N52 Swap Discussion

[hoveringuy]

That's cool. will the Porsche pump bolt in place? or can we get the regulators separately?

BMWs tend to have overboosted steering anyway, so I doubt the pressure loss will be a big deal.

The Porsche pump would bolt into place perfectly, but the shaft to the pulley flange is 10mm shorter so it would need a spacer. The regulator will just swap over, so no need...

I found that as a car gets heavier, it gets a smaller pulley (more volume) and higher pressure. Makes sense that the Cayman has low pressure and a big pulley.

The cool thing is that this works on any 120bar Luk pump for other BMW engines.

As an aside, the one on the far right looks different but works the same. I think is has the square seat so that when you disconnect the HP hose all the fluid doesn't drain out. At rest, the spring pushes the seat against the outlet, blocking it.

[nando]

That's cool. will the Porsche pump bolt in place? or can we get the regulators separately?

BMWs tend to have overboosted steering anyway, so I doubt the pressure loss will be a big deal.

[hoveringuy]

My other initiative is that I've been looking at how to reduce the 135bar pressure of my pump. My initial guess was that I would need a stiffer spring, but after collecting a variety of LUK pumps I discovered that they all had the exact same 9lb spring. They also had the exact same seat depth for the spring, pressure and vent port spacing and everything. I was kinda stumped on how they actually changed pressure between pumps until I got the 100bar Porsche Cayman pump in the mail. Same, exact LUK LF-30 pump that we used with some slight changes in pulley depth, but otherwise identical.

With a 100bar, 120bar, and 135bar pumps laid-out, I could finally see that the regulation happened in the throat of the outlet. The black cylinder is balanced by PS fluid on each side, but the side on the spring is static and the side towards the outlet sees the output pressure.

The higher the rated pump pressure, the smaller the shaft that sits in the outlet orifice. Since it's the backpressure of fluid exiting the orifice that drives the cylinder into the spring to unseat the vent port, the smallest shaft has the highest pressure.

Conversely, the 100bar pump has the largest shaft on the plunger, it's the quickest to create backpressure that vents the fluid.

The pump uses the dynamic interaction of moving fluid to regulate the pressure, the upshot is that any of these regulators are interchangeable, I can drop the 100bar assembly into my 135bar pump to make a 100bar pump!

My limited understanding of power steering is that at idle the pressure is only around 140psi as fluid easily slips through the steering rack rotary valve, and my presumption is that pressure increases with rpms until hitting rated pressure. The other way to get full pressure is to try to turn your wheels when they're blocked from moving, like against a curb.

I will measure the temperature change from the pulley alone and then swap the regulator to measure it independently.

I'm definitely excited about being able to tune my steering and reduce heat.

[hoveringuy]

I've been focusing on optimizing the power steering and have a small update. Props to LukeJ for fabricating an amazing PS pulley and shipping it to me so quickly! It is truly a work of art and I am very grateful.

This picture shows the original configuration of the power steering pulley and idler pulley, it's a 116mm PS pulley and 80mm deflection pulley. There's only about 10mm between the deflection and the PS pulley, so the deflection needs to get smaller in order for the PS pulley to get larger, so...



There are 70mm deflection pulleys. I ordered P/N 11-28-7-790-44, but it had a different arbor size in the bearing for an m8 bolt instead of m10, so I needed to swap the bearing with a press, no bigee.



With the smaller 70mm deflection, there's now enough room for a a larger PS pulley. This one is 135mm so it matches the e36 motors and spins 16% slower. Heat is very proportional to motor rpm so I should see a decent reduction in temps, and that's not including the fact that this pulley has a fan built in. Yes! The holes are canted and they blow air on the pump. I tested it with some dog hair, naturally.

The belt is now 1 1/4 inches longer, a Master Pro P/N K060507 works perfectly, it's a 6PK1290 with 1300mm OC.




I will update temps the next chance I get to flog the car.

I will also mention that hubcapboy turned a beautiful adapter that lets any e36 PS pulley be spaced to properly fit the N52, so there are several ways to do this.

[LukeJ]

The take-away from the day is that the car is reliable and fast. I got lots of questions in the paddocks from Porsche owners and even an M2 guy that struggled to keep up "what motor is in your car...?" The M2 guy did pass me but says he worked the hardest to pass me, so there's that.


Loving it! All good stuff here. Congrats!!

[hoveringuy]

The winner of track event #4 was the towing service. First session was 2 laps under yellow per standard practice, then green. 1 1/2 laps into green a Mustang GT-350R blew its (newish) engine. Black flag, all cars left the track.
Second session, an hour later. Green from the git-go, 2 1/2 laps in an e30 spun into the berm. Black flag, all cars left the track...
Third session, I actually did 11 contiguous laps! Lots of traffic so no new "best" laps although I did get an improved top speed commensurate with the boost in power.

The take-away from the day is that the car is reliable and fast. I got lots of questions in the paddocks from Porsche owners and even an M2 guy that struggled to keep up "what motor is in your car...?" The M2 guy did pass me but says he worked the hardest to pass me, so there's that.

I got some good measurements of the the PS temps and they're up around 275F.

I will focus on the "reduce heat" side of the equation before trying to install a cooler.

The N52 PS pulley is only 116mm compared to 135mm on most of our other cars, so it spins faster. Swapping to a 135mm pulley will reduce the speed by 16% and hopefully heat input.

The Luk LF-30 pump is rated for 135bar in the E90s compared to only 120bar in most previous cars, so I'm working to figure-out the pressure regulator to drop the pressure or possibly drop in the pump from a Cayman which is only 100bar.



Pictured below are the 116mm E90 pulley, a 135mm E36 pulley, and a 143mm Turner underdrive pulley for E36. The N52, M54 and M50 motors all have different back-spacing on the pulleys so they are not directly interchangeable.

[hoveringuy]

Would it continue to make power until an 8k redline? .

Yeah, this Dyno has 400 lb rollers so it accelerates quicker than it usually would, like 2nd gear on the street.

My understanding of the N52 soft limiter is that it's predictive so if revs are increasing quickly it will pull back earlier. Rev limit was set to 7750 here and it was pulling power starting at 7100-7200.
On a few pulls where we bumped the limit way up it carried power all the way through.
There wasn't ever a defined peak, just plateaued.

[nando]

Would it continue to make power until an 8k redline? I think you said it was torque limited somewhere. It's not that far off a stock S54. and this is with all stock internals...

[hoveringuy]

Update.

On the last episode, we had a pretty good track day with the MAF. Motor was running smooth even though it was a little down on power.
After another few days on the dyno, it's finally living up to all of its potential.

The baseline dyno showed that, indeed, it was a bit down on power at only 242hp/ and 227ft-lb. It had made around 270hp with no MAF (and no air filter...) and I expected to to recoup most of that, but expected a penalty for the MAF and the filter.
By playing with the timing and VANOS they were able to get it back up to 268hp and 246ft-lbs. It looks like there's a dip in torque at 2200 and 4000, but I think that the headers are just so strong at 3000 that it only appears that way. Drives great, pulls noticeably harder now and has an amazing amount of torque down low that makes me question why *anybody* would want a DISA intake on the N52.

The first chart is the before and after with the MAF.

The second chart is the no-MAF vs MAF plots, and how the MAF completely solves the ridiculous torque dip.

The chart is SAE corrected and calibrated to match Dynojet.

[nando]

My crimpers are actually pretty nice, the only real issue is ergonomics. I've probably done thousands of pins with them, but as you can imagine - not exactly good for the wrist. I know there's an updated version with better ergonomics. I kinda wish I had bought them now, although I ended up stopping making harnesses for people as it's just not worth the hassle (I got burned on a somewhat infamous S54 harness build, it hurt my wrist, and it cost me money in the end - screw it).

[wazzu70]

I'm pretty sure the crimpers I have will work just fine for those, they were like $40. I can't remember where I got them now, I'd have to dig way back. I use them for basically all the BMW wiring I've done, they work on all but the tiniest Tyco pins I've tried so far (I have another set I use for those). Actually I'm pretty sure I have some of those pins too, lol.

The generic crimpers are not perfect but its way better than just using needle nose pliers as it gets the generic shape correct. I usually make a light crimp to get the shape set and then use needle nose pliers to make sure it pinches tight enough one side at a time.

Is it perfect, no, but very close if you have patience. Also the crimping tool helps get the bends in the right place so the shape of the plier crimped pin is not too big to fit in the slot in the connector :)

Im spoiled because I have the real crimpers at work in our lab so everything else just feels like poo in comparison.

[nando]

I missed the link to the video - the engine sounds really good! although it's pretty quiet (probably a good thing, lol).

[LukeJ]

Cool video!

Congratulations on your new personal best lap time!!!

[nando]

heh, boiling the PS fluid - maybe an underdrive pulley would help that? BMW of course would put in a PS cooler. I actually have one I want to get rid of...

[hoveringuy]

Track event #3 on the N52 and everything is coming together. Event #1 I was in limp mode and way down on power. Event #2 it was making power but not smooth at all. Yesterday it was doing what it's supposed to do, haul-ass!

Some of the other issues also seem resolved. The coolant temps hovered at 190F +/- a few degrees the entire day. No oscillations or spikes. The motor will normally warm to around 205F before the MAP triggers and then it stays at 190 the rest of the time.

The cold air intake works GREAT. Intake temps just a few degrees above ambient.

Motor pulls happily from 4k to 7500 again and again...

Zero issues with oil pressure, not even a concern. No vibrations, thumps, driveline imbalance. Just smooth.

I had a puddle under my power steering rack my first event and thought it might be the rack; turns-out my PS fluid and resevoir are getting extremely hot and it had expanded out of the resevoir. So, that's one system that isn't happy with the high revs.

Other than that, I totally held my own in the advanced group. Ran a 1:38 (new PB!) in the first session and increased top speed to 133. Got passed by a GT350H on the straight, after he couldn't catch me in the corners, no shame in that. Let a bad-ass Honda Civic by that was just a cornering machine.

I'm running the 3.73 diff, and even with the 6th gear I'm turning about 3500 rpm at 80mph, so it's slightly annoying on the freeway but perfect for the track. I also have a 3.25 and I'll need to think about switching back to that.

The car goes back to the dyno today to evaluate the tune with the MAF, will hopefully find a little more smoothness and power.

https://www.youtube.com/watch?v=-uy--aNyIMg