SLK/R171: How does the SLK350 motor achieve 300 crank?
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From: Wyckoff, New Jersey & Alphabet City NYC
86 190E 2.3-16v, 92 500E, 03 CL55 AMG, 08 E3504M Brabus
How does the SLK350 motor achieve 300 crank?
Does anybody know how the 300hp crank numbers are achieved with the SLK motor vs the rest of the 350s? Is it a more free flowing exhaust, or a less restrictive intake plenum? I want my E350 make 300 crank and thought someone over here might now how MB made it. When it comes down to it I'm sure these motors are pretty much identical so I don't imagine the changes are drastic.
Also, these cars have a 7,200 red line correct? Wonder if any type of string coding with SDS would allow non SLK 350 motors to do the same? Can someone explain to me what is necessary to make the car rev higher safely? Maybe this is one of the differences in making more power between my motor and the SLK? Thanks much for any help guys! Some great looking cars over here
Also, these cars have a 7,200 red line correct? Wonder if any type of string coding with SDS would allow non SLK 350 motors to do the same? Can someone explain to me what is necessary to make the car rev higher safely? Maybe this is one of the differences in making more power between my motor and the SLK? Thanks much for any help guys! Some great looking cars over here
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AMG
Actually the change is quite drastic....
First and foremost, the SLK350 is the first production gas engine from MB with direct injection which is why it makes much more power but still gets better fuel efficiency.
Second, they eliminated the dual length intake manifold for a much simpler single length manifold b/c the dual length design ran out of breath at high rpms. The earlier SLKs power really tops off quickly and there would be absolutely any point in trying to increase the rev limiter its already running out of breath before redline as is, trying to up that to 7200 would probably make the car slower b/c there is now power up there.
Third, the software has been completely changed due to the different style engines (conventional vs. direct injection) and also even though they don't say it explicitly, I am sure they uprated the cams to a more aggressive one.
The downside to this is you lose about ~7ft lbs of torque but you gain some ~40ish HP so its a sacrifice well worth making. Its not something you can just "convert" over to, its a completely different design (at least the top half of the motor & electronics). The block itself may be the same and the actual crank gear but the rest has been change, modified, adapted to the newer design. Soon all of MBs engines will be direct injection.
hope that helps.
First and foremost, the SLK350 is the first production gas engine from MB with direct injection which is why it makes much more power but still gets better fuel efficiency.
Second, they eliminated the dual length intake manifold for a much simpler single length manifold b/c the dual length design ran out of breath at high rpms. The earlier SLKs power really tops off quickly and there would be absolutely any point in trying to increase the rev limiter its already running out of breath before redline as is, trying to up that to 7200 would probably make the car slower b/c there is now power up there.
Third, the software has been completely changed due to the different style engines (conventional vs. direct injection) and also even though they don't say it explicitly, I am sure they uprated the cams to a more aggressive one.
The downside to this is you lose about ~7ft lbs of torque but you gain some ~40ish HP so its a sacrifice well worth making. Its not something you can just "convert" over to, its a completely different design (at least the top half of the motor & electronics). The block itself may be the same and the actual crank gear but the rest has been change, modified, adapted to the newer design. Soon all of MBs engines will be direct injection.
hope that helps.
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86 190E 2.3-16v, 92 500E, 03 CL55 AMG, 08 E3504M Brabus
Yea it does thanks I appreciate it. So, what do you have for me? Pulley or something maybe?? Help a brother out?
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Corrolla
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I thought these new 350s weren't actually direct injected. That was used on some kind of car in europe I thought, but not in these SLKs.
I thought the SLK upped the power by as described changing some things to have it higher revving and giving up some torque.
I thought the SLK upped the power by as described changing some things to have it higher revving and giving up some torque.
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You are correct, we do not have the CGI engines in the US. They require higher octane ratings which are not available in here in the US. This is one of the reasons we do not get the new e-class with CGI but with the old 3.5 engine. Our fuel is not up to snuff.
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AMG
Not true, they are direct injection but only on the newest SLK350. Also, that is NOT true at all. Europe does not have higher octane they just use a different octane system. 98 octane over there equals 93 octane here you are just comparing MON vs. RON octane ratings. They are the exact same octane rating just a different number.
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From: Falls Church, VA
2005 SLK350
Does anybody know how the 300hp crank numbers are achieved with the SLK motor vs the rest of the 350s? Is it a more free flowing exhaust, or a less restrictive intake plenum? I want my E350 make 300 crank and thought someone over here might now how MB made it. When it comes down to it I'm sure these motors are pretty much identical so I don't imagine the changes are drastic.
Also, these cars have a 7,200 red line correct? Wonder if any type of string coding with SDS would allow non SLK 350 motors to do the same? Can someone explain to me what is necessary to make the car rev higher safely? Maybe this is one of the differences in making more power between my motor and the SLK? Thanks much for any help guys! Some great looking cars over here
Also, these cars have a 7,200 red line correct? Wonder if any type of string coding with SDS would allow non SLK 350 motors to do the same? Can someone explain to me what is necessary to make the car rev higher safely? Maybe this is one of the differences in making more power between my motor and the SLK? Thanks much for any help guys! Some great looking cars over here
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Couple different explanations, but you'll note none of them describe "less restrictive" anything.
"Less restrictive" is USA hot rod hype and nothing more. It's a concept mostly foreign to Mercedes, BMW, etc., as these car are engineered rather than whatever you call it that happens to small block chevies.
"Less restrictive" is USA hot rod hype and nothing more. It's a concept mostly foreign to Mercedes, BMW, etc., as these car are engineered rather than whatever you call it that happens to small block chevies.
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350 Tech Specs from MBUSA : 280 Tech Specs from MBUSA :
Last edited by UK-C200; Mar 12, 2009 at 04:32 PM.
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Not true, they are direct injection but only on the newest SLK350. Also, that is NOT true at all. Europe does not have higher octane they just use a different octane system. 98 octane over there equals 93 octane here you are just comparing MON vs. RON octane ratings. They are the exact same octane rating just a different number.
Check out this story about CGI engines and Octane ratings. May or maynot apply to the SLK350. I don't know.
http://www.automobilemag.com/reviews...dan/index.html
No direct-injection V-6 for America. Blame our gasoline.
In the United States, the 2010 E350 uses the same 3.5-liter V-6 as the 2009 car, with 268 hp and 258 lb-ft of torque, but the rest of the world gets a new 3.5-liter engine with direct injection and 288 hp. Unfortunately, that engine is not able to use our low-quality gasoline.
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I read that somewhere as well but I'm not sure I'm buying that since there are already several manufactures selling DI vehicles here in the US. 
Might be a PR attempt to mask their falling behind on getting these engines out the door.
Might be a PR attempt to mask their falling behind on getting these engines out the door.
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From: MILFORD,CT
E36M3 race car/Ferrari F355 GTS/1973 Mini 1275GT/Fiat Abarth/ML63/SLK55
hey guys i'm thinking of an 05 or o6 slk350 6 speed as a DD. how would you go about modding for more power? i see shrick has cams for 900 euro, i called super sprint they have headers for 1800 and i know they are various chip tuning options. i should get to 300 hp with what do think?
11.7 to 1 is pretty high for a non DI engine. looking at peak hp and where peak toruque is for 300 hp engine i imagine it must be quite enjoyable to drive...but a pity no manual transmission. does the slk automatic rev match (blip throttle ) on downshifts?
also i wonder if the 300 hp engine uses the same cams as the older 268 hp engine....peak hp has shifted 500 rpm but that could be just the intake mani improvement.
if anyone has specs for stock cams i would appreciate the data.
11.7 to 1 is pretty high for a non DI engine. looking at peak hp and where peak toruque is for 300 hp engine i imagine it must be quite enjoyable to drive...but a pity no manual transmission. does the slk automatic rev match (blip throttle ) on downshifts?
also i wonder if the 300 hp engine uses the same cams as the older 268 hp engine....peak hp has shifted 500 rpm but that could be just the intake mani improvement.
if anyone has specs for stock cams i would appreciate the data.
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From: Albuquerque
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The 300hp V6 is pretty much the standard now in all models with this engine, and the difference between it and the former 268 hp version is higher compression. Obviously electronic retuning to match.
It's BTW a clear demonstration that the true path to efficiency is high compression. The 300hp cars are rated at better fuel economy than the 268 hp cars.
The ultimate high compression engine, of course, is the diesel.
Of course in NASCAR they're at what, 17-1, 20-1 ... carburetors, of course. Don't think there's much connection to type of carburetion/injection.
You can look up cam part numbers using EPC. http://epc.startekinfo.com
It's BTW a clear demonstration that the true path to efficiency is high compression. The 300hp cars are rated at better fuel economy than the 268 hp cars.
The ultimate high compression engine, of course, is the diesel.
Of course in NASCAR they're at what, 17-1, 20-1 ... carburetors, of course. Don't think there's much connection to type of carburetion/injection.
You can look up cam part numbers using EPC. http://epc.startekinfo.com
Last edited by lkchris; Nov 21, 2009 at 07:20 PM.
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All the other 350 cars, C Class, E Class, etc. have the 268 HP version.
In Europe, the SL also has the 3.5 liter Sport Motor available.
However, only the SL (in europe) and SLK (everywhere) has this engine available.
However, don't despair. I've read that many think the Sport Motor isn't necessarily better. You lose some low end torque, so changing this engine in these sportier cars may be partly a mind game, to slap the 300 HP sticker on the cars.
I've never had the 268 HP version. I love my 300 HP version, but I doubt it's much different.
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From: MILFORD,CT
E36M3 race car/Ferrari F355 GTS/1973 Mini 1275GT/Fiat Abarth/ML63/SLK55
DI engines allow higher compression due to the cooling effect of the fuel; sprayed into the cylinder during the compresion stroke. higer compression=more given power/more efficiency=better mpg.
the bane of high compression is knock, you can stave off onset by using higher octane or retarding spark or head design or cooling fuel...plus other ways as well....
of course the diesel is the ultimate DI engine, the aim is to ignite the fuel by the heat generated by compression!
11.7 to 1 is high for a non DI engine running pump gas. the vaunted bmw e90 m3 and 997 911 997 gt3, both bespoke high performance cars, are at 12:1, just 3 points more than the 300 hp slk 350.
the shift of torque for the 300 hp slk is why i lament lack of a manual tranny.
the bane of high compression is knock, you can stave off onset by using higher octane or retarding spark or head design or cooling fuel...plus other ways as well....
of course the diesel is the ultimate DI engine, the aim is to ignite the fuel by the heat generated by compression!
11.7 to 1 is high for a non DI engine running pump gas. the vaunted bmw e90 m3 and 997 911 997 gt3, both bespoke high performance cars, are at 12:1, just 3 points more than the 300 hp slk 350.
the shift of torque for the 300 hp slk is why i lament lack of a manual tranny.
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From: MILFORD,CT
E36M3 race car/Ferrari F355 GTS/1973 Mini 1275GT/Fiat Abarth/ML63/SLK55
i'm looking for stock slk350 cam specs- lift, duration, lobe separation so as to compare against the shricks to have a quantitative and also qualitative sense of the diffences.....don't think part numbers will help.
