Heres a picture of the sheet of from injector rehab

I just ordered a walbro 255lph and this is showing they flow this much at 2.25 bar which converts to 32.6 psi from the calculator I used.

Injectors are stock 550's and gsl se 680s (I assumed they were 720s on fc fuel pressure.

Ill look up how much fuel pressure stock fc uses and see how much this walbro 255lph will push them, I'm also getting a rtek 1.7

Edit - from reading stock fuel pressure is 35-37 psi , I'm stumped as to why these injectors have such high test results. Can anyone explain?


Attachment 496347

I was told by a fellow rx7 owner that they get bigger over time. Though I've never heard that before

Yes, mazda underrates all their injectors versus the actual flow rates, this has almost always been the case according to the results from injectors that I send out to be cleaned. We're not talking a huge amount, maybe 5% or so above the rated flow.

What ???

Injectors flow more at higher pressure. If say the 550cc injectors at 2.25 bar or 32 psi flows 550cc, at almost 3 bar or 43 psi it would flow about 630cc.

Most injector cleaning shops flow test at higher pressure so the chart usually shows at higher flow rate.
Most 680cc charts I've seen were in 700cc range.

..and that is why a lot of guys get the GSL-SE injectors as they flow close to 720 and are half the Price of the "GREEEDY Injectors"!!

This test is showing 2.25 bar (32.6 psi) saying the 550's flow is 620's and the 720's flow is 760's.

According to my calculations
1) 550s flowed 12.7% higher than they'rerated
2) 720s flowed 5.6% higher than they're rated


What kind of fuel pressure should I be running on my walbro 255 lph? I've read 43.5 is a good starting point just hope I don't run really rich I did just order an rtek 1.7 which calls for secondaries to be 720 CC and an upgraded fuel pump.

They aren't 550 because 1980's manufacturing tolerances and years of service. They are what they are. Use them.
Rtek 1.x's use stock fuel maps. So it expects stock fuel pressure. Unfortunately, that's impossible with a walbro and stock FPR. So you need to decide what to do about that.

I'm planning on getting an aeromotive fuel pressure regulator, as far as which one I'm not sure yet.

i think every injector on the market is underrated
example- a bosch ev14 2000 injector ( think ID2000) is 2200

No offense to him, but it seems like the OP's MO is to put way too much thought into seemingly simple areas. :)

Why? Explain to me why you think you need one or could benefit from one.

By your own admission you are on a tight budget and will be doing well to get this car together (in near stock form) and running anytime this summer.

The stock fuel pressure regulator is quite reliable and is already set at an appropriate pressure level for this engine.

You need another one because _________________ .... ?

Take the money you'd spend on that, and spend it on car maintenance of this 25 year old chassis...belts, hoses, motor mounts, clutch, gas tank, fuel pump strainer, fuel filter, oil cooler lines, etc.

Modding a car for performance that you haven't even gotten to run stock yet is kind of like a middle school virgin talking to his friends about what position he is going to use first on his GF when he gets one. :lol:

A walbro 255lph is known to over run the stock fpr and the budget was bigger than I expected.

I've ordered/bought-

Belts, hoses, spark plug wires, dual alt pulley, fuel filter, motor and transmission mounts, front and rear transmission seals, oil pan gasket, intake gaskets, boost gauge , water temp gauge, block off plates for everything including omp, shifter bushings, o2 sensor, rad and filler caps, tstat, waterpump gaskets, oil cooler, oil cooler hoses, oil cooler flush, under tray, rad ducting, clutch fan, OEM pilot bearing and seal, injector cleaning, walbro fuel pump, rtek ecu upgrade, s5 Turbo, 88 t2 wheels, windshield wipers, coolant, oil and oil filter, lug nuts, Turbo gaskets, pre mix.

That's a big list, and I still need a few things, it seems to never end when you want to have a great car.

I should be done very soon , only need a few other things.

Also do you or anyone know if these metal cups with ridges/teeth that are on top of the motor mount are needed on both sides or only one. I only was able to find one in my parts I removed.

Oh and when I lost my virginity the girl didn't believe me when I said I was because I knew what I was doing and lasted so long. Lmao