Hi Everyone, The N54 has been reaching new levels regularly and we've noticed that there were quite a few people pushing the limit of their Stage 3 fuel pumps. When these were first introduced breaking 600whp was a big deal but now we're encroaching on 900whp so an update was needed. Consequently we revisited the Stage 3 setup to see how we could make improvements and maintain the flows and pressures we needed for these new boost and power levels. Ultimately the biggest restriction in the fuel system once the pump and fuel lines have been upgraded is the fuel filter assembly on the drivers side. We've all known that for some time but wanted to keep that fully functional so that all the return systems worked as designed and the system remained robust and reliable. Keeping all that in mind we set out to design our Stage 4 fuel pump and had a few mandatory criteria: -Keep all the in tank fuel transfer systems functional and as stock as possible -Maintain the DME's and Jb4's ability to monitor and regulate the low pressure fuel system -Achieve higher flows -Maintain greater pressures To do this we ended up creating a new design for our dual pump assembly that I'll outline below. Primary fuel pump: With the new design the primary pump is isolated and runs just like a Stage 2 pump. It remains PWM controlled by the DME and is powered by the stock wiring harness. In addition it utilizes the stock tank's internal plumbing so that all the venturis and fuel transfer systems remain functional, this will support approximately 550whp on E85. Secondary fuel pump: The big changes for Stage 4 is the secondary pump configuration. The secondary pump is now isolated so that none of it's capacity is used to feed venturi's nor is restricted by the stock fuel fuel filter assembly. Instead as you'll see in the pictures, the secondary pump is plumbed directly out the tophat where it is then routed toward the engine compartment via a -6an E85 compatible fuel line. External fuel filter assembly: The most obvious change you'll notice is the addition of our new dual input 6 micron E85 compatible fuel filter. This new 200GPH fuel filter accomplishes a couple purposes. The secondary pump is no longer running through the stock filter so it must be filtered. In addition to maintain the DME's and JB4's ability to regulate and monitor fuel pressures for everyday use and port injection we needed to combine the inputs. This new filter assembly does that and then supplies the fuel to the HPFP and port injection kit. This new filter is mounted under the chassis by the driver's footwell where there are two existing 8mm female bolt holes. Many are familiar with this location for mounting an ethanol sensor. If you wish to run an ethanol sensor as well, the alternate filter mounting location is in the metal "tunnel" area as the fuel lines enter the engine bay. As this thread progresses we'll update it with additional pictures of those mounting locations. Upgraded fuel lines: Another obvious addition to this fuel kit are the additional fuel lines that are included with the Stage 4 kits. These are required due to the addition of the secondary feed line and the filter assembly. Consequently if you have an existing fuel line upgrade or port injection kit that you will be upgrading from, those lines will have to be changed out. Fuel Pressure Regulator: To run this system, it is mandatory that you have an external fuel pressure regulator. Frankly by the time you get to the power levels that require this magnitude of a setup, you should be running one that is boost referenced anyway. We have not added it to the standard Stage 4 package because some of you already have them. If you don't have one, you can simply select that additional option when ordering your Stage 4 fuel pump. Answers to a few questions we anticipate we'll get... What's included with Stage 4? -A complete plug and play solution by simply replacing your stock bucket. However, to utilize the secondary, an additional wiring harness must be installed. -Two new E85 compatible Walbro fuel pumps -Two new Walbro filters -A custom fitting that is tuned to optimize the venturi and pump output -Spare vent tube clip -Wiring harness for the secondary pump -All the necessary -6an fuel lines to connect the pumps, fuel filter, HPFP, and port injection rail -6 micron E85 compatible fuel filter -Flow testing prior to shipping Can this be run like a Stage 2 until I finish my upgrades? Yes, just let us know when you place your order and we will cap the secondary feed line and return fitting for you. Once you complete your upgrades, you can remove the caps, install your secondary wiring harness, and upgrade the fuel lines. Can I trade-in my Stage 3? Unfortunately no, we can't re-use your Stage 3. Your Stage 4 will come with a new wiring harness and we would recommend removing your Stage 3 and selling it with the new wiring harness. Those are unchanged and this will supply your buyer with a new wiring harness to complete their installation. If you will be utilizing our trade-in option and need additional time for your buyer to return their stock core to you, let us know and we're happy to work with you on that. Can I trade-in my Stage 2? Yes, our normal upgrade policy rules apply to this as well. Can I trade-in my Stage 1? No, but you can use your core for the trade-in option as long as it is otherwise stock and undamaged. Can the parts for the upgrade be purchased separately? No, we get asked this quite a bit and here is why we don't do that. First off who better to build your pump assembly than the company that builds them every day? Second, there are specialty tools and procedures used to build these. Most don't have those tools in their possession. Third, after it's built, don't you want to know that it has been bench tested for flows, pressures, current draw, and functionality before putting it in your car? Otherwise if you have issues dialing everything in, how are you going to know where to start? At least if you've started with a known good pump assembly, you can investigate possible installation issues, or other possible causes without it being a bad/plugged venturi, bad pump, or whatever else may have happened during the installation process. Do you have an option to add a 3rd pump? No, there is no need at this time. One pump will max out the HPFP at approximately 430whp on E85 but is capable of flowing enough fuel for approximately 550whp. With our design we utilize that additional capacity and add an additional pump that is also capable of supporting over 600whp as it's not feeding the venturi's. Consequently adding a 3rd pump at this time would create additional expense and complication that is not needed. How much power will this support Theoretically it should support 1000+ whp. This setup runs dual -6an lines from pumps that are capable of supporting over 500whp each. We have simplified this design with our Y adapter to feed the HPFP and the port injection and it's currently a -6an line. Should the need arise as we approach 100whp, we'll also make a dual output filter available so the HPFP and port injection rail can be supplied by individual -6an lines as well. Overall power potential is going to also be subject to the AFR targets, fuel type, and requested pressures. As more questions arise we'll add them to this post and continue to update this thread with install pictures, videos, and additional information. Below we have included a brief video description of the pump assembly, a few logs, and some pictures of the products. Video overview: http://www.n54tech.com/forums/showthread.php?t=32482&page=9 You can also find these on our website here... http://www.fuel-it.biz/e-series-135i...-line-upgrade/ *The Ultimate Fuel System Upgrade Package* The Package includes: -Port Injection w. Return -Port Injection Controller of your choice -Stage 4 LPFP -Upgraded e85 compatible -6an fuel lines (ethanol sensor & analyzed optional) -Ring removal tool -Hobbs switch Enter the code: ufsu400 ...and SAVE $400 at checkout http://www.fuel-it.biz/e-series-135i-and-335i-ultimate-fuel-system-upgrade-save-over-400/ Here are a couple log examples from our 135i running high boost levels on E85 targeting AFRs of 11.9:1. You'll also notice in these logs that as our boost levels rise, so do our fuel pressures to compensate for the increased manifold pressures. Generally with these pumps the LPFP pressures will max out between 85 and 90psi and our base pressures are set at approximately 58psi.