[Vwdiesel] Diesel braking - again

[Roger Brown]

Erik Lane wrote:
> 
> sorry, i guess i misunderstood and took what you were
> saying a little too literally.
...
> but that's my point - everyone DOESN'T agree that a
> gas engine has more braking. that was my question, or
> at least the why's of the difference. my diesels
> always seemed to engine brake VERY well. problem is, i
> haven't had a chance to directly compare two simliar
> cars with different engines.

I think there is a little more braking in a gas engine with throttle closed than in a
diesel.  A lot different, no (like within a factor of 2).  I find my '82 Caddy w/ 1.9D
engine brakes about as well as my old Landcruiser (~5500 lbs, 3800cc engine), but
it was a fairly low compression engine (~7:1). I guess someone with two similar vehicles,
one gas and one diesel could stage a downhill coast test to answer it once and for all.
And my current 4Runner (2400cc engine, 4600 lbs, 9.2:1 compression) does
out-brake the Caddy.  You can really feel the drag increase as you back off the throttle
and watch the vacuum gauge climb.  And at higher elevations, where the max. vacuum drops
from 25 down to the 15-20" range, you can feel the loss of engine braking.

Here's some info. on-line:
	http://www.dieselpage.com/bdebm.htm
	http://www.bankspower.com/tech_howexhaustbrakeworks.cfm
	http://www.humvee.net/hid/engine/engbrake.html
	
The search used to find this:
	http://www.google.com/search?hl=en&ie=ISO-8859-1&q=Compression+Braking+Gas+Diesel+Engine


--
	Roger