Forum » EFI Tuning Fundamentals » over 100% ve

over 100% ve

EFI Tuning Fundamentals

Discussion and questions related to the course EFI Tuning Fundamentals

Page 1

is it common to see over 100% ve on 2 valve engines. I currently tune 2 valve twin cam Harley Davidson engines and regularly see over 100% values in my ve tables even when tuning relatively stock engines with minor upgrades such as intake and exhaust systems.

The values in VE tables are supposed to represent how well the engine pumps air in and out. As a practical matter though, they are somewhat arbitrary multipliers in the fuel calculations. Sometimes it's easier to just add to the VE table to get the car to do what you want it to do. You may have some other fueling setting not "quite right" so that your VE table ends up a little higher than expected in the theoretical sense.

So your VE table says the engine has 105% VE, but realistically it may be 90 or 95% if you could actually measure it in a lab environment., We can say that because it often takes variable length intake runners or variable valve timing to get that kind of VE in reality, or a very highly tuned intake or exhaust manifold. But if punching 105% into the table gets the job done, I wouldn't worry about it.