Hey, I'm trying to clear up some information. I've heard both true and false, so I don't know which is right. Does "X" amount of boost on a stock s5 turbo require the same amount of fuel as a larger hybrid (say a bnr stage 3 or 4) @ the same boost level? Essentially, does 10psi of boost on a hybrid require more fuel than 10psi on a stock turbo? If it does require more fuel....why? As I've said, I've heard both yes and no...so which is right?

 

Boost does not necessarily mean more power.
That's a general rule.

But, since we're talking about almost identical set-up's with the exception of the compression section...yes, the hybrid should make more power at the same amount of boost.


-Ted

 

but is it using the same amount of fuel or does it require more?

let me try wording a different way....assuming I'm running an s5 turbo @ 10lbs and I'm getting afr's @ 11.5 @ 6000rpm....then I change only the turbo out to a large hybrid and run it at 10 lbs...would my afr's be any leaner? Would I need to add more fuel even tho I'm still running the same amount of boost?

 

Large compressor side implies more airflow at any given boost over a smaller compressor side.

So, yes, it will require more fuel to keep AFR's safe.


-Ted

 

it's like the difference between pressure and volume right? there will be more airflow(volume) through a larger pipe at the same boost (pressure) than through a smaller pipe.
i think....im thinking about anatomy and physiology here, blood vessel dynamics....

 

makes sense now...thanks!

 

That is assuming the turbo with the larger compressor increases the volumetric efficiency and/or decreases the air temperature vs. the smaller turbo. While this is usually the case, I just want to point out that sometimes it doesn't work out this way, so the answer to the poster's question is not an absolute.

Hopefully.

It's more about density and efficiency. In this situation, pressure is a constant as stated by the original poster.

 

Well, no, the answer to this particular poster's question IS an absolute. The BNR stage 1-4 turbos will increase volumetric efficiency, because it WILL flow more CFM at a static boost level than the stock turbo.

So yes, it WILL need more fuel =O

 

i still have trouble wrapping my head around this.. from my understanding, different turbos can have different airflow at a fixed boost pressure, but only due to differences in intake temps and exhaust turbine backpressure

meaning, if the exhasut side was the same, and boost pressure fixed, a bigger compressor will flow the same or less, due to the higher drag of the bigger compressor

however most hybrids have clipped or modified exhaust sides, which lowers backpressure, which causes more airflow (power) at a given boost pressure

 

Bad assumption...


-Ted

 

Indeed. A lot of hybrids just have a larger compressor side mated to the stock exhaust side.

 

Look at it from a horsepwoer standpoint. Forget pressure, compressor size and the rest.

The hybrid turbo (should, and for this example lets say will) make more hosrepower. To make more power then before you need two things. More air. And more fuel. The two together equal a more explosive combustion, which results in more work performed on the eccentric shaft, which means more smiles on your face.

Kapeesh?

 

definitely has more power....6lbs on this hybrid feels like 10-12 on the stock s5 that was on it before.