Whats the biggest injector i can run with stock pump?

[sheffester]

As the title says, whats the biggest injector I can run with the stock fuel pump??? I'm looking at either 550cc's or 650cc's. Thanks!

 

[sureshot971]

cant you run any size injector with the stock pump? Beacuse it will not flow any more then the stock one can handle.

 

[fourreGsixty3]

I'm not sure on your question, but I the stock pump should be able to handle your injector choices, but I will say this. DO NOT cheap out on a $90 wally 190, upgrade the fuel pump, and injector's at the same time. This is fuel we are talking about and not an area that should be done half ass cause you will ruin something that way.

 

[timloomis]

The stock pump can't even handle the stock 450's at more than 16psi. The 190 is a good pump, and so is the 255. You actually need a bigger pump before you need injectors.

 

[wimploki]

If your tight on cash, i suggest that you buy a Evo 8 or 9 Fuel Pump. Around $60 to $70 dollars. Make sure to buy a rewire kit as well. Check Ebay - $25

 

[snox135]

The stock pump will handle the 650's with upgraded lines, but it's easier/cheaper to buy a bigger pump.

 

[GinNBoost]

You shouldn't even be thinking about bigger injectors if you're running a stock fuel pump.

 

[staticbrainwash]

You shouldn't even be thinking about bigger injectors if you're running a stock fuel pump.

Too true, but just be wary, you SHOULD run an afpr with ANY larger fuel pump. Yes i know everyone says a 190 is fine with a stock pump, but try checking your fuel pressure. You will see you are overrunning the stocker. Is it horrible? No, not anywhere as bad a running an unregulated 255. But still something to consider. I had a 190 that i bought and never put on because i knew id end up needing an afpr anyway, so i'm trying to sell it for a 255.

 

[nightspeed87]

If your goals arent bigger than a e316g I really doubt that youll need more than a 190.

 

[Boostdclips99]

After you buy that fuel pump(if your looking at the 255) and the injectors, get ready to buy a new fuel pressure regulator. I didn't upgrade mine at first and after I put my Aeromotive in I could tell a noticeable gain in efficiency in fuel pressures and air/fuels.

 

[Xeiros]

I don't recommend you up your injectors without upgrading your FP. That being said, I'm hoping a wiseman or someone very knowledgeable sees this post, because I'm very curious about this.

According to RRE, the stock pump rewired @ 14v and 43PSI will net you around 140lph.

If that were the case, then using the calculation

(power x BSFC) x (1 + Safety Margin) = Pounds Per Hour
pph / 7.25 = Gallons Per Hour
Gph x 3.785 = Liters Per Hour

I found that the stock pump, running at almost max capacity (130lph) would produce around 290HP at the crank. That would put you somewhere around 220-230whp I believe.

Now my question is, how much do the stock 450's flow in lb/hr? Would those injectors indeed outflow the additional power, or would a rewired pump actually outflow the 450's?

 

[Eclipse98_RS]

I had 550's on my car with a stock pump and my car ran just fine. Although I finally did upgrade to the 255 wally.

 

[xveganxcowboyx]

You need to upgrade your pump if you want to really use those injectors. I put in my evo injectors before upgrading the pump and still saw knock around 15psi. (had same problem with 450's) I put a better pump in and the problem disappeared. Of course every setup is a little different, but you can safely assume the fuel pump will run out of steam around the same area your stock injectors will.

 

[nightspeed87]

I don't recommend you up your injectors without upgrading your FP. That being said, I'm hoping a wiseman or someone very knowledgeable sees this post, because I'm very curious about this.

According to RRE, the stock pump rewired @ 14v and 43PSI will net you around 140lph.

If that were the case, then using the calculation

(power x BSFC) x (1 + Safety Margin) = Pounds Per Hour
pph / 7.25 = Gallons Per Hour
Gph x 3.785 = Liters Per Hour

I found that the stock pump, running at almost max capacity (130lph) would produce around 290HP at the crank. That would put you somewhere around 220-230whp I believe.

Now my question is, how much do the stock 450's flow in lb/hr? Would those injectors indeed outflow the additional power, or would a rewired pump actually outflow the 450's?

The injectors out flow the pump. The pump is said to only be good up to 15psi on stock set up. The stock injectors have been known to go past 20 on a evo316g with some other tricks or mods. You can put as big as injectors as you want on any fuel pump as long as you want but injectors wont help you when your exceeding the fuel pumps max output. ( Which has nothing to do with the injectors themselves ) since all the pump does is push XX amount of fuel to the injectors.
Therefore without pump upgrades also, no matter how big your injectors are it will still lean out because of an incapable fuel pump not incapable injectors.
Thats how this happened

You need to upgrade your pump if you want to really use those injectors. I put in my evo injectors before upgrading the pump and still saw knock around 15psi. (had same problem with 450's) I put a better pump in and the problem disappeared. Of course every setup is a little different, but you can safely assume the fuel pump will run out of steam around the same area your stock injectors will.

Therefore bigger injectors is great but they wont be much of a help till you get bigger pump also... Its almost like upgrading your manifold and leaving a stock exhaust system in a way, cant expect much because the rest of the system negates the gain of the manifold.

 

[steve]

how much do the stock 450's flow in lb/hr?

At 43.5 psi the injectors flow 450cc. RC Engineering says "To convert cc / min to lbs. / hr. - Divide by 10.5". So they would be about 43 lbs/hr but at 1G stock fuel pressure they are only about 39 lbs/hr.


Steve

 

[sheffester]

Well, this is my problem.

My car runs great until it reaches temperature. It will then run like crap. It wont boost and it will die out if I give it more than 10% throttle. So, when it starts to act up, I have to be close to home or I'm screwed. I have no idea what this could be. Plugs are brand new, and the wires are couple months old. The motor has 32 miles on it. Any ideas or suggestions will be greatly appreciated.

 

[snox135]

Have you done a boost leak test?

 

[steve]

There are plenty of things that could malfunction once they get hot.
My TPS when it got hot would go open and the car would start to buck and hardly be drivable.
Later one of my injectors would go open when hot and again the car ran like crap.
In both cases I get a CEL that gave me a clue where to look. Logging provided additional clues.

You'll have to provide more data on what's happening or we will just be guessing.

Steve

 

[edenTSI]

would i have to change my pump if i change my injectors? my 1g is a/t so it has 390cc injectors. the standard 1g's have 450cc so i wanty to switch over to the larger injectors.

 

[staticbrainwash]

When i first got my car, i had 2 injectors that would short when hot. I'd lost at least one cyl on hot starts. Your first check would be for fuel and spark, then id check compression just to be sure.

Is it a miss? Or is it bucking, or. . . ?

 

[xveganxcowboyx]

Therefore bigger injectors is great but they wont be much of a help till you get bigger pump also... Its almost like upgrading your manifold and leaving a stock exhaust system in a way, cant expect much because the rest of the system negates the gain of the manifold.

My point exactly. Weakest link. You can upgrade everything else, but if your fuel pump won't match you're stil SOL.

 

[sheffester]

Well, thanks for all the answers about the fuel issue. Now I have done a boost leak test, and fixed all the leaks. How often should I check for leaks?? I have never gotten a CEL, and I don't have access to a logger. It just seems to die. It will run fine till it reaches temp, then start to run like crap. I can shut the car down, let it sit, then start it, and it will be fine. Now, I don't know if this will make a difference or not, but it takes a really long time to start, whether its hot or cold (longer time when its colder). But when it's hot, I have to crank it for like 5 seconds, stop, let it sit, then try again and it will start. Now, is there anything I'm missing???

 

[GVR4592]

Sounds like a coolant temp sensor problem or a bad connection at the sensor. The wires get brittle with age and they sometimes break. I would pull the plastic sheathing off and inspect the wires for damage. You should also get a datalogger if you plan on modifying your car.

 

[sheffester]

You know, I never thought of that. The connection was bad down there anyways, so I know have the fan hotwired along with the coolant temp sensor. Do you think its worth a shot replacing the sensor and wires/plugs???