Max Hp LPFP

martymil

Major General
Sep 6, 2017
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Down Under
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S65 1m
I'm extremely picky when I buy a vehicle which I've got my eye on a car but they are asking around 10k to much.
 

briankreed

New Member
Oct 12, 2020
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After talking with a few people, I ended up going a different route all together since I wanted to make closer to 550whp with some headroom. I haven't got anything on the car yet but I'm going PI and also going to run the new Walbro 535 lpfp. Yes, 535, not the 525. The 535 doesn't have a check valve and thus doesn't take as much juice from the stock ekp as the 525 does. There are a few guys that run them without any issues since the BMW fuel system stays pressurized and primes before start-up anyways. I'll be FBO plus Pure Stage 2 High Flows with a custom MHD flash. I'm hoping for 550whp+ on an e85/91 tune..... time will tell.
How did the Walbro 535 go? I had one installed in a stock bucket, replaced the fuel line with -6an, added Motiv Flex Fuel kit, drilled out the small opening in the fuel rail, removed the HPFP filter and added an inline 10 micron ceramic one. However now when running e50-60 on MHD Stage 2+ my HPFP dips too low and I get an idrive fuel warning and 2aae code. Did you all have to have your tuner change anything to take advantage of the 535 pump since we don't have a sensor?
 

sjobusen

Lurker
Aug 8, 2021
16
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Has anyone found the limits yet for e89 oem lpfp? It would be nice to know before replacing the original pump. Thanks.
I have tried limits of stock LPFP on Z4. With upgraded turbos 17T, I can run e30mix. If I raise to e40 my lpfp is not holding up to support the hpfp.