Rev Range Question

August 30, 2010

I gather that the VVTi is a high revving engine as today on a motorway run was revving up to 4500 rpm then changing gear. In 5th was doing 70mph @ 3200rpm.

Question is at 4500 rpm (nowhere near redline) engine sounded like it was starting to scream. At what point does the VVTi max out rev-wise. How safe to take revs higher.

The acceleration was very quick, for me, anyway. Normally only do around town runs, lots of stop/start and taking it steady.

Will occasionally 'Thrashing' the engine give it a clear out or potentially cause problems.

Hope this all makes sense

August 30, 2010

its a matter of opinion amongst folk.

My RAVs, with a 3sgte engine needs to be run hard; taken to operating temp; then trashed hard to help clear the engine of gunge. but then I'm talking of almost 8000rpm.

4500 for a petrolengine is pretty low. These things run up to almost 6000- and you will know because the ecu floods the engine with petrol to minimise/stop any damage.

August 31, 2010

its a matter of opinion amongst folk.
My RAVs, with a 3sgte engine needs to be run hard; taken to operating temp; then trashed hard to help clear the engine of gunge. but then I'm talking of almost 8000rpm.
4500 for a petrolengine is pretty low. These things run up to almost 6000- and you will know because the ecu floods the engine with petrol to minimise/stop any damage.

Thanks Bothy

Just that it sounded really thrashy at 4500 through the gearbox to 5th.

Can you explain about the ecu flooding the engine to minimise damage, please.

September 2, 2010

its a matter of opinion amongst folk.
My RAVs, with a 3sgte engine needs to be run hard; taken to operating temp; then trashed hard to help clear the engine of gunge. but then I'm talking of almost 8000rpm.
4500 for a petrolengine is pretty low. These things run up to almost 6000- and you will know because the ecu floods the engine with petrol to minimise/stop any damage.
Thanks Bothy
Just that it sounded really thrashy at 4500 through the gearbox to 5th.
Can you explain about the ecu flooding the engine to minimise damage, please.

b asically the oem ecu looks after the engine and helps to stop you over-revving it by making the petrol - air mixture extremely rich which chokes the engine and gives it a max rev threshold....ie it just runs out of puff as its too busy trying to burn off the oodles of petrol...

The way you accelerate is by allowing more air (and fuel) into the engine. Now, think of it (going back to the good old days of a manual choke) you then are hurtling along at 5000rpm then pull the choke on to put more fuel in - it does just that...chokes the engine. That way you don't get to give the engine high revs and a very lean mix which could create knock and punch holes in the pistons.

Now, there's a completely unscientific way of describing it!

I have graphs somewhere which show this effect when the car was on a rolling road.