Max boost with stock fuel pump

[BlackbirdOfPrey]

I know this may have been answered before, but I searched and didnt find an answer to my specific question.

I just ordered my Joe P MBC from Forced Performance, and I was wondering how high I can turn up the boost, on a stock fuel pump without runing into lean/fuel cut issues. It is a 1992 Tsi AWD and mostly stock except for a K&N and boost guage.

 

[Quasimondo]

15 psi is about the limit, but if you're going to crank up the boost, you should rewire your fuel pump to compensate.

 

[sexehtopper]

so it would be wise to re-wire the fuel pump before turning the boost to 15psi? on stock fuel pump that is...and owuld i rewire a non stock fuel pump? and would a supra fuel pump work? and one more.. what else would i need with this fuel pump so everything runs cool.

 

[Quasimondo]

If you're staying on the stock pump, do the re-wire. The re-wire replaces the stock harness with thicker wiring that can carry a higher and more consistent current to the pump. It will eliminate the chances of having your car run too lean especially in the upper rpm's under WOT.

As far as using the Supra pump goes, I'd run that with the re-wire mod too, but I'm not sure how much it flows. If you end up running too rich with that pump, you may have to get an adjustable fuel pressure regulator to turn it down a notch.

The DSM VFAQ http://www.vfaq.com/FAQlocator-fuel.html will show you how to do the rewire. All the items you need can be purchased at your local Radio Shack. It's not a difficult mod to perform, I did mine in less than half an hour.

 

[BlackbirdOfPrey]

I plan on getting a 255lph walbro, but I dont have the money to buy it right now (but it is my next mod planned), and I don't plan on doing the rewire for the stock pump (because its getting replaced anyways.) Would 15 psi still be safe? or should I go 14 just to be on the safe side?

 

[Quasimondo]

If you're going to crank up the boost beyond stock levels, you NEED to do the re-wire mod. I can't stress that enough. It could mean the difference between having the money to get that walbro pump and using it as part of a down payment on an engine rebuild.

Even if you are going to install a walbro pump, I still recommend doing the re-wire mod. That way, you'll know that your pump is pumping at a consistent rate and if it's flowing too much, add an adjustable fuel pressure regulator, which you should be doing anyway if you're going to add a fuel pump that large.

BTW, what supporting mods and turbo are you going to be using with that fuel pump. Someone correct me if I'm wrong, but if you're still on the stock turbo, or even a 16G you won't need a fuel pump that big. A 190lph will do just fine.

 

[CowPimp]

If you're going to crank up the boost beyond stock levels, you NEED to do the re-wire mod. I can't stress that enough. It could mean the difference between having the money to get that walbro pump and using it as part of a down payment on an engine rebuild.

Even if you are going to install a walbro pump, I still recommend doing the re-wire mod. That way, you'll know that your pump is pumping at a consistent rate and if it's flowing too much, add an adjustable fuel pressure regulator, which you should be doing anyway if you're going to add a fuel pump that large.

BTW, what supporting mods and turbo are you going to be using with that fuel pump. Someone correct me if I'm wrong, but if you're still on the stock turbo, or even a 16G you won't need a fuel pump that big. A 190lph will do just fine.

I think the re-wire mod is overrated. Even without rewiring my 190lph pump my car runs pretty rich. Do some searches; the re-wire mod is not the necessity people make it out to be.

Also, I can run 17PSI just fine on my Big28 with a 190lph pump and stock injectors. I usually keep it at 16PSI while it's hot, and the boost naturally jumps up a pound when it's cold out.

 

[sexehtopper]

so what fuel presure regulator would you recommind for my near-stock talon?

 

[BlackbirdOfPrey]

If you're going to crank up the boost beyond stock levels, you NEED to do the re-wire mod. I can't stress that enough. It could mean the difference between having the money to get that walbro pump and using it as part of a down payment on an engine rebuild.

Even if you are going to install a walbro pump, I still recommend doing the re-wire mod. That way, you'll know that your pump is pumping at a consistent rate and if it's flowing too much, add an adjustable fuel pressure regulator, which you should be doing anyway if you're going to add a fuel pump that large.

BTW, what supporting mods and turbo are you going to be using with that fuel pump. Someone correct me if I'm wrong, but if you're still on the stock turbo, or even a 16G you won't need a fuel pump that big. A 190lph will do just fine.

Correct me if I'm wrong, but doesnt the rewire take about 30 bucks to do? Thats about 1/3 the cost of my new pump, on a pump that is going to be thrown away in a matter of weeks (I plan on getting my new pump next check). The 255 is going to be used to power an intended PTE 50 or possibly 56 trim (I haven't decided) and with a 50+ trim, you will max out the 190, meaning I will just have to replace it again (waste of money, and money is an issue). I do not wish to waste money on items that I will get rid of, I plan to do this in a one buy fashion (hence why I haven't bought a lot of the first tier mods, and won't until I get my new turbo, so that all the mods are optimized for it.

 

[Quasimondo]

If you're getting a a 50-trim, then sure, go with the 255 pump. The way it sounded to me was that you had a stock car with a stock turbo, and a stock exhaust, and the first thing you were doing was putting in a monster fuel pump. If I'm wrong, then I'm wrong.

Now, this is why I recommended the re-wire: An ounce of prevention is worth a pound of cure. A $30 re-wire modification (which is easily reversible once you install the 255lph Walbro) is a helluva lot cheaper than having to rebuild your motor because it ran too lean during a WOT run and detonation occured. We're talking about a 12-year old car. How well can you trust that 12-year old piece of 14-gauge wire to supply a consistient amount of power to that pump so that you don't run lean at the wrong moment? I'm not willing to risk that, and I wouldn't recommend anyone else risking it either.

 

[sexehtopper]

so how many pounds can i run off the re-wire on stock turbo setup?

 

[1993TalonTsiAWD]

I don't know if you know this, but is you still have the stock exhust you need to change that first before you turn it up to 14-15psi. I persanaly wouldn't run pass 15psi on the stock injectors. If you don't do the rewire be prepared for things to come and stay at least at 12-13psi.

If 50trim is in your furture then just wait and buy the injectors,pump,fuel controller, andAFPR, thats what I'm going to do after I install my EVO 16g,

A good rule to remember is before you turn up the boost always have the supporting mods.

One more thing if you haven't try the free mod of removing the plastic piece in the factory boost soilnoid to gain 1-2psi more like .5-1psi. Directions can be found on VFAQ or someone may post the link

Derek

 

[BlackbirdOfPrey]

The reason I haven't gotten new exhaust is because it is expensive (compared to a MBC, and fuel pump, though the prices have been coming down a bit as of late) and I don't think a 3" turbo back will bolt up to the stock 14b o2 housing/turbo (I may be wrong) that is also the same reason I have not bought an air intake as well. Yes you do have a point, I don't want to cause detonation, which is why I will probably not go to 15 psi, I was wondering what a "safe" level would be (mine runs at about 8-9 hot, and about 10 psi cold). However I do believe my car tends to run a little rich to begin with (I have no clue why) so uping the boost would help lean out my a/f right? or is there a flaw in my logic?

 

[sexehtopper]

but really my question is, would i be ok with the afc, and not having mods like exhaust etc etc... i just can pick it up for a hell of a price.

 

[Quasimondo]

A 3" will bolt up. You just have to check and make sure that the downpipe is flanged for the stock O2 housing. The Pacesetter 3" down pipe I have bolted up no problem.

As far as turning up the boost on a stock exhaust, it's restrictive enough as it is, so more boost = more backpressure, so you're not going to see the big bump in horsepower by just cranking up the boost. You'll probably see a bigger jump from just putting in a more free flowing exhaust.

sexehtopper, get the AFC because it's a helluva bargain, but you're going to still need to get an exhaust. And while you're at it, get a logger if you're going to be making adjustments on it

 

[sexehtopper]

thanks man.. now i just need a less-expensive alternative to exhaust (im in college). got any ideas, my freind said dont get the press bent downpipes or whatever that are like 99 bucks. let me know what a good 2.5 exhaust setup will run me, but witha ok price tag.

 

[BlackbirdOfPrey]

Ok I got another question for you, will the stock o2 housing even fit a 50+ trim? Because I dont want to have a dp flanged for the stock o2 and then have to replace the o2 when I get the 50 trim. Yeah sexe I can empathize, I'm a poor college student as well, and thats mainly why I don't have my exhaust, I been looking at local shops though, and I might be able to get mandrel bent ss catback for about 200, unfortunately with a decent dp (N1 or something like that which is another 200) its still going to cost a lot. BTW thanks for your help guys, I hope I didnt come off sounding like a jackass, its just cuz I'm not going the standard route, and not a lot of folks understand what I;m tryin to pull off.

 

[its3much]

if you get a 255 with no regulator you will over run your car you wont be able to go past 4500 at wot it'll bog an sputter till you shift an just run like shit period. just some advice cause i purchased my car with a 255 an nothing else

 

[BlackbirdOfPrey]

Ty for the info, I almost forgot that I need an FPR to run a 255, well more money down the drain, but can anyone answer my q about the o2 housing and the 50 trim?

 

[mach1one]

kinda extension of the original topic, which is better to do first? Would a 190lph be sufficient to turn the boost up, or should I go w/ injectors first? Most people I see on here buy injectors first, but a supra or 190lph pump is alot cheaper.

 

[flinguist]

kinda extension of the original topic, which is better to do first? Would a 190lph be sufficient to turn the boost up, or should I go w/ injectors first? Most people I see on here buy injectors first, but a supra or 190lph pump is alot cheaper.

To control the bigger injectors you need some kind of tuning device (safc, or DSM link), or the car won't run well. So go with the 190 lph pump. I found a used 190lph pump on EBAY for 30 bucks, and it works fine.

 

[1993TalonTsiAWD]

the pump should come before the injectors. The injectors have a bit more in them, they just need a FPR and AFC to get it. Always get the pump first then injectors.

Derek

 

[Cheks_Talon_TSi]

I will suggest that before geting some expensive mods (fuel pump and iny) you may want, in order to get more punds of boost, to either hack your MAS or even better if you get a 2G MAS.

Right now I am running with 15-16PSi on stock fuel pump and stock inyectors. My car is not getting leaner (as far as i can see in the A/F Ratio Gauge). My only mods are: k&N Filter, supertrapp exahust, cat removed, ngk wires and plugs, underdrive pulley, hacked MAS, MBC, Gauges and I think that's all.

I have heard of some persons in this forum that are running with even more punds than I (17PSi) on stock fuel pump and stock iny without any problems (On 1G DSM cars). Maybe thats kind of risk, but I think that we your current mods, 14-15 Psi will be complety safe.

Sergio G.

 

[sphillips91]

Correct me if I'm wrong, but doesnt the rewire take about 30 bucks to do? Thats about 1/3 the cost of my new pump, on a pump that is going to be thrown away in a matter of weeks (I plan on getting my new pump next check). The 255 is going to be used to power an intended PTE 50 or possibly 56 trim (I haven't decided) and with a 50+ trim, you will max out the 190, meaning I will just have to replace it again (waste of money, and money is an issue). I do not wish to waste money on items that I will get rid of, I plan to do this in a one buy fashion (hence why I haven't bought a lot of the first tier mods, and won't until I get my new turbo, so that all the mods are optimized for it.

Better Idea is too just save up and buy what you want all at once. Never know what is going to happen in between the time you buy a pump, wire it, turn up the boost, break something random that may be expensive (break for whatever reason not just from modding) Ive learned my lesson from my laser. Put money into things to support a 20G or bigger but never got too that point because things just broke randomely. Alternator, power steering pump, had to get a new clutch, and finally timing belt. So I was left with a car that wont run, cost too much to fix with all these mods on it too support a big turbo. YEY

 

[1993TalonTsiAWD]

Also if you replace the MAS get a GM one or better yet a blow through setup if your going for big power 320-400+HP

Derek