Hitachi HPFP

[zbeasty]

I couldn't see that anyone had posted about this before but I have discovered that the Mazda 3 and 6 MPS also run a Hitachi HPFP. Apparently the internals are the same but the low pressure lines are in a different spot to the VW/Audi pump. Some of the guys on the Mazda forums are talking about running up to 160Bar which is a fair jump over the standard 130 that we run. Going to find out what internals they are running as I assume they can't do that with a standard pump.

[Corey_R]

There are different pressures being run in different versions of the T(F)SI. However, it's not necessarily the fuel pump which is the limiting factor for pressure. The HPFP pumps into the "Fuel Rail" and on the fuel rail you have a "Fuel Pressure Sensor" which opens the "Pressure Limiting Valve" at approximately 120bar. The valve is connected to the "Fuel Return Line" which runs back to the low pressure side, coming in somewhere before the "Low Fuel Pressure Sensor" so that the "Fuel Transfer Pump" in the petrol tank doesn't need to send as much fuel in that situation.

As far as I'm aware, even if you upgrade to the APR HPFP or other brand of aftermarket modified HPFP, the operating pressure of the fuel rail (and pressure release valve" are not changed. The bore (and stroke?) of the APR HPFP, for example, has been increased to allow approximately 40% more volume of fuel and overcome the inability of the stock pump "flow enough volume of fuel to maintain the system pressure".


I'd be happy to learn more about this topic though.

[zbeasty]

There is talk of another FPS that will allow the higher pressure. It will come down to whether the computer can interpret the values that come from the sensor. I know that we can fit the RS4 return valve but it seems to be no point until fitting an upgraded pump as the standard pump won't feed enough (pressure or volume) to warrant it. I know that I'm going to have to do the pump if I want to go further than I have now so I'm just trying to find out if there are any competitors for APR in terms of rebuilt and tested pumps. Not sure I want to pull my pump apart and fit new internals. By the time you factor in the cost of a new pump (US$300) plus the new internals at about US$400 plus shipping and labour to get someone else to do it you'll be up around $1k. For that price I can get my brother who lives in the US to order me a pump from APR over there. I was hoping that someone would have found another solution by now but given DI is only in its infancy people are still building knowledge. I did have to laugh at a mate of mine who has an STI. He said just get a Walbro or something and you'll be all good.

[Corey_R]

I'm not sure how practical it is to pull apart your own pump and fit new internals. Based on the fact that these pumps have been around for 5+ years and the number of aftermarket companies producing modified pumps is less than what you can count on a single hand, I would say that it's not an easy thing. From what I've read in VW self-study/service documents and APR's HPFP page, the internal tolerances are so precise that the pump internals can be damaged simply by touching them with bare hands!

[VW Central]

I have RS4 fuel rail and Autotech HPFP

[Corey_R]

Yeah - Autotech are one of those "count on less than one hand" companies making a HPFP.

Can you expand on your comment though DeanCorp. Like is there a company webpage which documents the benefits/advantages, or a forum page? What are your personal thoughts and experience with it?

[VW Central]

Yeah - Autotech are one of those "count on less than one hand" companies making a HPFP.

Can you expand on your comment though DeanCorp. Like is there a company webpage which documents the benefits/advantages, or a forum page? What are your personal thoughts and experience with it?

Basically from my understanding - The OEM fuel return valve opens at 130 bar and then allows pressure to drop to 127 bar and then starts building pressure back up again until it reaches the 130 bar and then the cycle is repeated. However with the upgraded RS4 valve it doesn't open again until the pressure reaches 136 bar and allows itself to drop but only to 130 bar before building the pressure back up.

In my case, and mods I am running, it was highly recommended for me to do so.

EDIT: Takes about 3-4 hours to install.

[zbeasty]

Autotech & KMD are both piston kits that you or your mechanic have to pull your own pump apart and fit the new internals. APR are the only ones that sell a complete upgraded pump that is tested after its finished.

[BLURR]

06F127025K https://www.ecstuning.com/b-hitachi-parts/high-pressure-fuel-pump/06f127025k~hit/ is this an upgraded fuel pump or a standard issue Golf R MK 6 pump?

[Lucas_R]

^ that is just a stock replacement HPFP.