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      11-30-2012, 01:02 AM   #14

Drives: '07 e92 AT Sport Montego Blue
Join Date: Sep 2011
Location: Portland, OR

iTrader: (3)

Originally Posted by ign335i View Post
Was a good aftermarket solution? Its an OE solution that can outflow the HPFP. It is not dropping pressure anywhere. Terry's RB car on 100% E98 (requires more fueling than 100% E85) is not losing low pressure anywhere in the rev range. That includes peak torque, which btw is not where you would max a low pressure pump at (this happens at peak power). He is making well over 500whp with no meth and the bad bsfc that comes along with stock housings. It seems you have evidence this is not the case though. I'd love to see it and get down to the bottom of this since I am considering upgrading the low pressure system and have been waiting to see the results of both solutions.

That being said, I was hoping for something a little more professional than a booster pump slapped on to compensate for the stock pump. I will wait to pass judgment on this inline booster pump, but to me the concept sounds more like an "aftermarket solution" that doesn't integrate properly with the OE fuel system. If the stock pump doesn't flow enough it should be replaced with one that does. Maybe I am missing something, guess we will see.
Well, considering I didn't do the testing I can't provide you all the details regarding BMS's testing, but I did talk with Terry at Shift S3ctor. I was under the assumption that they were still seeing fueling issues with e85 at higher power levels, but you seem to be very knowledgeable regarding this so please feel free to correct me if I'm wrong.

The ability of a fuel delivery system to maintain a specific pressure (in PSI) is an important factor when analyzing a fuel system. It should not be confused with volumetric or ability to deliver a specific amount (in Gal. per minute or Litters per minute) of fuel. As a rule of thumb, when a system can not maintain a specific pressure, the vehicle will probably run very bad or not run at all. On the other hand, it is quite common to see vehicles with good fuel pressure and have performance problems due to a lack of fuel volume. Good fuel volume is the systemís ability to maintain a specific quantity or volume regardless of vehicle operation and that is the key point that everyone seems to overlook.

When two (or more) pumps are arranged in serial their resulting pump performance curve is obtained by adding their heads at the same flow rate as indicated in the figure below.

Pumps in series are used to overcome larger system head loss than one pump can handle alone.

* For two identical pumps in series the head will be twice the head of a single pump at the same flow rate - as indicated in point 2.

With a constant flowrate the combined head moves from 1 to 2.

Note! In practice the combined head and flow rate moves along the system curve to point 3.

* Point 3 is where the system operates with both pumps running
* Point 1 is where the system operates with one pump running

So I'm not saying that for most the replacement of the LPFP will fix the issue if the volume of fuel is increased by the replacement of the old pump. But when your system demands more volume that a single pump can deliver, adding a booster pump will increase the flow rate required to sustain the HPFP at peak demand.