M50 versus M52

BiBimBap · 10-15-2003, 12:43 AM

Okay, I realize that the 1993-95 323 engine is rated at 189hp with 181 ft.lbs of torque...

However, the 1998-99 323 engine is rated at 168hp with the same amount of torque..although at a lower rpm.

This the the question.. since both engines are the same displacement (2.5L) and the relatively the same layout (I6, 24V) - why does the latter engine have a 20hp deficit??!

I realize that OBD came into effect in 1995.. but 20hp is a HUGE drop.

Anybody know?

**Mystikal** · 10-15-2003, 12:44 AM

Oh oh oh!

There's a good reason, I remember, but it's in a European Car E36 buyers' guide I have, and I have no idea where I put it. Haha, sorry, I'm really of no help.

BiBimBap · 10-15-2003, 12:45 AM

Darn.. i'm looking it up - but no one seems to actually explain why...

**Mystikal** · 10-15-2003, 12:46 AM

Okay, I'll go take a quick look.

**Mystikal** · 10-15-2003, 12:52 AM

Found it. 2 good quotes:

Quote:

The 323i, as noted earlier, was actually powered by a 2.5-liter engine. The new engine was rather underdone in the exhaust department and benefits greatly from a performance system.

Quote:

While the 1998-1999 323i netted us six-cylinder motivation for four-cylinder prices, the new 2.5-liter engine was strangled by a 2-into-1 exhaust system...the Lord giveth, and the Lord taketh away.

There you have your answer. So I'm guessing with a full exhaust off of a 328i you'd have close if not the same power as the 325i.

BiBimBap · 10-15-2003, 12:55 AM

Wow. So just an exhaust system can free up those horses?! I guess the exhaust has to be re-routed somehow to avoid the 2 to 1 squeeze.

Hmm.. maybe a new exhaust should be in the works.. i wonder if there are any other 323 owners out there with exhaust mods with wicked gains?

**Mystikal** · 10-15-2003, 01:02 AM

I bet it wouldn't take much. The entire floorpan is the exact same, and I'm sure the headers are not much different, if not the exact same dimensions as other 6-cylinder cars.

I can definitely see why they say it is so restrictive. My car has a twin-pipe system all the way down, and it's known that if you go cheap and convert it to single, you lose a LOT of power. The same should apply to the M52, it's the same displacement.

BMW_M52_M20 · 10-15-2003, 01:36 AM

I have the M52 engine and have driven the m50 2.5L 189bhp 325i as well.....My engine is more advanced timing wise.......It has a more solid torque curve then the m50 especially at lower RPM's........

The 20 hp drop doesn't make it any slower then the 325, I think they just found a way to get a little more power out of a more efficient design.....

The M52 is a very smooth engine right throughout the rev range and has no problem staying with a 328is......, also it is excellent on gas for a 6cyl.....
Jay

BiBimBap · 10-15-2003, 02:04 AM

Yeah, I got the same engine as yours..mines the 99 323is.. I love the smoothness and the torquey feeling - but i'm getting used to the power..and need more.

Jay - have you done any performance mods to your 323?

97 Z3 2.8 · 10-15-2003, 07:00 PM

So let me get this right

93 to 95 M50- 189 hp.
99 to 00 M52TU- 168 hp.
All M50 and S50 engines use the same studs for the headers, so you're saying that by swapping in collectors that collect just before the cat (or at the cat)will give this car power?
Just clarifying here, I don't know anything about the 323 cars as they were labelled.

Bill

Peter1998 · 10-15-2003, 10:25 PM

i think the cam inside the M50 325 is different than M52TU 323.. that is where 20hp lose..

**Mystikal** · 10-16-2003, 12:46 PM

Quote:

Originally posted by 97 Z3 2.8
So let me get this right

93 to 95 M50- 189 hp.
99 to 00 M52TU- 168 hp.
All M50 and S50 engines use the same studs for the headers, so you're saying that by swapping in collectors that collect just before the cat (or at the cat)will give this car power?
Just clarifying here, I don't know anything about the 323 cars as they were labelled.

Bill

All other 6-cylinder equipped cars have dual pipes all the way down, while the 323 had the 2-1 setup, strangling it. Dual pipes will give a lot more power.