Injector Boss Position

[Cupman]

Hi guys,

I'm making a custom inlet manifold and just looking for some assistance with the location of the injector bosses on the runners. I have done a bit of research into where would be best and found that it depends on the size of the injector, entry angle etc but still not sure how close the head they should be. I am using a 16mm thick flange and there is about 5mm on the boss before where the injector will sit. Is 21mm or so enough or should I move it towards the plenum?

I could only move it back a further 20mm or so before the fuel rail will hit the plenum anyway.

All thoughts welcome!

Cheers,
Steven

[Cupman]

No one?

[Adey aka Ewok]

not sure buddy, the only thing ive been told is to try and get the injector spraying at the back of the valve

[youngscottie]

this is a how long is a piece of string question
injector position effects engine characteristics
decide what you want from the engine then work from there


or use my approach look at standard efi manifolds on ebay and get an idea as to where manufacturers position them

[Andrew Cooke]

this is a how long is a piece of string question
injector position effects engine characteristics
decide what you want from the engine then work from there


or use my approach look at standard efi manifolds on ebay and get an idea as to where manufacturers position them

it's also injector dependant, so look specifically at the manifold that your injectors came out of.

[youngscottie]

it's also injector dependant, so look specifically at the manifold that your injectors came out of.

this guy knows what hes talking about take his advice

[youngscottie]

what engine you making this for?

[Andrew Cooke]

this guy knows what hes talking about take his advice

I wouldn't say that, read what I write, and make your own mind up what I will say is that OEMs spend a lot of time getting stuff right, it's easy to stuff up their good work.

[Cupman]

Engine is a boosted F4r and the injectors I have are 630cc Deka's. The car is going to be used purely for track too. Looking for upwards of 300bhp as well.

Looked at loads of manifolds and done a lot of reading but still unsure. A lot of the Honda boys spray directly onto the valves but if I go over a certain injector size i'll get poor atomisation. Just not sure what size of injector that is.

I'll get a pic up of my intentions when I get photobucket to work.

[Andrew Cooke]

Do those injectors have twin nozzles for 2 valves?

[Cupman]

No they don't mate. They have a wide spray pattern if that makes a difference.

[Scoff]

Dekas work fine right up to the flange Steven, they'll be fine

[Cupman]

Cheers Scoff!

Want to get a few things finished and get this back down to you ASAP!