fha772
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| posted on 13/2/14 at 11:37 PM |
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How critical is injector position?
Hi all,
I've bought a complete set of throttle bodies off of an E46 bmw M3, to fit to my Merc 280E as part of my future EFI conversion.
It's got me thinking, this is a complete, ready to fit set up, that just needs a short adaptor manifold making to fit it to my engine.
But I now have 2 options as to injector location...
1, leave the injectors in the throttle bodies, so there about 2 inches up stream of the inlet valves, and plug the holes where the original K-jet
injectors are in the head.
2, fit the injectors in the head, so they squirt almost directly onto the inlet valves , and plug the holes in the thottle bodies.
The first option is probably the easiest way of doing it, but I was wondering exactly how critical is the difference in the 2 injector locations?
Cheers Frank.
http://www.ppcmag.co.uk/forum/viewtopic.php?f=47&t=6743&start=105
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mark chandler
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| posted on 13/2/14 at 11:58 PM |
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Option 1 will give best power, option 2 lowest emissions.
My blade engine has 2" runners, the injectors are the wrong way up to keep the profile low and it makes great power 
Further up the runner allows fuel to mix with the air better.
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fha772
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| posted on 14/2/14 at 12:05 AM |
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So the easier option should actually be the best option, that makes a refreshing change... 
http://www.ppcmag.co.uk/forum/viewtopic.php?f=47&t=6743&start=105
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daxtojeiro
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| posted on 14/2/14 at 07:00 AM |
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The height is relavent to the air flow speed.
Higher speed, higher position.
As I would guess thats not going to be a fast reving engine you should fit the injectors as low as possible.
If you can get up around 7-8000rpm out of it then fit them higher, or better still, stage a second set to come in that are higher up the inlet,
thanks
Phil
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Nickp
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| posted on 14/2/14 at 07:10 AM |
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Go option 1 Frank if that's easier. The 2" difference won't make much odds IMO. If you were putting them at the end of the runners
squirting into trumpets then yes you'd probably suffer lower down.
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Pat_T
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| posted on 14/2/14 at 04:45 PM |
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If option 1 is significantly easier then go for that. It should work well and won't give you any problems.
However if it is not too difficult then option 2 is probably the preferred option providing however you are going to map this engine you have the
ability to play with injection phase angle.
Injecting closer the inlet valve will reduce port wall wetting (the amount of fuel droplets that end up all over the walls and make their way to the
combustion chamber after some indeterminate amount of time). High levels of port wall wetting make AFR more difficult to control during transients
(accelerations).
If you can phase the injection to fire directly on a hot inlet valve shortly before it opens or as it is opening you can get some increased
evaporation, and reduced intake charge temps.
Also check your calcs on the duty cycle of the injectors, as Phil mentions E46 M3 stock items might be a bit big for your application unless you also
are going to rev to 8000+ ? (that E46M3 engine doesn't make peak power until 7900rpm)
www.instagram.com/patroclueus
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fha772
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| posted on 14/2/14 at 07:15 PM |
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The standard redline is 6200rpm, but with a couple of minor mods it can safely go to 7200rpm.
Standard bhp is 185bhp, with the EFI conversion I should see 200-210bhp(going by what others have achieved), then once the I've got the EFI
working, I'm turbo'ing it, which then should take it to 280-300bhp.
So, I'm hoping the M3 injectors will be suitable for the job...
http://www.ppcmag.co.uk/forum/viewtopic.php?f=47&t=6743&start=105
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