N62 Z3 Swap Supplement - Why N62

Every time I mention I am doing a V8 swap into a Z3, I get the same responses... "LS? Cool, I love those!" or "M62/S62? Cool, I love those" then I say no, N62... and am met with this face

And you know what - I am who I am and I know who I am - I will shout it from the rooftops if I have to! I AM... SOMEONE WHO LOVES THE N62

Read my intake article here for a basic understanding of why I love it... But some basic bullepoints:

  1. Valvetronic gives it phenomenal throttle response, in theory better than ITB's

  2. Good power stock and have a very robust torque curve, great bang for the buck

  3. Once their core reliability issues are sorted they are pretty darn good engines!

Before I move on lets talk about that last point. Reliability. I own a 2006 X5 4.8is with the N62 4.8, I bought it with 194,000 miles and it now has 205,000 in just under a year (it's not even my daily... I just drive a lot). Previous owner took care of the critical repairs so I've just been enjoying it and changing the oil (knock on wood). That's the thing with the N62 - they get a bad rap because sure a lot of them smoke due to valve steam seal issues. Others leak coolant from the coolant transfer pipe and still others leak oil from the alternator gasket. It's a mere $300 in parts to fix all these issues (okay, its more like $850 because you wouldn't do valve stem seals without doing a lot of the main gaskets too... but, still). And these are all fairly easy jobs with the engine out. And then you have a pretty solid engine

Also for any N62 guys reading this - there is a permanent fix for the valve steam seals if you replace them with the Elring Klinger seals. These are made of Viton with an improved internal design and they will not fail like the OE parts

For comparison...

M62 will destroy timing chain guides and fail catastrophically sometimes -the chain will break and it will bend valves (I've personally seen it happen)

S62 and S65 eat rod bearings (so does S54 if we want to compare to I6's with comparable output) plus those all have other issues (VANOS and throttle actuators come to mind)

LS is reliable but I'm just not a fan of the LS - I prefer razor sharp throttle response and I'm a BMW dork -I think it's just cooler doing BMW swaps in other BMWs (plus for me it's easier to swap in a BMW engine)

Let me also expand that second point a bit, especially in relation to the engine's value. Firstly, they cost pretty much the same an M62, but make more power than the M62. In fact, their power is much closer to the S62 - the N62 4.8 making almost the same peak torque as the S62 - but N62's are on average 1/4th the price of an S62 or even cheaper. The N62 is also rear sump, which greatly simplifies the swap process. Sadly it doesn't fit completely behind the stock subframe, but with minimal modifications, it can be made to work. As a point of reference - I spent less, including freight shipping, for my N62 with 6 speed manual than the M62/S62 oil pan conversion kit costs alone (which converts those engines to rear sump). I also may be saving $200-400 by being able to re-use the stock steering shaft (not confirmed yet) and even the M54 A/C compressor bolts to the N62, negating the need for custom A/C lines

Below, I talk specific details about the N62 - or more so, how I hope to mix and match parts to produce an N62 more powerful than any stock variant

Let us take a little detour from the sane world, into my brain of deductive logic and half hearted reasoning...

AKA I saw a dual intake 750 the other day and was like "Hmm" then spent the past 40 minutes today trying to apply incoherent logic to gratuitously rounded data. Yay

Please note, the below is a lot of "hopeful" logic based on assumptions - the biggest assumption of all being that BMW stated their power figures somewhat accurately. BMW has been known to round by amounts way larger than my threshold of accuracy below. However, the core of the logic is sound as long as the reported numbers are somewhat representative of these engine's power differences in relation to one another. AKA the numbers and %'s I give may not be accurate, but as long as the numbers BMW provided are somewhat accurate themselves (ie. engines they claim make less power do in fact make less power) then the logic is sound, the specific numbers may not be entirely accurate though

I am talking about two things below - the DIVA vs DISA intake and the dual intake from the 750

Dual intake 750i pictured below (2006-2008)

Source for these power figures HERE

Stock 745 (4.4) makes 333/450 with the DIVA manifold and single intake

Stock X5 4.4 (4.4) makes 320/440) w/ the DIVA manifold and single intake

Stock X5 4.8is (4.8) makes 360/490 w/ the DIVA manifold and single intake

Stock 550 (4.8) makes 367/490 with the DISA manifold (not DIVA) and single intake

The 750 (4.8) makes 367/409 on paper with DISA and the dual intake pictured above (either the dual intake didn't do anything or BMW didn't care to publish different results for something that was probably within 1-2% of the power of the others)

Some observations - it seems the X5 version is the least powerful (likely due to the restrictive exhaust manifolds on the X5 vs. other models)

The same 4.4 engine and same DIVA/single intake setup in an E60 545i made 12hp an 10tq more than that same 4.4 setup in the X5. This represents a 4% increase in HP and about a 2% increase in torque. I use percentages instead of raw numbers for comparisons, because power differences are a factor of overall power, as opposed to net numbers

What I mean by that, is if 545:X5 4.4 is a 4% difference in power, I expect a 550:X5 4.8is to have a similar difference in power if equipped the same. However, the TU motors dropped the DIVA intake so direct comparisons are not available (for cost reasons most likely, as the DIVA was the only production intake manifold in the world with a continuously variable length intake manifold and it was expensive to produce and hard to package)

Some deductive reasoning here...

The X5 4.8is if equipped with the DISA and single intake (same as the E60 550i) should make ~4% less hp and ~2% less torque than the E60 which makes 367/490. This would mean about 350hp and 480 tq. But the 4.8is has the DIVA intake, which gives it +10hp and +10tq over those expected figures, as it makes 360/490. This represents a gain of 3% in HP and 2% in torque with the DIVA intake compared to the expected values. So lets say the DIVA intake manifold adds 3%/2% over the DISA manifold

The most powerful version of the N62 doesn't use the "best" intake manifold (the DIVA manifold). Nor does the best DIVA-equipped engine come with the cool 750 dual intake design.

Its hard to say what the dual intake system actually does as for power as it isn't rated at any more than the 550 and 650 which have a single intake box (though very large, these single intake boxes can't possibly flow as much as the dual setup)

I added this image merely to break up the wall of text. But this is a diagram of a DIVA intake. Oooh, aaah

My thinking is eventually I will use a 4.8L (the ones making 367 and 490 tq) then add a DIVA intake AND the dual intake setup from the 750 to make the ultimate N62

The stock DISA 4.8's make 367/490. With the DIVA increasing these figures 3%/2%, we get to 378hp and 500n-m

Lets use an alternate method to try to determine the numbers - we determined earlier the E60 makes 4%/2% more than the X5 chassis. The X5 4.8 with DIVA made 360/490. A 4%/2% increase gives us 375hp and 500n-m. That is with a single intake

Both the above methods got us to almost the same figures - 375/378hp, both giving 500n-m

As such - I think its fair to realistically expect around 375-380hp and 500n-m of torque out of the N62 4.8 with DIVA and dual intake. And thats with the single intake - the dual intake system may add another .5-1% in hp/torque though there is not enough information to make an educated guess on how much specifically it adds

For now though, on this swap with the 4.4, I'll be making due with a mere 333hp and 450n-m

Some points of comparison:

S62 394 hp and 500 n-m

N62 367 hp and 490 n-m (4.8 stock)

S65 414 hp and 400 n-m

N62 333 hp and 450 n-m (4.4 stock)

S54 315 hp and 341 n-m

M62 282 hp and 440 n-m

S52 240 hp and 320 n-m

M54 228 hp and 300 n-m (3.0)

M52 168 hp and 245 n-m (TU 2.5, what I took out of the Z3)

Also note how the S65 kind of stands out a little bit? I've said a long time that I prefer the S62 over the S65 and those figures are why. The S65 is definitely more fun around a track, but with 100n-m more torque, the S62 is better everywhere else. You also have to rev the S65 to the moon to make power... that just doesn't fit my driving style. I'm really more of a cruiser - drive slow, enjoy the scenery. The torquey N62 should compliment my driving style very well

One of the most common comparisons of the N62 is to the M62. Both came in 4.4L displacements and both had dual VANOS. However the M62 throttle response is very lazy (N62 has great response thanks to Valvetronic). In addition to that, the N62 DIVA intake gave it more torque over the entire rev range - and more peak HP. BMW included the below graph in the N62 technical release which illustrates the power differences

The solid lines are the N62, the dashed lines are the M62 (They don't cross over at 5252 RPM because they are using metric units for power - Thanks Steven!)

That torque curve being that much better is all thanks to the DIVA intake. By the way, if anyone is curious why I love the N62's "DIVA" intake manifold so much (or you are just wondering what the hell a DIVA is because you thought that was a term for a famous female singer) I wrote about it a bit here

Also - I will be ordering a 750 dual intake setup to try to retrofit on this 4.4 as well. So that may be good for a few extra ponies as well. 333hp? Ha! More like 335hp!!!

Honestly I just think the dual intake looks cool as heck and will look especially nice under the Z3 hood if I can make it fit...

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