Added 15 to 20 HP to my 1977 450 SLC

[breastroker]

OK, everyone says you can't add that much without changing to a 560 engine. Bull, 275 cubic inches is very easy to improve.

As a long time hot rodder there are tried and true ways to help any V8.

The car had 2" cat converter which I enlarged into two separate 2.5 in/out cat converters. Also larger pipes back to a dual in/dual out 2.5" muffler that hugs the rear end, not sticking down like the stock muffler.

I combined that with 8 new Bosch Platinum Plus 4 plugs, they make the engine run GREAT!

I also changed the stock heavy steel air cleaner with a lighter MB aluminum air cleaner housing with K&N air cleaner. Big thing I did was cut out 90 percent of the tiny 1/8 inch aluminum that the air cleaner fitted against. I estimated the tiny holes restricted air flow by 45%. Proof would be on later MB dual snorkel air cleaners the holes are much larger, closer to 3/8 inch.

I just got a later dual snorkel air cleaner, sold without top, which I already have. I still have to fit a smaller snorkel on the passenger side, so far just removed the huge plastic one there. Need to run cold air to the smaller snorkels.

OK, you are asking why I think I have more HP? I live next to a freeway on ramp, and have calibrated the speedometer with my 6 inch GPS unit. I am nearly perfect at 60 MPH on the speedo as I changed the tires out to 205/65/14.

So when I first got the car, 0 to 60 mph was between 10 and 10.7 seconds.
I run fuel system cleaner with every fill up of 91 octane gas and the car engine now runs so smooth.

I can now spin the rear tires if I am not careful, but more telling is the 0-60 time is between 8.5 seconds to 9.5 seconds. The 8.5 seconds was on a 100 degree day, many of the slower 9 second runs were at 80 degree days.

I am changing out the Borla rear muffler as it is just too load for a Mercedes, but still will be using a 2.5 inch In/out Walker "Quiet 3" muffler.

If I can do it, I might change out the coil and regulator to a MSD unit that I have in the garage. More voltage with more amperage over a longer duration still helps any car to run better.

[Diseasel300]

I'd have expected you to be able to do 0-60 in 8-9 seconds completely bone stock in that car. 10.7 seconds is getting dangerously close to a W124 diesel's 0-60 time around 11-12 seconds. That is SLOW for a V8 coupe.

Just throwing this out there, but making HP claims without dyno charts to back it up is begging for disagreement. I could throw a Type R sticker on the back of my Honda and if it did a 0-60 run 1 second quicker, I could say "See, the sticker added 10 horsepower!" We're sort of in the same boat here...

[breastroker]

Here is the single MB 380SL air cleaner, note the tiny holes that restricted air flow by 40-45%.


Here is the K&N with the set up I am running right now.


Here is a later 126 Dual snorkel air cleaner with lot bigger holes in the support.

[breastroker]

Stock the 1977 450SLC was about 10.5 seconds on a real good day. Your 500SL Euro would do about 8 seconds, the 380 was closer to 11 seconds. The 560 SL supposedly 7.5 seconds, but on a really great day. They didn't call them the Panzerwaggen for nothing.

I have never seen any article about a 1977 450 SLC doing under 10 seconds, all of 180 HP chocked by the air cleaner and small catalytic converter.

Heck my C230K can blow the doors off the 450 SLC, and I once owned a 1969 300 SEL 6.3 that was under 6 seconds, more than once blew the doors off of hopped up Honda's.

[Tomas7]

If your 0 - 60 went down a full second, then you added more than just 20 HP on that car. It takes more than 20 HP to lower a full second.

[breastroker]

It's not HP that makes you go faster, it's torque.

The main reason the 560SL is much faster is not the larger engine, it's the torque multiplication of the first gear going from 2.31 to 3.6. Even with the lower numerically rear gear the 560SL torque multiplication is over 20% greater.

Tomas, you my be correct, I have been using chassis dynos since 1968. I was fortunate to have many friends and mentors in the speed industry in southern Kalifornia. I was into small block Fords then, built a 330 HP 302 Ford, then a 400 HP 351 Windsor using Pontiac 389 valves.

Not worth a chassis dyno now, but if I take the intake manifolds and enlarge the lower plenum it might make another 20 HP. But I would need a tuner who understands the Bosch fuel injection, how many like that exist?

So for now I am quite happy with the better acceleration.

[Tomas7]

Originally Posted by breastroker

It's not HP that makes you go faster, it's torque.

The main reason the 560SL is much faster is not the larger engine, it's the torque multiplication of the first gear going from 2.31 to 3.6. Even with the lower numerically rear gear the 560SL torque multiplication is over 20% greater.

Tomas, you my be correct, I have been using chassis dynos since 1968. I was fortunate to have many friends and mentors in the speed industry in southern Kalifornia. I was into small block Fords then, built a 330 HP 302 Ford, then a 400 HP 351 Windsor using Pontiac 389 valves.

Not worth a chassis dyno now, but if I take the intake manifolds and enlarge the lower plenum it might make another 20 HP. But I would need a tuner who understands the Bosch fuel injection, how many like that exist?

So for now I am quite happy with the better acceleration.

Feels good doesn't it and yes, you're correct about the torque. Torque picks the weight up quicker and gets it going....

[breastroker]

Switched to a true dual snorkel from a later 126 560.


Still need to get the 2.25" fresh air tubing for the drivers side, and have to fix the passengers side snorkel. Am thinking I can push the plastic snorkel about one to two inches further into the aluminum housing, and trim to fit. That way I hope I can get fresh air tubing to that side past the rad overflow tank.

I will be moving the overflow tank back about one inch towards the wheel well, just about as far as it can go. MB managed to route a lot of wires where I need the tank to move.

[rbtoj]

Originally Posted by breastroker

...But I would need a tuner who understands the Bosch fuel injection, how many like that exist?.

I believe there are quite a few of them on the Porsche circle. They seem to like the CIS. Heck, when rebuilding my fuel distributor a lot of helpful info came form Porsche people on the net.

Just for giggles, here is a 600hp 911 with CIS: https://www.youtube.com/watch?v=PUfyR5biNOE

[Tomas7]

Originally Posted by breastroker

Switched to a true dual snorkel from a later 126 560.


Still need to get the 2.25" fresh air tubing for the drivers side, and have to fix the passengers side snorkel. Am thinking I can push the plastic snorkel about one to two inches further into the aluminum housing, and trim to fit. That way I hope I can get fresh air tubing to that side past the rad overflow tank.

I will be moving the overflow tank back about one inch towards the wheel well, just about as far as it can go. MB managed to route a lot of wires where I need the tank to move.

You know....the colder the air........

[breastroker]

I ordered both air intake tubes from FCP Euro, $12.79 for one and $32 for the other. There are small gaps in the lower spaces between the wheel tubs and the radiator. Not going to cut holes but there should be enough cooler air. Of course cooler air in Las Vegas is rare.

[Tony H]

If you want a large intake on both sides you can get the intake from a 560SL housing and replace the small one on the DS

https://www.ebay.com/itm/1986-1989-Mercedes-560SL-107-Air-Cleaner-Filter-Box-0140945002-OEM/332394818061?hash=item4d64466a0d:g:6bMAAOSwD9dZzXKw&vxp=mtr

That's what I'm doing on the custom 560 engine I'm building

Ignore the price-this was just to illustrate it

[breastroker]

Already ordered the air intake tubes for a 560SEC, $45 for both new.

Keeping the smaller drivers side tube as all the A/C stuff is encroaching into where I want to pick up cooler air.

[Tony H]

Figured there was a reason the tubes were different sizes. on mine there is nothing in the way of the bigger DS intake(yet)
I will see when I get it together if it fits.

[breastroker]

Tony H, can you post a photo of your radiator overflow area and where the large passenger snorkel tube would go?

Today I used my old air cleaner to test fit the large snorkel, pushed it almost 2 inches into the air cleaner. Can't post phots from Photobucket but the large inside bend of the plastic snorkel is stopped by the flange on the air cleaner that holds the bolt to attach the air cleaner lower housing.

I used a mini-torch to heat that inside edge or the plastic and was able to gain about a 1/4" additional room. That translates to almost an inch closer at the large round end of the snorkel.

I am going to try relocating the radiator overflow tank by raising it 1/4" to get over the large wire loom and then push I in as far as possible on the existing supports.

If that doesn't work I will spend $100 to get the 71-73 brass overflow tank. It is rectangular and might give another half to one inch clearance for the snorkel.