M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

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M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by kimrh » Sun 05 Mar, 2017 3:30 pm

Finally a decent engine shop in LA USA decided to strip down a 5.6litre M117 engine out of a 1986 560SL and really get down to business to assess the engine in detail
(This engine was in fact rebuilt beforehand by a Mercedes shop with request for AMG spec ported heads and more aggressive cams - however the owner was not happy with the outcome and find out why - it would shock you!!)

So read on and "finally understand" how to "unleash the beast" and really show the true potential of these engines backed up by flow bench testing and plenty of time in the engine dyno room to properly evaluate and get the desired result before the engine was put back in the car.
https://www.youtube.com/watch?v=PEBGltN4w7g

http://www.carobu.com/other-finished-pr ... ng-project

Engine Builder comments-
The starting point of this project was a very nice Mercedes 560SL that had a rebuilt “improved” engine done by an expert Mercedes tuning shop.
The owner of the car was not happy with the results, which had a poor idle quality and soggy bottom-end power.
The mandate was to improve the power output, calm down the idle and fatten-up the torque curve for additional performance.
We agreed that these were all important goals that we could accomplish.

So that there would be a scientific basis for gauging future improvements, the car’s owner approved removing the engine from the car and dyno testing it on our engine dyno in order determine how much power the engine had before we rebuilt it.

While the concept of testing it on the dyno was simple, getting the engine to run on the dyno required a lot of work due to the various electronic/fuel injection systems that all had to operating properly to obtain an accurate power reading.
In the end, the existing engine from the tuning specialist generated 288-hp at 5,100 rpm and 332 lb-ft of torque at 4,100 rpm. Both these numbers seemed weak to us.
The stock V8 560SL engine is rated at 227-hp by the factory so the above initial dyno numbers were not very impressive (see graph below).

We knew that the other shop had installed a more aggressive camshaft, ported the heads to AMG specs and added a full European exhaust system.
They claimed over 300 HP but had no dyno graph to back up the claim.
It is common knowledge that Mercedes made more powerful versions of the stock 560 engine (not for the USA) that made 300 HP. We didn't understand why this supposedly tuned engine was such a dog.

At this point we received the OK from the owner to tear the engine down and find out what was inside.
Much to our surprise, the engine had stock, low-compression pistons (9:1) and one cylinder head that had been ported but the other one was left stock!!
This was a shocker.

The existing camshaft that was in the engine was put on the camshaft digitizer so that we determine the specifications.
It had the following specs: Intake- 237.2° @ .050” and maximum lift of .421”. Exhaust- 243.6° @ .050” and maximum lift of .439”.
Compare that to the stock cam specs: Intake- 192° @ .050” and maximum lift of .412”. Exhaust- 192° @ .050” and maximum lift of .412”.
Basically, this performance cam had much more duration, but only a small amount of added lift improvement over stock.
Based on past experience with Bosch CIS fuel injection systems, we knew that the idle would not be stable with this amount of cam duration/overlap, so a new cam would be needed.

The next step involved flow-testing the cylinder heads. This would be a nice comparison of stock heads versus AMG-ported heads as we conveniently had both types on hand.
The results proved interesting as there wasn’t much difference between the two! While we were checking out the heads, we were measuring all of the basic engine dimensions so we could start building a relatively accurate model to use for simulation work.
Our program is Performance Trends Engine Analyst Pro Enterprise Edition and over the years it has proven very helpful to finding power in various engines before actually beginning the engine building process.

One of the areas that we knew could be improved was the intake manifold.
The standard runners are pretty convoluted and the plenum volume is small, both of which restrict optimal air flow.
Based on our calculations, the throttle body seemed adequate for the power level we needed- which was 350-plus horsepower.
We decided to flow test just the runner section of the 2-piece manifold as the lower plenum wouldn’t fit on the flow test rig.
The result showed a definite reduction in flow, but not enough to explain the low power.

Based on past experience, we knew that the early 450 SL EFI intake manifold had straighter runners.
Also, if we used that manifold, then the CIS injection system would have to go and be replaced with EFI.
The test shown below displays how much better the EFI runners are at higher flows.
We used the Extrude Hone process to increase the EFI runners to 40mm which then matched the original 560 CIS manifold runner size.

Another area of the intake manifold that needed help was the plenum area.
Although it is out of sight unless you cut it open like we did, the ability of the air to make a tight 180° turn is limited by the low headroom in the plenum.
In essence, this is the same as running a restrictor plate on the engine.
The stock 560 throttle body flows about 577 cfm by itself, but based on our calculations, the CIS intake manifold cuts that in half!

So, the heads are flowing well, the throttle body is big enough, but there is a huge restriction in the manifold! Who knew?
This is why using traditional tuning methods on the single-cam Mercedes V8s has been such a failure if the stock intake was retained.
Better flowing heads weren’t the answer or more aggressive cams; the manifold just needed some attention.

The solution lay in modifying the plenum chamber for more depth.
This isn’t that easy because the "V" area of the engine between the heads is a tight space.
A compromise was made of cutting the runner/plenum junction back a ½-inch and then dropping the roof of the plenum chamber down about the same amount.
This would allow extra room for the air to turn back up into the runners without killing the flow.

After solving the intake flow problem, the next step was enlarging the engine displacement with high-compression (10.5:1), +2mm oversize Mahle forged racing pistons.
Mahle was chosen as they are one of the few piston companies that can add the correct skirt plating for the Alu-Sil block.
The +2mm sizing was chosen because that is the limit of the stock head gasket fire-ring.

Because we used new pistons we now needed to use different connecting rods.
Mahle only has room on their piston forging for a 22-mm piston pin size. The stock pin is 25-mm. If the difference had been small, say .5-mm, then the original connecting rod small end could have been re-bushed, but 3-mm is too much.
Consequently, new Carrillo rods were made with the correct size small ends.
The big advantage to the new piston and rod combination was a dramatic weight reduction.
By comparison, the OEM parts look like they are from a diesel engine.
To compensate for the reduction in weight, the stock crank was re-balanced.

Once the engine was assembled, attention was turned to adapting various systems and components on it to work with the modern EFI (electronic fuel injection) that was being used.
Many modifications and a substantial amount of custom engineering and fabrication were necessary to make this work.
This included fabricating a new throttle shaft, fuel rails, etc. and of course sourcing the correct injectors, sensors, etc. that allow the engine to run correctly.
Many hours were involved with getting the EFI up and running on the dyno.

With over 380 HP and 423 lb-ft of torque this was just what the doctor ordered.
The beast had been unleashed at last! This should be a seriously fun Mercedes to drive.
Interestingly, the engine simulation tracked fairly well with the dyno results, as you can see in the graph below.
The next step is re-installation in the car and some fun road testing.
To be continued --
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by Giles » Sun 05 Mar, 2017 8:51 pm

Mmm, nice story, I would shudder to think what the build cost was.
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by cuisses » Sun 05 Mar, 2017 8:58 pm

Everyone is jealous that their engine doesn't produce 382 hp. :laughing6:

Good to see an attempt to do things scientifically. With any engine there are lots of variables that can be tweeked, and these guys seem to have the experience and have narrowed down what is important. As Giles says, one figure that was left out is the cost of this whole operation. It would not have been cheap - many hours of specialist labour.
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by kimrh » Tue 07 Mar, 2017 12:31 am

More pics and comments from the owner himself-

I wanted to see how much performance could be had from a M117, so I challenged one of the premiere euro engine shops in the US - Carobu Engineering to further increase power and torque - while keeping it a safe strong and reliable motor. That meant normally aspirated - a non turbo / supercharged motor and not a 6.0 bore as I felt the walls would be too thin.

It's now 5,774cc with higher compression - 10.5:1, Mahle pistons, the same larger cams from the first Blue Ridge build and EFI.

I forwarded several BW threads to Tate, the owner and engineer from Carobu and he responded that all key engine components had to be bench flow tested to determine where we needed to put our focus. Much to my surprise, the single weakest aspect of the motor design was the intake manifold.
After flow testing both a K Jet and D Jet manifold we changed to the D Jet manifold as it tested much better and Carobu altered the height of it.
Yes you can get a D Jet manifold to fit on a 560 - with a little help.

I'm going to hold off on the 722.6 5 speed trans for awhile as well as custom made exhaust headers as I'm dying to drive it.
Tate thinks we can get over 400 hp with new headers

What I'm most excited about is how Carobu managed to safely coax more power from the 2V single overhead cam motor than AMG managed with the 32 valve dohc motors - even the 6.0's.
The AMG 5.0L 32-valve DOHC engine delivered 340BHP, the bored 5.4L engine 355BHP, the later 5.6L AMG Hammers developed 360BHP and the 6.0L engine 375BHP.

Not sure why but I've been on a mission to crack the 400hp ceiling.
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by CraigB » Tue 07 Mar, 2017 10:17 am

Thanks Kim, what an interesting thread! I only skim read it but can break it down to the main performance improvements if you started with a stock engine on a budget, is cams, head flow, intake manifold and they are suggesting the exhaust could take them over the 400. Obviously the increased bore will help and the rods will help its resilience to punishment, less reciprocating weight them and the pistons, but I would put money on that expensive part of the process (including re-treating bores) to be substantially the most expensive parts of the build. I wonder how much difference they thought it made. I gather in chasing the 6.0 DOHC figures they thought they would get as close as possible to that.

Is there any mention of how similar the AMG cam is to the 'blue ridge' item they used?

Looks pretty simple to lengthen that plenum.

Also i see on the dyno they are running tri-ys, but do the secondary y pipes look like originals on a lhd 107? W126 tri -y secondaries are much longer than that and go down under car. Wonder if that is a plus or a minus or maybe even something they knocked together for engine dyno? Given the space in a 107 that sounds optimistic (to uneducated me) to go from tri y to another manifold and get that much more. But good on him for trying to squeeze out as much as he can - must have a big wallet!

I've got a djet manifold sitting there, (and know of another one) and a 560 engine - can't wait to have a play!
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by kimrh » Tue 07 Mar, 2017 9:16 pm

Going plus +2 on bores is just tidying any any fine scratches to the bores as MB offered pistons in +1 and +2 in over size for tidying up bores which is not really increasing the bore diameter as such.
If you were using a 10:1 high comp 560 300hp engine as a base and just improving the intake manifold and the plenum chamber mod it would not be an expensive excercise as you would be retaining the KE-Jet system.
I wonder how much they would charge for a set of cams now that they have the desired spec to make more copies of their design? and if they are still a roller cam or gone to a solid cam?

One improvement to the head design would be ditching the factory 9mm valves and getting replacement Ferrea 6mm valves and appropriate custom valve guides to allow more intake flow which i am surprised they did not do in that engine build. It would have got them over the 400hp mark more easily without affecting street torque and lightened the valve train in the process.

I reckon Tri-Y's are good enough without spending stupid money on custom designed headers.
The Dukubus Franken-CIS option would have been an easier path by just modifying the 560 Plennum chamber as they did and sticking with the 560 runners versus a custom EFI system and all associated costs of going down that path with custom tuning costs etc.
How big is your cheque book otherwise!!!
Last edited by kimrh on Wed 08 Mar, 2017 12:26 am, edited 1 time in total.
87 White Euro 500SEC "ECE" 195kw
88 Black Euro 560SEC 220kw
89 Midnight Blue Euro 560SEL hydro 220kw AMG Kitted
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https://www.flickr.com/photos/krh2013/albums/72157668572599252

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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by CraigB » Tue 07 Mar, 2017 10:47 pm

While i think of it and for the record, do you know of a part number and supplier for the Ferrea valves? My initial look is they aren't crazy money for other cars. My question about the cams is that I have a set of those Hendric AMG cams and would like to use them with lightened rockers / solid lifters - hoping they are not too far off the mark.

In concept i like the idea of EFI for that total control of parameters, but more things to worry about first.
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by kimrh » Wed 08 Mar, 2017 12:38 am

Ferrea "competition Plus" - they can match our specs required with a 6mm stem
"Ferrea Competition Plus Valves have built a reputation as the industry's most reliable extreme duty valve. To manufacture the valves we use special aerospace quality alloys, including the EV8-Z18, which provides high tensile strength. An exclusive two-step slow forging process ensures proper grain flow and virtually eliminates any damage to thematerial structure. The valves are then heat-treated and stress-relieved over a 48-hour period, which is the crucial base of our molecular integrity. These valves feature avionics-quality hard chrome along with a specially applied hard tip"
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by CraigB » Wed 08 Mar, 2017 8:30 am

So I take it your saying I need to find the company and approach them direct with all the dimensions, not a part they have listed. Any idea about how much for 'one off' orders? from others experience?
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by kimrh » Wed 08 Mar, 2017 10:57 am

Aprox US$500 I have a contact in the US who track races and does a lot of R&D work on his own Merc track car.
His comments-
The 560 heads were flow tested and produced 202cfm's after some ala AMG porting we retested and improved that to 240 cfm's, my goal was looking for more than that and the work continues, 6mm valves are capable of 230cfm's no porting at all, hence the advantage goes to 6mm big time.
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by kimrh » Thu 09 Mar, 2017 12:55 am

Interesting that even way back in 1988 AMG had there own version of a much better intake design for their 32V heads with twin plenum chambers and long intake runners to tip the engine over the 400hp mark - but retain good street torque by use of those long runners versus the track version.
These guys were real genius engineers "way ahead of their time" with their Motronic Hammer 400hp package released in 1988 - see attachment
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Last edited by kimrh on Thu 09 Mar, 2017 10:28 am, edited 2 times in total.
87 White Euro 500SEC "ECE" 195kw
88 Black Euro 560SEC 220kw
89 Midnight Blue Euro 560SEL hydro 220kw AMG Kitted
http://www.flickr.com/photos/krh2013/sets/72157632548663623/
https://www.flickr.com/photos/krh2013/albums/72157668572599252

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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by CraigB » Thu 09 Mar, 2017 2:39 am

That certainly solves the problem being referred to. Doesn't look that hard to replicate. I guess air cleaner is incorporated at the end of that tube at the front, but those big conical k&N filters would do the job.
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Re: M117 5.6litre (SL560) 382hp / 423lb-ft tqe (engine dyno)

Post by oversize » Mon 04 Sep, 2017 6:16 pm

Interesting that it seems to highlight a 'flaw' in the K jet design that positioned the throttle body at the front and consequently made the runners longer. The early D jet design has the throttle in the middle and thus shorter runners. Shorter runners means the plenum can be larger and not restrict flow. I don't really know why they didn't just build their own manifold from scratch, since they were to use aftermarket EFI anyway?? They may have found even more hp.

Sadly it highlights issues with the K jet M116/M117 and M100 which are all similar designs. Swapping a K jet for a D jet manifold/aftermarket EFI would create all sorts of EPA issues and would likely require testing to comply with ADRs before registration would be considered (unless you're lucky enough to have an import). Another possibility would be to high-mount the original upper manifold using spacers/machining, thereby allowing more space to modify the lower one and making it larger (deeper). However this will probably create throttle linkage issues and require a bonnet bulge, or scoop!

PS I love how they treated the rocker covers!
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