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Walbro or Brushless?

WagenWizard

Ready to race!
Location
Pennsylvania
I was able to get a great deal on a slightly used PR MPI kit with the 925cc injectors already installed on a euro manifold, upgraded fuel lines and sensors, APR boost tap, Walbro 535 stage 3.5 v2 AWD LPFP installed in basket and ready to go, and a torqbyte AWD PM4 controller.

These all arrived and I am ready to schedule an install but I am considering getting the brushless RS3 pump instead just to keep it simple. I know I will be saving some install costs due to the Walbro pump already being assembled and also the PR kit also being pre-assembled on the euro manifold, but the simplicity of the RS3 pump and not having to fiddle with the PM4 controller has me tempted to sell the Walbro and PM4 to fund the brushless pump.

So, what would you do? I have a FBO IS38 4motion Sportwagen, UM turned, the plan is UM flex tune with the MPI install.

Appreciate your thoughts and opinions! Apologies to all who may have seen this on the Sportwagen FB group, trying to get as many opinions as I can since I can't seem to make a decision myself. 🫤
 

WagenWizard

Ready to race!
Location
Pennsylvania
The hope is to eve
Seems like an unnecessary added expense. The 535 is more than enough for an IS38
I hope to eventually move on to a larger turbo, nothing crazy as I have no intention of building my motor. My main concern is with the PM4 and if that complicates things more than they need to be. Not sure what is involved with installing one or if it makes the tuning more difficult, my thought was the brushless with its controller being OEM parts may simplify things a bit and maybe be more reliable?

Are there any advantages with the PM4 over the controller from an rs3 brushless pump?

I think the standard answer I see from UM is they can tune about anything, so maybe I should not really be concerned with it at all. I will be paying a shop to do all of the work so I am hoping the labor will be a bit less considering the pump is all put together and the MPI and accessories are already installed on the euro manifold and ready to go, should be pretty straightforward.

Thanks for the reply, it is appreciated!
 

Diggs24

Autocross Champion
Location
de plains! de plains!
Car(s)
2015 GTI
I think I am at about 460whp right now and the 535 is pretty much out of fuel, but adding a PM4 would allow me to stretch that even further (500WHP??, turbo is maxed out so no way to confirm). UM shouldn't have any issue tuning the car with either setup. Labor-wise a drop in RS3 would be cheaper but wiring in a PM4 isn't that difficult that a shop couldn't add it pretty easily. Tough choice. Can't go wrong either way, just do what makes you feel more comfortable.
 

WagenWizard

Ready to race!
Location
Pennsylvania
I think I am at about 460whp right now and the 535 is pretty much out of fuel, but adding a PM4 would allow me to stretch that even further (500WHP??, turbo is maxed out so no way to confirm). UM shouldn't have any issue tuning the car with either setup. Labor-wise a drop in RS3 would be cheaper but wiring in a PM4 isn't that difficult that a shop couldn't add it pretty easily. Tough choice. Can't go wrong either way, just do what makes you feel more comfortable.
I'm leaning towards the brushless pump if I can sell my pump and pm4 quickly. I will check the classifieds to see if anyone has a new or slightly used brushless for sale, hoping to have this done by the end of September if possible. Thanks again for your thoughts on this, it is always nice to have some opinions from people who have more experience with these things than I do! 😀
 

railroader

Autocross Newbie
Location
Yuma Arizona
Stage 4 pr kit doesn't require a pm4, flows more than an rs3 pump and also cheaper considering everything you get with the kit. It is the best flowing kit for the price. The 535 pump with a pm4 and fuel line will flow just about as much as an rs3 pump
 

Wastegate13

Autocross Champion
Location
SoFla
Stage 4 pr kit doesn't require a pm4, flows more than an rs3 pump and also cheaper considering everything you get with the kit. It is the best flowing kit for the price. The 535 pump with a pm4 and fuel line will flow just about as much as an rs3 pump
The biggest benefit of the rs3 is that it’s drop in. I went from a 450 and pm4 that I can only assume was a bad pump or a bad initial install. Rs3 is fool proof.
 

MeltedSolid

Autocross Newbie
Location
San Francisco Bay Area
Car(s)
'15 Golf, e36 328i
I've been running a 450 with no controller. After I spent a bit of time adjusting the fuel pump duty cycle table, it's been perfect. Idk exactly how much difficulty the PM4 controller will add, but I suspect either way, RS3 or the 535 with PM4, won't be very complicated. If I were you I'd probably just use what you already have.
 

railroader

Autocross Newbie
Location
Yuma Arizona
99.9999% of issues with the pr kit or any other walbro kit is install, you can get them pre installed so it is just drop in also, plug n play, you pay 12-1400 for an rs3 pump that's good for approximately 600whp, 535 with pm4 will cost just under 1k if you get pm4 used and install the pump yourself, pr stage 4 kit outflows the rs3 pump hands down, you get the dual 450 walbro kit, fuel pressure regulator, and -6an steel braded fuel line for around 1100 if you install yourself, install is easy and straightforward, biggest issue people have is when they drill the basket, you can build your own rs3 kit for around 700 or so I think
 

WagenWizard

Ready to race!
Location
Pennsylvania
99.9999% of issues with the pr kit or any other walbro kit is install, you can get them pre installed so it is just drop in also, plug n play, you pay 12-1400 for an rs3 pump that's good for approximately 600whp, 535 with pm4 will cost just under 1k if you get pm4 used and install the pump yourself, pr stage 4 kit outflows the rs3 pump hands down, you get the dual 450 walbro kit, fuel pressure regulator, and -6an steel braded fuel line for around 1100 if you install yourself, install is easy and straightforward, biggest issue people have is when they drill the basket, you can build your own rs3 kit for around 700 or so I think
I was lucky, I picked up the already assembled 535 pump, the PR kit already pre installed on a euro manifold, PM4 controller, PR upgraded fuel lines, 4bar put, 5bar map, APR boost tap for $1200 shipped. Since the pump is put together and the PR kit is installed on the manifold I am guessing this should cut back on the labor cost of install. I just was not sure about the PM4 and how difficult it was to wire up and install. The OEM route always sounds good to me and the not having to mess with the PM4 controller.

This car will never see over 450 to the wheels because I am not interested in having the motor built, also not interested in blowing it up so I'm trying to be as safe as possible. Not sure what the IS38 with flex tune and MPI will get me, maybe 375? But I know which ever way I go I will have plenty of fueling for the current setup. I'm gonna talk to my installer and see what the difference in labor costs would be between PM4 and Brushless route.

Thanks for your thoughts, much appreciated!
 

Wastegate13

Autocross Champion
Location
SoFla
The pm4 is the easiest part of the install. You could do it yourself on the stock pump before you even take the car into the shop.
 

Mk6shyenne

New member
Location
Fort Walton beach Florida
Car(s)
Mk7.5 gti
I've been running a 450 with no controller. After I spent a bit of time adjusting the fuel pump duty cycle table, it's been perfect. Idk exactly how much difficulty the PM4 controller will add, but I suspect either way, RS3 or the 535 with PM4, won't be very complicated. If I were you I'd probably just use what you already have.
How long you been running it with no controller?
 

MeltedSolid

Autocross Newbie
Location
San Francisco Bay Area
Car(s)
'15 Golf, e36 328i
How long you been running it with no controller?
Almost a year. It won't work without custom tuning though, I had to decrease the pump's duty cycle to not throw a CEL or blow a fuse.
 
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