rghinzel

I've got a 99 5 speed 230 SLK kompressor and recently had a chance to drive an auto C230 while my front bumper was getting resprayed (those stone chips were starting to bug me!). I noticed that my SLK230 seems to have alot more grunt (power/torque)than the C230. Am I imagining this or are these cars tuned differently/or have they got diffferent engine specs. Maybe it's a auto/manual difference. Anyone have any ideas.
-Rob

Driller

The engine specs are identical but there may be a difference in gearing and, I would think that the C230 is heavier than the SLK.

beantownrich

The CLK is only 250lbs heavier than the SLK... that's like having a big passenger in your SLK. This is not the cause of the performance edge of the SLK.

The issue here is "compression ratio". Basically, the more the air is compressed in the cylinder, the more energetic the gas/air mixture will be - and hence - the more powerful the 'explosion'. The result.... MORE POWER!

The SLK has a compression ratio of 9:1 - that is, when the piston is fully depressed into the cylinder, the air has been compressed to 9x it's original pressure. The C230K has a compression ratio of 8.7:1. That's close on 5% less compression than the SLK. With the increased power due to an increased compression ratio and some smart engine management, your SLK230 is capable of generating more horsepower.

Here's the comparison:

Horsepower:
SLK230: 192lb @ 5500rpm
C230K:189lb @ 5800rpm

Torque:
SLK230: 200lb/ft @ 2,500 rpm
C230K: 192lb/ft @ 3,500 - 4,000 rpm

0-60mph (automatic gearboxes)
SLK230: 7.0s
C230K: 7.5s

Brian_R170

If you mean the C230 sportcoupe, here are the differences that matter:

Vehicle: '99 SLK230 / '03 C230
Weight: 2,975 lbs / 3,250 lbs
Differential: 3.46:1 / 3.26:1
Peak Power: 185hp @ 5300 rpm / 189hp @ 5800rpm
Peak Torque: 200 ft-lbs @ 2500-4800rpm / 192 ft-lbs 3500-4000rpm

So, there's a bunch of little things that add up to make the SLK feel quicker (of course, it IS quicker, too). The difference in peak hp doesn't make any difference in the "grunt" that you feel.

I disagree with beantownrich about the compression ratio. It's the power and torque curves of the engine that matter. How you get there is irrelevant. Not to mention that he quoted figures for the '01-'03 SLK230. The compression ratio of the '99 SLK230 was 8.8:1 and the peak horsepower was 185hp.

rghinzel

All,
Thanks for the spec differences on the SLK230 and C230 coupe. Here is a photo of my SLK230. It's got the AMG Sport package from MB. I've put some racing pedals on, but apart from that it's basically Stock.
-Rob

beantownrich

Sorry, completely missed that he was talking about a '99

Brian_R170

Nice car. I also had a '99 SLK230, Brilliant Silver, Sport pkg, and manual transmission, but I had the two-tone oyster/charcoal interior. Yours looks like solid charcoal although it's hard to tell from the picture.

rghinzel

Thanks,
It's the same as your previous SLK. I do have the solid charcoal interior. I'm really pleased with the vehicle. The 5 speed is great. I've driven manuals all my life and it's up there with the best. How do you find the new '02 SLK32 AMG'. Nice back drop in the picture. Looks like you've got some nice open roads to take the car out on.
-Rob.

Brian_R170

Quick. Very quick! I had a severe case of phantom clutch syndrome when I first bought it. After driving the '99 SLK230 for 2 1/2 years, every time I'd get into the '02 SLK32, I'd be reaching for the clutch.

Nektopoli

rghinzel: Was the C230 a Kompressor motor ? Safe to say they gave you a car off the lot as a loaner ? Also do you remember what year the C-Class was ?

NP

x15jq

The 2002 C 230 K coupe, im readin this from my Window sticker is

192 HP@ 5500 RPM
200 Ft-Lb Torque @ 2500-4500 RPM

I do know that the older slk compressors and old c class had a clutch on the SC unit. This was eliminated in 1999 and changed the horse power from 185-192 final.

The airbox also had a revision over the years, now for modern day slk it is similar to c coupe.

Brian_R170

Actually, the change happened for the 2001 model year (starting in May 2000 for US-spec SLKs), but there were alot more changes to the engine than just the supercharger clutch and the airbox.

BTW, anybody know why the power and torque rating of the 2003 C230 Sportcoupe is lower than the 2002 model? And since the SLK230 uses the same engine, why wasn't it's power/torque decreased as well? I see that they lowered the compression ratio form 9.0:1 to 8.7:1 and the fuel economy increased by about 10%, but the 0-60mph performance isn't listed on the website for the 2003 C230 sportcoupe.

Tai230K

2002 c230k has a 2.3L with an output of 192 hp, while for the new 2003's they put in a new 1.8L engine with an output of 189 hp. Supposedly the new engine is better as in smoothness and fuel consumption, but the 2.3L has a higher torque and a nicer grunt.

I also drive a SLK 230 for mostly dates (only need a 2 seater) and it definitely feels quicker when going from 0-60 compared to the c230k. BTW the SLK i'm talking about is a 2001 version.

Brian_R170

I didn't realize that the US-spec C230 Sportcoupe was using the new 1.8L GDI engine! Now it makes sense. Too bad M-B doesn't make a 2.3L GDI engine, but I guess it would kick butt on the 3.2L V6, wouldn't it.


BTW, Shouldn't they call it the C180 Sportcoupe? Of course, then they would have to change the name of the C240 to C260 and the CLK55 to CLK54, and the S600 to S550, etc.

Nektopoli

Woo hold on there was no way MB would dump the clutch on the SC unit WHY ? MPG would plumet(about 8 MPG). Where did you get this info.

The HP was 185 from 1998-2000
Then in 2001 MB bumped the compression up from 8.8:1 to 9.0:1 and HP jumped to 192.

The C230 Coupe was new in 2001 and got the same engine as the SLK that year. The Coupe has 192HP@5,550 RPM the SLK 192HP@5,300 RPM both car used SIM 4 engine management that year.

In 2002 both Kompressor motors got a liquid-to-air intercooler.

In 2003 the C230 Coupe got the 1.8L Kompressor motor with 189HP@5,800 RPM.

The 2003 SLK230 got the 2.3L Kompressor with 192HP@5,500 RPM but I don't know what happened to the liquid-to-air intercooler.

There were changes in engine management from year to year and I don't know how much the final drive comes into play here.

All stats come from www.MBUSA.com and represent USA spec cars only.

NP

Nektopoli

Looks like they both have GDI


2003 C230 Coupe 1.8L:
Fuel and ignition system SIM 4 engine management. Integrated sequential multipoint fuel injection and ignition with individual cylinder control of fuel spray and spark timing. Electronic throttle.

Intake system Variable intake and exhaust valve timing. Intercooled supercharger.

2003 SLK230:
Fuel and ignition system Integrated sequential multipoint fuel injection and ignition with individual cylinder control of fuel spray and spark timing and antiknock. Electronic throttle. SIM 4 engine management.

Intake system Variable intake-valve timing. Intercooled supercharger.

NP

Brian_R170

All C230 sportcoupes in the USA have the Kompressor motor.

The last time a C230 was sold in the USA without a supercharger was the 1998 C230 sedan.

Nektopoli

Brian_R170: I didn't know they gave him '03 C230 Coupe as a loaner.

NP

Brian_R170

Well, actually, he didn't say it was an '03 C230 coupe. Although he did say it was a coupe in a reply, so it could have been an '02 or an '03.

Nektopoli

Smaller engine better on fuel, and the 1.8L has dual balance shafts, I just hope the stafts are not sitting in the oil.

NP

trench

There are several different versions of the M271 Kompressor motor, all have the same displacement but have differenent horsepower ratings due to changes in the engine management system (possibly different boost levels as well). Since the engine displacement has remained the same, the CXXX numbers reflect the horsepower differences: the 1.8L C180K has 105 kW (143 hp), the 1.8L C200K has 120 kW (163 hp) and the 1.8L C230K has 141 Kw (192 hp, 189 hp for the US version). There is also a 1.8 L direct injection version as well with 125 kW.

The M271 engines should appear in the W171 SLK. I guess they decided it wasn't worth sticking them in the W170 for only a single year, probably more for servicing issues rather than a question of fitment.

The supercharger clutch was eliminated at the beginning of the 2001 model year. It was removed from supercharger because of the incorporation of completely new bearing technology within the supercharger itself. This allowed two improvements, the parasitic losses from the supercharger were lessened, plus the supercharger wasn't as noisy (the clutch was partially on there to reduce NVH as well). After the new bearing design it was no longer necessary to uncouple it when the engine was idling. An added bonus, the omission of the supercharger clutch meant an overall weight reduction for the M111 engines.

This is a typo on the MB website, all of the 230Ks have air-to-air intercoolers. The SLK32 and C32 have air-to-liquid intercoolers.

Cheers, BT

ibjhb

Not that it's anything scientific, I raced my friend with a C230 (I have an SLK 230). He has an 03 and I have a 99. We both have a stick shift. Only thing was I had a passanger. Both times we raced I was able to pull ahead on him.... and the second time I even gave him the 'jump'.

I drove the C230 that same night and I didn't like it as much as my SLK. It didn't seem to handle as well...

Just my .02....

Nektopoli

Now this means that the engine intake is always pressurized and the air bypass system can be done aways with, it will be a few years before anyone can really say is this will be a good thing.

NP

trench

Acceleration of the SLK is better because it's lighter (~250 lbs), plus the '99 M111 motor has a better torque curve than the '03 M271, which helps as well at the stoplights. Handling is better due to the lighter weight and a much lower center of gravity.

Sorry, my last post was somewhat misleading. Although the supercharger still spins at all times, there is a bypass valve that opens at idle and when cruising with no acceleration - this lessens the parasitic drag from the supercharger (since if it isn't kompressing anyting the motor doesn't have to work as hard to turn the supercharger).

Cheers, BT

Tai230K

You're right... the C230 doesn't handle the twisties and corners as well as the SLK..... the SLK is lighter and lower..... the c230 has crazy body roll but not anything new sway bars and new springs couldn't fix...

Also, the SLK Revs a bit higher than the c230... dunno why... same engine....