DIY 500whp e61 build--looking for advice

[swag_on]

Finally starting my build after much hand-wringing and anxiety but still feel unsure if I'm going about this the right way. End goal is a "modest" all-day-everyday 500whp on e60/some e85 mixture. Running MHD, can also add JB4 if recommended.

What's been done:
* Walnut blasting
* Valve cover gasket & oil pan gasket
* Plugs and coils (1 step colder, I know this is unnecessary at the moment)
* MHD (does plugging something into your OBD port count as "work"?)
* Cooling system (reservoir, upper radiator hose, lower radiator hose, the stupid plastic flange on the face of the head), will probably end up doing the pump along with the turbos
* PCV valve, Crankcase breather hose
* HPFP and index 12 injectors (previous owner)
* Oil change with ~2k on it
* BMS boost catch can

Currently in the midst of installing an ARM Motorsports 7" FMIC kit (w/ q flange chargepipe). Next up is BMS inlets and the tial 1/4" line conversion.

Here's what I'm planning for the rest of the year/early next year:

Fueling
Stg 2 LPFP--probably not bucketless but input is appreciated here
Motiv FF kit (necessary?)
Definitely need suggestions here. See below for more details.

Lungs
Unsure if outlets are necessary, especially at this power goal/level. Also unsure of what intake, if any, I should run. Sort of screwed myself with the ARM chargepipe seeing as the flange is so close to the front of the car. Would have been nice to use the injen kit but oh well. Don't want to waste money on heat sponges. Any suggestions are great. Not entirely opposed to going a custom route, either.

Exhaust
VRSF Catless
RBTurbo TD03 2+ (yes, absolutely overkill, but I'd rather keep everything as low-stress as possible)--btw, do these actually fit e60s?
Don't think there's really much else to this. Sound is a concern very low on the list so not electing to purchase an exhaust just yet.

For the fueling questions:
Some say you need a full supplemental DI kit (manifold or plate) for anything north of 450whp. Others say that an e85 mixture is fine. Others say still that you're stupid if you're not going VTT single-barrel shotgun HPFP + 2 LPFPs. I'm just confused on the conflicting accounts and would rather not spend more money on stuff that I don't really need to. Trying to avoid methanol at all costs (too much stress for what feels like diminishing returns). Also, has the DI technology for this platform improved appreciably at all? I've been seeing talk from 2016-2019 about how awful DI piggyback solutions were and I can't seem to find much else within the last couple years.

Please let me know your thoughts, if I'm missing anything, or if I need to re-evaluate. 500whp achievable? Thank you a million

Also, there's plenty of plan left out. Just trying to focus on the engine specifically. Most of the car will be touched at some point.

 

[swag_on]

Bump?
Edit: to make this more interesting installing the ARM 7" (correctly) completely killed an odd timing correction issue I've had since purchasing the car that remained unsolved addressing the usual suspects. Can post a before and after log if anybody’s curious. Would pull up to 5 deg WOT in 3rd w/DTC off on some bad runs--not SUPER terrible but not at all ideal, either. Very pleased with this! Now I have an odd WGDC spike at about 55k which is probably due to non-ideal fitment between the charge pipe and throttle body. Will address with a new (correctly sized) o-ring this weekend.

Next step is an oil change + analysis from blackstone--while the car is empty I'm going to take care of the oil filter housing gaskets (no evidence of failure but I can't stop thinking about the possibility of coolant getting into the sump), clean the oil cooler, and install the BMS inlets I just got in the mail. Maybe if I'm feeling super great I'll take care of the waterpump so I can stop being a freak about it. Allegedly you don't need to cut the rear inlet/drop the engine for the e6x chassis which is GREAT news for me (and pretty unexpected). If this is true I will report back with pictures and maybe a nice little guide if I have the brainpower. Once I can verify everything's installed correctly I'll FINALLY throw on the MHD Stg 1+ OTS tune to make sure all the connections are dandy.

Once this is all taken care of I'm planning on addressing fueling and exhaust. Again if ANYONE has input on what a good solution is for my power goals please drop your advice. Feeling pretty confident that a stg 2 bucketed 450 will be fine but please weigh in if I should reconsider. Is it true that the 450 is pretty easy on the EKP? Also if you have VRSF downpipes on an x-drive car I'd love to hear what your experience was.

 

[SLOWESTN54]

As a previous E60 owner, The stage 2 bucketed pump will be plentily for your goals, I recommend changing out the fuel filter/regulator that sits on the driver side in tank as well. Flex fuel kit isn't necessary, as long as your ok mixing E without it.

Outlets are unnecessary at your power goals, Inlets i'd highly recommend. I did mine along side my turbos. I got turbo's and inlets from RB. Had no issues with either. As for intakes i ran a hot air intake setup (Dual Cones) with no issues, No hot iat's, no heatsoak. I also had the same intercooler as you, with the upgraded hose's that arm offer's. I had the RB OEM+'s but you won't have any fitment issues with Rb turbos in a 5 Series

For downpipes i used VRSF, but my car was rwd. I do know of people with 535xi's here that use the awd vrsf downpipes. As for exhaust i modified my stock exhaust, we deleted secondary cats, and modified the rear mufflers, so when valve was open there was no muffler, and once the valve closed it used the factory muffler.

As for fueling, you will not need PI. Factory DI system will be able to happily support 500wheel.

 

[swag_on]

As a previous E60 owner, The stage 2 bucketed pump will be plentily for your goals, I recommend changing out the fuel filter/regulator that sits on the driver side in tank as well. Flex fuel kit isn't necessary, as long as your ok mixing E without it.

Outlets are unnecessary at your power goals, Inlets i'd highly recommend. I did mine along side my turbos. I got turbo's and inlets from RB. Had no issues with either. As for intakes i ran a hot air intake setup (Dual Cones) with no issues, No hot iat's, no heatsoak. I also had the same intercooler as you, with the upgraded hose's that arm offer's. I had the RB OEM+'s but you won't have any fitment issues with Rb turbos in a 5 Series

For downpipes i used VRSF, but my car was rwd. I do know of people with 535xi's here that use the awd vrsf downpipes. As for exhaust i modified my stock exhaust, we deleted secondary cats, and modified the rear mufflers, so when valve was open there was no muffler, and once the valve closed it used the factory muffler.

As for fueling, you will not need PI. Factory DI system will be able to happily support 500wheel.

You’re so real. Thank you for this—it really helps quite a lot. Appreciate you mentioning things I didn’t even think of. A million rep

 

[wheela]

Bump?
Edit: to make this more interesting installing the ARM 7" (correctly) completely killed an odd timing correction issue I've had since purchasing the car that remained unsolved addressing the usual suspects. Can post a before and after log if anybody’s curious. Would pull up to 5 deg WOT in 3rd w/DTC off on some bad runs--not SUPER terrible but not at all ideal, either. Very pleased with this! Now I have an odd WGDC spike at about 55k which is probably due to non-ideal fitment between the charge pipe and throttle body. Will address with a new (correctly sized) o-ring this weekend.

This is interesting - what did you find wrong with your IC installation that was causing corrections? Was something loose and vibrating against something?

 

[swag_on]

This is interesting - what did you find wrong with your IC installation that was causing corrections? Was something loose and vibrating against something?

Sorry, I could've worded this significantly better. Yes, the first pass at the IC install was pretty gnarly (first-time modder, long-time wrencher), but that itself wasn't the cause of my corrections (or, it at least didn't contribute). Even with a non-ideal installation the issue pretty much disappeared.

Since purchasing the car earlier this year I've had various corrections under throttle both under the stock map and MHD stg 1 91. Spent a long time chasing it down. Using a splash of E85 helped but not as much as you'd expect. New coils and slightly colder plugs with a tighter gap quieted things down a bit but the logs never looked "right" enough for me. No suspected fueling issues seeing as fuel rail pressure is always very strong (though occasionally my LPFP pressure dips relatively largely % wise, which I'll address shortly with a new pump and sensor) and there is no evidence of injector leakage/blockage (stock plugs looked great, no sign of fouling, etc).

So this is just a very long-winded way of saying that my IATs were throwing things out of wack. The stock intercooler was a mess. Filthy in and out. I don't know where the 90 year old man who owned this thing last drove but apparently through every wasp nest in Western Colorado. You know how much fun it is to have a million dried out wasp corpses fall on your face in a single car garage? At least a solid noggin smack on your subframe's worth.

 

[wheela]

Glad you got everything sorted! Sounds like you had quite the time under there!

 

[swag_on]

Glad you got everything sorted! Sounds like you had quite the time under there!

It's always a good time. Always a little gift. Massive grasshopper this week. I should probably start wearing a mask or something. I don't know what it is about this car but it seems to attract more bugs than normal. Anyways, enough rambling.

 

[swag_on]

I think the scope of this project has shifted pretty significantly. I think I overestimated the strength of the N54 and am probably going to shoot for a solid ~450-480whp. Reading a lot of stuff on here about cracked ringlands and bent rods at around 600 crank which I'd pretty significant overshoot given the e60's x-drive loss of about 10-20% (is 20-60hp significant? I think so). Don't want to push it right up to the wire where even a slight hiccup could turn into weeks of headache. Rebuilding an engine is just not something I need to deal with any time soon. However if you have an alternate perspective or experience I'd love to hear it. Lots of contradictory information but it does seem like a consensus has been reached in the last 2-3 years that most of the internals other than the crank, while still being stout, aren't that strong.

Stg 1 mhd at ~17psi is honestly pretty remarkable given that 90% of everything is stock (and the fact that it's just some OTS flash) and I can't really imagine wanting much more. Still want to make my heart beat too fast given the opportunity. My desired list of mods hasn't changed but I think I'm probably going to go with a lower-spec hybrid or something. Maybe.

I do want to say that working on these cars is a remarkable experience. Insanely intuitive and easy. Don't know where most of the complaints come from. Very lego-like with almost zero ambiguity. More access than 90% of modern engines of this caliber. Everything clicks in and out of place. Fasteners have a great design language. Makes organization a breeze. Fuel pump access in these cars is a triumph. Zero drama. Have most everything I need torn down to do my maintenance/mods and I can almost 100% confirm that the rear inlet on an e6x will just slide out without any cutting. Lots more clearance between the firewall and rear of the engine than the e90 it appears. This is corroborated by the fact that the rear inlet is secured to the turbo by a single 10mm bolt, which I don't think is the care for the e90. However this is a visual assessment and my opinion might change tonight when I actually start to tackle the install. Wish me luck!

 

[Boorda]

I think I overestimated the strength of the N54 and am probably going to shoot for a solid ~450-480whp. Reading a lot of stuff on here about cracked ringlands and bent rods at around 600...

I'm a late E90 owner (N55), but everything I've ever read/heard about the N54 is that it's internals are actually quite strong and very capable of 500-600whp. I'd rather an actual N54 owner chime in on this, but keep in mind that strength of the engine components is only one aspect of being able to handle higher horsepower, you can absolutely destroy a capable engine with bad tuning. Just something to think about before you shotgun your aspirations of 500+whp.

x-drive loss of about 10-20% (is 20-60hp significant? I think so).

I have an x-drive myself, to me the 10-20% loss in power is subjective. Making power is good, but being able to distribute that power to the ground is also important and if you're just burning rubber every time you take off then you're probably wasting just as much power at wheel spin. For me I love the instant traction and would rather put the 10-20% into the system than burn it up.

Stg 1 mhd at ~17psi is honestly pretty remarkable given that 90% of everything is stock (and the fact that it's just some OTS flash) and I can't really imagine wanting much more.

I said this once, then I wanted MOOOORE! I think a lot of us have said this hahahahaha.
Be warned my friend, the urge will come.


Also, hadn't seen anyone else address your JB4 question; I have been running the JB4 and MHD together for the past 5 years and have been quite happy with it. That being said, when you start adding things like port injection and water-methanol, with the JB4 you'll have to start wiring in additional modules to control that stuff. While not really that difficult, I think there are newer options out there like the Motiv Reflex+ that may be a better option if you decide to start adding all that jazz.

And good luck with your build, looking forward to reading about your progress.

 

[swag_on]

Cant believe it’s still October. Wow.

So we’re just wrapping everything—bolting up belly pans and radiator supports and whatnot.


Here’s and incomplete list of everything so far:
- water pump and thermostat + new hoses
- OFH gasket(s)
- tb gasket
- intake manifold gaskets
- belt, pulleys and tensioner
- rear and front inlets
- catless downpipes

Definitely forgetting things but oh well. Sort of shocked I let it get out of hand so fast. Worst case of “while I’m in there” I’ve ever had by a long shot. I guess I didn’t want to have to do some of the more PITA stuff twice? I really don’t know.

Anyways, everything’s in and ready for a proper leak down. Just need to finish bolting things up and then I’ll have her running in a small, poorly ventilated space in no time! You cant believe how much money I save huffing fumes instead of drinking beer.

Now, if you want to keep reading, here’s a few general observations:
- the water pump is not hard, just tedious. plenty of access through/around the XI subframe. No need to drop it. Just make sure to be clever about where your clamps/fasteners end up and where they face. The factory position for the rear hose has the clamp terminate right between a gap in the subframe. Use it to loosen the clamp. Unbolt the thermostat for the pump and pry them apart to release the hose that goes to the block. Don’t waste time trying to unplug the motor in the pump while it’s in position—it’s much easier when you have the assembly nearly out.

- you don’t need to remove the passenger axel/bearing carrier on an XI e6x series to remove/install downpipes. In fact I strongly recommend you leave your bearing carrier in place. You can use it for leverage to get your cats into perfect position and hold tension until you have your clamps on. Btw, the VRSF downpipes are hilarious. They’re very well-made but the “bend” on the bank 2 pipe is laughable. It fits, though, and it’s not like I’m going to be looking at it much. Cant complain for the price they’re going for.

- The amount of space you save with catless DPs is insane. I have clear access to my rear inlet and practically everything else you could want to get to. For this alone they are worth their weight in gold.

- speaking of which, screw vband clamps always and forever. biggest headache/hurdle this whole project.

- you cant lift out the rear inlet on an e6x. If there was even a centimerer more clearance it’d fit. Nope. Had to cut. Maybe I’m just dumb and did it wrong, who knows. Cutting really isn’t that bad, so I don’t know why I was so averse to this to begin with.

- Rear inlet is a total bastard. I don’t have any advice for this other than be prepared to struggle for a long time. This was the thing that I hated doing this most by a long shot.

Overall harder than I expected and easier than, too, in some cases. I think if I didn’t have a day job and was actually good at working on cars I could’ve knocked this out in a week. Not touching any serious mechanical bits for a LONG time. If something big breaks (knock on wood) anytime soon it’s going to be an indies problem. Nearly a month under jackstands has done something to my psyche (and my body).

Otherwise I’m still moving forward with my plans with some additions. PR coil packs show up soon as does my “CAI”. Ordering my LPFP, regulator, reflex, and ECA here in the next week.

Once I get that all wired up and pretty I think I am going to run PI. Did not realize that Reflex was sequential and has as much granularity as it does for fuel control/injection. That kills pretty much all my anxiety, so why not do it? I like the look of the black market parts plate/manifold and if you have experience with either let me know. Not doing this for power gains necessarily but more for insurance and the possibility of running straight e85 if I ever feel like it.

Attaching some pics. Anyone else see Frankenstein in the support plate?

 

[swag_on]

I'm a late E90 owner (N55), but everything I've ever read/heard about the N54 is that it's internals are actually quite strong and very capable of 500-600whp. I'd rather an actual N54 owner chime in on this, but keep in mind that strength of the engine components is only one aspect of being able to handle higher horsepower, you can absolutely destroy a capable engine with bad tuning. Just something to think about before you shotgun your aspirations of 500+whp.



I have an x-drive myself, to me the 10-20% loss in power is subjective. Making power is good, but being able to distribute that power to the ground is also important and if you're just burning rubber every time you take off then you're probably wasting just as much power at wheel spin. For me I love the instant traction and would rather put the 10-20% into the system than burn it up.



I said this once, then I wanted MOOOORE! I think a lot of us have said this hahahahaha.
Be warned my friend, the urge will come.


Also, hadn't seen anyone else address your JB4 question; I have been running the JB4 and MHD together for the past 5 years and have been quite happy with it. That being said, when you start adding things like port injection and water-methanol, with the JB4 you'll have to start wiring in additional modules to control that stuff. While not really that difficult, I think there are newer options out there like the Motiv Reflex+ that may be a better option if you decide to start adding all that jazz.

And good luck with your build, looking forward to reading about your progress.

Gonna post a real reply to this in a bit. You’re a real one

 

[Boorda]

Worst case of “while I’m in there” I’ve ever had by a long shot. I guess I didn’t want to have to do some of the more PITA stuff twice? I really don’t know.

I am very guilty of this, literally every time I do anything on my car.

speaking of which, screw vband clamps always and forever. biggest headache/hurdle this whole project.

I concur!

I like the look of the black market parts plate/manifold and if you have experience with either let me know.

I have had a good experience with BMP on my E90, pics below.
Ignore the copper-colored rail/components, that's my meth setup and not part of BMP manifold.

 

[Boorda]

Also....

Did not realize that Reflex was sequential and has as much granularity as it does for fuel control/injection

This would be an advantage over older tech like the JB4 PI since it is a batch fire system.
I'm actually considering moving to Reflex+ myself before too long so I can integrate additional sensors via CAN-BUS and have sequential fire tunability.

 

[proboner]

To give my personal context, as someone who is kind of going through the same thing right now...

First of all, kudos on all the maintenance work, seems like you're experienced and thorough, which is like 90% of the battle!

I have a N54 powered Z4 that the previous owner did a lot of maintenance and performance modifications to before I bought it. Basically every bolt-on, 335is clutch, 450 fuel pump, Pure DD turbos, etc. When I bought it I just planned on doing aesthetic mods and calling it a day. Of course the power bug bit and now I want more. Similar to you, I'm just looking to squeeze a few more ponies out, but over my time digging into adding that power and understanding a the landscape better, I've come to conclusions I wish I'd known before I started. Keep in mind, I'm by no means a veteran here, but thought I'd add my perspective.

• Don't go over 600whp if you want reliability- Sounds like your reading has already brought you to this conclusion. Just a good thing to know that making over 600whp will require a significant investment (built engine at the least) to actually be reliable. There are tons of people who do it, but IMO you're on borrowed time.
• Stock turbo, stock DI cars can make ~500whp- So here's the thing... full bolt-on, stock turbo, stock DI (just fuel pump) cars can make close to 500whp with ethanol tunes. To get to up to 600whp you need to buy new turbos, additional fueling (PI or HPFP overdrive), and a custom tune, which is basically +$5k for 100whp... not a great ROI given the roughly $500 it takes to make the first additional 100whp. As already mentioned above, going over 600whp would mean a built motor on top of that, so like $15k+ added for 100whp+. The point being, ROI drops significantly as you go above 500whp, and 500whp is basically achievable with just bolt-ons.
• If you're not shooting for at least 600whp, stay with stock turbos- unless your need new turbos for maintenance reasons, then get a decent sized stage 2 turbo. As stated above, you can pretty much hit your power goal on stock turbos, so why upgrade? The PO of my car upgraded to Pure DD turbos, which I was super excited about, but now kind of hate. Yes they make more power than stock... but barely. I'm glad they're Pures, as reliability is a main goal, but spending a couple hundred more on the Pure High Flows would have been a better choice. I'm now just super limited in power potential, and hardly making more than stock turbos but with the huge time/money cost of going aftermarket (which of course I didn't incur, but you would).
• Beware the spun crank hub- Didn't discover this one until recently, and it's really ruined things for me. Crank hubs spin (aka dead motor) and there doesn't really seem to be a consensus on WHY. It seems to happen across power levels, but anecdotally is more likely at higher power? DCT and manual cars are most effected. Supposedly it's happened on stock power cars along side high HP cars. It's $1k+ and quite a bit of work to fix it with a pinned/splined crank hub. Personally, it's just another headache I don't want to solve for, and makes me less likely to want to increase the power of my car. Figured you'd want to know this, given your goal of reliability.
• Just go 535 fuel pump- 450 has been the common purchase for a while, but semi-recently the 535 was found to be a better upgrade flow wise and from my understanding is even easier on the EKP. The cost difference is also marginal.
• Reflex is a great choice, but realistically overkill- It's probably the best way to get more fuel into the cylinders, but it's realistically unnecessary for your power goals. It's pretty much just throwing away $1k+

To me, the overarching point is, unless you want to spend a shit ton more money for diminishing output, it's really not a great ROI to go beyond stock turbos with stock DI.

edit: PR Coils aren't necessary at this power level. Another place to save some money by using Delphi/Eldor coils.