[Gmecm] Understanding injection system acronyms

[William Lucke]

I have acquired two sets of 98-99 Suzuki GSXR 750 throttle bodies in 
order to go throttle per cylinder on my Cadillac Northstar. Sport bike 
throttles are very handy because they already include injector bosses 
and vacuum ports as well as a way to integrate them into a single 
actuation mechanism. The 98-99 GSXR 750's have the biggest per cylinder 
sport bike throttles (46mm). Suzuki GSXR 1300R (Hayabusa) throttles are 
much more common and are around 42mm. Beware that many of the most 
modern sport bikes use ECM controlled secondary throttles behind the 
rider controlled primary throttles to smooth the power delivery. You'll 
either need to chose a set without or remove the secondaries and plug 
the shaft holes if you buy a set with.

Also check out: http://www.msefi.com/viewtopic.php?t=6627 for motorcycle 
throttle info.

In extreme racing engines, particularly dragsters, it is possible to run 
both PFI and TBI at the same time... PFI supplies fuel at idle and low 
throttle and when the PFI injectors get maxed out, the larger TBI 
injectors start spraying. This allows the latent heat of vaporization of 
the fuel to cool the intake charge and supplants the need for 
intercooling in alcohol fueled forced induction cars.


Will



> From: "Robin Handley" <Robin at FuryWorld.fsnet.co.uk>
> Subject: Re: [Gmecm] Understanding injection system acronyms
> 
> Ah, so there can be multiple throttles/butterflies in all of them(?)
> 
> Reason for asking is that the one throttle/butterfly and injector per
> cylinder is v. common amongst my fellow car builders, and I have been
> planning to go that way (replacing my DCOE 40s) with GMECM.
> 
> Thanks,
> 
> Robin
> 
> ----- Original Message -----
> From: <davesnothereman at netscape.net>
> To: <gmecm at diy-efi.org>
> Sent: 13 May 2006 20:23
> Subject: Re: [Gmecm] Understanding injection system acronyms
> 
> 
>> TBI = injection on the atmospheric side of the throttle butterflies.
>>
>> PFI = port fuel injection, injection on the engine side of the
>> butterflies
>>
>> MPI = Mult- port injection, marketing name for PFI
>>
>> MPFI, same as MPI
>>
>> TPI, Tuned Port Injection, marketing name for specific intake system
>> using PFI and curved, tuned length runners.
>>
>> DFI, Direct Fuel injection, fuel is injected directly into the cylinder.
>>
>> Look to exotic car makers for marketing names for multiple butterfly
>> manifolds.  As far as the injection type, use the position of the
>> injectors relative to the throttle butterflies to determine injection
>> type.
>>
>> Zaphod
>>
>> -----Original Message-----
>> From: Robin Handley <Robin at FuryWorld.fsnet.co.uk>
>> To: gmecm at diy-efi.org
>> Sent: Sat, 13 May 2006 19:53:22 +0100
>> Subject: [Gmecm] Understanding injection system acronyms
>>
>>    I've been scratching my head over this for a while. Could somebody
>> tell me
>> if I've got these right:
>>
>> TBI = TPI = just one big throttle body/butterfly that feeds all
>> cylinders/ports, and one great big injector at the body
>> PFI = just one big throttle body/butterfly that feeds all
>> cylinders/ports,
>> and one injector near the engine end of each inlet runner (i.e. one
>> injector
>> per cylinder)
>>
>> What do you call a system which has multiple throttle bodies/butterflies
>> (i.e. one throttle body/butterfly for each cylinder/port) and multiple
>> injectors (i.e. one injector for each cylinder)?
>>
>> Robin