What size injectors?

duncan · Post by **duncan** » Sat Nov 18, 2006 10:42 pm

To help with fuelling on my car I need to fit bigger injectors

At present it has 565cc injectors and I have gone as far as I can go with them I think.

If I was to change to 740cc - do you think that would be okay or would 650 cc do the job better?

boxy · Post by **boxy** » Sat Nov 18, 2006 10:45 pm

Thing is Dunc will you be happy going for that will do the trick(650cc), or this will do and do more later on with more mods?(750cc)

duncan · Post by **duncan** » Sat Nov 18, 2006 10:55 pm

i havent had a chance to check with my mapper as to the recommended size but gut feel says the 740cc will give the right amount of headroom so long as they dont ruin things if i am not running them to potential.

It is very difficult to answer though although I think that you can resell on used injectors quite easily to recoup upgrade costs.

boxy · Post by **boxy** » Sat Nov 18, 2006 11:25 pm

I could be wrong here but surely it`s just a case of having the size capable of doing what you want, but not necessarily using it. Surely you can set up your ECU to run as though it had 650cc injectors even though you have 750cc fitted. Therefore having potential for future upgrades. After all the ECU controls how much fuel it will send to the injectors, not the other way round.

duncan · Post by **duncan** » Sun Nov 19, 2006 7:12 am

I believe it can be an issue if the injectors are too large at low load where the pulse width is so small it can make the engine lumpy on idle

boxy · Post by **boxy** » Sun Nov 19, 2006 9:15 am

surely an expert is waiting in the wings to put us right?

hybrid dreams · Post by **hybrid dreams** » Sun Nov 19, 2006 9:31 am

most standalone systems out there will have no problem controlling injectors of that size. when in doubt. go bigger on injectors. will leave u room to grow. so I say 750s. Hell I got a friend running saturated 1000CC injectors on a Honda and it idles pretty smooth at 1k.

boxy · Post by **boxy** » Sun Nov 19, 2006 9:56 am

sounds good to me Dunc, what you going to go for?

drifter · Post by **drifter** » Sun Nov 19, 2006 10:22 am

I had a chat to Gary@APT about this for when my new turbo and PowerFC go on. I could get away with 550cc injectors, but being as I could get 740cc injectors cheap and the idle would be fine I got them instead. 740cc seems to be the limit for the SR20 with still having a smooth(ish) idle. Before Gary went mad with the Evo he was running 1000cc injectors with not too much trouble

I say go with the 740's

stockcar · Post by **stockcar** » Sun Nov 19, 2006 11:28 am

650's will have the potential for 450+'ish therefore unless your going "internal" personal choice would be for these to retain a much nicer response, etc...........