Fritch

anyways it died last week when I got home, for what reason I'll never know

So I go out to test things to make sure and I'm getting 12v to the pump, yet I can't hear it running (Its a noisy lil sucker, Walbro) so I know its not a fuse or relay. Guess I'll be ordering a new pump.

Question though, its the Walbro pump that came with the older JRSC kits for the NB a while back. Can't for the life of me recall if its a 190lph or 255lph, though I'm guessing 190lph. Anyone know for sure? And a cheap place to pick up a genuine replacement?

Thanks guys

Ben

iTrader: (33)

Can't tell ya with certainty which pump you had, but most of the JRSC guys run the 255 for whatever reason. I'd go with the 190lph hp from lightning motorsports. Got mine for $~90 shipped.

Tex Miata

How exactly did you test it? The only sure way is to jump the wires (g and FP) in the diagnostic port in the engine compartment.

Fritch

Cool, just looked there. They've got the 190lph for $79 right now, not bad

Fritch

yeah I did that, and when jumpered I would get a constant 12v at the connector but the pump wouldn't run.

Ben

iTrader: (33)

Get the $5 high pressure upgrade. Mine's not noisy. I put the sleeve on it and clamped it tightly to the assembly.

Ben

Fritch

really? I'm not using an AFPR (car is a NB) so is there really a need for the HP unit?

And man my pump was pretty noisy, I even put the sleeve on it and it barely made a difference.

Ben

iTrader: (33)

Maybe your dead pump was a 255 then. They're supposedly louder than the 190s. My 190 is pretty quiet.

I didn't know you have an NB. They use a returnless fuel system and don't run pressures that our FI NA cars do, so you don't need the hp. How modified is your car? A stock fuel pump will provide enough pressure and flow for most NB JRSC applications.

Fritch

it isn't a JRSC anymore, that was long, long ago but I've since removed that pile o crap and went turbo but kept the fuel pump since there was no need to take it out. Turbo setup is very basic at the moment, GT2560, no IC, 6psi with the FM voodoo box (like JR powercard) for fueling. Just trying to figure out what pump was already in the car since it was working fine and providing enough fuel already.

Ben

iTrader: (33)

I would guess it was a standard 255lph. I don't know what your goals are, but for where you're at now, I'd stick by my previous statement that the stock pump will more than enough fuel @ 60 psi (your rail pressure). And it's silent and cheap. Someone posted pressure vs flow charts for different pumps, but I couldn't find it.

Get a cheap ebay stock pump and use the saved money to swap your injectors for 01+ injectors (280 vs 310cc/min @ 60 psi, plug n play).

Ben

Fritch

oh really, I wasn't aware the 01+ injectors were larger...

I plan on getting the IC done shortly after I move into my house in a month or so and then throwing 2-3psi more at it and from there maybe an emanage or something else. Not too sure yet but I really want to hit 220rwhp eventually, currently at 175rwhp.

I'm just going to pick up another walbro pump (most likely 190lph, found on another forum that thats what came with the kit) since it was working fine already.

cjernigan

iTrader: (13)

Thread jack- Would the +01 injectors help that much or just be an extra safe guard against running lean at higher boost, I have stock '99s right now with the voodoo box and stock fuel pump as well. I'm looking into running MS though and i guess if I'm gonna get injectors maybe I should go for the RX-7 or Supras.

Ben

iTrader: (33)

Again, someone posted flow vs pressure charts for several pumps, including the stock pump. I wish I could find them so I could give specifics, but what I remember is the 190 and stock pumps were nearly identical. Your returnless fuel delivery will never go over 60 psi. If I were spending my own $, I would find a used stock pump for $10-15 instead of going with the walbro.

Your stock injectors would be over 100% duty cycle at 205 crank hp, and that's assuming your engine is very efficient. Supra 305's would be at 83% duty cycle and should (?) idle with your stock ecu. That's still assuming a very efficient engine and 60 psi of fuel. I don't know the limits of what your ecu will idle. To get 250 crank hp at 80% duty cycle you're going to need ~400 cc/min. That will probably require an aftermarket ecu.

Ben

Ben

iTrader: (33)

I think you're going to be shocked at how lean you're running when you get the wideband in. I'd get the biggest injectors you can cleanly idle now, and then go with the RX-7 440's when you go MS.

Ben

cjernigan

iTrader: (13)

Sounds like a plan, thanks Ben. WB should be in within a week as long as i go get the turbo tomorrow. Still cleaning the residual oil out of my IC pipes and bar/plate intercooler from the seals going bad from before i bought the car.

Braineack

iTrader: (62)

https://www.miataturbo.net/forums/sh...97&postcount=5

Ben

iTrader: (33)

To clear any confusion, the numbers I used are not secrets.

The baseline pressure for injector flow measurement is 43.5 psi. Flyin Miata tested:
year cc/min
90-93 228
94-97 268
99-00 238
01-05 264

na supra 305 <-- these were not tested by FM,
na rx-7 440 but are common upgrades

Therefor:
Flow, same injectors at 60 psi (fuel pressure inside fuel rail of NB miata):
year cc/min
90-93 268
94-97 314
99-00 280
01-05 310

supra 358
rx-7 517

calculation:
flow @ 60 psi = (sqrt (60/43.5)) * flow @ 43.5 psi

Crank HP for NB miata, injector potential assuming 60psi, .60 BSFC, 80% duty cycle
injector hp
90-93 136
94-97 160
99-00 142
01-05 157

supra 182
rx-7 263

calculation:
hp = 60 psi flow / 10.5 / BSFC * duty cycle * no of cylinders

Crank HP For NA miata, injector potential, assumptions as above but 100 psi fuel pressure:
injector hp
90-93 176
94-97 206
99-00 183
01-05 203

supra 235
rx-7 339

calculation:
hp = 100 psi flow / 10.5 / BSFC * duty cycle * no of cylinders

Above figures are crank hp numbers, but can be considered safe and conservative due to well tuned turbo miatas running more efficient than .60 BSFC and the ability to run a little higher duty cycle. Also NA miatas can have greater than 100 psi fuel pressure in the rail.

Ben

iTrader: (33)

Thanks for the link.

Looks like at 60 psi the stock pump flows enough fuel for 265 crank hp at .60 BSFC (conservative) and 280 crank hp at .55 BSFC.

Ben

Fritch

wait a second, I could have sworn the NA 94/97 injectors were rated at and flowed the same 230cc

hustler

iTrader: (6)

i thought walbro's were reliable. I don't know what pump to buy.