJet) numbers versus absorption dynos (Mustang), inertial dynos are generally considered to be the more accurate, even though absorption dynos generally provide higher and more pleasing numbers.

This is because inertial dynos operate by accelerating a drum of know rotational moment of inertia, and measuring the amount of time it takes to accelerate that mass. The math required to determine the force required to spin up the drums(s) in a given amount of time is neither complex nor controversial. And as the mass of the drum(s) does not change over time, and modern elapsed time systems are far more accurate then needed, there is nothing to calibrate--only verify.

OTH, absorption dynamometers use some sort of electrical, hydraulic, or even mechanical system to absorb the power--these are all subject to variation in their absorptive qualities, both when first produced and over time. These types of systems need to be initially and periodically calibrated again known standards and can easily be "fudged" to make whatever numbers the customer wants to see¹.

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¹ - This could of course also be done with an inertial dynamometer, however it would be much more difficult to hide because the mass of the drum is listed in the systems specs and certified by the manufacturer--and, time is is pretty much a universal standard unit, difficult to muck about with.

mustang51js

thanks guys, i was under the assumption that the dynojet read higher,so my car should be what its at then. I do plan on changing the block but i thought i had a little more power in there before i was maxed out, now i just cant wait till the warmer weather.

Eagle2000GT

I too have been told over and over that Mustang Dyno's read lower than Dynojets. My experience was that they read the same. I've had tunes on both and they came out about the same. I have also heard that there a loaded Dynojets and non-loaded one. The ones with the load are supposed to be more accurate and read more like Mustang Dynos.

Mustang_NTriangle

420 on a mustang dyno is like 400 on a dyno jet. OP you are running 13 lbs of boost on a stock motor??? You got a ticking time bomb on your hands regardless of 400 or 420 rwhp. I hope you got money aside for next build.

I am assuming you are not pushing your car hard or regularity at high rpms then.

Eagle2000GT

+1

I read a post from a guy just last week that was running a similar set up but slightly higher numbers. 14 psi, 435 rwph. All boost no supporting mods. His motor lasted two months. I hope you have better luck than he did.