How do we compare the new 3 valve engines to the pervious I-6, V8 and V12, in terms of performances and fuel enconmy ? which ones is better ?
Does C43 share the same engine with rest of the V8 Mercedes ? C43 has 3?? hp while the others only hp outputs 275 on the CLK and E-series.

The new 3-valve/twin-plug engine family has the greatest "power-per-gallon" of any engine family to date. They don't make more power than the previous DOHC engine family but they are lighter so there is a positive power-to-weight improvement.

The C43 shares the same block and some engine parts with the E430/CLK430 but has been massaged by AMG. Camshaft work, internal engine mods/upgrades, and exhaust/breathing enhancements give it the edge in power over the other 4.3 V8's.

As far as which one is "better" that can get into a "politics and religion" debate. (or politics, religion, and oil) After driving many examples of new and old here is what I have observed: the new engines have more low end torque and better throttle response (while improving on past fuel economy) but don't quite have the thrust of the old DOHC's at high revs. While not entirely fair, I have seen a 500E take a C43 stoplight style. Off the line they are about equal (half a car length to the 500E) but as speed builds so does the 500E's lead. (read: once the 500E is off ASR the C43 is toast) My ex 400E vs Bill Wood's E430: The E430 would pull an advantage off the line, then I'd catch and stay with him to any speed under the E430's electronic governor.

It has been my experience that almost all of the DOHC engined cars were under-rated performance wise. The new engines seem to be pretty much "as advertised" when it comes to meeting performance specs. The electronics, especially the 5-speed automatic tranny, on the new cars let you use more of the engine's potential. The 4-speed automatic in many of the DOHC cars have is a hinderance in comparision. Either family is a blast to drive in its own way. If your a torque lover, you probably like the new family better. If you like the rush as the valve timing advances and the rpms rise then you like the DOHC's. The fact that MB can meet and exceed the previous family's performance while significantly improving fuel economy is an advantage nobody can ignore.

Hope this helps...Lee

Best Miles/gallon ? I think Mercedes need to work a bit on that.
Its biggest rival BMW with camshaft technology VANOS could push 321 with a 3.2 L. I think Mercedes should probably do something similar (dual variable valve timing )
Also weight distribution is another big concern.
I don't understand why Mercedes replace the 4-valve with the 3-valve instead of 6 valve or 5 valve? ( Big one and a small one with twin spark design) better fuel , more enviromental ? But what about the performances concern ?
It will be great if Mercedes could remain its character while be more aggressive with the performance.

The BMW double VANOS you speak of is the Euro spec M3 engine. While it does make exceptional power per displacement, the engine is very soft/flat until you get past 1500-2000rpm then builds thrust from there. The M3 engine pulls duty in wind-up sports car type cars, the MB engines pull duty in sedans and sports sedans that need the low rpm torque for daily driving. (doesn't hurt for 060 either) Another item worth mentioning....the US spec M3 would do 0-60 in almost exactly the same time as the euro spec motor. The difference? 240 HP with a flat torque curve vs 321HP but peaky power.

Weight distribution? The new engines are much lighter weight than the DOHC engines from MB or BMW. (vanos or not!) The DOHC 4 valve per cyl is the ultimate for high rpm power. (F1 uses 4 valves per cyl not 5 but with oversquare cylynder dimensions) The BMW's first priority is performance. Just look at their add campaigns, aftermarket support, etc. Mercedes seems to try and offer a more total package. Fuel economy overseas is a much greater concern than here in the US. Also the lower emission levels means it can spend research dollars elsewhere when its competitors are rushing to meet the tougher upcoming emission standards. It is not a matter of what one "can" do, but a difference in marketing/company philosophy. Anyone who thinks the idea of performance from MB is dead need only look at the C43, E55, or upcoming SLR. Just a few years ago the idea of OEM 18" wheels on a benz would have been laughed at.

BMW touts a 5.3 0-60 time for the new M5 (with its standard 6-speed manual) MB rates the E55 at 5.4 seconds with a 5-speed automatic. Without arguing which is more converservative, it can be said that 90+% of the public cannot drive a stick faster than an automatic 9 or 10 times out of 10. The E55 does all that while giving up the advantage of transmission (and automatic's greater parasitic losses) and having 50 less HP to work with to start with. There is something to be said for a flat torque curve and repeatable performance.

Lee

I was thinking about replacing my C36 with a C43 but didn't find any great improvement in performance even with the greater "advertised" power from the C43's V-8. Magazine test also confirm what Lee is talking about. C43 hasn't tested much faster than C36 in any of the major auto magazines. Concerning the E55 0-60 times, Motor Trend, Car and Driver and Road and Track all have tested it to 60 in 5.0 sec or less. Anyways, I think the new M5 will beat the E55. The old M5, with a 3.6L 310hp and manual trans, was tested by Car and Driver to 60 in 5.6sec in a comparison with the 500E, 5.0L 322hp and auto trans, which did it in 5.5sec. Even the lowly 6-speed 540i does 0-60 in 5.5 sec now. I am a MB enthusiast. But that new M5 has something I really wish the E55 had, a manual trans. Which, thanks heaven, my 240D has.

LJADJA,
Both BMW and MB are known for rating their cars a bit conservatively. My experience with the 3-valve/twin-plug engines is that they run pretty close to rated specs. The E55 may be different, but from the C43 on down they do almost exactly what the literature says they will. Then again, most of the ones I've driven are quite new. As these motors gain miles they may gain power. Virtually all the DOHC motors I've driven are already "broken in". When the first US spec M5's hit the shores and are tested we will see. Between the 50 HP advantage and the manual tranny the M5 should win 0-60. As far as I know the only testing done thus far has been in Europe. Then there are always the loyalists on both sides. Bimwads will buy M5's, MB faithful will get E55's and those that don't know any better will get Jag XJR's. j/k

I think the reason the 500E beat the E34 M5 was not a HP difference, it was the real world difference between 354+lb-ft of torque in a flat curve vs 295lb-ft of peaky torque in the M5. I do know exactly what you mean by the annoying 4-speed. In my opinion it is the single worst point on the car or at the very least MB could/should of done better. Shame the electronic 5-speed will not retrofit.

Oh BTW, I ran accross a E39 540 the other day that was out on a test drive. The salesman gave me the finger as I pulled away. If BMW wants to pass my 500E they better bring an M5. EG


Good talkin as always...Lee


[This message has been edited by Lee Scheeler (edited 06-30-1999).]

I test drove both 2000 S430 and S500. They pull off from still with ease, but when after they gain some speed, I feel that 3-valve V8s has "lower" output then DOHC V8s. Mercedes usually have conservative for their cars' performance specs. But for new V6s/V8s, guess they are "start to tell the truth!?"....

Use my '92 400SE for example, factory 0-100km/h time is 8.6 sec., and no matter how I measure it, I did it in about 1 sec +/- 0.3 sec. faster then factory. The engine for my car is rated at 282hp(for 1992 and early 1993 only), but it feels about the same as 500SEL for that same year!!

Andy Kuo
'92 400SE
69000 km