hello my fellow scooby friends
my car will be running 350bhp
i will eventually get 400bhp
but!!!
by adding say 720cc injectors will it make my car run bad?
it will be mapped at the same time they are fitted
or shall i add the 550's and wait til i got the bigger turbo etc
cheeeeeeeers

 

With a nice map they should run ok.

 

550's are good for 400 mate so no need for 720's imho

 

Get the 740's as they will idle just the same but will give more room for mods in the future.

 

Was reading posts on here before saying people have removed the cap on the bottom of the injectors so they produce 770cc so it doesnt cost anything to do the mod?!

Just had a search, its called de-capping, which all you do is use a dremel to remove the bottom cap off the injector and you have yourself 720cc injectors for a bit of your time (only works on classics though by what ive read?)

Seems to be popular in America and Austrailia

How to:
http://www.teamscss.com/Subaru%20WRX...ctor%20Mod.htm

 

seems a no brainer to buy 720's rather then payin out twice

 

i think they are newage injectors they are modifying in your link

 

why would he buy twice
550s are good for 400hp

 

They are in the link, but apparently side feeds are the same (except the STI4's)

 

550's will be on the edge at 400bhp so it would make sense to go for the larger ones to start with as they will run just the same but will have room for later improvements.

 

B@ll@cks, i have an sti 4 so a no go for me then!

 

My 550's were on the limits at 380 ish.So you'd prob end up having to buy a fuel reg to go with the 550's for 400,so i'd just buy the bigger ones and do it once

 

i got a STI4 aswell
so what Jamz is sayin is that by taking off these caps off standard injectors it makes them 770's????

 

Yes but he is saying sti 4 injectors cannot be done though.

 

Aye apparently the standard injectors on an STI4 are different and there is no cap as the whole lower end of the injector is one piece, but if you have after market injectors you should be able to do this mod.

Best thing would be to remove the injectors ad see if you can see micro welds around the lower part of the injector

 

running 740s in mine at 350bhp runs fine

 

Can this be done with the 380cc injectors as well?

 

Yep, all they did was weld on different caps on the injectors, ie 330cc 440cc 550cc... when infact all the injectors are 730cc with restrictors welded on the end... going to do this to my 330cc's

 

very interested in the results from this...save me £ on my build

 

Mr Smash, keep an eye out, just got a set of 370cc injectors, will be doing this mod and getting them cleaned / flow tested

 

cheers, thats what i wanted to see

 

Well I've been proven wrong the 380's cannot be done, just having a look at the phase one 440's and they look the same... wonder how the yanks have been doing it then :S

Looking at this picture:


Phase 2 one's should be able to be modified... not phase 1's

 

Do you have any pictures of phase 2 ones? i take it that the ones in the picture would be from a version 4?

 

jdc1 they are phase 2 in the picture above.

 

Aye the picture above are phase2 injectors (440cc)

Here's 380cc Phase1 injectors:



Note the injector on the left hand side is how they come as standard, the one on the right hand side I have removed the plastic sleeve to see if there was a sleeve welded over the top, but this injector has like a "pin" that sticks out the bottom (can see on the image) I am assuming this pin goes in when petrol is squirted out of the injector (might get the 12v battery out and test this) - This pin should make the injector produce a good spray in an O shape into the engine.

Watch this space for more info

 

So my v4 sti has phase 2 injectors?

 

Here's a good read to distinguish what injectors you have
http://www.carldavey.co.uk/article.php?id=4

If you have a facelift Classic, then yes your's will be phase 2

 

Basically this is what I'm looking for (example here of a set of STI Pink 550cc Top Feed Injectors I have here):



You can see on the bottom picture, where the cap has been welded onto the actual injector housing, removing this weld will mean the injector can flow more then 550cc to something above/around 700cc without this cap (will need to get them flow tested to get the exact flow)

Basically I am trying to find which injectors (side feed) has this cap welded on, so far its not on the phase 1 injectors (380cc or 440cc), Now im looking towards Phase 2 injectors (if someone could take some close up pictures of the bottom i could probably see if they could be modified or not) - I'm thinking they can be.... if so, there are adapters available to convert phase 1 fuel rails to fit phase 2 injectors here:
http://www.carldavey.co.uk/product.php?id=2

 

Thanks for the link Jamz, mine are phase 1 injectors which can not be modified

 

So are mine lol... was trying to avoid converting to top feed, but looks like I'm gonna have to (unless I can get some phase 2 440cc injectors modified, although once i get them flow tested and things, the top feed rails wont be that much more.... hmmmmm