In a few weeks I am going to well over 300whp. Probably close to 320-325whp

 

Just get the pump

 

I've been beat down on this subject a few times... the short of it is you don't know what you’re missing until you install one. It smoothed out the power band of my stock, less Works P1 flash, all by it self. I even pulled it out and put it back in to make sure that it really was the pump and not a fluke... The OE pump may be capable of maintaining such and such hp, but there seems to be something lacking in consistency...

 

If you're at sane altitude levels and ~300whp, the Walbro is overkill, IMO.

 

In flow it is... I think there is more to be found though...

 

buschur doesent use injectors and pump till stage 4. and thats with race gas....
i was gonna go stage 4 (injectors and pump) they told me not to bother without the race gas...
????

 

thats probably because they were running 22-24 psi..

 

It keeps the fuel pressure steady at higher RPMs. It's especially useful if you're running 20+ PSI to redline.

 

OK, please educate me here. I'm reasoning based on my reading and other second hand knowledge. I don't know for sure and I'm not an experienced tuner, but I would think that the injectors might have a bigger role than the fuel pump... I don't know if the fuel pump can deliver enough fuel to supply the stock injectors at 100% duty cycle, but if it can, using larger injectors would allow the fuel supplied by the pump to be delivered with shorter duty cycles. This might be a more desireable scenario.

Another thing here, looking at the statement above regarding the FMIC upgrade causing a change in tune and running rich, what benefit can a bigger (stronger, more powerful) pump can offer to lean out the mixture? Also, at the risk of highjacking the thread, according to Shiv the FMIC upgrades are of dubious value or at least offered inconclusive results when tested by Vishnu performance. If that's indeed the case, it would seem that the FMIC would have no effect whatsoever in the tune or A/F ratios. Does this make sense?

I'm going to go with more engine upgrades too such as cams and intake, full TB exhaust, etc. (I've been thinking about the IC upgrade too). I've already purchased a set of RC 660 injectors and a Perrin fuel rail. The injectors would appear to deliver plenty of fuel at 23 psi to support 350-400 hp at less than 85% duty cycle. Will the stock pump delived enough flow to supply the injectors? Can the stock ECU regulate fuel delivery through up-graded injectors? Does the up-graded pump have any effect on the ECU's control of the engine?

Thanks

 

I was told that if you don't replace the pump at over 305whp you run too lean and therefore burn stuff up

 

The stock ECU is set for the stock injectors and the stock pump, it is not set to adjust for the larger injectors. If you do the big pump it will be okay because this is a 2 stage pump and it will just recerc the gas back into the tank. If you do the injectors as well as the pump you will have to download a new free map if you have a xede or in your case have a new dynoflash map made for each new mod to the car.

 

Maybe it's the cold weather, but I'm running 21-22 through redline.

 

So what does the pump do? put more fuel at higher pressure through the same openings? What controls the fuel pressure of the up-graded pump? Back in the F/I Miatas/GSR days, the deal was to replace the stock fuel pressure regulator in the Superchaged cars (the pump as well in the turbo charged Miata). The fuel tuning was done by increasing the fuel pressure.
I think that there must be a reason why the stock pump is operating at 23 p.s.i. Perhaps that's the best pressure for the rest of the fuel delivery system..... I'd think it would be better to spray more fuel at the correct pressure (whatever that is...) during the right period of time. I guess the best way is to have the ability to control the injectors proprely....

 

as far as shiv saying the fmic is ineffective.....i know for a fact that after i put it on it was running rich....the smell, the boost, and the butt dyno, plus it almost stalled all the time. took the intercooler off and the problem went away. therefore shorter lower piping and better airflow through the core had an effect regardless of what some may say also, the fuel pump regulates pressure at a more consistent rate for higher fuel delivery in modded cars, especially during high rpm's. I would not do cams before i did a fuel pump, but that's me....You will need some sort of fuel control.....best options are either emanage, which controls fuel, ignition, extra injector, engine anti-stall (vta bov), and several more things, or a stand alone. This is just my opinion though. Some may opt for a SAFC if they are only doing minor tuning and modding. fuel supply is not fuel delivered to the cylinders, but fuel available to be delivered the cylinders....the more hp you add the more fuel you are going to need in order to stay knock-free....also, it is better to upgrade the pump before you need it

 

we made 303hp with a customers evo tuned with the aem ems. we were seeing 75%ish duty running around 12:1 afr. if i leaned it out to 12.5 the we were only at 70%i wasnt having to keep adding fuel as the rpms went up, which leads me to believe the stock fuel pump is good for at least what the injectors are good for. id say 350-375hp will be about all the stock fuel system is good for so long as you have it tuned perfect.

we saw no difference in power from 12:1 to 12.5:1 so i tuned the car for 12:1 to be safe.