N52 Engine Differences?

[JeffW]

Hi all.

I'm thinking about picking up a 128. I drove both the 128 & 135, and they are both good fun. The 135 has amazing torque all over, but realistically, I don't need that much power in everyday driving. Also, I am little suspicious of long term reliability of this engine & turbos. The 128 was great fun to drive too, but I know I will want a little more out of it.

The N52 in the 128 is the same engine as in the Z4si. As far as I could tell, technical specs were identical, yet the 128 seems to be missing 25hp/20 lb-ft that are in the Z4. This missing power would make the 128 perfect in my opinion. Anyone know what makes up the extra power (cams, ECU programming?) and how easy to mod the 128 N52 to a Z4 N52 power level?

[Tom K.]

It's actually closer to the current Z4 3.0i (215 hp, 185 Ft lbs.), not the 3.0si. Many of us were hoping that the more powerful 255 hp version would be offered in the U.S. (a 130i), but no such luck.

Coming from an '03 Z4 3.0 (225 hp at that time), I notice my 128i 'vert's slightly lower torque - but the real difference is the nearly 500 lbs. additional weight of the 1er cabrio.

Nonetheless, from what tests I've seen published, the 128i droptop is only about 1/2 second slower to 60 than the '03 Z4. And acceleration for 50~90 mph safe passing in 3rd is quite impressive.

Tom

[Artmasterx]

At this point, there does not seem to be much available to significantly bump the power, especially at a reasonable price. Intake an exhaust would get you a little bit, but maybe an ECU tool will come out that gives more bang for the buck. Who knows though... It would be nice to have 255 hp and more torque at a reasonable cost, but it may be a pipe dream.

[Lucky1]

Originally Posted by JeffW

Hi all.

I'm thinking about picking up a 128. I drove both the 128 & 135, and they are both good fun. The 135 has amazing torque all over, but realistically, I don't need that much power in everyday driving. Also, I am little suspicious of long term reliability of this engine & turbos. The 128 was great fun to drive too, but I know I will want a little more out of it.

The N52 in the 128 is the same engine as in the Z4si. As far as I could tell, technical specs were identical, yet the 128 seems to be missing 25hp/20 lb-ft that are in the Z4. This missing power would make the 128 perfect in my opinion. Anyone know what makes up the extra power (cams, ECU programming?) and how easy to mod the 128 N52 to a Z4 N52 power level?

Tom K. kind of alluded to the fact that the 2006 330i had the same 3.0 litre engine and put out 255hp. I wonder what is different between that engine and the 128i's that makes up the difference. It sounds like BMW had reached the upper limit of what they could push out of the same engine so in order to compete with Infiniti and they like they decided to turbocharge instead of manufacturing a separate, larger engine for the 335i. Or they knew down the line that the 135i would become a reality and needed to keep the engine small.

[Tom K.]

Ever since BMW dropped the 2.5l 6 (called the 323i at one point) in the U.S., there have been two basic tunes for the N52. The higher tune (225hp in 2003, 255hp currently) was marketed as the 330i, 530i or Z4 3.0 (now the Z4 3.0si) and the lower tune was in the 325i or Z4 2.5 (now the Z4 3.0i). To further add to the confusion, the lower tune currently has two variants - 230 hp/200 ft lb in the 328i & 128i and 215 hp/185/ft lb in the Z3 3.0.

All of these motors are 3.0 liters. And no one has answered the question of why the U.S. can't have a 130i, which is a one series N52 with around 255~260 hp and 225 ft lbs of torque - as is found in other parts of the world. Especially for those of us who don't particularly care for turbos...
Tom

[jkp1187]

Just to add some more confusion for completeness' sake - there's also an "N51" engine which is a SULEV-II (super low emissions vehicle) variant of the N52 engine sold in the 128i and 328i in the SULEV states of California, New York, Maine, Massachusetts, Vermont, Connecticut, Rhode Island, Oregon and Washington State. See this thread:

http://www.e90post.com/forums/showthread.php?t=52608

[adrean8j]

Well if history repeats itself as with the X23i vs. X28i engines the major differences ARE the cams and the manifold....When I had my euro-spec E39 523i I had to do basically what OP and others said and added an CAI, catback, and Schrick cams....didn't spring for the manifold due to cost and age of the car by the time I finished with some other mods (wheels, paint, custom stereo stuff).

[cagekicker]

get the 135 and end all that guessing.

[Mad Dragon]

Originally Posted by Tom K.

Ever since BMW dropped the 2.5l 6 (called the 323i at one point) in the U.S., there have been two basic tunes for the N52.

There never was a 2.5L N52 in the U.S.

There are currently 3 versions of the N52K in the U.S,: the U (Z4 3.0i), M (x28), and O (Z4/X3/X5 3.0si). The N51 is the SULEV version of the engine, which includes secondary air, steel fuel lines, and a bunch of other added emission features.

[Tom K.]

[quote=Mad Dragon;4797141]There never was a 2.5L N52 in the U.S.[quote]
Don't think I said (and didn't mean to imply) that the 2.5L was a N52 - only that the multiple tunes of the N52 began after the 2.5 was dropped from the U.S. market.
Tom

[demosthenes]

After I ordered my 328 two years ago, I learned about the two engine choices. Although I looked very hard, I couldn't find any info on the performance differences between the N51 and N52. But I did learn that the N51 has a 10:1 compression ratio and the N52 has 10.7:1. Therefore, I canceled my N51 order and ordered a N52.

Does that mean the N52 puts out more torque or did BMW change the engine management system so both engines put out the same? Or does the N52 put out more torque but BMW didn't publish two sets of specs because it would discourage N51 sales? Or are the 230 hp/200 torque specs an average of the two engines? Or do both engines put out the same torque and HP? Who knows.

I can tell you that my 328 with 6MT is quicker than I thought it would be.

[konradsa]

Originally Posted by demosthenes

After I ordered my 328 two years ago, I learned about the two engine choices. Although I looked very hard, I couldn't find any info on the performance differences between the N51 and N52. But I did learn that the N51 has a 10:1 compression ratio and the N52 has 10.7:1. Therefore, I canceled my N51 order and ordered a N52.

Does that mean the N52 puts out more torque or did BMW change the engine management system so both engines put out the same? Or does the N52 put out more torque but BMW didn't publish two sets of specs because it would discourage N51 sales? Or are the 230 hp/200 torque specs an average of the two engines? Or do both engines put out the same torque and HP? Who knows.

I can tell you that my 328 with 6MT is quicker than I thought it would be.

N51 and N52 put out the same, since the N51 has the 3 stage intake manifold to compensate for the lower compression. It's even possible that the N51 puts out slightly more, but BMW didn't bother changing the specs. If the N51 would have less HP, on the other hand, BMW would have to disclose it. The N51 is definitely more expensive than the N52, that's why BMW limits its numbers to where it is required due to emission regulations.

[cvandenhaute]

Originally Posted by Lucky1

Tom K. kind of alluded to the fact that the 2006 330i had the same 3.0 litre engine and put out 255hp. I wonder what is different between that engine and the 128i's that makes up the difference. It sounds like BMW had reached the upper limit of what they could push out of the same engine so in order to compete with Infiniti and they like they decided to turbocharge instead of manufacturing a separate, larger engine for the 335i. Or they knew down the line that the 135i would become a reality and needed to keep the engine small.

My understanding is that the main difference between the engine of the 128i and the European 130i (265hps) and (I think) previous 330i, is the injectors. It is snot simply a different programmation. That being said, that 6 inline is a sweet and smooth engine, just test drove a 128i and a 135i yesterday, loved them both

[JimD]

I messed around on RealOEM looking mainly at the X5 version rated 265hp (N52) versus N52 and N51 engines in the 128i coupe and vert. It won't accept my VIN and only lists productions as recent as 1/2009 - nothing since then. So I was searching the most recent version in RealOEM in each case. They all had the same intake and exhaust cams and the same valves. I did not check pistons. Given the comment above about compression ratio they should be different. I also looked at the little rockers and they were also the same.

The 128i N51 has different injectors than the 128i N52 or the X5 N52. The intake of the 128i N51 is the same as the X5 N52 but the 128i N52 is different. The X5 N52 has different exhaust manifolds than either 128i motor. The pictures in RealOEM make the X5 exhaust look more like a header. I don't know how realistic that is.

It would be interesting to see what the X5 3 stage intake and exhaust manifolds would do for the 128i N52. Or the other way to go would be the X5 injectors and exhaust manifold for the N51 (plus maybe pistons?).

This is discussed in the thread where the guy posts several dyno runs of his modified 128i. It is interesting that the dyno run for the 128i N52 is pretty close to the 330i dyno run. There is probably a mileage difference that may help explain it but it suggests the 128i N52 is under-rated. The hp unmodified is above the ~200hp you would expect for rear wheel hp with a 230hp flywheel rating. The best the guy got with mods was ~220hp at the rear wheels. But if you figure 15% losses that would be 255hp at the flywheel.

Jim

[demosthenes]

According to Bentley Publishers' 3 Series service manual (page 100-6):

"N52 engines in 328i/xi and 330i/xi models are equipped with 3 stage variable intake runners in a system know as DISA."

[driverman]

Originally Posted by konradsa

N51 and N52 put out the same, since the N51 has the 3 stage intake manifold to compensate for the lower compression. It's even possible that the N51 puts out slightly more, but BMW didn't bother changing the specs. If the N51 would have less HP, on the other hand, BMW would have to disclose it. The N51 is definitely more expensive than the N52, that's why BMW limits its numbers to where it is required due to emission regulations.

Thank you for your post.

Since I ordered my car 2 1/2 years ago, I couldn't figure out why BMW gave the N51 and N52 same T/HP ratings, even though the N52 had a higher compression ratio. Fitting the N51 with the 3 stage intake manifold to make up for the difference explains it.

So the bottom line is that many of us that ordered the N52 thinking it was faster may have shot ourselves in the foot! We might have been better off with the N51. We knew about the compression ratio difference but not about the manifold differences.

The N52 may provide better low-end torque due to the higher compression ratio but the N51 probably comes on better at high rpm due to 3 stage intake manifold. Agreed?

[roo97ss]

Originally Posted by Tom K.

Ever since BMW dropped the 2.5l 6 (called the 323i at one point) in the U.S., there have been two basic tunes for the N52. The higher tune (225hp in 2003, 255hp currently) was marketed as the 330i, 530i or Z4 3.0 (now the Z4 3.0si) and the lower tune was in the 325i or Z4 2.5 (now the Z4 3.0i). To further add to the confusion, the lower tune currently has two variants - 230 hp/200 ft lb in the 328i & 128i and 215 hp/185/ft lb in the Z3 3.0.

All of these motors are 3.0 liters. And no one has answered the question of why the U.S. can't have a 130i, which is a one series N52 with around 255~260 hp and 225 ft lbs of torque - as is found in other parts of the world. Especially for those of us who don't particularly care for turbos...
Tom

Actually, in the US the N52s came out in 2006 and BMW used the 2.5 liter motors up to 2006 in the 3 series coupe and convertible, and x3.

the previous 325/525/z4/x3 2.5 all had a 2.5 liter motor, (these were the M54 models..185hp).

Up to 2005 (2006 in the 3 series coupe, and x3) the -30 and 3.0i models were a 225hp m54 also. Driving an 05 z4 3.0 vs 06 3.0 back to back was a noticeable difference with the older M54 motor being much stouter.

In 06, the N52s came out in the 325/525 as a 3.0l lower output 215hp, the z4 3.0i too.

the 530, 330, and 3.0si z4 were 255hp, the x3/x5 260hp outputs.

Then they added the 128, 328, 528 moniker for a middle of the road version (output wise) at 225 as they went to the top level turbos in the -35s.

I don't portend to know the specs of the n52 in detail, why 1 is stronger than the other....there is some pretty good explanations here...

Moral of the story..the m54 2.5 liter was around till 06 here in the USA...

I know, i owned a 325ci 2004 for a short while...

Joe

[allmotorh22]

Originally Posted by driverman

So the bottom line is that many of us that ordered the N52 thinking it was faster may have shot ourselves in the foot! We might have been better off with the N51.

Nope

Originally Posted by driverman

We knew about the compression ratio difference but not about the manifold differences.

The N52 may provide better low-end torque due to the higher compression ratio but the N51 probably comes on better at high rpm due to 3 stage intake manifold. Agreed?

No. replacing a manifold is a lot easier/cheaper than replacing the pistons. (compression = the engine's potential for power)

[driverman]

Originally Posted by allmotorh22

replacing a manifold is a lot easier/cheaper than replacing the pistons. (compression = the engine's potential for power)

Good point.

I'd like to see dyno runs of a stock N52 and a stock N51, both rated at 230 hp and 200T, back to back to see the differences in output at the rear wheels.

[BlueforMonaco]

This would be an interesting comparison. I made sure I was getting the ULEV-N52 for the higher compression.

[driverman]

Originally Posted by BlueforMonaco

I made sure I was getting the ULEV-N52 for the higher compression.

Me too.

[JimD]

If you could find a N52 from a X5 that had major damage (so you could buy it cheap) but had intact intake and exhaust manifolds, you could see what you could get out of a manifold swap. My guess is the three runner manifold helps mostly with mid level torque. I know on my SUV, it has a dual runner intake and a double torque peak as a result. The torque graphs of the bimmer motors do not show a definite peak but I believe each runner is optimized for a specific rpm range. My guess is that is low and high for the dual runner, thus my guess the three level would help the mid-range. Maybe the dual runner is not as optimized for high end to give it better mid so it would also impact peak hp.

The exhaust should help mid to high rpm output. There are also headers advertized that might fit and accomplish the same thing.

I will probably not do any of this to mine, however. I like the acceleration it has when revved up above 3,000 rpm. I wish it felt like it had a bit more torque down low but it is fully adequate. If you boot it from 2,000, it feels like you have to wait a bit until it gets with the program. A downshift eliminates the lag and is what a driver should be prepared to do.

Still, with another 30-50hp it would make a difference.

Jim