Performance/ Economy exhaust upgrades?

[lunchbox]

Hey guys,

I have a 73 280sel with the 4.5 and I searched, but could find nothing on performance upgrades. I can't imagine that no one has upgraded their exhausts... Can someone tell me how restrictive the setup on the 73 model is? I am looking for a few extra MPG wherever I can get it with that 4.5L

Sam

[Chas H]

Borla East did make custom exhaust systems. They made a bunch for me back in the day. Do a search, sit down, and give them a call.

[Tomguy]

Think about the cost of a custom exhaust, then think of how much gas that will buy you.
Realize that, even with the most efficient setup ever, your 4.5 will never get higher than 17MPG 100% highway running full lean with a tailwind. You're lucky if you get over 13 in daily driving, very lucky to get over 15.

Now, maybe if you replaced D-Jet (and those massive volume injectors) with a MegaSquirt setup and more efficient injectors, you may realize a much larger mileage benefit. Custom dual exhaust (with 2 pipes each side) may yield some power, but I doubt that would mean efficiency.

[Tony H]

Has anyone looked into installing a 6.3 exhaust on a 108? I think the 6.3 system has larger tubing and is essentially the same as a 108 4.5 system so it seems like it could be adapted. I would think it could be tied in at the crossover just after the engine pipes.

[Tomguy]

The 4.5 probably loses most of its power at the exhaust manifold/headers, not the muffler and rear pipes, so I don't think that would help much.

[Emmerich]

The restriction may not be the exhaust, if there is one. A lot of times a new exhaust gives you worse performance. The whole intake/outtake system on a car is designed to work as a unit. I would imagine MB does a good job putting all the pieces together. So without changing something major, like the other guy suggested, you may not see any gains at all.

However, major manufacturers have in history left some performance on the table in the exhaust area. Porsche had a 911 that was that way.

[lunchbox]

I understand the whole "as a unit" idea, but i know for a fact that strict emissions regulations caused alot of auto manufacturers to slap on whatever they could to meet the standards. You truly believe that better performance can't be had on a car from 1973 by switching to a newer, more free flowing muffler?

maybe it's just me...

[Mark DiSilvestro]

But keep in mind that, by 1973, most cars sold in the US, including Mercedes, had reduced compression to allow the use of unleaded gas, which was only widely availble in regular-grade at that time. Coupled with leaner mixtures, more restrictive exhaust manifolds, modified camshafts and distributor timing curves optimized to reduce emmisions, simply jamming on a fatter exhaust-system may not gain any significant performance increase.

The most significant performance increase I've experienced with a specific car was due to differences in engine compression. In 1980, I replaced a 1972 Audi (8.5 : 1, 85 hp) with an almost identical 1971 model (10 : 1, 100 hp). In addition to the noticeable power improvement, my highway mileage went from around 26 to over 30 mpg - enough to justify the cost of the premium gas I had to use in that '71 Audi.

Happy Motoring, Mark