rolfs_7

ok so im going turbo with my SE so i got the 2 720s but i need another set. what years of rx7 injectors would work. incase your wondering im using a TII LIM and UIM. or what other injectors from other cars would work?

steve84GS TII

What ECU are you running?.....standalone or TII?

If you are running standalone,then you can run anything thats the right resistance.Take your pick from just about any rotary,as most piston engine injectors are WAY,WAY smaller than even an N/A 13B.Use the 720's as secondaries and run some smaller injectors as primaries,for a smoother idle.A standalone will allow you to adjust injector pulsewidth to any % you want.Youll be limited to HP output,but that can change by slapping the 720's in the primary position and getting some 1200-1500cc aftermarket "whatever" brand injectors for the secondary positions.

If your gonna run a factory RX-7 ECU,then youll need to determine what impedance the 720's you have are.Low impedance means youll need to run an 87-87.5 TII ECU.High impedance means youll have to run an 87.5-88 or 89-92 ECU.Using the 720's as secondaries and 550's as primaries will allow you to just about max out the stock ECU's abilities,and put you around 160-180 HP with no more than 12-13psi of boost.No mods to the ECU are needed,you just have to provide enough air to match the increased output of the injectors.
I run 550's and 800's with my stock S5 ECU and a TO4B hybrid turbo hitting 14psi max.Its right at the edge of the ECU's capacity and makes about 300 reliable HP.

Siraniko

iTrader: (13)

720 for secondaries? thats too small but use it for primaries instead and run 1300+ for secondaries.

REVHED

Get another set of 720's. According to the injector calculator that will be good for about 350hp at the flywheel.

rolfs_7

standalone and i didnt think i would want 2 go smaller than 720s. my plans were either 4 720s or PI 720 and SI somthin bigger. what are the FD rated at? or the TII 2ndaries?

Siraniko

iTrader: (13)

Since you have a SE, use the SE injectors for primaries (750cc IIRC) then send them to RC engineering for cleaning/stamp for say $30/each

steve84GS TII

SE's have 2 injectors, both 680cc,low impedance.

The N/A 2nd gens have 460cc injectors at all 4 positions and come in both low and high impedance flavors,depending on year.

The TII's all have 550cc injectors at all 4 positions and come in both low and high impedance flavors, depending on the year.

The FD has 550cc primaries and 800cc secondaries.But they are sidefeed,so they arent compatible.

If you got lucky and found a 12AT,they have big 800cc injectors, because there are only two,like the GSL-SE. All 2 rotor EFI engines after the SE, have 4 injectors,usually all the same size.The FD is the exception.

To put it in perspective,the stock TII injectors are the same size as injectors for a Big Block 454 Chevy.The vast majority of piston engines have injectors in the 250-400cc range......rotaries really suck it down.Your best bet is to keep the injectors you have for primaries and get some big'uns for the secondaries.....something like 1300-1600cc.You can always crank them down to lean-tune for power.They arent gonna come on-line until about 3500rpms anyways. Just run a big pump and tune carefuly!

REVHED

Your best bet is to buy injectors that are suited to the power level you plan to run. There's no point going overly big because it makes staging the secondaries a lot harder.

rolfs_7

max of 12 psi for now but i will most likely be at 10 or so...

steve84GS TII

Hell, thats easy going.
I was hitting 14psi on occasion with just 550's and 680's and it never went lean.My typical,max boost was 12psi,but its would run to 14psi in the higher gears because of the stock turbo I was running at the time.Never once got a rumble or rattle from the engine.

You should be just fine with four 720's..... and like REVHEAD said,itll make the transition smoother,which equals less tuning.I just assumed since you were running a standalone,that youd be going for bigger numbers.There are guys hitting 10psi with stock 550cc injectors and light bolt-ons.

Naegleria_Fowleri

So Rolf, when am I going to get to see this beast in action? Oh, and do you ever talk to Steve any more? I've been meaning to get ahold of him to meet up some more.