Hey guys, i am doing a full bridge 12a with tbi. it has 2 injector and according to my calculations for hp somewhere around the 270 range i need 924cc/min injectors would it matter if i just do 1000cc/min each or would that already make them too large?

 

Are you stuck with only using two injectors? If so, a pair of ID1000s would probably be your best bet.

 

what tb are you using?

 

yes i am stuck with 2 injectors, it comes with one injector per throttle body

its an ida style tb i just bought of the forum. The owner told me that i comes with 55lb/h injectors which i know thats not nearly enough for a full bridge.

this is the thread so you can take a look at it
https://www.rx7club.com/race-parts-only-228/twm-independent-throttle-body-assy-971939/

 

i'd use the ID1000's also, they should be just the perfect size. you can also run higher fuel pressure with them, so if you need a little more fuel you can do it

 

k perfect do you have a link for them? Will they be a direct fit with the delphi injectors?

 

http://www.t1racedevelopment.com/ind...cs/id1000.html

 

thanks alot, but holy crap, thats way out of my price range, i know those are the best but geez they break the bank. Could i just go with these?
http://www.diyautotune.com/catalog/d...owz-p-280.html

 

You could try them, but you might have trouble controlling them at idle. The reason j9fd3s and I recommended the ID1000s is because they work well at low pulsewidths, which is going to be important for you since you're wanting to only use two injectors. On the other hand, they are low impedance injectors and the engine is a bridgeport, so they might be okay.

There's a reason most rotary people use staged injection. You might also look into adding a couple of extra injector bungs and grabbing a set of stock 550cc injectors from a TII. Could be cheaper than two ID1000s, I don't know.

 

the ID's are nice because they work at low puslewidths, and also at high fuel pressure, basically its more flexible.

an EV1 style injector flows the same, but they don't work as well at low pulsewidths, and don't have as good a spray pattern, and don't like as high a fuel pressure as the newer ones.

the ev1's might work fine, actually i'm not sure about the BSFC a bridgeport will do, and the real hp number, so there is some room with the ID's

 

According to the injector calculator I made for myself a while back using howard coleman's figure of 1.92 CFM/WHP, those EV1 style injectors should max out at around 245 WHP, assuming 3 bar fuel pressure, 85% duty cycle, and 12.2:1 AFR. Realistically, that's probably plenty for a bridgeport 12A. The ID1000s should be good for 260 WHP at the same fuel pressure. I'd be more worried about the low RPM performance.

 

Forgot to mention that that 1.92 CFM/WHP number is intended for turbo engines, which typically run much less ignition advance and have lower compression ratios than NA motors. So those horsepower figures are conservative. You'd have to know the actual BSFC to get more accurate results. If we say the engine has a BSFC of 0.6 lb/hp-hr, for instance, the IDs will get you 285 WHP and the Delphis will get you 269. Much more than enough.

 

Thanks alot for the replies. i know that the ev1 would suffer on the low rpms, but i just cant bite the bullet with the ID. Also it wont be a street car at all, its a full circuit racer so most of its time it will be at the high rpm apart from when i am idling it.

Also the website says that the 97lb/h injectors are at 43 psi, but can hold up to 72 psi for 123lb/h, although you would still have the lower PW to deal with and a crappy idle

What has been the most power seen on a 12a full bridge?

 

Email FIC and ask about a EV14 style injector for your application. ID's are EV14's with some freak-sauce applied. I doubt the lay-person could really tell the difference. FIC has great prices too. That's what I do for all the cars I screw with.

 

So the EV14 will fit right in or do i need to make an adapter?

 

at the wheels? or the flywheel? the one i recall seeing was like 269hp at the flywheel with .69bsfc @peak power, mixture was mid 12's

 

yeah thats somewhere what ive been told 270 at the flywheel.

Will thes injectors swap right out with the Delphi EV1?
http://www.fiveomotorsport.com/impor...fuel-injectors

 

So i emailed FIC the guy told me that he can provide EV14 900cc/min that fit right in, no need to move anything or adapters, if i need more flow i can run it at 62 psi to get 1100cc/min. Resonable pricing too $205 for both, just for anyone that may want them as well. Thank you all for the response and the help

 

That's a pretty high BSFC for an NA, isn't it? That implies 2.30 CFM/WHP assuming 85% drivetrain efficiency and 80 degree F intake air and 12.5:1 AFR. That's even higher than howard coleman's figure for turbo engines.

Anyway, using those numbers I'm getting a required injector flow rating of 1085cc with a max of 85% duty cycle. That's per rotor, of course.

 

somwhere in that range the injectors FIC recommended will work since he said i can up the pressure to flow 1100cc or increase it even more and flow almost 1300cc.

 

Sounds good, then. I'd use them. Just make sure to get a fuel pump that can supply at least 40-45 GPH at that fuel pressure.

 

i think the walboro 255 would be adequate at somewhere around 60 psi, but i doubt i would need to increase the pressure much since its not like ill be making 350hp or so to need 60 psi. thanks for the advice though

 

Yeah, a Walbro 255 will be plenty.

 

i'd have to go look, but at the HP peak BSFC is rising, however its not ever very good on a sideport rotary.

 

i have a Walbro 255lph inline used if you need one. need to upgrade to the 400 myself. only have about 1500 miles on it if that....