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F.I. Inc. · 02-21-2013, 12:12 PM

Update,

This dyno chart shows the comparison from Tuesday night and yesterday. Below are the comparative specs.

Run #13 from 2/19/2013
9.77 psi peak
18 Degrees of timing
91 Octane (pump)
2.5" FI straight test pipe Non Res X Pipe CBE

Run #6 from 2/20/2013
10.20 psi peak
22 degrees of timing
100 octane (pump)
2.5" FI straight test pipe Non Res X Pipe CBE

As stated in previous posts, we are dropping fuel pressure during the run. We currently are running the Aeromotive 340lph fuel pump in tank and have amped the voltage with a relay and thicker gauge wiring. In addition we have drilled out the swirl jet on the bottom of the canister as well as the FPR (Fuel Pressure Regulator). The pressure drops but stabilizes around 42 psi during full throttle in the higher rpm range. This is monitored by a gauge directly mounted to the fuel rail. We are in the process of adapting a secondary gauge to the fuel canister itself to find specifically where the pressure drop is occurring and why. Together with Charles from CJ Motorsports "aka" phunk we will come up with a solution. We are not totally convinced that the only solution is to switch to a return style fuel setup.

Since Uprev does not allow you to monitor fuel pressure in the software nor does this car have an external fuel pressure sensor plug-in anywhere, you are either installing a fuel pressure gauge right off of the fuel rail or bringing one into the car. Like I stated earlier, we feel that most people are not monitoring fuel pressure as long as the car is not running lean during testing on the dyno or street. You can see from our chart above that even though we are dropping fuel pressure we are still able to get the air/fuel ratio at an acceptable level. We are not comfortable turning up the boost anymore with the fuel pressure at 42-44 psi under a run until we can fix the issue. Because the fuel pressure is dropping it is requiring us to add substantially more fuel in the higher rpm range to the table. Every pound of boost added will make the fuel pressure drop lower in the current state that the car is in.

It is possible to run a boosted 370z with dropping fuel pressure for many years and never having an issue. That being said, there is eventually a breaking point where the pressure drop will become an problem. For example, as time goes by fuel pumps degrade, filters start to clog and your fuel pressure will eventually go lower and lower. It only takes your fuel pressure to drop below that breaking point for a split second one time at the right boost level to cause catastrophic engine failure. In addition keep in mind that your fuel pressure is much more erratic beating the car up and down the street than on the dyno. In between gear changes, constant on and off the throttle. At the end of day you are dealing with a fuel system that is mechanically regulated at the tank while fuel atomization is happening 7-8 feet away at the engine. Case in point, by the time the engine runs out of fuel it is too late for the regulator compensate.

In closing, we are getting ready to head back to the track first thing tomorrow morning. We have the car in a safe state and will run the boost around 8 psi and potentially turn it up to 10 psi. We will see how the day goes and keep everyone informed throughout the day and weekend.

Thank you all for your time and stay tuned...

Tony

02-21-2013, 12:12 PM	#558 (permalink)
F.I. Inc. The370Z.com Sponsor Join Date: Feb 2009 Location: Simi Valley, CA Posts: 2,989 Drives: 2010 GT-R/2007 F-250 Rep Power: 685	Update, This dyno chart shows the comparison from Tuesday night and yesterday. Below are the comparative specs. Run #13 from 2/19/2013 9.77 psi peak 18 Degrees of timing 91 Octane (pump) 2.5" FI straight test pipe Non Res X Pipe CBE Run #6 from 2/20/2013 10.20 psi peak 22 degrees of timing 100 octane (pump) 2.5" FI straight test pipe Non Res X Pipe CBE As stated in previous posts, we are dropping fuel pressure during the run. We currently are running the Aeromotive 340lph fuel pump in tank and have amped the voltage with a relay and thicker gauge wiring. In addition we have drilled out the swirl jet on the bottom of the canister as well as the FPR (Fuel Pressure Regulator). The pressure drops but stabilizes around 42 psi during full throttle in the higher rpm range. This is monitored by a gauge directly mounted to the fuel rail. We are in the process of adapting a secondary gauge to the fuel canister itself to find specifically where the pressure drop is occurring and why. Together with Charles from CJ Motorsports "aka" phunk we will come up with a solution. We are not totally convinced that the only solution is to switch to a return style fuel setup. Since Uprev does not allow you to monitor fuel pressure in the software nor does this car have an external fuel pressure sensor plug-in anywhere, you are either installing a fuel pressure gauge right off of the fuel rail or bringing one into the car. Like I stated earlier, we feel that most people are not monitoring fuel pressure as long as the car is not running lean during testing on the dyno or street. You can see from our chart above that even though we are dropping fuel pressure we are still able to get the air/fuel ratio at an acceptable level. We are not comfortable turning up the boost anymore with the fuel pressure at 42-44 psi under a run until we can fix the issue. Because the fuel pressure is dropping it is requiring us to add substantially more fuel in the higher rpm range to the table. Every pound of boost added will make the fuel pressure drop lower in the current state that the car is in. It is possible to run a boosted 370z with dropping fuel pressure for many years and never having an issue. That being said, there is eventually a breaking point where the pressure drop will become an problem. For example, as time goes by fuel pumps degrade, filters start to clog and your fuel pressure will eventually go lower and lower. It only takes your fuel pressure to drop below that breaking point for a split second one time at the right boost level to cause catastrophic engine failure. In addition keep in mind that your fuel pressure is much more erratic beating the car up and down the street than on the dyno. In between gear changes, constant on and off the throttle. At the end of day you are dealing with a fuel system that is mechanically regulated at the tank while fuel atomization is happening 7-8 feet away at the engine. Case in point, by the time the engine runs out of fuel it is too late for the regulator compensate. In closing, we are getting ready to head back to the track first thing tomorrow morning. We have the car in a safe state and will run the boost around 8 psi and potentially turn it up to 10 psi. We will see how the day goes and keep everyone informed throughout the day and weekend. Thank you all for your time and stay tuned... Tony __________________ *Follow us on Facebook: Fast Intentions Inc.* Phone: (805) 522-FAST (3278) Email: tony@fastintentions.com www.fastintentions.com "FUELED BY PASSION"