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injector position
Craigorypeck - 18/12/12 at 10:52 PM

wheres best position to mount injector bosses on a custom manifold? will it make much difference if they are real close or say 2" from head?

HowardB - 18/12/12 at 11:20 PM

there is a lot written about this,..

on to the back of the valve - helps cold start - common on tin tops
further out (2" or so) gives the fuel a chance to mix
even further out (often a second row) better still at very high rpm - common on high performance bike engines


so it is worth having a look and seeing what others have done with the same TB/engine combo

hth



[Edited on 18/12/12 by HowardB]

Craigorypeck - 18/12/12 at 11:55 PM

thanks! thinking of converting to efi from bike carbs and have tapped holes in my custom mani for vacuum ref so considering weld on bosses in their position and a diy fuel rail.

Craigorypeck - 19/12/12 at 12:13 AM

regarding fuel rail- can you get a weld in boss that clamps the injector in place and then can be plumbed with flexible hose from regulator and not need a rail?

mark chandler - 19/12/12 at 12:57 AM

Why not use the injectors in the TB's, there is nothing magic about car engined injectors.

Any big bikes will flow up to 200bhp these days.

The bike will have a MAP take off on the TB's as well

matt_gsxr - 19/12/12 at 09:39 AM

quote:
Originally posted by mark chandler
Why not use the injectors in the TB's, there is nothing magic about car engined injectors.


I guess because he is using bike carbs, so no injectors.


You might be better off selling the bike carbs and getting TB's though and doing as Mark suggests. Its a popular and well proven route. gsxr1000 k1-3 throttle bodies are the best to use for several reasons and you can reuse the injectors, and such.

That is what I did although I was fuel injecting a bike engined car.
http://www.matt_phoenix.talktalk.net/GSXR1100_fuel_injection_hardware.html

Matt

Craigorypeck - 19/12/12 at 11:18 PM

my runners are well long and the injectors would be near 7" from the head if i replaced the carbs with throttle bodies. hence my first post. can get welding done for nout by a mate so may go for weld on bosses,

mark chandler - 20/12/12 at 08:37 AM

My runners are long with a 30 degree bend in them, idle is spot on and makes good power, same applied before I stuck a turbo on.

OEM squirt at the back of the valves for idle emissions, 7" is not a problem.

coyoteboy - 20/12/12 at 01:30 PM

The difference in location will only have minimal effect until you get to 4+ inches IMO, you're best sticking with the sorts of distances the bulk of tin-tops use unless you're planning to run high RPM a lot, then maybe move it out but accept you may get reduced idle quality.