View Full Version : Overrev

01-15-2004, 03:26 AM
How much dangerous is running in overrev?
I have spin up an Piaggio Purejet to 12600rpm on the stand, after that the rev limiter turned on. On the road the revs barely reach 10000, but by designing the right exhaust I think it would be possible to achieve 12000 rpm. Would it be dangerous for the injection system to run at that rpm?

01-15-2004, 04:56 AM
hm, the question is;

how would you overrev your ditech on the road?

nobody now..maybe you?

01-15-2004, 07:22 AM
I'm pretty shure I can. I think the main thing to work on is the exhaust. But I haven't an engine to work on. The DI engine works on the same principle as the carburetted 2T-s.
Maybe we shoul wait that someone makes some software for the PC with which we would be able to remap the engine ourselves.

01-15-2004, 10:58 AM
let me explain something:

in carb models:

u can use racing exhausts; u get MORE top rpm and your scooter has bigger speed

but here in ditech models:

u have an electronical blockade of top rpm, that is way the changing of the exhaust brings only a little bit more speed; cause the motor cant rev in bigger revs

the only solution is to electronicaly remove this blockade (but there is no known way) and that the exhaust could bring more rpms to the machine

thats why...u cant do it

like u really think that u re the first one to think on something like that? :bond:

01-15-2004, 11:59 AM
Jebediah: no, that's not true. It is not the electronic blockade that limits DI engines power. It is the injection system.
An real resonance exhaust changes the ammount of fresh charge that fills the cilinder. But the injection is calibrated for the original exhaust. So the problem is that the injection doesn't spray the right ammount of fuel for the new conditions with an real exhaust. The DiTech and PureJet don't have the lambda sensor (like cars do) to correct the fuel injection.
The electronic blockade turned on at 12600rpm. That is more than enough to make good power.
However, one of these days I will recieve an DI purejet scooter, with the piaggio diagnostic tool.:D