General question

[thomas walter x5955]

> From: pantera at dris.com (David Doddek)

>Tom writes:
>>On a MGB witha  5 port...

> Actually the injectors could be fires is a batch sceme twice a revolution
> and still maintain a even fuel distribution.  Firing on the open valve is a
> contriversial subject.  

Agreed with all the good stuff.

Problem with that siamese ported MGB head is if you batch inject
the fuel, that 1 and 2 will get different charges of air/fuel.

Firing order is 1 3 4 2 (standard 4 cylinder).

With cylinders 1 & 2 sharing the SAME intake port, (ditto 3 & 4),
Of a given 720 degrees of crank rotation, cylinder 2 has access
to 540 degrees intake charge, cylinder 1 has only 180 degrees.

So if you batch ONCE per revoltion... you MIGHT get a double
dose of fuel into cylinder 2, but ONLY air into cylinder 1!
Yikes.  

Admitted this applies to the 5 port head, something of which most
of the members on the list haven't seen. ;-) 

#1 INTAKE OPEN xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
#2 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx INTAKE OPEN  

   ^---------^----------^----------^----------^
   0        180        360        540        720 crank degrees

   -------------######---------------######---- worse case
												batch injection

   ---###-------###-------###---------###------- "twice per rev"
												Uh oh... 

[Please forgive the ASCII art, but this is a neat example
of odd ball problem].  ###### = injector is on.


Sigh, seems like the TBI IS the better solution for this
engine (compared to Port Injection). So I will kindly eat
my words that "port injection is preferable over TBI". ;-)

 
> By the way, I am going to turbo and fuel inject my neighbors mg sometime in
> the future.

neat... curious as to the fuel delivery system. ;-)


Cheers,

Tom Walter
Austin, TX.