2stage MBC, fuel setting questions

[NylenS]

Hey guys I just ordered a few parts and a 2 stage MBC was one of them. I was just wondering, on the stock fuel system on my 93 Tsi, if I set my low at seven psi and high at fourteen psi will I have to adjust my air fuel settings when I change from low to high or will fuel system compensate for this change??? I just get the motor back from the machine shop this week and am dropping it in this weekend. I don't want to blow it up because I am running to rich at 7psi and to lean at 14psi. Please help!!!

 

[Absit]

Fuel's based on load and RPMs. Changing boost changes load, which the fuel system will compensate for - assuming it can.

 

[NylenS]

So I can use my MBC and switch from low to high boost without having to change any fuel settings?!?!? Will my stick fuel system be able to handle 14psi??

 

[Absit]

Every car is different, follow your wideband carefully and tune according to safe AFRs.

 

[nickk90]

You won't be able to go down to 7psi on the stock wastegate. The stock wastegate is around 12-14psi. If you do the BCS mod you should already be around 14psi of boost or soo and yes the stock fuel system will handle that no problem but a fuel pump rewire wouldnt hurt.

 

[NylenS]

I have a 14b turbo. I don't think I was running 14 psi from factory?

 

[skatershawn]

A 14b with the BCS on, on a stock car should be (i believe) 11.3psi, with the BCS is should jump to 12-14psi easy!

 

[LiquidX]

You can only go as low as the wastegate spring will allow. The 16g for example will only go as low as 10 psi because that's the spring pressure.

For being on a stock fuel system, a dual stage controller isn't needed as you can only go to a max of 15psi on the 14b and a max of 13psi on a 16g before hitting 100% IDC (injectors no longer pulse [work correctly]). Once you do your fuel system and get a tuning device then the dual stage will work great being able to run stock or a little higher boost and then your next level could be at 23psi+.

But for now, keep it at a max of 14psi and Absit was correct as well, every car is different and a logger will help determine how much boost you can safely run.