Subaru TBI

[dzorde at erggroup.com]

>Date: Tue, 7 Mar 100 10:46:38 +0800 (WST)
>From: Bernd Felsche <bernie at perth.dialix.com.au>
>Subject: Re: Subaru TBI
>
>>On a different note.  I just picked up a Subaru TBI (centre point injection,
>>think its of a 1.8L import motor), the injector is a 1.6 ohm unit.  Can
someone
>>tell me if this has to be driven as P/H or whether it can be driven as
saturated
>>(if so does it need a resistor ?)
>
>No resistor required. Injectors are normally driven by sinking
>current through them; no "ballast" required. The duty cycle of
>pulsing determines the flow.  No fancy timing requirements.  It's
>just a cheap way of implementing an electronically-controlled
>carburettor. ;-)

True, but at only 1.6ohm, this poor little thing would be sinking around 8.5A if
operated as a standard saturated injector.  Whereas if operated as P/H this
current would drop back to 1A or so after switch on and just hold it open.  I'd
prefer to operate it as saturated as this is what my ECU is designed for, but I
don't want to fry the injector.

>You may be better served with a multi-point injection system. The
>TBI system you're using is probably limited to delivering enough
>fuel for maybe 75kW.

The 5 port head design (1 inlet, 4 exhaust) doesn't allow for port injection
unless I make some extremely radical head design changes, to physically fit the
injectors in the head (going to be extremely hard to weld). I can always add a
2nd staged injector, the ECU has the facility for it.  Could even add this
before the intercooler to get a bit more of a cooling effect.

Dan  dzorde at erggroup.com




----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org