Sequential Setup?

[RAGHBIR SIAN]

>At 03:40 PM 2/8/96 CST, Tom wrote:
>
>>At idle and partial throttle is where you would expect the
>>largest gains in performanace/economy. I have heard figures
>>ranging from 2% to 10% improvements by properly timing
>>the injection on sequential injections. 
>

 At 21:58 -0500  08/02/96, Peter Wales wrote:

>We did a lot of tests on the dyno on exactly this and found NO improvement
>in power. The reason is simple, you need air, and fuel to burn in it, and if
>you have the right amounts of each you will get the most power.
>
>The economy was another matter altogether. By timing the injection so that
>there is the minimum time for the fuel/air mixture to sit in the inlet you
>got the most economy. This is because the droplets coalesce and form larger
>droplets, which take longer to burn. Hence you need more of them to get all
>of the air used and thus economy suffers. I was given the parallel of the
>droplets being like onions, you need to burn off each layer until they are
>all gone, the bigger the droplet the more layers.
>
>
>>For sequential injection, most common method, is to time
>>the injector to CLOSE with the closing of the intake
>>valve. 
>
>Exactly
>

Peter may i ask you how this particular research was carried out (i mean on
an Engine dyno or Chassis dyno)? 

The reason i ask this is because you CANNOT quantify any results without
looking into mixture preparation, temperature's of the inlet valve, fuel,
inlet manifold wall,  port velocity  and also the differential of pressures
in the inlet ports, Combustion chamber and the exhaust ports, preparation of
air prior to fuel injection, fuel droplet size.............. also how the
engine air is polled (Queing)........ i could carry on but have decided to stop.

You said that there were No improvements in power 

Well i must say different.
I carried out some (well alot of) research on this subject from a combustion
point of view. I saw a reduction in harshness (uneven combustion) and
INCREASE in Power (Torque) when you FINISHED or JUST FINISH injecting the
fuel just before the inlet valve started to open. 

I am also assuming that you did your tests at a steady state. Test done in
steady state only sometimes give you an increase, but mostly show NO
increase in power.

The only way to see the effects of the above is to be in constant TRANSIENTS
which is were our engines spend 80% of their time.

I cannot say alot more than this as i am contractually bound but if you
would like me to expand on this then i will certainly try my best within my
constraints. 

The other thing that really gets up my nose is when people say that they
have an increase in power but no increase in torque. These two items are
interelated.

I do beg your pardon for any spelling or typing errors made.

Regards

R.S.Sian
  

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                     Raghbir Sian    
  Engine Control and Combustion Analyst

"As Always A ***CONTROL*** Freak"
A committee is a group of the unwilling, chosen from the unfit, to do the
unnecessary....   Anonymous
Life is just one damned thing after another...  Joseph Heller
Time spent on any item of the agenda will be in inverse proportion to the sum 
involved.

E-mail: sian at mail.bogo.co.uk
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