Quad throttle injector options

[jezza323]

Im putting some motorbike quad throttles on my toyota. The throttle bodies are CBR600RR and have injectors mounted in the throttle bodies, just after the throttle plate and at quite a shallow angle to the runners.

Which injectors will give the best fuel/air mix into the cylinder? I can use either the standard injector location which is injector mounted in the head, or the injectors in the throttle bodies. The manifold will only be around 70-80mm from the head flange to the injector in the throttle bodies

Thoughts opinions pls?

[Ben Wilson]

Is it a street car or a track special?

For street use, I'd go with the factory injector location, at a guess, the outboard injectors should be good above 5-6k or so...

[jezza323]

its for a street car

just to make sure im clear the throttle body injectors are on the head side of the throttle plates

[Sam_Q]

can you show a pic?

[jezza323]

yeah ill get some pics of the throttle bodies up tonight, cheers

[jezza323]

here are the pics

[Ben Wilson]

Are they like the GSX-R ones in that the injector fires into the side of the throttle plate at WOT?

[jezza323]

nah, they are just after the throttle plate, even at WOT, but i would think the throttle plate would introduce some turbulence and give a more even mixture

but then the fuel is more likely to stick to the runner walls at low RPM.......maybe i should just use both sets of injectors...both at the same time though....dont have staging on the ECU im gonna use. should give best of both worlds....and i will be able to run quite a small duty cycle that way...maybe even too small

EDIT: actually the ECU does do staging, but only 2 outputs upto a certain load point, then all 4 outputs.....could run the standard injectors upto a decent load point then add the 2nd set of injectors in...

[Sam_Q]

i am with ben, for street use the head mounted ones, if its for track then use the throttle mounted ones

[jezza323]

thanks guys

i will let you know how it goes once i have a manifold made up and a road tune done.

cant rep either of you im afraid...gotta spread the love

[MWP]

also with ben...
the head mounted injectors are made to fire on to the back of the valves to vaporise the fuel giving better economy at low throttle openings.

[jezza323]

so if i get a decent ECU i should run the head mounted injectors at low load, and the others at high load too easy!

[takai]

Pretty much, you can ramp over. I would be usign the throttle injectors for anything over 40% throttle.

[jezza323]

would there be a benefit in running both sets of injectors off the 4 outputs i have at this stage? so you get fuel from both?

[Ben Wilson]

Check out this thread for more information..