HP discrepancies between SLK 320 and Crossfire
 

Hey folks!

I have always been kind of curious why there are discrepancies on paper between the HP of the Mercedes SLK 320 and the Crossfire.
Supposedly the Crossfire has a tad less hp but at the same time reaches 60 mph quicker than the SLK, which on paper is slightly slower but has more HP.
Am I reading something wrong or is there a reason for this?
Could it be that Mercedes did not want the Xfire to outperform their baby or was the engine "adjusted" better in the Crossfire to make it more effective despite less hp?
Does the Xfire actually weigh less than a Merc SLK?

Looking forward to your responses.

Nick

Re: HP discrepancies between SLK 320 and Crossfire
 

There have been several theories on that. Reported HP is often a marketing tool. Many of us assume this to be the case and our HP from the same engine, with the same management system for essentially the same car would be,,,,the same or 225 HP.


Something perhaps the Mercedes people did not want their SLK customers to hear.:rolleyes:


For the record, this has sometimes been the basis for many a heated discussions here about post mod HP calculations.

Re: HP discrepancies between SLK 320 and Crossfire
 

Sorry I did not mean to cause an argument or heated debates. I guess I haven't been here long enough to know about those discussions in the past :D
I absolutely agree with you - same engine needs to produce same HP. Only question, is it really 225? I thought it was 218?
Has there been an official report or dyno results to see what the real numbers are (no matter whether SLK or Crossfire)??

Re: HP discrepancies between SLK 320 and Crossfire
 

AH-Yep!:rolleyes:

Re: HP discrepancies between SLK 320 and Crossfire
 

Discussions and debating is welcomed. Just get over yourself if you aren't right...lol. Been there done that. But, after years on here and working on two cars with some of the best aftermarket manufacturers and tuners, you pick up a few things. Take for instance I found some info on the engines shipped to Karmann from AMG. Same motor used in their version was used in the SRT6. Same! So, how do you come up with 330hp over 349hp? You lie! Can you imagine a car company lying? It is what it is. So, the big disagreement was just how much HP do you gain with the aftermarket parts based on the 330 number vs the 349. I won't go there as we know what HP we have gained roughly thru dyno after dyno and comparing similar modded cars. That is what I suggest you do Nick. Compare the mods others have done and see where you would like to go.

Re: HP discrepancies between SLK 320 and Crossfire
 

Nick, according to Motor Trend magazine's comparison road test of a 2003 SLK320 vs a 2004 Crossfire in their Dec. 2003 issue, both cars had 215 h.p.
In their test the SLK ran a 14.84 sec 1/4 mile, to the Crossfire's 15.18. Even though the SLK weighed 70
lbs. more.
The quicker times were attributed to the smaller wheels on the SLK.

Re: HP discrepancies between SLK 320 and Crossfire
 

Re: HP discrepancies between SLK 320 and Crossfire
 

AMG's site puts their supercharged 3.2 at 354HP, and lists it in both the Crossfire and the SLK.

go figure...

Dave

Re: HP discrepancies between SLK 320 and Crossfire
 

I watched several YouTube videos the first week I had mine. I believe it was in the SRT video that was an explanation
from concept to production. A VERY boring video, hardly no pics, bunch of engineering guys talking about 13 mins long
maybe. ANYWAY....one dude kind of snickered when he was talking about that. Said something to lead you
to believe it WAS marketing driven. I would find it and post.... but I just can't watch it again... lol
Tracy

Could have something to do with the 29lbs. apiece rear wheels, alot of rotational weight. Depending on brand and size a 19x10-10.5 roto formed wheels can weigh between 18-24lbs. 19x9's even less. And be just as strong or stronger then oe's. Removing 10-20 lbs. of rotational weight makes a big difference on acceleration and braking

Re: HP discrepancies between SLK 320 and Crossfire
 

Yes it does, I lost about 30 lbs total with new wheels and while it wasn't earth shattering the difference was noticeable. One of the reasons I am about to lose the back CATs and resonator.

Re: HP discrepancies between SLK 320 and Crossfire
 

Be careful comparing quoted horsepower. German cars usually use Pferdestärke (PS) for their horsepower ratings. SLK320 are often quoted as having 218hp. However, since the Germans use PS it is actually 218PS which is equal to 215 BHP (the usual American rating). It's all about understanding the units of measurement.

Re: HP discrepancies between SLK 320 and Crossfire
 

Lots of good info here. Problem is, no matter if we measure by German PS or American BHP the specs of the engine need to be exactly the same as it is the exact same engine. Only thing I can think of is marketing as so many of you have said.
That to me is a pretty big joke as we are not talking about huge performance differences just a few hp more or less. I would doubt that would make someone picks a SLK over the Xfire or the other way around!

@SRT6GRL - The video you are speaking of I bet it this one here. Watched it a while back, even though technical I thought it was real interesting:

Talks about some of the "big guys" involved in the production of the Crossfire! NOTE folks are even wearing sweet Crossfire polo shirts ;)

EDIT: The part SRT6GRL is talking about starts at 6:18 where without saying directly it becomes evident that the Xfire is anything might have better HP than his big brother but Chrysler wasn't really allowed to say! Very interesting and spot on.

Re: HP discrepancies between SLK 320 and Crossfire
 

A group of us were able to meet with them at the Woodward Dream Cruise. Many of us were able to discuss a lot things about the cars with them one on one. I learned a lot. I even put my belly pans back on.....lol.


BTW for those who don't know. That is Rob's car in the video, from Needswings.

Re: HP discrepancies between SLK 320 and Crossfire
 

What did they tell you about them Doc ?

Re: HP discrepancies between SLK 320 and Crossfire
 

I took them off thinking I would get better cooling allowing some air to get into the engine bay. Come to find out in their wind tunnel work, they do have an affect on top end and handling at high speed. My MB E type is flat as flat can be underneath, and so is the crossfire. Good ole' ground affects.


Another question I asked, which I had a hard time believing if I hadn't heard it from the engineers, is the down force from the N/A wing and the SRT wing are all but identical.

Nice what wheels sizes and offset did you go with.
I thinking about roto formed tsw's and redrilling rear hubs to a 114.3 so I can use there 19x10.5 since the 10.5 does not come in a 5x112.
Niche has direct bolt on 19x10 but 36 lbs apiece the targas

Re: HP discrepancies between SLK 320 and Crossfire
 

I figured that was not a STOCK SRT6 as the shifter looks totally different. On the other hand, I like the look of that "ball" shaped automatic shift knob. Anybody know where to get that exact same one?
For me it was worth this thread cause I have learned a lot of good info even if FRANC RAUSCHER thinks all I tried to do was stir up drama I guess??? :D

Re: HP discrepancies between SLK 320 and Crossfire
 

Nick, now I feel guilty about not being ENOUGH of a gear head! Lol
I DID however watch it, and learn SOMETHING apparently. ;)
And yes, I am ALWAYS jealous of things like polos or pens or notepads!
Moral: ADHD a little? YES!!! I need pics and exciting things. Not just engineers (even if they have cool shirts)!

Re: HP discrepancies between SLK 320 and Crossfire