Dyno debate?

Most dynos that we have used are very operator dependent and can be manipulated to show what they want to show...... or not.

 

My take is your question has no realistic or useful answer. Machines differ and, most certainly, the 'drive train loss' ratio that is used to convert 'rear wheel HP' into HP at flywheel or crank is typically different, even manipulated by different operators, with the result that HP results differ significantly. To this add the reality that no one really knows what a correct 'drive train loss' ratio should be for various cars. It's usually imputed by guestimates.

The more useful answer to your question is (i) don't try to compare dynos, but (ii) use ONE dyno to do a 'baseline' run, and then after making modifications, do addtional runs on the SAME dyno to establish changes in HP (that you can reasonably attribute to your modifications). Indeed, that is the ONLY valuable use of a dyno at all.

I've done a lot of car mods, and a ton of dynos, and come to learn that much of the business is pure hooey, unless the same dyno, under similar conditions is used to estimate changes in 'rear wheel HP' due to modifications on the same dyno.

 

The prior posters said it right. The only comment about that I can add is if you are to use the same dyno to try and go in on a day where temperature and humidity conditions were the same as well.

Regarding surgical accuracy. The mustang aka heartbreaker dyno is more of a real world figure, but there is a far more advanced dyno on the market now which is even more accurate and even calculates exact drivetrain loss at specific rpms.

A few years back Audi/Porsche/Mercedes/BMW got together and funded a German company called machinenbau haldenwang (maha) to build the ultimate dyno. These dynos calculate bhp at the wheels and flywheel and are surgically accurate to the point that the above named manufacturers which they of course requested by built, use them in their factories daily. The dyno runs are different than other dynos and last longer. The fan system used in front of the cars is far more advanced as well and simulates real speed with greater accuracy than your average giant shop fan which every dyno shop uses. Sometimes the numbers are greater than a Mustang dyno by a few % and sometimes they are lower. Regardless, they are still lower than a dynojet by at least a couple %. An example is my 308 showed 185 on a Mustang but 200 on a dynojet. It is very common to be this different. Haven't fooled around on a maha dyno yet as there are only a few in the country around now.

 

Neither one is "more accurate".

They are measuring different things.

Jim

 

But the maha dyno *is* right. From wheels to bhp readings at the flywheel and power lost at specific rpm to drivetrain. They are as right as they get.

 

+1!