Author Topic: how fast should you drive these cars? (Read 7259 times)

n/a · « **on:** October 22, 2005, 08:16:08 »

I have a 1969 4 speed manual transmission 280SL. I have had the car up to about 108 or so for very brief spurts but typically drive it at cruising speeds on Calfornia freeways which is about 80 MPH / 4300 RPMS on the 280 in 4rth gear. Is this speed / RPMs too hard on the engine at this point to drive long distances? The engine was rebuilt about 5 years ago and has about 5K miles on it since then. It performs fine at this speed but I have heard that I should keep it under 4000 RPMS

Cees Klumper · « **Reply #1 on:** October 22, 2005, 09:17:55 »

This has been discussed before and common opinion is that these engines, provided in at least o.k. condition and tune, should easily be able to run at 5,000+ RPM essentially all day long (which is what I have done in the past on looooong hauls to France and southern Germany). The good thing about that high RPM level is that, at least in my car, you basically cannot hear the engine anymore due to other noises so it does not irk me at that point. These engines were designed to run at high RPMs. The fact that many engine parts are relatively old does not mean that they do not perform like when they were new.

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

Chad · « **Reply #2 on:** October 22, 2005, 14:48:10 »

I agree with Cees.

It sounds like your engine should be in great shape being rebuilt 5,ooo miles ago. Anyway, I run the engine vigorously often. These engines should be well equiped to handle higher rpm when in very good shape. If not so, then perhaps the manufacturer should have designed a different engine for a car with sportscar aspirations. In any case, I have little doubt from looking at this engine and driving with it that it is meant to be and built to be a sporting engine.

Enjoy the drive!

-CD-
1967 230SL, 113.042 10

TheEngineer · « **Reply #3 on:** October 22, 2005, 21:24:33 »

I make it a point to wind up the engine when I enter the freeway. I shift into 2nd and rev it up to 6000 RPM. This way, I don't exceed legal speed and do what the other drivers expect me to do: Merge
P.S. I have not observed any smoke doing this, but sometimes in the morning, when I drive out of the garage, it smokes white for a while.

n/a · « **Reply #4 on:** October 22, 2005, 21:33:04 »

thanks to all.....I surely don't baby it and am glad to hear others feel the same way.....I love to suprise other cars on the freeway when I fly by their assess......

hands_aus · « **Reply #5 on:** October 23, 2005, 05:21:24 »

Max freeway speed in my area is 60mph/100Kmph so I rarely get an opportunity to travel faster. Further south the max speed increases to 66mph/110Kmph. I have taken the car to 70mph overtaking on a long haul with no problems at all.
However I can watch the fuel gauge drop away very quickly. It likes around 60mph for best economy.
Yesterday, on an entrance to the freeway, I wound up my 250SL..the car was building up speed but seemed slow so at about 45MPH I kicked it down a gear.
It took off leaving a huge plume of black smoke coming out of the exhaust.
It frightened me a bit. I figure that is what an Italian tune-up would do.
As soon as the trans changed into top gear the smoke stopped. The car never blows smoke at any other time hot or cold.
The car loves my regular weekend jaunts.
Rarely do I need to kick-down a gear because the engine has enough torque to handle most situations.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

Bearcat · « **Reply #6 on:** October 23, 2005, 08:11:22 »

I drove mine at over 100mph / 160 clicks last year. I wont do it again. The noise was unbearable and I felt uncomfortable driving a 35plus yr old car at these speeds. Also my timing went off after that run. Wind noise is a big issue. I find driving at 60mph is nice / relaxed. Whats the point in gunning the old girl? Yes it's a sports car but not porsche.

As Cees says we had this conversation before and there are two schools of thought on this.

280SL 1970

Malc · « **Reply #7 on:** October 24, 2005, 08:22:05 »

Remember these cars were built to cope with high speed cross continental driving, plus they were rallied, so IMHO they are capable of being thrashed :twisted:
If you can put up with the wind noise, rattles etc and you happen to be in a place where its legal I can't see the harm of "cruising" at 80 - 100 mph
As long as your car is well maintained it should be more than capable..... and you remember your dealing with technology designed in the 1950's in regard to suspension, handling, and the brakes!
Have fun
Malc

Benz Dr. · « **Reply #8 on:** October 24, 2005, 16:04:48 »

No they can't.....

IF everything is in perfect condition then you can drive it a high speeds for long distances. The more internal engine wear you have, the faster it will break. I have one in the shop right now that let go on a long distance high speed drive. It's not apart yet but I pretty much know what I'll find.

Anyone have a late 280SL block laying around?

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

TheEngineer · « **Reply #9 on:** October 24, 2005, 22:29:32 »

Dan: Benz Friendz (206)762-7691 have many blocks. They come from 280SE.I got an almost new head: Surfaced once to 84.9 mm and exhaust guides did not accept the no-go gage. But as to winding it out: I like to do that sometimes: I qualify for the Italian tuneup. Today I watched the tachometer: Full throttle in first goes up to 5000RPM until it shifts into 2nd. That's about 30MPH with my 3.27 rear axle. Still legal speed. Fun to do.

'69 280SL,Signal Red,007537,tired engineer, West-Seattle, WA

Chad · « **Reply #10 on:** October 24, 2005, 23:45:04 »

Perhaps I should tone down things in my driving.

-CD-
1967 230SL, 113.042 10

Benz Dr. · « **Reply #11 on:** October 25, 2005, 08:59:43 »

Two different things can happen and they happen in two different ways.
1) rod bearing can let go at high RPM while shifting even though the rest of the engine is in good shape. Happens mostly after a valve job on an engine with low oil pressure.
2) ring ( s ) can break at high RPM during a long drive at high speed. Anything over 4,000 RPM is pushing it on a well worn engine. Normal compression is around 170 PSI with 150 being rebuild time ( acording to MB ) but your engine will still run at 120 PSI. For each lb of compression loss lower max RPM by about 60 RPM or 3,500 RPM at 120 lbs compression.

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

J. Huber · « **Reply #12 on:** October 26, 2005, 13:06:13 »

Seems like this question comes up year after year. The responses are always similar: either let 'er rip or take it easy on the 'ol Fella/Gal. I always side with Dan that pushing too hard has risks involved. And having sprung for a new short block once, and then later for an upper end rebuild, I tend to treat mine with a lot of respect.

I think what happens for a lot of us is our pride gets in the way. A well-tuned 113 is definitely capable of hauling butt -- and lets face it -- is a blast to drive fast (or slow). The only time its not fun is when its on a towtruck...

James
63 230SL

Bob G ✝︎ · « **Reply #13 on:** October 26, 2005, 16:18:43 »

Let us remember the famous line in the movie Gum ball ralley with brook yates and the actor who played his Italian nemious competor in the Ferrari Daytona Spyder. " first rule of Italian driving (taking the rearview mirror in his hand and throwing over his sholder out of the car) Whata behine me does nota matter".

Bob Geco

TA250SL · « **Reply #14 on:** October 26, 2005, 20:59:04 »

Who would like to try this with their Pagoda?

Download Attachment:

MBTest.jpg
68.96 KB

Tom
1967 250SL
Los Angeles

Chad · « **Reply #15 on:** October 26, 2005, 21:41:15 »

What is that car? It's not a 6.9.

-CD-
1967 230SL, 113.042 10

Douglas · « **Reply #16 on:** October 26, 2005, 22:25:45 »

Bob,

That was the late Raul Julia, who hailed from Puerto Rico, playing the Italian driver in the Ferrari Daytona in "The Gumball Rally."

Douglas Kim
New York, NY
280 SL #016220

norton · « **Reply #17 on:** October 27, 2005, 03:55:26 »

I can'a no deny her

Mike Halleck
Chesterfield Mi
71 280SL
68 250SL (parts car)
94 E320 Coupe

ted280sl · « **Reply #18 on:** October 27, 2005, 07:50:40 »

It seems that no one has noted in this string that we have different rear ends. I do not mean to imply that some of them are cute and others are not. I apologize for that terrible pun. The US 113's had larger rear ends which translates into higher RPM's at highway speeds. I had my rear end changed a few years ago. My 113 is much happier at highway speeds with a lower ratio rear end.
Ted 1969 280SL w/ 4 speed and small rear end

ja17 · « **Reply #19 on:** October 27, 2005, 17:15:01 »

Hello Chad,
By the looks of the chrome wipers and the vent with windshield washer, it would have to be pre-1968. Possibly a W109 6.3 sedan or another era W110, W111, W108, W109, sedan. Could also be a coupe or convertible (W112, W112) of the same vintage.

Joe Alexander
Blacklick, Ohio

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Author Topic: how fast should you drive these cars? (Read 7259 times)

n/a

Chad

n/a

Bearcat

Malc

Chad

Bob G ✝︎

TA250SL

Chad

Douglas

norton