BT and fuel

[GTIracer]

Hello guy's.

I have a GT30 custom rebuilt in my car. all the hardware is done, now my software engineer have the car to make a good software.

Some moods:

AXX engine with audi S3 rods and pistons, modded cylinder head, S3 injectors, APR HPFP, APR intank pump, S3 cams, GT3071 turbo, BSH Catch Can, APR IC, DSG software, fuel exhaust, special rail pressure valve (135bar) .........

Now the problem we have is the fuel. After installing a new APR intank pump we have enough fuel from the tank. but during the acceleration the rail pressure is first 135bar, everthing is fine, but than the pressure drop to under 100bar, so the power also drop down.

So how we can get more fuel into the engine ? :iono:

I often read here about BT Kits, but i don't know how you guy's make that in the usa with the fuel.

I read here about RS4 injectors, but they have an other injecton angle.

I want a car which is running perfect, no smoke, not to lean and save for the german highway.

 

[eurocars]

can you check injector pulse width? maybe you maxed you the s3 injectors?

 

[GTIracer]

it is possible i maxed out the S3 injectors but i need more fuel.

 

[ViRtUaLheretic]

Any idea how much power you are currently making?

 

[GTIracer]

my tuner think about good 415hp (engine power). we don't want to get much higher hp, because i only have the S3 rods and i don't want to open my engine again. maybe later.

i only want to know how you guys in the us solve that problem. are you all running RS4 injectors?

 

[Tmsracing37]

Any engine codes or EPC light popping up? Possible Fuel pressure regulator issues (hardware or even software) or pressure relief valve fault?

 

[xSabretoothx]

RS4 injectors will work, but also look into the other parts of the fuel system. People have been using the RS4 return valve w/ success, also look into the low pressure fuel pump system made by USP.

 

[ViRtUaLheretic]

RS4 injectors will work, but also look into the other parts of the fuel system. People have been using the RS4 return valve w/ success, also look into the low pressure fuel pump system made by USP.

This is what I was getting at, if you already have the APR HPFP and are still running out of fuel you might want to try and get the RS4 injectors and USP LPFP. Probably try out the RS4 injectors first.

 

[GTIracer]

current i have APR HPFP, APR Intank Pump, 135bar rail valve, S3 injectors.

I don't know which engine codes the car have. My car is in Germany by my software engineer and he made some test drives with vagcom and say the rail pressure drop down.

but when my S3 injectors exhausted, why decrease my rail pressure? For me its a sign that my APR HPFP can't deliver enough fuel.

 

[Tmsracing37]

Is it a rapid drop off (i.e. as soon as it reaches 135 bar, it suddenly drops off to 100 bar) or does the raol pressure tapper off to 100 bar through RPM's?

 

[GTIracer]

good question, i don't know. i have to confer with my tuner.

 

[eurocars]

ok, time to do some homework. Im sure your tuner knows (or should) how to calculate injector flow rate but i'll show you anyways. Injector flow rate = (HP x BSFC)/(#injectors x maxcycle) where the flowrate = lb/hr of gasoline at a specified pressure, HP= projected engine horsepower, BSFC = brake specific fuel consumption in lbs/hr (for your application, assume .55 bsfc), # injectors is 4, maxcycle is another way of saying maximum injector pulse width. anything above 80% pulse width can cause injector failure due to overheating. so... Flow = (415 x .55) / (4 x .8) ...flow = (228.25)/(3.2)... flow = 71.33 lb/hr injectors required as minimum flow requirement (anything with larger flow capabilities will work) to convert from lb/hr to cc/min, multiply by 10.5 (divide if going from cc/min to lb/hr). i came up with 748.95 cc injectors required for your particular application. BUT lucky for us apparently none of that matters, BECAUSE DI applications change the game (just called a fuel injection company because the #'s didnt make sense) sooo, i sent them an e-mail with your specs and i will have flow rate numbers shortly. if the s3 injectors flow anything under this number, then you need bigger injectors. let you know soon

 

[eurocars]

oh, and if possible, i need the specs for your intercooler (for air flow rates)

 

[GTIracer]

thank you eurocars. i think my tuner will know how to calculate everything, because he made many many fsi cars, normal K03 and K04 turbos. but i'm the first with a big turbo on a fsi i think. all the tuning should be stable, i mean hot summer day, 35°C, german highway and pedal to the metal. i think you will know what i mean. i don't know exact specs for my ic, its an APR tfsi IC.

in few days my tuner will get special motorsport fsi injectors. i hope that will help. i will post it here.

 

[MMD]

Getting bigger injectors will maintain the power level u ask for, but it wont solve the drop in the Rail pressure...
the drop of the rail pressure results in the drop of power, so focus on solving the rail pressure issue.
I have the same problem with my GT30+RS4+HPFP , and all other stuff installed.

I keep reading RS4 pressure relief valve would solve the problem , but Im not convinced with that , since the job of the valve is to release the rail pressure when it hits 136bar, and this is not the scenario here.

Other said check If the fuel feed from LPFP to the HPFP is insufficient due to a dirty fuel filter or some other item, this will cause issues withe rail pressure, that sounds rational , but im not sure if it would solve that issue..

My tuner altered the requested rail pressure to 125bar in order to help the actual rail pressure to meet the requested rail pressure , but nothing changed, there is still a drop in the Rail pressure..!!?

I logged the Requested/actual rail pressure , and the LPFP to get a clue where to start but I have no clue :biggrin:

Is there anyone knows whats the correct LPFP readings... ?