Quote:
Originally Posted by foggyjames
I'm sorry...you've lost me. Surely flow rates are a secondary consideration...i.e. ideally you size an injector to give you the flow rate you need to achieve the optimal AFR for a given load and engine speed and no more, thus giving you the best resolution possible at the bottom of the map...right?
Do twin injectors give more power? In my experience, they're ususally used when a single injector is so large that its output at very low duty cycles is unstable, making for a lumpy idle, for example.
If twin injectors *do* give more power...all I can think is that it's related to distribution of fuel within the airstream. Standard injector placement is non-optimal, in my eyes, whereas the F1-style "in front of the ram pipe" is healthier.
cheers
James
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If your building an engine like this one James and you know what BHP figure you want to achieve you can calculate the size of injectors required. AFR’s can only be used when the engine is running so flow rates can’t be a secondary consideration.
Quote:
Originally Posted by austenw
Not wanting to go off topic, i see the injector comment has gone over a few peoples heads
It has nothing to do with the amount of fuel delivered to the cylinder and has nothing to do with AFR
Is all to do with the fuel mixing with the air, the better it is mixed the better it will ignite
On a higher reving engine the air speed in the inlet tract will increase as revs rise, therefore if you use a second set of injectors further up it will give the fuel more time to atomise with the air giving a bigger bang in the cylinder.
This is why it is used extensively on touring, rally and rally cross cars I have come accross
The WRC Puma gained 12bhp from this set up
SB Developments has dyno proven it works too on there 2.0l 300bhp duratec
I have also used this on a 4cyl turbo engine in the past and seen noticable improveents in power and driveability
Do a google search for more info as its off topic
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We are a bit off topic, however the examples you give are all low pressure systems so I assume you’re not aware that higher fuel pressure systems also = fuel evaporation hence an excellent air/fuel mix from one injector.