w126 560 US spec

[flat6buster]

Hi all

looking at a US 560sel 1987. I understand these are down to c. 230BHP from 300BHP from the Euro spec ones. Anything one can do to get them back up?

 

[alabbasi]

The biggest bolt on improvement that you can make is to swap the exhaust manifolds over to the Euro style ones (either logs or try-y). The US manifolds are restrictive with the left manifold wrapping around the back of the engine and joining the right manifold into a pre cat that goes into a single pipe to another cat. Having a full dual pipe set up like the Euro cars do will open the engine back up. The rest is compression.
You can also swap the rear end from a 2.24 to a 2.47 or 2.65:1 to wake up off the line performance and modify the valve body to take off in first gear as it usually takes off in 2nd. There is no switchable mode on the gearbox fr the US cars.

 

[flat6buster]

Thanks Alabassi. I guess a free-er flowing exhaust may get back 10 or 20 missing horses. Forgive my total ignorance but there's a compression issue too, can I overcome that or is this 'baked in' to the engine and insurmountable?

 

[alabbasi]

Fuel at the time was more crappy in the US so the engines had lower compression (8:1). There's not much that you can do about that without changing pistons and in my opinion, that juice is not worth the squeeze. I've had my fair share of US spec 560's and still have two in storage. They're not slow cars especially at motorway speeds. The manifold swap makes a definite improvement in seat of the pants HP so I'm assuming more than 20hp.

There's a company in Chicago that's building performance parts for the M117 engine called Carobu Engineering. You can look them up on FB. They're getting some power out of an M117. You can also consider a turbo or supercharger.

 

[219]

At 230bhp you’re more or less equivalent to a 500SEL , which in Europe had 231bhp , although the 560s often had better spec , including the brilliant all round hydro pneumatic suspension .

My 500SEL had twin downpipes on each side into twin pipes all the way back , and no cats . It was a 1986 car ( D deg ) .

You might get lucky and find a Euro 560 engine from a donor car .

If going to the length of an engine swap I wonder how hard it would be to install the quad cam M119 out of a W140 since rough ones can be had for buttons then you’d have a complete donor car ...

 

[flat6buster]

Thanks chaps, this is a very low mileage car so the consideration is in not buggering about with it too much. Freer flowing exhaust is one thing but compromising matching numbers or blowing it would not be avenues I'd want to go down. Think the answer is to say it's never going to be nippy, get the gains from an exhaust and waft......