N52 Swap

[cwlo]

Yes, I've been following that thread. I'll have to modify my manifold sometime when I get a chance. Just wish I had a dyno in my garage to see the difference from each mod. Now we just need you to get that s54 intake working, and exhaust cam upgrade.;)

[ForcedFirebird]

Almost certain I will swap my car. It's just sitting and collecting dust. Have nearly unlimited resources in the fabrication department. Thanks for paving the way on this guys. Was tempted to go spec e30, but this is just so much more fun!

[wazzu70]

For the ITBs check with Rama at RHD. I know ForcedFirebird has worked with them in the past. Since the head has the lower part of the inlet manifold cast into it making an adaptor could be pretty straight forward. He actually sizes the ITBs properly too which is always a bonus!

Just something to consider. No affiliation.

[nando]

The problem is they need to be actuated by the DME, not with a cable. I don't know if he can do anything like that.

also I picked up the S54 throttles a while back pretty cheap. I want to say they were around $100.

An option of course would be adapters with no throttles, just to bolt up the plenum.. but there would be no failsafe in case of a valvetronic failure.

[cwlo]

Considering the N52 doesn't need individual throttles like most engines, Seems like a simple bolt-on trumpet, housed inside a plenum with the throttle actuator on the intake of plenum would be much simpler.

[nando]

Maybe, but it would kill the sound of the huge airbox. lol.

I mean, you *could* change the failsafe to something like 2-3mm of lift, and try to use ignition advance to limit torque output - just as a 'limp to the side of the road' mode. Then you wouldn't need a throttle at all.

[digger]

Considering the N52 doesn't need individual throttles like most engines, Seems like a simple bolt-on trumpet, housed inside a plenum with the throttle actuator on the intake of plenum would be much simpler.

you a properly sized and lengthed manifold without throttles is the go and alwayas better than throwing random parts on

[nando]

the S54 throttles are within 1mm of the N52 port size, and the same shape.. not exactly random.

I mean, I get it. But no matter what, there will be some sort of compromise. Currently people are using the N54 manifold, which is way off compared to the S54 throttles - but they're cheaper and much simpler to install.

[digger]

the S54 throttles are within 1mm of the N52 port size, and the same shape.. not exactly random.

I mean, I get it. But no matter what, there will be some sort of compromise. Currently people are using the N54 manifold, which is way off compared to the S54 throttles - but they're cheaper and much simpler to install.

the s54 peaks atleast a 1000rpm higher so the length is far from ideal for an engine optimised for lower rpm. people make over 350 numbers through the stock S54 runner geometry so its by anyones measure its overkill for even a stock s54 but thats the factory way to manipulate the torque curve and driveability with things bigger than optimum. Rama does a m54 kit, an N52 kit would have much better chance of offering less compromises IMO for one the s54 is a steeper port so the angle between the runner and port may not be very good

[nando]

It's much more complicated than that. The 200kw N52 peaks at 7k rpm mainly because of how the resonance of the 3 stage manifold works. Above that, the resonance turns negative and power drops like a rock - there's no way around it, except a different intake. BPC has done tests with open trumpets and found power beyond 7500rpm - that was before MILVS were even a thing. They took it to 8200rpm before they got valve float.

The port angle is irrelevant. The throttles are not angled, and the N52 head essentially has part of the plenum cast right into it. They line up with the ports just fine.

The point is you can use a bigger airbox with shorter runners and still keep a throttle for backup. There's certainly different ways to do that. If someone wants to build trumpets with no throttles, that's awesome - that's what I wanted to do in the beginning. :)

[CobraMarty]

Everyone always quotes the stock N52 throttle body as a 'failsafe' in case the Valvetronic fails.
But the truth is no one has ever reported a Valvetronic failure.

More likely the stock TB is there to create a vacuum at idle and to limit output when needed like limp home.

[nando]

But it does. Unplug your eccentric shaft sensor (which can and do fail). The Valvetronic motor will go to full lift, and the car will run off the throttle plate. The only difference is it's less efficient and you have a 6500rpm redline.

The Valvetronic motors themselves, I've never heard of a failure either (except removing them the wrong way and breaking off the shaft). but if it breaks the throttle isn't going to help you anyway.

[CobraMarty]

Fair enough, sensor failure.
I was thinking more of the 'mechanical' parts.

[thedivision]

So I finally got an exhaust system I am happy with. I was unable to get the engine quiet enough with any of the aftermarket stuff I tried. The Dynomax turbo that I used on the m54 was still too loud with the N52. That muffler is one of the quietest aftermarkets, so I looked into OEM stuff, and found that the X3 has a similar muffler configuration like the e30. (Most of the other models tuck the muffler perpendicular to the length of the car, which would not work on an e30. Anyway, from my understanding, the X3 muffler flows pretty well, and it also fits quite nicely. Sounds great without too much rumble. Very similar to my e46 M3 without the rasp. So, in short, I used SS headers, 135i middle section with cats and resonator, and then the X3 rear muffler.



While I don't have a finalized tune yet, the car is running very strong. It roars in the upper rpm range, and has a very similar feel to the e46 m3. Unlike the previous M54, this engine just keeps building power as you wind it up, and loves it. Hoping for a little more mid range which a finalized tune should deliver, but all in all, a great match-up!

Which X3 was the rear muffler from?

[nando]

E83 IIRC - whatever came with an N52 :p