N54 DI fuel rail 1M vs 335i

[Efp1103]

I’m going to be starting the process of upgrading my DI system to support heavier E blends soon. My only hang up is drilling the fuel rail. I’ve heard talk that the 1M rail is different than the stock 335i rail, the part numbers are indeed different, however I can’t find any information on what the physical differences between the two are. Does anyone know if there is a measurable difference between the two? I’d like to avoid drilling my rail altogether if I can just swap it out for a part that already has greater flow characteristics from the factory. Here are the part numbers for reference.

335i: 13537575480
1M: 13537535897

Thanks!

 

[Torgus]

Well the only way to 'upgrade' the DI system is by overspinning the HPFP. The VTT two shotgun still overspins and there have been numerous issues with their kit. Failing Helix and other overdrive products etc. Having to add braces and billet parts because of harmonic issues spinning a pump past it'd design limitations is just stupid.

AFAIK drilling out the HP fuel rail only gives you a small bump in headroom and then you need to install an quality in line fuel filter. Just drill out either rail. I have not seen any documentation or reason to believe one is better than the other, especially when drilled out. Remember, VTT used to charge $400 to drill out your HPFP rail which is a 30 second job!

Like most going to PI makes the most sense. Especially if you want to run full E85 and not mix at the pump which is PITA, especially if E85 aceess is hard to acquire.

When you factor in the cost of a HPFP overspinning product + a new HPFP PI makes even more sense. Or, overspin your 100k HPFP and see how long it lasts. Hopefully as long as the Helix etc. HPFPs and most pumps in general do not like spinning 30% past their design output for obvious reasons. If this was not an issues we would see 50% or 100% overspinning. There is a reason they do not.

A PI spacer + AIC is still the cheapest solution and you get the added benefit of never not having to clean your valves and the all the headroom you will ever need. At the end of the day the N54 injectors are always a hard limit in terms of injection and no high HP build is ever 100% DI based, and for good reason. DI upgrades are a band aid.

There is also the theory you should never run your fuel system past 80% of capacity LP or HP, especially HP. If you need the 3-5% the HPFP rail gives you it sounds like you are running on the ragged edge of your DI capacity anyways which is a recipe for disaster.

TL: DR Get PI Plate + 750CC

edit: I am not aware of a single post when someone had an overspun HPFP, then went PI and said, "Gosh I wish I went back to overspinning my HPFP and back to DI!"

 

[Efp1103]

I’m still tossing around the idea of going PI but with a reflex. The original goal for the build was to keep it simple and reasonable on DI only with a max goal of around 525-550whp on some ethanol. I’d like to keep that goal in place as this is a daily driver and I didn’t want to start over complicating things. It seems I’m already starting to push that boundary by drilling the rail and modifying the whole system though.. The plan was to upgrade the line back to the tank with the addition of an inline filter and ethanol sensor, remove the hpfp filter, and drill the rail to see what gains that would net me. I don’t believe I’ll need a lot of extra headroom to accomplish my goal but as you said I would probably be pushing the system to its limits at that point

 

[N54ROOKIE]

I’m still tossing around the idea of going PI but with a reflex. The original goal for the build was to keep it simple and reasonable on DI only with a max goal of around 525-550whp on some ethanol. I’d like to keep that goal in place as this is a daily driver and I didn’t want to start over complicating things. It seems I’m already starting to push that boundary by drilling the rail and modifying the whole system though.. The plan was to upgrade the line back to the tank with the addition of an inline filter and ethanol sensor, remove the hpfp filter, and drill the rail to see what gains that would net me. I don’t believe I’ll need a lot of extra headroom to accomplish my goal but as you said I would probably be pushing the system to its limits at that point

THIC Whips on you tube is doin g a 1M conversion. I bet he could answer that question...

 

[martymil]

The difference between the rails is the holding down brackets and that's it.

There are four main issues with the system.

Drill out the inlet on the rail.

The line between the rail and hpfp is very restrictive so you will need a new hp line.

The internal filter on the lp side reduces flow greatly into the hpfp starving it of fuel.

The inlet line to the hpfp than holds the lpfp sensor also is the size of a matchstick on the bends, this also needs replacing.

Or just get the PFS pod kit and it supplies you everything you need to Un restrict your di system.

Been running it for close to 3 years as have many others without issue except some grease leakage as the where overpacked on the first batch.

Pi has its own issues as it was never designed to run on our motors, if pi is so great why do bmw persist on improving the di system over implementing pi again. Unless all you want is to race your motor at the track stick to di for everyday reliability.

 

[martymil]

Also the pi mask any issues you have with the di side and thats not ideal, if you want total reliability stick with di or go pi with a stand alone.

 

[SLOWESTN54]

I personally haven’t had isssues with my PFS Pod. I’m over 700whp on full E still going strong.

 

[AshwinLB]

Pi has its own issues as it was never designed to run on our motors, if pi is so great why do bmw persist on improving the di system over implementing pi again.

Off topic but BMW did add port injection back on the b58tu2 to supplement the di

 

[martymil]

Off topic but BMW did add port injection back on the b58tu2 to supplement the di

Not from factory.

 

[AshwinLB]

Not from factory.

Yes it is PI from factory on the tu2 aka b58b30m2 and eventually b58b30o2

 

[martymil]

Hasn't been released yet and until it does we don't know the final specs, can't find any info.

If you can provide it please post.

Gathering from the limited info it will be pi only and many engines have been released with either one but not both.

A number of engines from other manufacturers have done it but are more trouble than they are worth.

 

[AshwinLB]

Hasn't been released yet and until it does we don't know the final specs, can't find any info.

If you can provide it please post.

Gathering from the limited info it will be pi only and many engines have been released with either one but not both.

A number of engines from other manufacturers have done it but are more trouble than they are worth.

They are already in the wild with the g70 740i and X7 lci. It is both DI and PI. I was able to find these images but I am still looking for the full technical document that these came from.

 

[martymil]

Interesting, basically being used to keep valves clean and supplemental fuel for di as it might not cope with the 7300lbs
dry weight the x7 has or it might be like the n55 first gen unicorn engine and not last long until they develop something better.

 

[Efp1103]

The difference between the rails is the holding down brackets and that's it.

There are four main issues with the system.

Drill out the inlet on the rail.

The line between the rail and hpfp is very restrictive so you will need a new hp line.

The internal filter on the lp side reduces flow greatly into the hpfp starving it of fuel.

The inlet line to the hpfp than holds the lpfp sensor also is the size of a matchstick on the bends, this also needs replacing.

Or just get the PFS pod kit and it supplies you everything you need to Un restrict your di system.

Been running it for close to 3 years as have many others without issue except some grease leakage as the where overpacked on the first batch.

Pi has its own issues as it was never designed to run on our motors, if pi is so great why do bmw persist on improving the di system over implementing pi again. Unless all you want is to race your motor at the track stick to di for everyday reliability.

Great info. Thank you. Would there be any additional benefit to upgrading the long line back to the tank as well? Also, with the POD, are you able to run full E85 on a single upgraded LPFP? I have a bucketed Walbro 535 and would love the simplicity of just filling with E85

 

[martymil]

I run a bucketless 535 and on 21 psi on e65 it's starts to just dip to around 65psi

 

[SLOWESTN54]

If you run it with dual lpfp’s you have enough fuel for over 750wheel. A tuner who knows what he’s doing is required tho

 

[Efp1103]

I run a bucketless 535 and on 21 psi on e65 it's starts to just dip to around 65psi

Gotcha. Sounds like I’ll have to look into a dual LPFP setup when the time comes. Still a lot cheaper and simpler than PI

 

[martymil]

Gotcha. Sounds like I’ll have to look into a dual LPFP setup when the time comes. Still a lot cheaper and simpler than PI

I wouldn't bother unless your dipping below 50psi as how much time do you really spend above 5500rpm on the street.

As long as you stay above 50psi it shouldnt be a problem up to 650hp but logging required to double check.

 

[Efp1103]

True. It’s not exactly a race car and I don’t plan on coming anywhere near that number

 

[Zelderlee]

If you run it with dual lpfp’s you have enough fuel for over 750wheel. A tuner who knows what he’s doing is required tho

Any tuners in mind I’d appreciate it?