More power?

[Buz]

Are there any ways to get a little more power out of the 280SL engine?  The non US cars were rated 10hp higher but I do not know what is different.  I was thinking a lower restriction exhaust and a little more timing advance might make a difference.

[Shvegel]

My understanding is that some of the difference is due to cam profile differences.

During the early years of NOx emmisions reduction the European approach was to lower cylinder effective pressure by retarding timing and playing with valve lift and duration as well as cam timing(American approach was reducing compression via bigger combustion chambers or low compression pistons).

I know this isn't scientific or even "professional" coming from a lifelong mechanic but I threw the book out the window and filled my tank with Sunoco 94 octane and then advanced my timing until it rattled then backed it off until it stopped.

I drive my car faily hard and I am more than happy with the power. If your car is an automatic as mine is you might want to make sure it is downshifting to first when you stomp the pedal if not it will appear alot more sluggish.

[ja17]

Hello Shvegel,

Yes I have used this approach myself on occassions to get the max out of these engines.  The trade off is a higher than usual cold idle and a bit more engine temperature.

The exhaust systems are already quite free flowing. You can drop a marble down the exhaust manifolds it will roll out the tail pipe!

A well tuned engine with the right  camshaft and distributor seem to be the strongest running.

Joe Alexander
Blacklick, Ohio

[Buz]

Which cams and distributor work the best?

[Benz Dr.]

There are number of small things that can add up. I use the cam shaft from a 230SL with the early header pipes wrapped with heat tape. My car also has a dual point distributor from a 300SE. I had to change the throttle valve back to vacuum advance in order to do this but I now have a 52 degree dwell angle.
I changed the coil over to the hotter red one with a 1.8 ohm ballast resistor and put on a good set of ignition wires.
When I rebuilt the engine I ported the head to match the gasket and polished all the cumbustion chambers along with a 5 angle valve grind. The valve area is where you can make a lot of gains. When I did the block I measured the piston height in the block and then milled the top of the block so that they stuck out about .010 This gives me about 180 PSI. I also use the late model oil pan that has the windage tray to help pull the oil away from the crank shaft.
I use the water oil cooler and synthectic oil in everything including the 5 speed trans. My car will go 10 km per liter of 94 octaine fuel at 100 km per hour.
I've also found that ballancing the crank along with the conecting rods and pistons will give you a little more bottom end grunt.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[Buz]

Is the 230SL cam the same as the european 280SL cam?  What about electronic points instead of the dual point distributor?  Great information, thank you.

[Cees Klumper]

You can get the Euro 280 cam from SLS. I did a couple of years ago (but still have to put it in ...). If I recall correctly it was around EUR 450 / $600. You may have to get new cam bearings with it.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[Benz Dr.]

The 230SL cam is similar to the euro 280SL cam on early cars. I advanced the cam timing with an off set woodruff key 2 degrees. This set up is very close to the euro specs. Intake valve should open at 12 degrees, whereas the 230SL opens at 10 dgrees.
After mid 1969, when USA cars had the new syle head, the 230SL cam won't work because of the different cam bearings that are used.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[Buz]

So the 230SL cam would fit a US 1968 280SL but a european 280SL cam would not fit?  What about Pertronix electronic points?

[TheEngineer]

The "09" cam  is a direct replacement of the "08" cam. No changes in cam bearings. The 09 cam provides considerable more valve opening times. This results in more complete filling of the cylinders and much more power. For comparison in valve opening times please look at the excellent tables provided by ja17 "Cylinder Head Discussion". I have confirmed the longer opening times by measuring both the 08 cam and the 09 cam. The 09 cam also provides higher valve lift. The 09 cam was standard in Europe where it was important to provide for the high speeds driven on the autobahn. Here in the US, it was more important to meet emissions,especially for California. From the beginning, the W113 was intended to be a comfortable touring car with adequate performance, it was not designed to be a high powered race car. Some owners have installed larger engines and created a hot rod. Often this makes for an unbalanced design where the weight distribution has changed, the brakes become inadequate and the geometry of the suspension is wrong. Often this makes for a dangerous car to drive. May I suggest, you take your car to a private track and, giving yourself plenty of room, go into a hard corner. You will understand what I'm talking about.

'69 280SL,Signal Red,Automatic,retired engineer, West-Seattle,WA

[hauser]

You should try contacting Karl Middelhauve.  He specialazes in the 600 Grosser he may have some suggestions for you.  Here's the website.

http://www.mbgrand600.com/

1969 280sl 5 spd
Gainesville, Fl.

[Buz]

I totally agree about not trying to turn a W113 into something it is not.  I have seen them with 6.3 engines and big block American V-8's and that does not appeal to me.  I have owned a W107 280SL 5 speed, a W107 500SL, a 280SE 4.5, and a 300SEL 6.3 and have extensive track experience and a racing license so I am very aware of how these cars abruptly lose rear traction when you exceed the limit.  A few more hp and a motor more willing to rev is all I am looking for.  The camshaft and other tweaks suggested should make a big difference.  A car with a 4.08 or 3.92 rear end needs to have strong high rpm power or it is just making a lot of unnecessary noise.

[merrill]

so, I wasn't sure if I should post this or not, but I was talking to hans at H&R and he said that aviation gas would make the sl really get up and go.  fuel for a cesna or small private plane to be exact.

I am not an expert so I do not know the octante or characteristics of the fuel and I do not no the legality of using the fuel in a car.



Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[ja17]

Hello,

As technology improved, Mercedes would produce replacement parts or equip newer models with improved camshafts. Often the "grind" was the same, but the material or construction was improved and the camshaft was given a new ID number.

The 230SLs always had a hot cam #76 and #84 the grind was the same but #84 had design or material improvements.  

The 250SL was the only W113 which shared its standard camshaft with some other Mercedes models. It is also a bit "tamer" than the 230SL and 280SL hot cams.  The 250SL used #86 or #11, both had the same grind. Here again the #11 was an improved material or construction.

The 280SL "hot" cams were #09 or #02.  both had the same grind. I believe #02 was the cam with improved construction. All the early 280SLs came from the factory with the "hot" camshafts. It appears that the latest USA delivery emission engines had a "tamer" camshaft also used on some Mercedes sedan engines.

Joe Alexander
Blacklick, Ohio

[Buz]

What is different about the cam and head of the 68 and early 69 US cars?

[Shvegel]

It is true that you might be able to extract more performance from a 113 by running it on aviation fuel as long as it was tuned to run on this increased octane fuel. Just pouring it in the tank probably won't do too much.

A couple of issues to consider. Federal road use taxes are not paid on aviation fuel which make it unlawful to use on the street(similar to filling your diesel with home heating oil).

Second aviation fuel is blended to work well in the cold of high altitude and not the heat of a clogged freeway in summer. If you have any hard starting issues when hot(vapor lock) you just might make them worse using avgas.

[mdsalemi]

Ahh, here we go again.  The quest for more power.

As a historical reminder to those who don't really know too much about the pedigree of this car, it's not fast.  It never was.  In any permutation of original configuration (euro cams, porting and polishing, etc. ) it likely never will be.  It didn't handle as well as sports cars of the era; it didn't accelerate as well either.  (brakes were pretty good however!) Fact of the matter is, it wasn't and isn't a sports car: simply because it has a drop top on most models doesn't make it one; it's a touring car that infused style and luxury for the period.

This endless quest for more power leaves owners broke and cars in partially finished or poor/non-running condition.

There's a reason why a well preserved original car, or a well restored car keeping to original equipment are the ones that get the higher prices.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[ja17]

Hello,

I agree with Michael. Your money would be better spent becoming a "faster driver" not making a "faster car". Spend some money on driver competition training, and buy a set of sticky tires with rims, go out and have some fun and learn how to get the most out of the power you have. There are many competitions for vintage cars these days.

We have some old timers on this site who ran these cars back in those days. They masterfully drifted these cars around  road courses or danced them through autocross pylons. some even raced them hub to hub in vintage racing.

Frank Cozza and his wife Alice, Pete Lesler, Bob Fellows and others, have a garages full of national MBCA trophies for competition in these W113 cars.

In the hands of an expert driver a well tuned and good running W113 can be awesome!

Maybe we can have these people do some recollections of those days gone by?

Joe Alexander
Blacklick, Ohio

[JimVillers]

Interesting thread that went from "more power" to "going faster on the track" that is a much more interesting topic.

Joe then mentioned the the important variable; tires.  I would add brakes. Then practice, practice and more seat time.

Power is just one varible; there is also camber angle, spring rates, sway bar, shocks and it goes on and on.  All fun; just do it.



Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor, MGB 5-Speed

[bsimaz]

I agree with Michael.   It's roadster and I'm happy just touring with it,

Bill Simaz
'66 230sl
Back on the Road

[Buz]

I have a track car that is a Lotus Seven type car that weighs 1350lbs and has 250hp.  Unfortunately I only have time for a few track days a year.  The only changes planned for the W113 are three point seat belts, Koni shocks, performance brake pads/fluid, 6.5 inch Bundt wheels, 205/70-HR14 summer tires (I wish the Michelin XWX was still being produced), a proper alignment, and probably a camshaft.  When it needs an exhaust I will probably go with a free flowing stainless system to compensate for an added high flow 200cpi catalytic converter.  I would like to take the SL to some local MBCA rally and autocross events.

[seattle_Jerry]

Instead of more power how about less weight?

lose the spare.

If you race/do track days just carry enough fuel for the laps you are doing and lose the passenger seat.

Better brakes so you can brake later.

Kompressor

Really though it will all be lame speed wise compared to a track day in a Lotus.

But you are just looking for more when driving around the street right?

1967 230SL Havana Brown Auto with A/C

[Ben]

Actually the spare wheel/tyre, particularly the older ones from the 230SL weigh a ton ! (Not literally)

I woiuld be surprised if a smaller than average owner could get the damn thing out of the trunk at all !

Regards,
Ben in Ireland.
'64 230SL 4sp.

[seattle_Jerry]

There really isn't a need for a spare 99% of the time. A can of fix-a-flat, cell phone and an auto club membership are all you need. I would take one on trips to remote areas. My car came with the ultra-rare factory delete on the spare tire.



1967 230SL Havana Brown Auto with A/C

[JimVillers]

Ben .... You can loose most of the spare tire weight with an aluminum disk rim.  They are somewhat hard to find but worth the effort.  With a search, you can find the previous discussions.

Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor, MGB 5-Speed