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Let the M117-968 560 Dyno Testing begin

27K views 161 replies 24 participants last post by  ianrandom 
#1 ·
The lads at Carobu Engineering are about to hit the engine dyno again with their own US Spec 560 test mule engine
https://www.facebook.com/pg/Carobuengineering/posts/?ref=page_internal

Their engine has just had the heads freshly re-furbed and new guides etc after they realised the valve guides were worn and the heads needed pulling after the last session on the dyno with the US spec factory exhaust complete bolted up (the whole exhaust right to rear muffler tip was removed from the car and dragged into the engine room and bolted up for testing if you scan down to their older FB posts showing the dyno read-outs as well

This time they have bolted up some AMG spec headers to see how they will perform

This R&D testing is to continue in phases as they work there way through various mods to see what will waken up the engine including swapping in 300hp cams i provided until they design their own cam and it will include mods they want to carry out in due course on the 560 intake to see if they can improve that intake without having to go to the expense a custom designed intake.

I think all of us will be able to closely follow this and enjoy the ride.
End result is they wish to come up with solutions for M117 owners with proven research on an engine dyno to back it all up

That last 560 engine they rebuilt was a full custom job with forged pistons and rods and EFI conversion using a highly modified D-Jet intake and custom AMG spec cams etc so that was an expensive build in the below link
1986 Mercedes Benz 560SL ? Carobu High Performance Parts and Accessories for Ferrari
 

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#2 ·
I was honored my d-jet intake manifold went to Tate for Pearson’s 560sl. :)

I am glad he is testing the components step-by-step and should be able to document the gains of each.

It seems that with Pearson’s 560sl the intake was a bottleneck. It seems that some boost would probably solve that. I wonder if they plan to test any boost systems.


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#5 ·
They completed their baseline run with both US exhaust and with tri-y's on their 9:1 US 560 motor.

Result, 26hp, 22ft/lbs torque.

Still lots more to come, apparently.
 

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#9 ·
So 26 HP gain just from the tri y manifold?
No not just from tri y, look at the two exhausts . One is a full USA exhaust with manifolds , caTalyitc converter , mufflers etc . Just like a stock car.

The other is just tri y with no mufflers or catalytic converters , a completely open straight pipe exhaust . No one would really run a car like that .

Figure 10-15 Hp for the tri y and 10 hp for the lack of catalytic converters and mufflers
 
#7 ·
If the tri-y's delivered a 26hp increase, then I'd expect that the Euro Logs with a dual exhaust sitting in my garage would get something in the middle, maybe 15hp. Hardly seems worth the effort. The 3.07 LSD I put in my 560SEC has made a huge improvement though.

Hope they come up with something commercially feasible for a reasonable HP increase!!
 
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#8 ·
Intake air volume (throttle body size, intake manifold design and engine bay hood clearance) will continue to be the primary roadblock to gaining significant performance gains for the M117. Head work, tri-y's, cams, fuel and spark systems (like Franken-CIS), increased compression ratio would get performance up to 325hp or so, but beyond that (assuming SOHC heads) is a challenge. Absent forced induction or quad cam heads, can't squeeze much more out of the M117. And getting to 325 ponies would probably cost $10-$15k.

Agree with Mike - a higher diff ratio is a good way to get noticeable performance improvement (at the expense of fuel economy - higher RPMs). Diff change and tri-y's are a sub $3k investment that would be really noticeable.
 
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#11 ·
Al the M117-968 heads flow well stock so that is really not an issue in the equation - although if you have them off for re-furbing then that is the time to tidy them up - but no porting is required other than removing casting dags and minor tough up work. Relieving the valves a tad for a bit more flow will help. My engine shop has just finished working 2 sets of 560 heads but that included swapping in aftermarket Ferrea intake valves to AMG Spec to help a bit more. I have aftermarket springs & Ti retainers but that is not necessary for a basic head makeover.

The intake Manifold plenum design is the main issue to restriction as i see it besides the stock US spec cams which are very mild

The 560 throttle is also not a restriction as proved by Carobu in the 560SL engine rebuild with flow testing done
 
#15 ·
Today the Carobu guys achieved another 10hp by running the lid off the air cleaner.

Illustrating all the restrictions our cars have in stock form. The CIS lump in the air cleaner restricts flow. Food for thought.

Carobu quote: "Currently, we are developing our piggyback fuel/ignition package that anyone can add. It will come with the control modules, a modified distributor, sensors and wiring harness."
 

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#18 ·
Hendrik is a very smart guy and he replicated the AMG design but in s/steel and i am sure if you purchased his product they would work just fine.
There was never very little difference in performance with the Tri-Ys versus the AMG design as MB tested the AMG version and came up with their own design being the cast-iron Tri-Ys. The internal diameter of the AMG version were slightly larger but that is not necessarily better for lower end street torque band.
 
#21 ·
I remember my Schnitzer CSL had a simple and open solution using the round tubular 1800 or 2002 air filters. The filters open inner tube had circular rubber gaskets at both ends, the inner was the same diameter as the intakes, a threaded rod up through the center, a round aluminum cap for the outside, and wing nuts to hold.
No housing, the air filters sat uncovered under the hood. Oh yeah, the intake sounded great too :grin
 

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#23 · (Edited)
Today's Carobu update: Tubular headers.

+5hp/6tq over the tri-y's.

Next up - cams and offset keys.
 

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#25 ·
Great thread.
That is impressive. I like the looks of those headers.

Re M117 engines, one thing to add is that the stock engine in the R107 560SL (like the car their initial engine went in) makes a little less power than in W126 sedan or coupe.
The 500SL Euro cars came with factory Try-Y's, but I assume there is less space under the hood, or it is the way the downpipes have to be compromised to get around the steering box etc ?
 
#26 ·
Well this should certainly answer the questions we have had on whether one should do xxx or not. When a set of tri y’s can be $1,000+ Its nice to know what to expect. I still wish there was an easy and affordable intake solution like an edelbrock manifold switch like the chevy/ford/chrysler guys have. Seems like from all the reads that is where the horsepower is
 
#30 · (Edited)
How much difference does the cool air drawn in from the front make I wonder. Via the intake tubes that is.

10hp is not to be sniffed at. I changed my air filter recently and felt it ran faster but thought probably just psychological. But maybe a new clean filter gave me a pony..
 
#31 · (Edited)
A clarification question: The increase in power from the Carobu headers and dyno run. Is the increase mentioned by Bondavi also include the stainless downpipes and the full exhaust (which looks like straight pipe from the pictures)?

When I installed my headers and 2.25" exhaust, I picked up 30-lbs.ft of torque and about 28hp. It really transformed my car.

Also pictures once installed, on the 126 custom headers are EXTREMELY tight on the left side due to the steering box, the brake components and how wide the heads are.
 
#32 ·
A clarification question: The increase in power from the Carobu headers and dyno run. Is the increase mentioned by Bondavi also include the stainless downpipes and the full exhaust (which looks like straight pipe from the pictures)?

When I installed my headers and 2.25" exhaust, I picked up 30-lbs.ft of torque and about 28hp. It really transformed my car.
What headers did you install, the iron tri y?

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