Non-diy_efi, dyno help

[AL8001 at aol.com]

In a message dated 99-06-05 11:36:59 EDT, n5xmt at bellsouth.net writes:

>Does the IM 240 dyno use a single roller?
>If so, how do they smog the AWD vehicles?  My explorers manual states that
>for emissions checks, if it must be run on a dyno, a 4wd dyno is required.
>===========================================================
>           David Cooley N5XMT           Internet: N5XMT at bellsouth.net

Here is the scoop on the Mustang IM 240 dynos.

The unit Bruce P is speaking of was designed for Enviro Test for the never 
started,now defunct centeralized emission tests in PA.  The system is 
currently used in Ohio but dosn't use the 4 WD system.  Full time 4 WD cars 
are subject to a idle test only.

Each station in PA  had 2 or more 2 WD units and at least one 4 WD unit.  The 
2 WD unit has ~ 11" rollers( two per wheel, 4 total)  a ~ 35 HP eddy current 
absorber ( made in Brazil), 4 inertia weights ( three are clutchable) and a 
variable speed 3 phase motor ( used to calibrate the dyno for friction losses 
and to provide coast down emission testing).

The 4 WD unit had a larger 3 phase motor, 2   90* gearboxes, tractor trailer 
looking drive shaft with a ~ 5 ft spline and a rear unit that runs on tracks 
to accommodate different wheelbases.  

The IM 240 test consists of mimicking a city drive and a highway drive 
lasting 240 seconds.  As far as I know the engine is never subjected to wide 
open throttle.  The inertia weights are engaged before the test is run to 
simulate "real" road conditions.  

Mustang is only slightly helpful since the dynos were designed for Enviro 
Test and the software was written by Enviro Test.  

How do I know all of this?  I was one of the people who bought a couple of 
dynos when PA dumped the centeralized emissions test.  They are currently in 
storage until I build my new garage.  Prior to the auction, Envirotest 
crippled the systems by removing the gas analysis benches from the stations, 
removing computers and dumping programs.  


Harold