Quote:
Originally Posted by Tall Jim
Can you elaborate on how the Dorch HPFP allows you to run lower pressure due to increase in fuel flow? That doesn't make sense to me because the injectors are the fueling limitation on these cars and not the HPFP. The reason we run a higher fuel pressure is because it allows you to push more fuel through the same size injectors, but lowering pressure because you have more flow from a bigger pump wouldn't do anything when you bottleneck is still the injector. I'm curious because I've tuned a few of these cars and currently I'm just waiting on an aftermarket injector because it doesn't seem like a bigger HPFP will do anything for power.
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We think you may have misinterpreted what was stated in our previous post. Yes, you are correct that the factory DI injectors are the primary bottleneck of the stock fuel system and adding higher flowing HPFP's will do nothing to increase the fueling capabilities of an otherwise stock fuel system. That is one of the main points we brought up on our first post. However, this only holds true based on your power goals and how reliable of a fuel system you would like to have.
Scenario 1: A turbo upgraded S55 running straight E85 looking to produce 750whp could easily do so on EU5 injectors without upgraded HPFP's, upgraded LPFP, or PI. However, just as you would need to target high fuel pressure on the HPFP side when getting close to the limit of the factory DI injector you will still need to do the same when reaching the flow limit of the EU5's. This is primary cause of injector failure as we previously discussed.
Scenario 2: The same vehicle and goals listed in scenario 1 with the addition of EU5's and HPFP upgrades will support the same power goals, but will do so without the risk of injector failure since upgraded HPFP's flow significantly more volume at a much stable and lower pressure.
Unfortunately, since we have not completed testing with EU5's and Dorch HPFP solution for maximum power without PI, we can not say for certain what the safe limit on straight E85 is just yet. However, we can say with certainty that a HPFP upgrade is going to be required for big power applications as fuel pressure will begin to crash at those levels.