injector placement ?

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
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razzor
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injector placement ?

Post by razzor »

For the more experienced guys.
What would be the pros and cons be of having the injectors placed in front of the intake runners rather than the norm of on the intake manifold ?
Roverdose
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Re: injector placement ?

Post by Roverdose »

in front as in the plenum pointing into the runner?

too far away for low speed running, good for a second set though?

Drew
VR6Turbo
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Re: injector placement ?

Post by VR6Turbo »

I think he means squirting into a trumpet like the below?

As you say, OK for twin injector setups but I can't see it working so well at low rpms.

Image
razzor
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Re: injector placement ?

Post by razzor »

understand now that each placement has its benefits.
stock location on the manifold is more practical for a street car.
stevieturbo
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Re: injector placement ?

Post by stevieturbo »

VR6Turbo wrote:I think he means squirting into a trumpet like the below?

As you say, OK for twin injector setups but I can't see it working so well at low rpms.

Image
No real reason why not though. Most single point injections fire against the throttle plate.

That's a nice looking setup there though !!
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ignitionautosport
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Re: injector placement ?

Post by ignitionautosport »

Theres a reason they moved to multipoint though:
  • No fuel on top of plates to explode
  • Better atomisation at low throttle opening (drivability) instead of dribbling past plate
If its a race car then you may consider having them outside trumpets like pic for that last bit of horsepower, but I see no need for it these days. Mainly from the safety aspect, I don't like fuel mist floating around. Backfires become real fun, as cool as the setup looks ;)
| '94 GSR Lancer | '96 Toyota Carib 20V | '83 Toyota Starlet | www.ignitionautosport.co.nz |
VR6Turbo
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Re: injector placement ?

Post by VR6Turbo »

I think the red rails are nitrous injectors, so would probably only come on at WOT when there's good gas speed. I suppose petrol injectors up there would atomise into the air stream quite nicely rather than impacting the back of the valves? Some engines may benefit from that I guess.
welshpug
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Re: injector placement ?

Post by welshpug »

I know a few engine builders favour twin injectors as they air mid range greatly, not just high end rpm work.

I guess it would depend largely on the installation and length of the inlet tract, plus the engine its being used on and its pulse tuning etc
razzor
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Re: injector placement ?

Post by razzor »

was interested seeing i am busy making my plenum for the VR6.
Was looking at having the injectors facing the intake trumpets but the complication is the staggered intake length of the cylinders seeing that 3 cylinders are further back from the front cylinders by around 9cm's.
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