MicroSquirt.com read only forum (Jan.15,2018)

Can any one comment on an alternate novel method that "Silent Hektik" has offered to mount the injector for fuel economy - that being directly behind the throttle plate and at right angles to the run, nozzle in fact pointed directly at bottom edge of plate when at closed postion. Their explanation is that 75% of vehicle operation might be at throttle states less than 33% open, and by reason of the increased air velocity through the throttle plate metering zone there is vastly improved atomization (or in their terms "lack of puddle").
For my motobike project (BMW aircooled, twin opposed 980cc) I'd like to try this location, however my twin throttle assembly locates roughly 12 inches and about 160 degrees of bend from the cylinder inlet port.
I'm concerned about the possibilities of lag or run on affecting throttle response for the bike (not a good thing). However, with small dia feed plumbing on a turbo induced system, this may not be detrimental?
I'm not looking for high speed performance, but good performance up to 5500-6000rpm, and power/economy.
Any feedback appreciated. Picture of their throttle arrangement can be seen here
http://www.silent-hektik.com/ICM_Pat.htm

Lorne

So they have tried this and it does work and gives better economy/atomization? The theory sounds good. Focusing the direction of the injector towards the edge of the butterfly sounds like a good idea too. This either works or it don't, good theory or not.

I've read that one of the first fuel injected Bimotas actually had the injectors faced backwards, towards the incoming air so as to improve atomization. I used to kinda worry that there might be puddling at low rpm with any type of EFI but remember, at 900rpm idle there are over 7 intake events per second. Not much time for the fuel to linger and puddle.

I am not aware of the benifits of pointing the nozzle spray at the lower throttle plate edge, in reading about Silent Hektiks approach it sounds reasonable, and I was seeking confirmation from others who post here. For my purposes, I will possibly add more than one bung location on the inlet track in order to test differences.
Another potentially benificial method I noted, was a special ported "bung" that utilized an air blast that swirled its way through the fuel charge heading towards the inlet valve. Unfortuneately on a motorbike there is not enough room/capacity to keep adding such additional components (pumps and such) like a 4 wheeled vehicle might employ.

So your throttle body is 12" from the intake port, where will the actual injector be located? If the injector is close to the port I think it will run just fine. Maybe quicker throttle response the closer the TB is to the port but might be very small or not even noticable.

I know that Bosch did a TBI injection study in the late 1970's and they reported that the best place for TBI injectors are symmetric in the bores, above the throttle plates, like is the standard for OEM injection. I am not sure if they tested this confguration, it may or may not work good. I agree the best thing is to experiment. And you may want to monitor exhaust temps to determine mixture distribution - Jerry at DIY is going thru this exercise right now and has good data on how injector placement can affect distribution with a TBI setup.

- Bruce

That is the type of TBI on my '89 Cadillac. Its throttle response is definately lacking but the automatic transmission makes up for it. Might be a real pain if it was a manual.