injector size

[fxgt race]

the smallport that we have built is we hope going to get 200hp ,with the standard injectors with me calulations are only good to about 190hp,correct me if im wrong,should we use 4agze injectors and will they work or is there a better option out there,anyone experenced with this and could guide us in the right direction.cheers

[Crucible]

the smallport that we have built is we hope going to get 200hp ,with the standard injectors with me calulations are only good to about 190hp,correct me if im wrong,should we use 4agze injectors and will they work or is there a better option out there,anyone experenced with this and could guide us in the right direction.cheers

7mgt 440cc injectors are good for 180 - 200kw
13bt 550cc will give you ample fuel for well over 200kw

both the above go straight into ze smallport rail, the stock plugs will go straight onto the 7mgt ones but you will need the plugs for the rotary 550s injectors. The head -> inj seals on the 550s are slightley smaller inside dia than stock 365ze ones so just use Mazda seals.

Evo 510s are suitable aswell, but not too sure if they go straight in? somebody may be able to confirm...

pays start with biggest injectors you can find, because if later you want to chase more power and have to up the size it will cost you more to tune as they will have to remap your fuel again from scratch.

[RedMist]

Are you running NA or turbo? It makes a considerable difference to the size of the injectors.

NA I ran just under 200 flywheel HP with 295cc 20 valve injectors. They ran at 85% duty cycle, so on the upper end of the scale.

You want to size the injectors as small as you can get away with while maintainnig about a maximum of 85% duty cycle. This gives the best spray pattern without fusing open the injector.

The 20 valve injectors are rated at 295 but I had them flowed at 315 (I dont know what PSI they tested them at). However wont fit your rail.
The ZE injectors are sligtly bigger again and should fit your stock boss and fuel rail.

[RomanV]

If you want some 20v injectors, PM me I've got a few sets here.

[IH8TEC]

The head -> inj seals on the 550s are slightley smaller inside dia than stock 365ze ones so just use Mazda seals.

i found the opposite when i had them side by side, so i ordered new 4agze ones, and will drill the centre out a bit more to suit the rx7 ones i have

[fxgt race]

i have 295cc in my engine with 210hp na,with the smallport redtop being topfeed injectors and 20v being sidefeed does the 20v fuel rail bolt up to the smallport engine,have two sets of injectors to use

[sergei]

20v does not have fuel rail as such.
it is part of manifold.

[Celica RA45]

try using the 365cc 4agze 1s and go for about 60 to 70 % duty cycle getting up to 85% is near there maxium which is what you dont wont

[RedMist]

try using the 365cc 4agze 1s and go for about 60 to 70 % duty cycle getting up to 85% is near there maxium which is what you dont wont

Actually you do want. You want the injector duty cycle to be as long as possible without burning the injector open. This ensures a finer spray of fuel mist and better atomisation of fuel in the air mix. 60-70% might be a reasonable duty cycle for a very well timed sequential system, but even then I see little benefit.

I have heard of 20 valve injectors running 95% duty cycle without fusing, however this is in a race vehicle running av-gas. I've seen the dyno plots and with more power than my 16 valve running the same injectors I have no reason to question this. However its not the way I would like to run my injectors.

[Celica RA45]

fair enough i use 440cc on the head of my motor and i also use 720cc out near the ram tube as i use a sequential system and using 10 % inboard and 90 % out board
the inboards on my std race motor go up to 70 % duty cycle and with the 2 stage the out boards are 50 % duty and we also use end of injection timming to stop stand off etc heance the 720 cc injectors