well the 240 v. 230k debate has to rage on in some form...

Outland is right all engines loose power on hot days and at higher altitude. Just drive a car through the Rockies and see the difference.

It happens for all engines. I have been designing gas turbines (jet engines) for what seems a lifetime and the same thing holds for those. At 123 degF in Phoenix planes cannot develop enough thrust to take off (actually happened once and they had to close the airport down). In Mexico City at a higher altitude the problem gets worse.

If you want to certify a specific power for an engine chose a cold day to do it as it will develop more thrust or power.

Other evidence of this effect are electrical "brown outs". Yes the demand is higher in the hot days of summer, but also the power stations (those that use gas turbines) produce less power.

This is probably way more than you wanted to know, but hey!!

No. Spraying water into the cylinder.

if i ever get this video off my digi cam ill post it for you. 3 races from 60-130 (fuel shut off) and the C240 wins every time by 5-10 car lengths. 05 C230k vs 04 C240. The C240 won even when the C230k had a solid 3-4 second jump. One race was from 40-130 as well. The C230k was slower from the get go and at NO point was it able to gain any ground on the C240. From a dead stop the C230 is quicker to 30 but shift into second and off the C240 goes. 04 C240's shift much quicker than an auto 05 C230k. The 4 cyl retards torque a great deal while the 240 seems to "rip" the shift far more quickly. This could be some of the issue as to why these C230k's are so bloody slow.

maybe then we can put this story to rest.

drove my C230k for a 1 hr canyon drive last night (60 deg night in so-cal) and after 10 minutes the car was a solid 10-15% slower than when we started. The car at one point got very weak up hill. The exhaust was glowing from the headers to the resonator in the center of the car.

yes all cars get slower as it gets warmer but cars wit FI suffer much more than NA motors. My C32 was dead slow in the heat and my E55k is far weaker if it is 95 deg out. Here comes summer so time to drive more carefully!

I tested this with my 03 C230k back in the days and came to the same conclusion. But it's pointless... From what I read here there is NO heat soak effect in the 1.8 and the c240 is sooooooooooooooooooooooo slow it's un believable.

You're welcome. :p

Cyn - easy fix - get a manny.

That is the problem! Too many people with the slushbox! I have no problems whooping a C240 in my C230 Coupe! But I went with the real tranny!!!! Auto's are for non-performance type drivers. Ones that only want to get on it and floor it once in a while. I have no issues with getting up to speed quick enough, nor do I have issues with passing or highway power.

I have raced a C240 and C320 to 130. Stock I lost to the C320, with the pulley I was faster than both

I hate to always be the one screaming "captan obvious", but the 03-05 are slower, in the real world, much slower than MB claims than the M111, the REAL C230... you silly guys and you C180s

The C240 has a gearing advantage in the low end, but ultimately it has a lower top speed, slower high range aceleration.

So you loosing to a C240 STILL makes no sense.

What rear gear is in the Auto C230K? I know my 6 speed has the 3.46!

Edit: Also I find that the 1.8 is fine as long as you keep the rev's in the proper rev band! Basically over 3000 RPM for spirited driving. Easy to achieve though with the 6 speed!

not to be an ******* or anything, but didn't any of you guys take chemistry or physics or something? lol
PV=NRT pressure x volume= number of moles times rate times temp
seeing how this is measured in kelvin, which is simply celcius+ 273.15, you can deduce that an increase in temperature of about 30 celcius will incur a 10% drop in horse power. This is only a theoritical approach and in real life the numbers will be a little different. An in humid air, it doesn't mean that because it's more dense it'll have more oxygen. Humid air means you have more water vapor and water vapor doesn't do anything positive for combustion.

The performance is pretty much negligiable. I think normally it's about 27 degrees celcius, I don't want to calculate the actual conversion, which I believe is about 75 degrees F and 36 degrees celcius is about 90 degrees F. So that would be about 10 degrees difference in celcius and when you do the whole the equasion above it'll only factor into 3% or 4%.
3% or 4% of 189 hp is about 6 to 7.5 horsies or so.
*my calculations are off because I don't want to go find a calculator and type in all the numbers*

Okay now how about this, if it's raining in China, partly cloudy in Quebec and sunny in Pheonix, will your car run 10.037% less horsepower in Kansas City?

The advantage of spraying it into the intake air is that it can lower the air temps by around 60 degrees. That works a whole lot better than spraying the water on the intercooler. The better bet for that is to use compressed CO2 sprayed on to the intercooler. As I stated in a thread of mine where I asked about engine timing, spraying water into the intake air also keeps the cylinders so fresh and so clean clean! It washes the carbon build up out!

I'm sure you took these classes, but did you pass them? R is not "rate" but the Universal Gas CONSTANT. It does not change.

I'm just busting your chops. Other than that, nice work, although you have over-simplified the equation needed (run it and see what happens when you increase temp...PV goes UP) and the situation in the minds of the readers here. The PV in the equation converts directly into Torque, which is then easily converted to HP. That's why the 10% change in absolute temperature has a roughly 10% affect on an engine's output.

The reality is, an engine's output relative to its rated HP is reliant upon the amount of Oxygen in the air, and nothing more. This is a factor of Temperature, ambient Pressure and relative humidity. Increased H20 vapor saps the air of O2, the crucial air element in the air/gas mixture.

Using SAE standards (ignoring the supercharger and inefficiency inherent in every engine ever built), and assuming the C230 engine is rated to 189 HP at 77 degrees F, standard atmospheric Pressure (29.92 in HG), and 70% relative Humidity, a temperature change (with constant humidity and atm. pressure, which is unlikely outside of laboratory experiment) to 67 degrees will increase output by 2%. To 57 degrees by 3.8%. 47 degrees increases output versus rated HP by 5.4%. 37 degrees = +7%. It's all about Oxygen saturation. At 87 degrees, we see a 2% Drop in output. At 97, we see a 4.3 % drop. These are pretty close the numbers you came up with. This engine will have approx. 10.5% more power at 32 degrees than 90 degrees (your 30 K range).

Of course in the real world, temperature does not move independent of pressure and relative humidity, but is directly related to them. So, in the end, this all adds up to...nothing.Well, maybe 20 minutes of my time wasted and a rough guideline for your engine's expected output according to Temp. If your in Phoenix, just enjoy!

What an amazing question. Clearly you fully grasp the subject.

The C240 has (3:63 or 3:73) Crap, I am mixing cam duration numbers and diff ratios in my head up... cams are in 6's??? 266/276/286??? Or **3? and the diff in my e30 is 3:73 I could search, but the truth is I am lazy and still working. Arg-

Great thread, but the numbers don't mean dookey to half the people here unfortunately. What most of us need to know is simply that, any motor will lose HP/TQ on hot days. It is more obvious in Forged Induction motors. The amount lost is relative to temp. increases. And if a C240 beat you, you motor is likely producing less than the acceptable margin allowed or you can drive. If you were in an auto, and your motor's fine, you scare me.

On a hot humid day, my poor car bogs out. On a cool crisp dry day, the output is difference is very evident. The pulley helps by not letting it be a complete dog, but the heatsoak is still there.

From someone like your self I would expect a tad more respect. If I have driven 4 different C230k's (2005) that ALL were slower than any given C240 loaner car I have been given I honestly think I can say for fact that a C230k is SLOWER than a C240...every day of the week.

Your gearing numbers are a bit off and a C230k and a C240 have the same exact gear spacing and both have a 3.46 rear end -- in auto form.

I am very familiar with FI cars being slow has heck on warm days and MB's seem to be the most sensitive to this of any car I have seen to date.

Last I checked my driving was fairly good but maybe i would scare you . My street driving last night melted my factory brakes and baked the pads so I just threw on the brakes form SMGC32's AMG on my car and it really stops better than it goes now -- even worse than before. Its late and I need to wake up in 4 hrs so off to bed I go... I hope i keep this car for a while i dont want to take those brakes off for a LONG time....
zzzzzzz

I didn't mean any disrespect but knowing you track I thought the driving comment would be a good sorry It's 4:30am, I just finished work and I am b!tchy. I started to search for links to the numbers, but I just don't have it in me, my day started at 7am. Please don't take offense, I was just trying to have some fun before.

No you wouldn't scare me. My new street pad is the ST-43 because I was cooking R4S pads, seperating the pad from the backing plate. The last set I removed, I touched with my finger and the material crumbled away. I meant to take pics but forgot. It was funny. What pads are you running?

At VIR on my OEM sized slotted stoptechs, with R4S pads, 600 F fluid, and R4S pads, I out braked the C32 on course EVERY time, every corner all weekend. He'd pull 15 something car lengths on me in the straights, then loose it all in the braking zone.

There are auto owners on this forum who've swapped to a lower geared diff into the C230. The diff comes from the C240 according to Potomac. I can not validate that. Just what I was told and have read on the forums and tech sheets for the cars. Maybe I missed something. Heirkrans (sp) had done the swap, but I think his is a manual.

I still do not understand the C240 thing. I have had different results, but my C230 is a manny and an 02. The C240s I've run against, dead stop and rolling starts from varying speeds, stock, I put a hurting on it. Are the C230 you're talking about all 03-05? Sedans? Have you ever done '02 C230 Coupe vs. C240? The M271 powered cars are slower vs. the M111 Coupe than stated. I had gone up against both the M271 coupe and sedan. The cars are like night and day, though I thought the M271 would still pound the C240.

I think MBs seem to see greater power loss with heat because of the "practically sealed" engine compartment. At CMP I removed the undertray, and punched out the unused air inlet. I didn't "seem" to lose as much power as I have with the full tray on in the past.

To truly FIX the brake baking issue, I have an idea for a cooling kit but it's a PITA. On my coupe, the washer fluid resivior is in the way, BUT, you could drilll out a 3" hole on both sides of the resivior, then plastic weld a section of PVC piping there. You get pass through for the kit and keep the functioning resivoir. Remove the backing plates and ziptie the 3" hose to the control arm running up to the back of the rotor. No more overheating.

I am selling the coupe though. Need a tow vehicle for the race car and I am sick of fixing the broken pieces on the coupe. Diffs/Trans/wheel bearing/ and CABs keep going bad on me. The front strut tower design really erks me, and there not being a LSD for under 5K is just insane. My 3:73 LSD for the e30 cost me $275

I looked into prepping the car for club racing. To remove the SC and get reasonable HP numbers N/A, I was looking at way too large of an investment on a car that would just get destroyed in Mod classes anyway.


EDIT: Sorry for being so off topic. Anyone with a C240 in the Baltimore, MD area? I've got a camera mount I can put on backwards

Hehehe! And if you find a C240 In Baltimore area I will bring my stock 2003 M271 6 speed coupe as well!!! Just to see what happens.

3 MB's flying down 95 :rofl:

IIRC, Marth Stewart reccomends this.

The C240 engine sucks donkey *****. Ok car, pathetic motor.

I stuck my Gtech in the last C240 loaner I had. It couldn't even get under 9 seconds to sixty. I think my best run, late in the evening, was 9.17. And the Gtech tends to be bit kind on times. So, real world, 9.5 seconds to sixty.

The last 1.8 C230 I was in, could do sixty in mid 8s- with an automatic. A manual is faster, but the dealer never gives out MT's. The 2.3L C230 is a good second faster than the 1.8.

The C240 has a lot less HP, less torque everywhere in the rev band. And its heavier to boot. Geez, how hard is this to figure out?

This race would be over withing a few seconds. An automatic C240 is soooooo slooow right off the blocks both C230's would already several car lenghts out.

gtech is the most useless thing ever made for testing performance. If you use that for factual information this may be the crux of our issue. If I listened to that wonderful piece of engineering my E55 does the 1/4 in 11.1 @ 122 stock. Uh sorry my cars not that fast….sure wish it were.

The C240 is faster every day of every week... sun up sun down.... wind blowing wind not blowing..... clouds no clouds.

I will get this video and post it for you. If races from 40-130, 60-130,70-130 are not factual enough for you I don't know what to say. For me fact is fact and that is all I can say. Trouble is I don't have time to sit around formatting video files.

Good luck... C230k's are **** slow....I own one and I can say its **** slow. Mini Vans ***** me out in that car, Ford SUV's ***** me out in that car, H2's ***** me out in that car, heck even an Audi A4 3.0 Auto Quattro blew me away (and that is one pathetically slow car). No my car is not broken and its faster than some C230k loaners I have had when I took me E55 in for work.

0-60 is a toss up being that a C230k DOES get through first gear with more oomph than a C240 but my lord half way through 3rd and a C230k is ready to go home and take a nap.

trouble is by 70 the C240 driver sees nothing but open road and the C230k driver reads some nice Chrome letters that say "C240"

just wait until the C240 is replaced by a 230 hp C280... then C230ks will be even more pathetic in straight line testing. I pray that MB does something to make this car faster. Its just a joke I think.. some sick german is messing with out heads and laughing every night before he goes to bed.

if we are going to turn this into a C240 bashing then let me say that the 240 sucks in every way.

it is a slower engine, it is a heavier engine and car, the car does NOT have the sport package so the springs are higher, whe whole car sits about 1 or 2 inches higher, more body roll, no sport brakes, just normal brakes, boring wheels, and no AMG body kit so the aerodynamics aren't there and the engine is still a snail.

last night I was driving home on I-95 from NYC and i ran into a w203 c240 with a Massachusetts plate, we drove about 80 together for about 10 miles before i realized it was another Merc (he had the frosted headlights and turn signals so it looked different). then we started racing.... i dropped to fourth and handed him is *** on a silver platter. it was no contest, we went from 70 to 120 and i left him by atleast a 1/4 mile, going uphill too.
then i slowed down and waited for him to catch up and we proceeded to do it again, 2 or 3 times just for fun. we drove together for about 20 minutes then I had to take my exit and he kept going on 95 north.

if it's anyone here, please post up. I'd like to see what you have to say LOL...