Hard data on effects of injector position on engine power

one to add to the mix

http://www.migweb.co.uk/forums/engines-transmission/383333-advantages-stand-off-injectors.html

and gentlemen, we have had 5%, 10%, and now I give you 7.5%...

http://www.honda-tech.com/showthread.php?t=663761

200 whp Honda B16 motor with TWM TBs, gains made going to pukka stand-off injectors outside the rampipes (195-209 whp) but power losses below 5K rpm.

interesting comment about standoff injectors having an effect through inlet charge cooling through latent heat of fuel evaporation......

 

Having the injectors out of the bell mouths presumably brings in the inlet pulse tuning complexities. IE trying to catch the 3rd or 4th pulse reflection depending on inlet runner length, cam duration, port diameter. It could be that is why the power loss is present below a certain rpm. Pulse tuning only comes into effect at certain points in the rpm range as far as I understand, so it could be when the pulse is out of phase it ends up with stand off exacerbated by the injector placement out with the port runner.

Have seen various setups using the 4 "close" injectors up until a certain rpm then switching to the outboard ones higher up the rev range. This could be to do with it.

 

i have somthing that cools the intake charge - 200deg

 

Time to get the cheque book out Rob, i bet your tempted

 

not yet - I am expecting gains from my current experiment (new injectors / DTH 48s / inc fuel pressure) and have not yet settled on an ECU for the future, so I cannot run 8-injectors yet anyhow

its easy enough to mount a second set in the rampipe wall if it looks like a good idea, but proper stand-off injectors will take some thinking about how to package that into my car - will need curved rampipes......not easy (although it will be considerably more easy with 48's than 45's, as 2" mandrel bent tubing is 48mm ID....)

in the meantime, I am looking forward to seeing what others find on VAG valvers

 

about 7% at best, worse in some places, big problems with fuel standoff

http://www.v-eight.com/tech_forum/viewtopic.php?f=4&t=485&start=0&st=0&sk=t&sd=a

 

It's possible to fit the 22.5 degree Jenvey curved 4 bolt spacers to the ITBs, then an alloy plate to the front of that, giving a bonnet clearance. The remote injectors can mount to the alloy plate, along with the rampipes.

As to whether you'd get a loss of airflow due to the position of the curved spacers, I don't know...


An easy solution to mounting remote injectors is to use the Jenvey remote mount kit, tig'd to a 1.8T fuel rail, using it's inbuilt FPR and fab some lugs up to mount it to the alloy plate described above. It's easy to adjust the proximity of the injectors to the bellmouths...assuming you can make the room out front.

Something like this:

 

External Nitrous foggers for better atomisation.



If the foggers are too close to the valve you get reversion, were the Nitrous just bounces off the back of the valve.

 

I knocked this up in UG the other day to see if a stand-off injector setup can be squeezed inside an ITG filter. It should just fit.

 

They can be squeezed under a Pipercross domed filter, if you apply a bit of careful thinking, and mix and match rem pipe length with spacer length:

 

thing is - the whole point of remote injectors is that they are away from the valves - if you start squeezing the whole system together, then isn't it defeating the object?

I read somewhere recently that stand off injectors should have the injector tip level with a plane that runs across the front of the rampipes - I reckon this can be done, but a curved inlet system is required with a shortened rad

 

From information I've found, level with the outer edge of the bellmouth is ideal (or even slightly further out, if the injector spread allows)...if you have the room.
Sadly, I don't...and any distance further back *should* give gains, if there are gains to be had.

I'm still looking into 22.5 degree spacers, which, along with a taller domed filter, should allow the injector nozzles to be brought pretty much in line with the end of the bellmouth - but it's getting tight for space.

I have gained another 100mm or so...getting them level with the end of the bellmouth would give around 300mm to the inlet valve.

 

Yes you ideally want the injected fuel to the airflow at the same angle. One addition to the staged injector systems with pre throttle injectors is the throttle plate assists with breaking up the fuel droplets to promote homogenisation with the air.

 

interesting stuff, I'd like to see the results too. mounting them through the airbox might make for an easier install?

 

In what way prof?
I'm unsure how you mean.

 

That looks a nice setup. In my model I had positioned the injectors in line with the end of the ram pipes.

What ECU are you using? I've got Megasquirt v2.2 which I think should be capable of running 2 banks with a VE table for each.

 

Ideally I'd have the injectors further out too...but it won't fit under the bonnet....so I've had to make it fit.

ECU is a Emerald K3, running the inners sequentially off 4 injector drivers, the outers in batch mode, off 2 drivers, and wasted spark ignition. Picks up off the standard ABF sensors - cam & crank position, AIT, water temp, lambda etc.

ECU is in the upper glovebox, with the selector switch mounted in the lid of the glovebox.

It runs a single set of tables for each map, user configurable injector changeover/phasing etc...but 3 maps can be stored so I should be able to map all inners, all outers, or the 'best' phased set-up. Or keep an MOT map, if required.

 

Pinched these from fthaimike's post here:
http://www.clubgti.com/forum/showthread.php?t=72936&page=50






Interesting that the outer injectors are further out, yet still within the inlet pipework, rather than external, over the bellmouths.

Thoughts?