Hybrid Car – More Fun with Less Gas

better mileage with higher octane? - Page 7

register ::  Login Password  :: Lost Password?
Posted by Buy_Sell on January 3, 2007, 6:47 am

Buy_Sell wrote:

Posted by Eeyore on January 3, 2007, 7:47 am

Buy_Sell wrote:

It says very little. So ?

Maybe it was found not to be terribly useful ? I can see there would be

Your turn.


Posted by Eeyore on January 3, 2007, 7:56 am

Buy_Sell wrote:

Ok. 2nd take.

I notice the comment that water injection has fallen out of interest since the
advent of intercooled turbo engines.

One problem with turbo'ing is the that the intake air becomes very hot due to
compression and the air-fuel mixture can prematurely detonate in the cylinder.

My own Saab ( lpt ) without an intercooler is limited to about 0.3 bar boost for
example to avoid such a problem..

Water injection into the hot intake air would actually cool the mixture thus
resolving the problem.

However since intercoolers perform the same function without the added
complexity of
water or water-alcohol injection there's simply no longer any need for it.


Posted by harry k on January 3, 2007, 3:41 pm

Eeyore wrote:

Used to be add-ons sold through places like J.C. Whitney.  Running the
old 30s and 40s cars, there was a very noticeable improvesment in
performance (don't know about economy) when the humidity was high or it
was raining.  Never noticed it after the advent of modern engine
control systems.

Harry K

Posted by Scott Dorsey on January 3, 2007, 3:52 pm

Water injection was a big deal in the 1940s and was used in a lot of WWII
aircraft engines.  The notion here is that you get the phase change of
the water during combustion, which produces additional effective power
(ie. more energy into the piston stroke, less energy wasted as exhaust heat)
as it turns to steam.

I don't think I have seen it on anything modern.... but it was one of
the big secret features on the B-29.

Normally it's not just water either, but a water/surfactant mixture so
that the fuel-air-water mixture would be more even.
"C'est un Nagra.  C'est suisse, et tres, tres precis."

This Thread
Bookmark this thread:
  • Subject
  • Author
  • Date
please rate this thread