[point330]

Got on the dyno for the fist time a week ago.
I was hoping for higher figures, but my mechanic did inform me that this dyno puts out some low numbers.
Hopefully with a meth kit I am soon to install I will hit 350 hp.

[Torqu3]

Quick google search says that dyno reads 12% lower than dynojet, which is what most people use as the standard.

Those are healthy numbers for the listed mods.

[RL18]

Hm I was under the impression that dynojet read power and torque to the crank and a mustang dyno reads power and torque to the wheels... at least that's what my dyno guy said.

Either way good numbers man looks like l you're at about 360hp! you should be closer to 390-410whp with meth, I'm at 348whp 532wtq on a mustang dyno with just a tune, exhaust, air filter, and race pipe.

[robnitro]

If it's saying power at the crank, that's done with a bull crap assumption of drivetrain loss.

Some dynos use momentum to measure power which is less accurate than the eddy current ones that put a more predictive load. I'm not sure which uses what, it's been a while since I read about them.

[RL18]

Originally Posted by robnitro

If it's saying power at the crank, that's done with a bull crap assumption of drivetrain loss.

Some dynos use momentum to measure power which is less accurate than the eddy current ones that put a more predictive load. I'm not sure which uses what, it's been a while since I read about them.

I wonder what jr is using for a dyno. Because he goes off our 335ds factory crank #s instead of getting a baseline with a stock car on a dyno (like bpc who baselined at 234whp and 384wtq on a dynojet). Not says his numbers are fake but more accuracy would be nice :

Check outpost #4 I think this guy explains the dynojet vs mustang dyno well.
https://www.corvetteforum.com/forums...omparison.html

[Rjb335d]

How does the car feel?

[Persian Whisperjet]

I'd say that is very respectable, almost exactly what I got with JR 2.0 and deletes.

[Soonerbilly]

SO there's no difference between JR2.0 and 2.8?

[RL18]

Originally Posted by Soonerbilly

SO there's no difference between JR2.0 and 2.8?

Suppose to be a 36hp and 68tq difference between the two tunes... atleast that's what it says

[robnitro]

Originally Posted by RL18

I wonder what jr is using for a dyno. Because he goes off our 335ds factory crank #s instead of getting a baseline with a stock car on a dyno (like bpc who baselined at 234whp and 384wtq on a dynojet). Not says his numbers are fake but more accuracy would be nice :

Check outpost #4 I think this guy explains the dynojet vs mustang dyno well.
https://www.corvetteforum.com/forums...omparison.html

Sounds like the mustang dyno is dumb too
"
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"

First of all, your 3er and my x5 weigh differently, but on a dyno weight is not a factor but how much force/energy is dissipated by the dyno.
The hp at 50mph is also retarded... You aren't on the machine working against air resistance... And again x5 and 3er with same engine would have different factors, why?

Those constants don't make any sense if the mustang dyno was eddy current... Eddy current and the inertial mass alone should determine HP at the wheels.


Is it those calculations that do correction? In that case they are calculating a dumb assumption of drivetrain friction.

[RL18]

Well isn't vehicle weight important? It gives you real world hp and tq numbers when your vehicles on the road... of course a car that weighs 3,800lbs and suv that weights 4,900lbs will put different hp and tq #s to the ground, they have to pull their own weight. You're also comparing a rwd car to an awd suv too... there's no comparison. Both vehicles put the power down differently as well as distribute it differently.

As for air resistance I'm not sure how that'd work. Maybe the dyno adds load to the rollers to simulate air resistance.

[robnitro]

No, you have the car strapped on a machine that measures power. They do that at factories without the transmission and drivetrain. At my job we test the generators using load banks.

By the words wheel hp, means energy dissipated to the wheels. Doesn't matter if the engine was in a mack truck or a car, the same engine should not have constants added to it based on what it drives. Wheel power doesn't distinguish whether you lost 20% to awd automatic or 10% to rwd manual. My point is that factor doesn't apply when claiming power put down by the wheels to the dyno.

The output that an eddy current dyno works on is similar to a generator that makes electricity. Again, the chassis weight and aero has nothing to do with its ability to spin that roller against the load. Aerodynamics is also not in play because on the dyno the car is not losing power to aero friction.

So the same tune on the same engine on 335d and x5 35d will have different constants, while their engines make the same power? Of course on the street the 3 will be faster because it is lighter. But the hp measured by the dyno considering the weight of the vehicle is not logical...

So I am confused at those constants and if true, it explains why these dynos are so inconsistent.

[RL18]

I'm not disagreeing with you. And I'm not advocating one over the other. I'm saying that a mustang dyno gives you numbers that actually translates to your x5 or my 3er moving down the drag strip (or as close as you can get to simulating that) and a dynojet will strictly give you what hp and tq you put out to the wheels, but that doesn't mean you're putting out the same #s when you're racing down the drag strip.

Which one is more useful? That's up to you and me and what our goals are.

[robnitro]

I get your point, but a dyno measures power output, not acceleration times.
So why would a dyno need weight and air friction? That's what doesn't make sense, physics wise. The coast down on the other hand is needed to subtract out momentum and drivetrain drag.

[Soonerbilly]

And where in the hell do they get this magical "hp at 50 mph constant" or the drag coefficient? I know Uncle Google is pretty awesome but not sure that info is just readily available is it?

[RL18]

Originally Posted by robnitro

I get your point, but a dyno measures power output, not acceleration times.
So why would a dyno need weight and air friction? That's what doesn't make sense, physics wise. The coast down on the other hand is needed to subtract out momentum and drivetrain drag.

Yes you're right if you want true power to the wheels the a dynojet is the best at that. But if you want to know how much of that power is actually putting you down the road then a mustang dyno will be better at doing that.

I'm going to be getting my 3er on a dynojet soon, cause I'm curious myself how the numbers will differ, since I've already done the mustang dyno

[Soonerbilly]

RL....what all have you done to yours so we can get an idea of what #'s to expect.

[robnitro]

Originally Posted by RL18

Yes you're right if you want true power to the wheels the a dynojet is the best at that. But if you want to know how much of that power is actually putting you down the road then a mustang dyno will be better at doing that.

I'm going to be getting my 3er on a dynojet soon, cause I'm curious myself how the numbers will differ, since I've already done the mustang dyno

That will help understanding by comparing your data. If you can log boost and exhaust pressure that would be cool too!

[robnitro]

I meant if you could log it, unless they need the obd pert for the rpm reading...

[RL18]

Originally Posted by robnitro

I meant if you could log it, unless they need the obd pert for the rpm reading...

Yeah they're using obd II for rpm. Wouldn't an obd II splitter work?

[Lukec335d]

Hi all! I’m wondering if you would be ok to take a look at the dyno print out I got with a 335d I’ve just picked up. It’s had DPF delete, turbo actuators sorted and great regular servicing from previous owners. But to me, I would expect to see a much smoother power/torque curve. Should I be worried? (this remap was done 5 years ago fyi)

[tryingtobebest]

What are the mods and tuner/stages OP and Luke???