FAO V-Bird

[user543]

Iain,
Been a while since I've had an interesting tech discussion so thought I would post something up here for you.....

Water injection is the subject but not in the obvious sense.....

Do you remember the discussion we had on the MLR about the inverted megaphone shape of an exhaust to set up the pressure waves to improve the scavenging effect?

If so then what about using water injection directly into the exhaust gases to slow them down to improve the range of rpm that you get the increased scavenging?

i.e. if you had the 'megaphone' located at a point that gave good performance improvements at low revs but then injected quantites of water at higher revs to cool the gas down and therefore get the same effect. If you used it with a programmable water injection system you could benefit from an improvement right across the rev range.

You wouldn't have to inject much water to reduce the temps enough and therefore it shouldn't cause too much of an issue with increasing back pressure.

What do you reckon?

The only reason I'm asking is that now that I'm back to an NA car the exhaust side gets a lot more complicated than on a turbo car where the bigger you can go the better (within reason)

Andy

[user540]

I will give this some thought...

[I did just receive/notice your PM...]

Happy New Year to you and yours.

Regards.

[user543]

Iain,
There are some more details about it in SAE 931506. In that paper, it relates to 2 stroke engines but I can't see why it shouldn't apply with 4 stroke as well. They are quoting low down torque increases in the order of 25% with the water injection running purely as an on/off device and not as a mappable system.

Andy