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Why is the US model 560 engine so underpowered?

8K views 83 replies 17 participants last post by  strife2 
#1 · (Edited)
Hello:

I was wondering why the 560 SL engine power rating is so much lower than the european 560 engines.

The first low compression 560 Euros with catalitic converters had 252 PS, while the high CR (10:1) reach 279 PS.

Where are the differences?

Camshaft, DME, injectors?

Just curious.
 
#3 · (Edited)
Hello:

I was wondering why the 560 SL engine power rating is so much lower than the european 560 engines....
Can you say, Eee Pee Aaa,? Smogged to death, is my opinion.

CR is 9.x:1, but can't remember exactly. 9.4 sticks in my mind, for some reason.

Edit...
From Piel De Toro: http://www.pruebas.pieldetoro.net/web/MERCEDES/dossier.php?ID=5

560SL (Sólo para el mercado USA)
Producción: Septiembre de 1985 a Agosto de 1989.
Nº de ejemplares construidos: 49.347
Motor: M117, 8 cilindros en V.
Diámetro/Carrera: 96,5x94,8 mm.
Cilindrada: 5.547 cc
Relación de compresión: 9,0:1.
Alimentación: Inyección Bosch CIS-E.
Potencia: 227 CV SAE a 4.750 rpm.
Par Máximo: 28,4 mkg a 3.250 rpm.
Transmisión: Cambio standard automático de 4 velocidades: 1ª-3,68:1, 2ª-2,41:1, 3ª-1,44:1, 4ª-1,00:1.
Grupo cónico: 2,47:1.
Suspensión: Independiente a las 4 ruedas, delantera con trapecios transversales, muelles, amortiguadores y estabilizadora, trasera con brazos oscilantes, amortiguadores y estabilizadora. Opcionalmente control de nivel hidroneumático.
Dirección: Servo asistida de recirculación de bolas y diámetro de giro de 11,5 m.
Frenos: Circuito hidráulico doble. Discos a las 4 ruedas y ventilados los delanteros. ABS.
Neumáticos: 205/65 VR 15.
Dimensiones: Largo 4,580 m., Ancho 1,790 m., Alto 1,290 m. Batalla 2,455 m., Peso 1.715 Kgr .
Velocidad Máxima: 137 Millas/h.
Aceleración: 8,0 Seg. 0/60 Millas/h.
Consumo: de 14 a 17 litros/60 Millas.
Tanque de combustible: 90 litros.
 
#10 ·
I'm pretty sure it's the combination of the compression ratio, possibly cam profile, and the exhaust. The euro version of the 450s that I've been looking at don't have cats and the addition of them in the US version caused an extreme decrease in power.

Is the combustion chamber in the head on these engines along with the 450?? If so you can just shave off some of the head to bump the compression back up. A machine shop can do that fast and it's super easy to do. Slap it back on and you should be good to go. I wouldn't think that these engines would have the valves anywhere close to the pistons to be worrying about them slapping each other with stock cams.

I'll probably be making a new exhaust for my 450. Not sure about the exhaust manifold. I finally got to see one and the stock US 450 exhaust manifold is HORRIBLE. It's way to small and it's just designed horrible.
 
#12 ·
I am going to once I find a set somewhere. I haven't seen any pics yet of a set of tri-y's. I'm wondering how big the exit is compared to the size of the ports.
 
#13 ·
Took a loot through ebay.de and didn't find any. Just full engines. Maybe I didn't search with the right german words but even so. Buying those on there would be at least a hundred or two plus shipping. I think I'd rather fab up a tri-y with a cross/x-pipe somewhere down the line. Main thing that would stop me from doing that is the exhaust manifold flange which I can get a CNC shop to cut me out one. Toss on some V-Band flanges and call it a day, or a few days rather to get the whole thing done. :p

Making a full header makes me want to put some turbos onto the end of them though. :p Ya know what I mean?
 
#16 ·
You definitely can't shave these heads to any point where it would help much, the manual gives a limit. Also, shaving the heads brings up a whole slew of geometrical problems - the shims (or possibly even shortening the valve stems!), the timing chain gears have to be offset, the intake manifold might have to be built up or assembled (very risky) with two sets of gaskets - hopefully, the valves and pistons wont hit (higher C/R engines have pistons shaped and relieved differently), and then, there is the issue of the combustion chamber itself and it's new, possibly non-optimal configuration. The engine might actually start knocking even on premium, so then you have to back down the timing...which might put you back where you started in terms of power.
 
#17 · (Edited)
My Friend David Poole of European Performance here in Dallas told me that he put a set of Tri-Y's on a 560SL and he said that it felt the front wheels were about to lift off when you punch the gas.

I've not seen the 560SL exhaust set up but if it's anything like a 560SEL, then I can believe it.

Bang for buck, it's probably the best way of freeing up power from your US spec 5.6 engine.
 
#18 ·
Is most of your thoughts speculation on what "could" happen because I realize that stuff like that could happen but when shaving a head to raise compression one point it's not really that much they are taking off. I know on my VW motors that have timing chains they can be milled a few times without any problems with the timing chains on those. I'd like to have some numbers to push around if anybody has them on valve clearance. I highly doubt they put a radical cam with high lift in these motors. If shaving the head for one point makes them slap, then putting in a higher lift cam would do the same exact thing.

The manual probably gives a limit because it wants you to stay with in factory spec. If you are bumping up compression you are obviously going out of factory specifications. I don't think you'll see any manuals that say shaving the head is ok on any car to bump up the compression. I say to bump up the compression because as we all know shaving the head to resurface them is common practice when doing head work. Shaving off .030" to .040" is a decent amount but I some how doubt it'll make the difference for the intake manifold. Saving off .030" to .040" should get the increase in one point.
 
#21 ·
Is most of your thoughts speculation on what "could" happen because I realize that stuff like that could happen but when shaving a head to raise compression one point it's not really that much they are taking off. I know on my VW motors that have timing chains they can be milled a few times without any problems with the timing chains on those. I'd like to have some numbers to push around if anybody has them on valve clearance. I highly doubt they put a radical cam with high lift in these motors. If shaving the head for one point makes them slap, then putting in a higher lift cam would do the same exact thing.
.
If you look at the heads themselves, there isn't all that much "meat" at the bottom of the head. The shim and offset issues have been experienced by some high-perf guys on other forums. The intake manifold problem is pretty common on an V-8 engine.

But the valve clearance and combustion chamber shape things are pretty unpredictable. It's disturbing to think that it doesn't take that much error on the timing chain to have a valve hit a piston on these engines. Certainly, reducing the height of the head will narrow the "safe" window here, and timing chains do stretch and gears wear down.

This is definitely one of those things I'd like some one else find out for me than find out for myself!
 
#19 ·
About those tri-y headers: are they pretty much an Ebay item or can they be found through a parts dealer? There is a shop locally that could fabricate some custom headers for my 560SL, but the cost would be astronomical.

I did a search but it didn't get me anywhere. :eek:

Any feedback appreciated!! :thumbsup:
 
#27 ·
Just get them from a dealer or the classic centre.

on the manifolds PDF;
Part 11 - exhaust manifold - 117 140 22 14 - List: $378.00
Part 14 - exhaust manifold - 117 140 23 14 - List: $364.00
Part 17 - exhaust manifold - 117 140 53 14 - List: $368.00
Part 20 - exhaust manifold - 117 140 27 14 - List: $330.00

on the exhaust system PDF;
Part 11 - exhaust pipe - 107 490 63 19 - List: $236.00
Part 20 - exhaust pipe - 107 490 64 19 - List: $220.00
 

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#20 · (Edited)
I looked on ebay.de since it's an Euro item and I couldn't find them on ebay. If they are not readily available or cost a whole crap ton I'd like fab up a set and then make a welding jig incase anybody else wanted a set. Making a jig after the product is done is super easy.

Or if somebody let me borrow their 500sl exhaust manifolds I can just re-create those. :p
 
#22 ·
When I rebuilt the 4.5 in my '73 the heads were shaved 8 1000ths. I was advised to put clay in the cylinders, put new head gaskets on, and torque the heads. I then turned the engine over by hand. I removed the heads and found there was not much clearance left between the valves and the top of the piston. Not much being that I could almost see through the clay (actually Play Doh in pretty colors) to the top of the piston.

Engine runs fine but I would advise against doing this.
 
#24 ·
Wow. Only 8/1000 and it was almost see through. Jeezus. That's insane. Didn't realize they made these so thin. :( Next question. What about different heads. Are the heads swappable from all of the V8 w107's or do the water/oil jackets not line up or the bolt holes? If they do match up do any of them have bigger ports than the other for better flow or do any of them have better angles in the head?

I can wait a month. If you are guaranteed going to have a set for me to borrow real quick I will put in a order for all of the materials to make the jig up or else I can make a simple one out of wood for the time being. :) Just let me know and then I'll see how cheap I can churn these babies out.
 
#33 ·
My 1987 560sl is the only 560sl I've ever driven.

I've read countless posts over the past couple of years on how underpowered the 560sl is. I don't know if my car is a "fluke" because for such a heavy car the performance is quite impressive.

It does 0 to 60mph in 6.27 seconds and it's completely stock.

Over the past 43 years I've owned and driven countless muscle cars such as SS396 Camaro's, 427 Corvette's, 440 Cuda's, etc. and I've acquired a very good sense of speed performance.

I guess I'll need to drive some other 560sl's to see how they compare to mine.
 
#35 ·
My 560 has a first gear start and a slightly tweeked advance adjustment (93 premium only), and it is fast enough for me. Of course, someone posted that ANY MB sold in the US today would be faster than the 560SL. That was posted a few years ago, so on the recent diesels, I don't know.
 
#36 ·
You have to judge it in the years it was made.
When I first bought the 86 560 I went to the state line and drove sedately about 6 miles west to check for the highway patrol. Once clear I drove east and backed off at 120mph. It is not a hotrod. It really comes into its own at about 60 with the foot to the floor. I don't get the under powered part. It has more than you can handle in the US.
 
#40 ·
My 380, however...is an absolute pig. And the galling thing is that it doesn't save ALL that much gas in comparison to the 560.

I hope to improve this with a complete intake manifold rebuild this summer (probably 30 different small vacuum leaks), and I will attempt to tweek and advance the cams to 3 degrees+ with offset woodruff keys (I have it on good authority that this a HP increase that you can definitely feel, puts the cams on a par with Euro cams).

Long term, I have some heads I'm working on polishing...and eventually, assuming that it hasn't blown up by then, a Megasquirt/EFI, EDIS ignition, Eaton supercharger, and GM throttle body/sensors. ON PAPER, this might get it very close in HP to the 560 with better gas mileage.
 
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