Injector positioning on ITBs

[Sensibleboy]

Quick one,
How important is injector positioning on a road car with ITBs?

Should I expect any driveability issues with the injectors placed in the bodies instead of pointing at the back of the valves?

I know for low revs it's better if the injectors are in the inlet but is it too much too expect it to rev cleanly as the engine is increased from idle?

Edited by Sensibleboy on Wednesday 20th January 19:29

Edited by Sensibleboy on Wednesday 20th January 19:57

[GreenV8S]

The further upstream the are the more of a challenge you'll have with transient response due to wall wetting, but the injectors you show there look pretty close to me - are those the ones you're concerned about?

[Sensibleboy]

Yes those are the ones in question.

The injectors were originally sat in the manifold but I've moved them. I'm hoping the current splutter as the throttle is opened can be resolved through adjusting the mapping.

[GreenV8S]

Sensibleboy said:

The injectors were originally sat in the manifold but I've moved them.

Absolutely everything else the same? If so I would just crank up the accelerator enrichment a little and see if it helps.

[Inline__engine]

i would have put them at the head.

[Zener]

Can not see any issue there like mentioned already they are far from remote as is , a map tweak will see you alright poss a tad more AE , nice tidy work there loom etc

Edited by Zener on Friday 22 January 12:01

[DVandrews]

As stated, best for idle and transient response is close to the valve, best for power in the trumpet, where you have them is a compromise but I wouldn't expect you to see any noticeable issues, I have setup up a large number of engines with them at approximately that position with no ill effects. If the engine is mapped Alpha-n then check the response of the TPS to make sure it is linear, fi so then examine the load/speed sites just off idle and consider (as suggested above) adjusting the accelerator clamp.

Dave

Edited by DVandrews on Friday 22 January 12:11

[Sensibleboy]

Excellent. Thanks guys.
That gives me some confidence that tweaking the map should fix the problem. I did think my set up wasn't anything extreme.

At normal revs it's smooth running but occasionally it spits and pops from the inlet and struggles to increase engine speed especially when cold.

It did get worse when I moved the injectors further upstream.

[spyder dryver]

Depending on what ECU you are using you may find that wall wetting compensation might be available. My MS2 does. It helped me iron out a weak spot during light "tip-in" throttle application, even on it's default settings.

[DVandrews]

Sensibleboy said:

Excellent. Thanks guys.
That gives me some confidence that tweaking the map should fix the problem. I did think my set up wasn't anything extreme.

At normal revs it's smooth running but occasionally it spits and pops from the inlet and struggles to increase engine speed especially when cold.

It did get worse when I moved the injectors further upstream.

Acceleration fuelling probably or occasional errors in TPS telemetry.

Dave

[Sensibleboy]

Decision made. The gentleman who is going to tidy up the mapping has suggested the injectors are best placed in the manifold pointing at the valves. So I've taken his advice and ordered a custom Jenvey fuel rail.
When that's fitted I'll have a look at the acceleration fuelling prior to it being looked at professionally.

Hopefully I'll get to tinker in the next week or so. I will let you know how it goes.