I was looking at some Holley in-tank fuel pumps, and they come in three different ratings. 155 LPH, 190LPH, and 255 LPH. The lowest can handle up to 491 HP, whereas the highest one can handle 800 HP. My question is, if I were to save myself the hassle in the future by buying the 255 LPH pump, what would I have to do to ensure it works right? Or are fuel pumps like fuel injectors? Is the output controlled by the PCM, so I don't have to worry about anything or having it running too rich? Or will I have to adjust my Fuel Pressure Regulator to compensate? I have no idea how fuel pumps (and their respective output ratings) work...Help?

 

TTT

 

Can anyone shed light on my problem???

 

I'm not an expert but I'm pretty sure this is how it works. The PCM does not regulate fuel pump flow, the fuel injectors and fuel pressure regulator will keep everything running right. The PCM will compensate for any rich condition as a result of the new pump. You can install the pump and leave everything else alone, no other adjustments are absolutely necessary.

 

So my car won't have a problem with running the 255 LPH fuel pump, even though it's not putting out more than 400 RWHP? Wouldn't such a high flow pump as the 255 LPH have to run at an extremely low pressure so as to not to over-do it? I dunno if I should get the 255 LPH or just take the safe route and buy the 190 LPH...

 

I have the 255lph Walbro pump. Your car is only going to use so much fuel. The rest goes through the return line back into the tank. So go ahead and get the 255lph now.

 

Thanks!!

 

Don't get the 255. Get the 190 unless you are going all out with NOS and deck the rest of the engine out. Just a suppercharged engine won't need more than 190 LPH. Also you are probably going to want to get higher pressure injectors. This should not effect the computer because it should be able to detect that more gas is being injected into the intake by way of O2 sensor and shorten the pulse width. I would double check withn a chevy dealer or someone who knows for sure. I read that for a gen1 motor, not a gen2, but I imagine that they should be about the same for something like that.

 

well, I do plan on putting a 150 wet shot on it sometime as well, but I will rarely use it. The 255 LPH is only $20 more...why not get it?? Are there any specific reasons than "unnecessary" Also what kind of injectors should I run? I've been reading around that 30# injectors are sufficient for similar setups to mine...all bolt-ons, heads & cam...does that sound right?

 

no, I can't think of any reason not to spend the extra $20 for the 255. Does that come with a new pressure regulator? I would go with 36lb/hr injectors for nitrous oxide. Only reason I say 36 is because I saw a setup in carcraft that said they used that.

 

I don't think it comes with a new regulator, but I'm buying an Aeromotive one that I'll be installing at the same time. As far as injector size, I thought maybe 30# was big enough since I'm running a wet shot anyways...unless those kits' fuel lines are powered by the injectors...but I thought that's what the fuel solenoid was for...I dunno, N2O is greek to me...

 

If you get 30lb/hr injectors and you've got 8 then total output is 240lb/hr. I guess that means you should be good with that and the 255 pump.

Cya, time to go to work...

 

ROFL!!! Wet kits don't have anything to do with the injectors. The added fuel comes via a fuel solenoid being feed by the fuel pump. Most people with LT1's tap into the schrader valve for the fuel solenoid connection. The fuel line with the NX kit just screws onto the schrader valve. Then just screw the other end to the fuel solenoid itself. I have heads, cam, NX 150-175 shot wet kit, 30# SVO injectors, 255lph Walbro intank, etc. 11.03 @ 125.53 spinning with a 3650 raceweight on a stock shortblock, 4L60E, and 10-bolt rear.

 

Derricks right, wet kits use a soleniod fed by the pump.

Your fuel pressure regulator will keep the fuel pressure at 35psi (or whatever is stock, I don't remember; unless you have changed it of course) whether you have a 190 or 255 liter pump. The 255 will just keep up the pressure where a 190 would lose pressure on a car pushing 600 hp for example.

 

Well, that's what I thought originally, but Metaldrgn mentioned that I'd need bigger injectors when running N2O, and I've never physically seen a N2O kit, so I began to question its mechanics. I guess Metaldrgn must have missed the part in my post mentioning that I would be running a "wet" kit...