Author Topic: Increase in compression ratio for w116 V8 engines.  (Read 6256 times)

carl888

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Increase in compression ratio for w116 V8 engines.
« on: 25 June 2006, 07:21 AM »
Curious to know if anyone has rebuilt a w116 V8 and increased the compression ratio?  Even a European specification engine sports a somewhat lowly 8.8:1 so I see no reason why you couldn't run at least a 10:1 on 98 RON fuel.  Anyone ever done up an engine with increased CR?  Curious to hear of any performance and economy increases if so.  Thanks for any information.

Regards,

Carl.


Denis

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #1 on: 26 June 2006, 12:58 AM »
Hello gentlemen

This is not a direct answer but may help identify the answer.

When you consider the design and metallurgy of the M116/117 (steel crankshaft with 4-bot main bearings, large oil capacity, oil cooler, generous waterways), you can only conclude that the "recipy" was  "detune a racing engine". How ? reduced compression and mild camshaft timing to achieve a smooth power unit. People on other lists have reported major gains with compression over 10 to 1.

What does AMG do to such engines other than camshafts and pistons ?

Cheers

Denis

Paris, France

Nutz

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #2 on: 26 June 2006, 03:14 AM »

I had my M117 in my 76 450SE Euro shipped down to the lower 48 to get rebuilt to Stage 1 specs .The results were a bit disappointing considering how much I spent to get it done though.Compression ratio is at about 9.5:1

Work done ;

High Performance Pistons and Deves rings
Chrome Moly wristpins
Copper head gaskets
Every imaginable part glasspeened
Jetcoated combustion chamber


Pistons
Balanced
Knurled
Glasspeened and heatshielded
Lightened
Bosses drilled for oil

Rods
Balanced
Recut and aligned
Glasspeened

Crankshaft
Balanced and glasspeened
Turned and polished
Knife-edged

Block
Dipped,bored 0.30,honed
Main saddle line bored

Heads
Glasspeened
3 angle valve job
Ported and polished
Chambers contoured

Theres was more done too,just can't recall every little thing.


carl888

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #3 on: 26 June 2006, 03:21 AM »
Hi Nutz,

Tahnks for the info, I would have thought there would be no advantage unless you incorporated some ignition advance as well.  What RON fuel are you running?

Regards,

Carl.


Nutz

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #4 on: 26 June 2006, 03:34 AM »
I got a luminition ignition system from them too but never installed it.I run super unleaded 91 RON with some BS octane booster (claims to raise the fuel octane by 3 points  ::) ) I also replaced the stock muffler with a Supersprint muffler off of a donor BMW that was totaled to help it flow better (nice tone  ;D )


Currently the SE is being transformed into an extreme widebody (bumpers replaced with a full front airdam and rear valance with diffuser 8) A teaser pic

« Last Edit: 26 June 2006, 03:40 AM by Nutz »

john skene

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #5 on: 29 June 2006, 03:02 AM »
Nutz, If the very mild cams of the detoxed 76 engine were not modified, and the retarded ignition curve modified, there is still a lot of power left in your engine to extract. In fact, these two mods would have probably given you similar power to the expensive mods already carried out.

AMG69

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #6 on: 29 June 2006, 03:13 AM »
Nutz, did teh car go on a DYNO before and after? or at least after anyway?
sigh....sitting back contemplating the next purchase..!

Denis

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #7 on: 29 June 2006, 10:58 AM »
Hi fellows

Like John Skene was hinting, Nutz wont get much more power unless the cams change. I hate to repeat but compression + cam timing = power.  An overbore and engine blueprinting (especially on a Merc) would not yield much more power. Those cams ARE quite conservative.

Good luck

Denis

Paris, France


Nutz

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #8 on: 29 June 2006, 03:52 PM »

Hi guys,

The cams were replaced too with a mild grind,not very "lumpy" though. There are 5 stages of engine modifications that were available;

Stage 1: Basically a street engine with slightly higher compression ratio (which is all the pocketbook would allow at the time ).

SRE A little more than a Stage 1 and not quite a Stage 2.

Stage 2: For the street and also slaloms and drag racing. Gobs of torque and compression ratio usually 10.5:1 to 11:1

Stage 3: 8) Not suitable for streets and run 12:1 compression ratio.

Stage 4:  :o Usually for SCCA or drag racing and use 13:0 to 14:0 compression ratio. Wicked power and the cost was twice of the Stage 1 build.

Chris M,
No dyno,just what they told me ,around 230HP skeptically.It revs way quicker though thanks to the knife-edged crank.

If I could find some extractors (headers) then some more ponies can be unleashed and also a larger airflow sensor.


Denis

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #9 on: 30 June 2006, 01:00 AM »
Well Nutz, since a Euro M117 has 225 hp DIN straight from the factory, the promised 230 hp is not so impressive  :(

Just a compression increase from 8.8 to 9.5 should provide more than 5 hp...

Sounds like Stage 2 is the right choice for a normal car - if your legislation lets you do this  >:(

Denis

Paris, France

john skene

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #10 on: 01 July 2006, 01:19 AM »
Nutz, I think that you would now gain a lot by using the standard 450 European cams and distributor as they have no emission / power sapping  modifications.

robertd

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #11 on: 01 July 2006, 03:22 AM »
Carl Jones,
              Is that the same "Leica" Carl Jones I know from Lt. Bourke St.
Regards Robertd Ex "Phototime"
« Last Edit: 01 July 2006, 03:23 AM by robertd »
116   1978 450SEL 6.9 #  4848
116   1979 450SEL  6.9 # 5884
116   1979 450SEL  6.9 # 6225  SOLD
116   1978 450SEL  6.9 # 5128  SOLD
116   1979 450SEL  6.9 # 5884  SOLD
116   1974 450SEL  DJet

carl888

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #12 on: 02 July 2006, 06:28 PM »
Carl Jones,
              Is that the same "Leica" Carl Jones I know from Lt. Bourke St.
Regards Robertd Ex "Phototime"

Hi Robert,

Yes, that's me!

How are you?  What are you doing now?

Regards,

Carl

robertd

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #13 on: 03 July 2006, 03:16 AM »
It is indeed a small world, I'm very well thanks, have swapped my interest from German cameras to German motorcars (mercs) Classic ones. I would like to know if you still have some connections in the tyre industry, am looking for a set of 215/70x 14 for a 6.9 with correct speed and load rating.
What are you up to these days.
Regards Robert.
116   1978 450SEL 6.9 #  4848
116   1979 450SEL  6.9 # 5884
116   1979 450SEL  6.9 # 6225  SOLD
116   1978 450SEL  6.9 # 5128  SOLD
116   1979 450SEL  6.9 # 5884  SOLD
116   1974 450SEL  DJet

carl888

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Re: Increase in compression ratio for w116 V8 engines.
« Reply #14 on: 03 July 2006, 07:20 AM »
Hi Robert,

215/70-14 XWX are no problem but they are $440 each inc GST ex France.  Sold my last set a while ago but I can get more.  Give me a call if you like, 0411 878 338.

What am I up to?  Leica product manager for Australia.  Bet that made you laugh!

Regards,

Carl.