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Discussion Starter · #1 ·
Hi

What is better and more accurate for a turbo engine a Dynojet or a brake dyno? If i am right they are both chassis dyno. Recently i dynoed my car on a MAHA dyno, which was i think a brake dyno. The run took about 50 sec starting from 1500rpm. Would a Dynojet show higher or lower numbers?

Thanks
 

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Dynojet might show higher numbers because the sweep is shorter. MaHa Dynos are more accurate (longer sweep). Some Bosch Dynos are known to have issues with turbocharged cars and produce far-out numbers.

Yours,

Philip
 

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Discussion Starter · #3 ·
Hi Philip

Are the MAHA dynos like the Mustang ones? And which one is being used from tuners and Manufacturers? I have read, that Dynojets numbers are 5-10 % higher than Mustang numbers. Could all these HP and torque numbers, we see on their webpages, be Dynojet based?

9-5 aero
 

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The quoted figures from manufacturers may be at the crank rather than at the wheels, a favourite of motorcycle manufacturers. At the wheel readings are lower due to loses through the drive train.
 

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Discussion Starter · #5 ·
Originally posted by Brock:
[qb]The quoted figures from manufacturers may be at the crank rather than at the wheels, a favourite of motorcycle manufacturers. At the wheel readings are lower due to loses through the drive train. [/qb][/b]
Yes they are crank Hp but corrected, and to what? (SAE, DIN e.t.c) and do they use a chassis dyno or an engine dyno (without losses)? It is like in sound area with Watts max and Watts rms! I think we must have a common line when we compaire two things.
 

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I think that an engine builder will give BHP & Torque figs at the flywheel where a car Manu factor will get these from the road driven wheels, the same way as engine tuning shops would, on a rolling road, to get this sort of thing from the engine would mean removing the engine, placing it in a jig, loading it with sensors and running the hell out of it, the sort of thing the F1 guys do. HONDA R5 engine in practice trim 1500BHP at 15000rpm, from 1.5L engine, turbo boost (I think if I remember) 4bar.
 

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I think you'll find all car manufacturers will use 'flywheel' figures as they are the highest availible and therefore the best for marketing purposes.
The fact that it is the torque at the wheels is what is accellerating you up the road escapes them somehow...
Nick.
 

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As i have understood until now it's useless to compaire dyno numbers from different dyno facilities. Thats why i opened the thread about dynos. There are so many variables, which complicate the whole situation. There are Dynojets, who give higher dyno numbers, then Mustang dynos (more realistic), HP corrected to SAE, to DIN, or not at all corrected! From a dyno to an other we could also have differencies although they use the same equipment.  [/b]
I answer this here because I think it would be off-topic in that other thread.

I think it is of use to compare dyno values from different dynos. But the dynos have to be well calibrated and operated.
Most dynos I´ve heard about in Germany, UK and Finland seem to be calibrated well. I´m not so sure about some US dynos (please don´t take this as a negative statement again).

I think the most interesting number for comparing different cars is wheel-hp / torque.

The dyno is a mighty tuning tool. Dyno runs before and after a modification show its impact and help optimising the result.


Yours,

Philip

P.S. I do not know anything about Mustang dynos, and I saw DynoJet print-outs from the US that seamed too high to me.
 

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I think the key to dyno numbers is just as Philip said. You really need to do a run both before and after the mod to gauge what effect it had. Otherwise, atmospheric conditions, location of the dyno and maybe even the operator can greatly affect the numbers. I do believe though, that we should agree to use the corrected flywheel numbers, as most good dynos can do it and will give us all a relative idea of where we stand, as that is the figure most often quoted by the manufacturers and at least in the US, the magazines.
 
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