DIY 8 stack fuel injection

[kavi]

Hi,
Depends on cc of the engine, 40 to 50mm, some are parralel bores but most are tapered. taper from 42mm engine side to 50mm airfilterside is most common I think. There is a lot of information about this on locostbuilders.co.uk and various english ford and zetec forums.


Super cars
Sports cars

 

[Dave K]

This set-up was fabricated based on a Weber manifold. The manifold was cut to separate the banks and heavily re-worked to match a set of Yates heads. This requires a separate valley plate, but has the advantage of lower weight and flexibility to be mounted onto multiple deck height motors.
Billet alum adaptors were fabed to mount the throttle bodies. 16 total injectors are used. 8 fire into the top of the airhorns for max HP, and 8 others are mounted close to the port for best throttle response.

More pics here Racing Engines

Dave

 

[Randy V]

16 total injectors are used. 8 fire into the top of the airhorns for max HP, and 8 others are mounted close to the port for best throttle response.

Hi Dave -

Curious as to the need for two injectors with differing locations. I've not heard of mounting injectors at the top of the airhorns for max HP.
Was this done due to insufficient size/duty-cycle of the injectors?
Curious also as to the programming of the injection events and how they may be staggered, etc..

Thanks.

 

[Fran Hall RCR]

Randy,
many modern race injection system systems use two injectors, the upper injector cools and condenses the intake charge.
We did this on the IRL engines and made considerable gains.

Honda does this on some of their high end street bikes too.

 

[Randy V]

Thanks Fran... It seems I'm a bit behind the times! :stunned:

Makes sense though....

 

[Dave K]

Randy,

Yes, exactly what Fran said - thanks Fran! And very interesting to learn that this strategy is also used on bikes.

The upper injector acts as a 'fogger'. But for many race engines, ranging from F1 to V8 Supercars, the only injectors are those located at the top of the airhorns. They can get better top end HP there but can sacrifice throttle response - hence the 16 injector approach i.e. the best of both worlds!

As far as how the injectors are controlled, that can be simple or complicated depending on what's trying to be achieved. The 'simple' option is to just drive the pair of injectors in parallel for each cylinder. The more 'complicated' approach is to drive each injector separately and optimize for given set of objectives.

For the latter approach there are a couple of options for ECUs: either spend mega-bucks on an ECU that will directly drive 16 injectors or use two lower cost ECUs ganged together with each driving one set of 8 injectors.

I'm guessing that the Indy cars used the 'mega-buck' approach:thumbsup:

Dave

 

[Maurice Butler]

sequential injection - ie 8 individual control injectors are only needed at low-med rpm to reduce emmission and smoother idle once you get over 25% duty cycle most ecu start bank firing where they fire multiple injectors at once due to lack of processing time. mega squit web site MegaSquirt - Electronic Fuel Injection Computer by Bowling and Grippo ©2010 has some great documentation and information.

 

[Paul Thompson 'Hooligan']

Probably dependent upon injector type but I've seen ECUs that will run 8-inectors sequentially, happily control 16 too. The second set of 8 do not get powered until a certain point in the mapping at which point their power is enabled and the ECU then see's all 16 as 8 pairs. The smaller ones opened first and gave good idle/part throttle and emission characteristics, with the 2nd larger set providing additional fuelling when required.

Worked very well too.