Dyno test

[Drift]

Im not into tuning cars for speed, but when a car goes on a dyno bed for a test the whole point it to test engine power to Flywheel and road wheels, but Ive not seen one with a fan at the front.
I say this because most engines depend on the rush of air through the rad and intercooler to run efficiently be it diesel or petrol turbo's, so how do they account for that when measuring performance?

Just a thought.

[Sir-Doris]

Not necessarily Ste. A lot of vehicles air intakes are off to the side or away from the rush of air altogether, the Frontera being an excellent example as the air intake is tucked away in the wing. A stationary engine with a properly maintained cooling system is just as efficient as a moving one.

[Drift]

Yer, Im more thinking about the air flow over intercoolers and Radiators, as they are positioned to get the best airflow at the front in most vehicles or using a bonnet scoop.

Just say you had a super charger that would deffo benefit more at speed with an air flow

[Sir-Doris]

But wait, theres more! The Dynamometer machines you are talking about are stationary ones. There are also chassis dynamometers that measure the HP and Torque on a moving vehicle but I cant for the life of me remember how they work.

Dynos are also a tad inaccurate in real world situations as airflow, G forces and different temperatures as well as different modes of vibration in a vehicle can cause significant differences in power output.

I kind of agree with you but in practical terms..... Well..... It isnt really.

[Drift]

you been at the port

It just popped into my head the figures cant be real life accurate, they must be just a stand still bench mark, so when the car is on the road aerodynamics and engine cooling and airflow must give an edge that cant be measured in BHP or torque, though not being an expert I may have missed something there

[Sir-Doris]

Bingo!

[Drift]

[FUDDY MUCKER]

[mikey-d]

Most dyno centres do have great big industrial fans to stick in front of the cars, but tbh, they only use them to try and keep the temperatures down. Contary to your first post, I've not yet seen a dyno centre without a big fan!

[Drift]

I didnt know if they had fans or not, would that replicate wind flow at speed



Oh and Fuddy

[meooo]

when we used to tune Escorts with the old BDA engines and the like (up to 300 real BHP......not this foreign measure) the car had to be strapped down and a very large cooling fan put in front...otherwise head gaskets would blow.

When we tuned engines out of the vehicle, the amount of coolant being passed through both it and the water brake was also cooled by a fan, but the flow was altered if temps got too high.

In Vauxhalls Ellesmere Port, every car was run up on rollers, with several different fans to keep them cool.

You have to remember that as you increase speed, you also increase load so you may top out @ 60mph, but the vehicle is trying to climb up a mountain in effect......many a poorly tuned engine has died on a dyno

Even after tuning for max power on a dyno, final tweaking was usually done on/during a road test, simply because the car could be undriveable when set up for max output....then we altered carbs/air filters/timing, mostly by ear or eye .......nowadays they re-set everything with a laptop

[Mudskipper]

motor bikes are fan assisted on dynos as they usually run ram air effect on most sports bikes nowadays, thats my 2 penth worth

[Sir-Doris]

On another note about dyno's, taken from wikipedia:

Engine damage: Can dyno testing damage engines? A brake dyno, in steady state mode only provides a load that is equal the amount of power that the engine is making at any specifically selected rpm point. If the engine makes 200 brake HP at 5000 rpm, the dynamometer's brake or power absorber will provide exactly 200HP of load against it, keeping the RPM at 5000 rpm. That's a realistic load, it's as if the engine was in a vehicle pulling a large trailer up a hill. Should be no problem on the dyno - if there's no problem on the road. However, the apprehension over dyno testing and engine damage does have solid roots in fact. Old style dynamometers commonly used an inexpensive water brake type of power absorber. Load was increased or decreased by filling and draining water in the housing to change the amount of internal water volume to change the load, all the while draining and refilling the water to keep the water from boiling - It would sometimes take quite some time for the operator or computer to get inflow and outflow rates stabilized and that is the problem. It's not the "amount" of load, it's the amount of "time" spent trying to stabilize the load at the desired rpm.