[TheObviousChild]

Google is useless. I have the MPPSK on my 340 and am considering the Dinantronics. In reading up on that vs JB4, I keep seeing people referencing fuel limits when discussing the potential increase to HP. I just haven't figured out what the fuel limit of a car is.

[robbiep]

Originally Posted by TheObviousChild

Google is useless. I have the MPPSK on my 340 and am considering the Dinantronics. In reading up on that vs JB4, I keep seeing people referencing fuel limits when discussing the potential increase to HP. I just haven't figured out what the fuel limit of a car is.

Quite simply, it's how much fuel each cylinder - and thus the engine - can efficiently burn and produce power from on each ignition.
There is no point in chucking unburnt fuel down the exhaust. It doesn't add to power generated by the engine when it flames out by the tailpipe.

[rosstin]

I thought it was either a fuel pump limit, or hardcoded ECU limit. Either way something that is not easily sidetracked on the b58, yet

[rlmesq]

It's sometimes called a "flammability limit" or "explosive limit."

If the air/fuel mixture is too rich, it can actually inhibit combustion.

https://en.wikipedia.org/wiki/Flammability_limit

[Roki187]

Originally Posted by TheObviousChild

Google is useless. I have the MPPSK on my 340 and am considering the Dinantronics. In reading up on that vs JB4, I keep seeing people referencing fuel limits when discussing the potential increase to HP. I just haven't figured out what the fuel limit of a car is.

No one figured out what the fuel system limit of the b58 is yet as there is a fuel cap burned into the dme. The only way to find out the limit of our fuel system is to flash the dme......

[ishowerinjager]

Originally Posted by Roki187

No one figured out what the fuel system limit of the b58 is yet as there is a fuel cap burned into the dme. The only way to find out the limit of our fuel system is to flash the dme......

This is the correct answer.

[riskmaker76]

The fuel limit we talk about has to do with the amount of fuel we can deliver to the motor to reduce the AFR while balancing the amount of boost and usable timing (Boost plus timing = power). I rarely see the fuel limit hit unless your adding octane... When you add octane (such as E85, etc.) your boost is limitless up to 22psi, timing will be well advanced... thus your ability to make power and suck in air is amazing - thus you need more fuel... if you dont add more fuel you WILL run lean (NOT RICH!!!!)..

When your AFR runs lean you need to add more fuel to richen the mixture. To do this you must increase fuel pressure... issues come into play as you add fuel pressure one of two things occur 1. the trick to increase fuel pressure could cause a fault since your tricking the car into thinking fuel pressure is low, thus the computer raises it OR 2. As you raise your fuel pressure (within normal parameters) it lowers your boost target as a different protection mechanism which no one has yet to figured out.

High amounts of E85 have diminishing returns because E85 is essentially diluting your tank of gas (E85 is less efficient as a combustible - but dont confuse this with octane rating), thus you need to add MORE fuel, above and beyond the fuel needed for the added Boost and Timing you just added. Eventually you will cause the fault since your computer will think it lost too much fuel pressure .. With race fuel, your volume of gas is not affected thus you can push the limit and will hit the fuel limit lowering of boost target well in advance of any fuel pressure issues...

[NISFAN]

Originally Posted by TheObviousChild

Google is useless. I have the MPPSK on my 340 and am considering the Dinantronics. In reading up on that vs JB4, I keep seeing people referencing fuel limits when discussing the potential increase to HP. I just haven't figured out what the fuel limit of a car is.

Fuel limits has a few meanings, but in the context of the B58, the ECU works on a 'closed loop' self tuning algorithm. So instead of the ECU looking up a map table and injecting fuel according to the 'mapped' values, the B58 ECU puts the emphasis on the Lambda (O2 sensor in exhaust) readings, and adjusts injector duty to keep these Lambda within a target value.....

.....but there is a limit to how much fuel it can deliver written into the software. That fuel limit is in effect a horsepower limit too. That's why you can't go much beyond 400hp without fuel coming from an additional source, meth injection, or upstream extra fuel injector(s).

So in your case, MPPSK already uses up some of the fuel limit headroom. Adding another tuning device might not bring the additional power it would on a non MPPSK car, due to the hard fuel limit.

Hope that makes sense.

[eluded]

Originally Posted by NISFAN

Hope that makes sense

Nope.