Hi Guys,

I have been scratching my head with this one for a while now. Cant not find the answer anywhere online which points to it being a completely stupid question.
However I have no logical answer so hence the post.

When tuning a car on aftermarket management and initially setting up the fuel map you run through each RPM zone increasing throttle opening and manifold pressure.

For example at 2000 RPM you run through varying manifold pressures (-100 KPA -> 0 KPA) by adjusting the amount of throttle.

How does increasing the amount of throttle or running wide open throttle not increase RPM at the same time? I have seen videos where tuners can hover in a single RPM zone and increase the throttle opening without RPM increasing.

Do some dyno's have some sort of function to stop this?

Any feedback would be appreciated.

Thanks

 

You can apply any load you like on the dyno so as you increase the throttle, you increase the load to keep the RPM the same. Most videos show "shoot out" mode, where the load increase is held back a bit to allow the revs to rise. It's also possible to run at any throttle and alter the dyno load to allow the engine to increase or decrease rpm. This allows the tuner to check fuelling and ignition under any load condition.

 

A decent Dyno will allow you to lock load, or RPM. so in the scenario you suggest I would lock the Dyno to 2000rpm and then it will ensure my engine can't accelerate past that speed. Once I've done all the sites at that speed I will move the rpm to the next column and lock it there.

 

This video from about 40 seconds in demonstrates exactly what I'm describing. Left hand controlling rpm while I recalibrate the cells it's moving through.

 

Thanks for the reponse guys. Ironically i actually found the answer to this question as soon as i posted. Doh!

I noticed in say for example a dyno pack dyno you can set an RPM limit where the car will not be allowed to exceed and hence you can go all the way to wide open throttle.

Totally understood the different load tuning concept i was just under how this was achievable in the real world but the Braking dyno answered that.

Thanks for your input.