Advice on 1g fuel system

[sc2_ct]

I've searched a bit but didn't really find the information I was looking for. If this is something that has been covered and you remember where, please let me know.

Anyway, I'm getting a 1g talon that has a JDM engine (still need to identify *which* engine, but I would assume its the 4g63t) for my daily driver and winter car since my other car has become somewhat less than practical for that and AWD is great for new england winters . Being a performance nut though, I'd like to adjust the wastegate a little bit, and aim for around 1 bar occasional and about 10psi daily with a boost controller. My questions have to do with the fuel system and spark. I would assume that the stock injectors by around 1 bar will be running a pretty high duty cycle, and was thinking that the solution would be to pick up some 5% larger injectors and just adjust down the fuel pressure while watching a WBo2, does this sound about right?

Also, what is the rated flow of the OEM fuel pump and at what pressure? Would an inline fuel booster pump be in order, a new in-tank pump, or could I get away with something like the Ken Belle boost-a-pump or the MSD fuel pump booster?

As far as ignition retard goes, I was thinking of retarding about 3-5 degrees and running 93 octane fuel with colder plugs.

Anyway, I'm new to the DSM scene (haven't even picked the car up yet ), but not new to cars in the general sense. I just wanted to check with some of you who are familiar with these cars and see your opinions/recommendations.

 

[Stanford]

If all you want to do is get a manual boost controller and run somewhere around 15lbs of boost (1bar being 14.7 or 14.5 depending on who you ask). Then you only need a fuel pump upgrade, the Walbro 190lph would be plenty. You do not need to retard the timing at all and for that level of boost stock plugs would be fine also. You would want to check out which version of the JDM 4g63 is in the car though, some JDM's have larger turbos and injectors.

 

[sc2_ct]

Originally posted by Stanford
If all you want to do is get a manual boost controller and run somewhere around 15lbs of boost (1bar being 14.7 or 14.5 depending on who you ask). Then you only need a fuel pump upgrade, the Walbro 190lph would be plenty. You do not need to retard the timing at all and for that level of boost stock plugs would be fine also. You would want to check out which version of the JDM 4g63 is in the car though, some JDM's have larger turbos and injectors.

I was thinking actually of using an electronic boost controller so that I have presets. Eventually I may switch to a programmable MSD ignition, but am also wondering if the fuel control between boost levels can be handled with a rising-rate fuel pressure regulator?

The injectors are another matter. I don't have the car here yet and haven't bought a manual on it yet so I can't easily look it up, but what type of injectors does the TSI use (bosch, etc) and are they high or low impedance?

I put up a post in the newbies forum to see if there is any kind of page where I can identify the engine based on a stamped code or what-not. I don't know much about JDM engines what with coming from a domestic sport compact background, but I do understand that identifying the particular 4g63t JDM motor can be tricky.

I understand that 16 psi is about the maximum that the factory fuel system can handle, but what about the internals? I know that the primary concern relating to an engines limitations are the fuel system, but I was wondering where is the point where components start to fail?

Thanks for your quick and informative reply by the way

 

[markgholland]

Originally posted by sc2_ct
I put up a post in the newbies forum to see if there is any kind of page where I can identify the engine based on a stamped code or what-not. I don't know much about JDM engines what with coming from a domestic sport compact background, but I do understand that identifying the particular 4g63t JDM motor can be tricky.

I understand that 16 psi is about the maximum that the factory fuel system can handle, but what about the internals? I know that the primary concern relating to an engines limitations are the fuel system, but I was wondering where is the point where components start to fail?

Thanks for your quick and informative reply by the way

The JDM engine he is referring to is the GVR-4 RST engine which comes with the 16G, and I *believe* slightly larger injectors, maybe 495cc?? You will be very lucky if you get one of those.

16 psi is really all you want to push with the factory fuel pump, but this can easily be fixed with a Walmart 190 and an adjustable FPR. Yes, people will tell you that you can tune a 190 without a AFPR and they are right; just something I would suggest.

Don't worry about the internals for now. They will be fine for whatever power you ever want to make, unless you plan to make over 550 whp.

There is a lot of good information for people new to the sport available on this site and others as well. Check around, you'll be surprised the amount of information available.
~Mark

 

[sc2_ct]

So it sort of sounds like the "JDM" engine is just the same as the USDM version? In that case, I don't quite understand why you'd get one (if someone just wants the bigger turbo and injectors, it would be cheaper to just get them than buy, ship and swap a whole engine).

about 15psi or so sounds good to me for now, since this car is going to be a daily driver and get me back and forth across the state for work. Eventually when I pick up a truck or something to haul my other project to the track, then I might be able to turn my full attention to the Talon performance-wise.

So, to recap, just dialing it up tp 15psi won't require anything but adjusting the FPR? Any estimates of the whp on a setup like that with a 2.5" cat back, bored TB and air filter? I'm not quite sure what to expect in the way of drivetrain loss due to the AWD. 200 to the wheels would be a nice start. If I really get desperate, I've got all sorts of nitrous stuff lying around, I could just fill that sucker up with co2 to spray onto the intercooler (co2 is cheaper than n2o and stores at the same pressure levels anyway, so the temperature drop due to gas expansion is about the same .

 

[Stanford]

It has 510cc injectors, and yes the 16g. You will probably not get that motor but it is a possibility. The internals will be fine as Mark said they can handle gobs of power. The factory ignition is also fine, other than plugs and wires it is plenty for what you want. As more air enters the MAF the ECU will compensate by adding more fuel so you can switch boost levels all you'd like and be fine. This is only the truth with a fairly stock setup which is what you are looking at. Once you start swapping injectors, turbos, etc. then you would have to get some fuel control.

Edit- You don't need a FPR to run 15psi but when you swap in a larger fuel pump it is something a lot of people install to help from over running the factory fpr. You may have to Hack your MAF to avoid over running it also. Visit DSM.org and VFAQ.com lots can be learned from these sites.

Edit #2- Get a test pipe(replaces cat,quicker spool-up and more power) and re-wire your fuel pump so the voltage doesn't drop off at higher rpm's. You can find directions for the fuel pump re-wire at VFAQ.com.

 

[markgholland]

Originally posted by sc2_ct
So it sort of sounds like the "JDM" engine is just the same as the USDM version? In that case, I don't quite understand why you'd get one (if someone just wants the bigger turbo and injectors, it would be cheaper to just get them than buy, ship and swap a whole engine).

about 15psi or so sounds good to me for now, since this car is going to be a daily driver and get me back and forth across the state for work. Eventually when I pick up a truck or something to haul my other project to the track, then I might be able to turn my full attention to the Talon performance-wise.

So, to recap, just dialing it up tp 15psi won't require anything but adjusting the FPR? Any estimates of the whp on a setup like that with a 2.5" cat back, bored TB and air filter? I'm not quite sure what to expect in the way of drivetrain loss due to the AWD. 200 to the wheels would be a nice start. If I really get desperate, I've got all sorts of nitrous stuff lying around, I could just fill that sucker up with co2 to spray onto the intercooler (co2 is cheaper than n2o and stores at the same pressure levels anyway, so the temperature drop due to gas expansion is about the same .

You really only NEED the adjustable fuel pressure regulator if your running any pump larger than a 190. Even some people try tuning 255's with just an AFC or alternative tuning device, which works for a lot of people. I think that it would be a wise investment for you to get a 190lph fuel pump so you don't run into the problem of fuel cut on a cool night. They are approximately 100 bucks or so. Just a suggestion.

Don't worry about the drivetrain. You'll never need to worry about that with slightly over 200whp. Also, not clear on why you want to "bore" your throttle body...
~Mark

 

[sc2_ct]

Well, not boring techically, but giving it a parabolicly tapered and textured bore and port-matching it to the intake manifold. I'm not sure if I'll bother actually having the plate seat widened and a new plate cut, but just giving it a good parabolic taper with a slight texture should help out a bit with the venturi effect allowing a bit more air into the engine. I've done enough throttle bodies now that I almost consider it a 'christening' of a new car :laugh:

Oh, and I'll take your advice on the fuel pump. I really hate how manufacturers decide to go with fuel-cut instead of spark-drop limiters and safeties. On Saturns the rev and speed limiters are both fuel-cut, and needless to say, this has caused some people running nitrous a few problems .

 

[markgholland]

Originally posted by sc2_ct
Well, not boring techically, but giving it a parabolicly tapered and textured bore and port-matching it to the intake manifold. I'm not sure if I'll bother actually having the plate seat widened and a new plate cut, but just giving it a good parabolic taper with a slight texture should help out a bit with the venturi effect allowing a bit more air into the engine. I've done enough throttle bodies now that I almost consider it a 'christening' of a new car :laugh:

OK, but it's fine as is.

 

[sc2_ct]

Well, not boring techically, but giving it a parabolicly tapered and textured bore and port-matching it to the intake manifold. I'm not sure if I'll bother actually having the plate seat widened and a new plate cut, but just giving it a good parabolic taper with a slight texture should help out a bit with the venturi effect allowing a bit more air into the engine. I've done enough throttle bodies now that I almost consider it a 'christening' of a new car :laugh:

 

[sc2_ct]

Sorry, I hit back and it re-posted the response again.

 

[KFT0001]

With 1 bar of boost, not too much needs to be done on the car. I had no problem running mine regularly at 1.2 bar with no fuel modifications on 91 octane gasoline. A fuel pump would be a nice safety upgrade, though probably not altogether necessary. You should rewire the power wire to your fuel pump either way though.

 

[markgholland]

Originally posted by KFT0001
With 1 bar of boost, not too much needs to be done on the car. I had no problem running mine regularly at 1.2 bar with no fuel modifications on 91 octane gasoline. A fuel pump would be a nice safety upgrade, though probably not altogether necessary. You should rewire the power wire to your fuel pump either way though.

You ran your stock fuel system at 18+ lbs of boost without getting fuel cut and on 91 octane gas? Wow, I'm impressed. Did you ever throw a logger on it to see how bad you were knocking?
~Mark

 

[sc2_ct]

Is there a primer on the fuel pump wiring? I assume that there is a relay inline that allows the ECU to cut the fuel, and you're essentially just re-routing the power wire without the relay (or whatever other triggering signal that the PCM uses? Would it work to just run a dedicated line directly from the battery to the pump with a relay off the ignition circuit?

 

[Stanford]

Go to VFAQ.com for instructions on the re-wire. It uses the factory fuel pump power to turn on and off the relay, so even though you are now getting straight power from the battery you can still hit fuel cut. I am not even sure if this is what happens during fuel cut(ecu drops voltage to fuel pump). I just think its easier and more practical to use the factory fuel pump power to turn the relay on and off.

 

[KFT0001]

Originally posted by markgholland
You ran your stock fuel system at 18+ lbs of boost without getting fuel cut and on 91 octane gas? Wow, I'm impressed. Did you ever throw a logger on it to see how bad you were knocking?
~Mark

I wasn't knocking too bad. I don't remember the exact knock count, but my timing was in the 20's even in the higher rpm ranges. One time I made a mistake and left my wastegate pressure source open and I boosted 1.7bar with no fuel cut either. Both of those numbers were on a 14b though.