Mustang EcoBoost - Turbo 4cyl - 2.3L

310hp 350ftlb

4.7 sec 0-60mph on 3600lbs car

When revving in neutral at WOT it takes like 0.9 seconds to go from 1200rpm to 5000rpm

The physics don't seem right. So I'm thinking it's electronically limited by software to not go all out in neutral.

Since I feel like if it can take a 3600lbs car from 0-60mph in 4.7 seconds it should be able to rev itself by 3800rpm in like 0.1 seconds, not 0.9 seconds.

My question is how many times faster could cars rev if they weren't electronically limited like this? I didn't do the kinetic energy calculations to see how quick in theory it could be based on 0-60 of the car since I feel there would be less efficiency due to lower load when revving.

What could it do?

  • $\begingroup$ I think the normal justification is so they can maintain emissions compliance. The governed throttle response permits feedback loops to be effective. The sensors have a nominal sampling rate and the timing and mixture controls take time to respond. $\endgroup$
    – Phil Sweet
    Apr 2 at 11:30
  • $\begingroup$ I just noticed this was a turbo. That changes things. Until the turbo spools up, you have a lower manifold pressure than if you had no turbo. And you can only apply so much force to the delicate turbine before you break stuff, so getting it up to 200,000 rpm or so takes a second. $\endgroup$
    – Phil Sweet
    Apr 2 at 21:22

The question of how fast it will change revs is down to the amount of rotating mass.

Marketing demands a smoother engine ie driving experience which means the engineers move towards more rotating mass.

Racing tends to want the fastest speed for changing revs - allowing quicker gearchanges etc which is why race tuning goes for lighter flywheels etc, but the drivers won’t be worried about a high idle speed or a lumpy idle as they are rarely sitting at lights at idle.

And to cover the question in the title, the ecu knows which gear is selected and can/will limit the Rev range or rate of change when in neutral or when the clutch is disengaged to prevent the engine over-revving. Some manufacturers do this and others don’t.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.