A Stupid Question..

"Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW." (aya-yu)
08/30/2014 at 15:05 • Filed to: None

What is the difference between the 4.7 litre V8 inside the W212 E500 and W221 S500? How does the one inside the S made an extra 17hp and 73lb-ft more torque compared with the S? Here's a nice E500 for your answer..

DISCUSSION (10)

carcrasher88 > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW.
08/30/2014 at 15:16

From what I've read, the reason is because the E500 has a de-tuned version of the M278 engine.

They're twin-turbocharged, so I assume the answer lies within how the turbos are set up with the boost.

GhostZ > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW.
08/30/2014 at 15:18

I don't know shit about mercedes-benz motors, but here's the ways you could do it, keeping in mind that only the PEAK numbers are dropped, and we have no idea what the numbers look like under less throttle or outside of their peak power RPMs.

1. Cam profile. Select a cam where valves stay open for shorter periods of time (duration) or valves that don't lift as much (lift) and it will reduce the amount of air that can get into the cylinder for a given RPM. This drops power. This is very much likely the case since there's a 200RPM drop in where the peak numbers lie.

2. Exhaust and intake shape. Likewise, at certain RPMs, the exhaust and intake make ideal power. Change the shape of the exhaust or intake manifold and if they aren't making power at the same RPM that the cam does ideally, then peak power will drop. This includes the runners, catalytic converters, etc.

3. Variable valve timing/throttle mapping. Restrict the valves at the peak level, make them flow better at lower numbers. This can be done to make sure the engine isn't too loud or harsh at higher RPMs. This can be done to improve peak fuel economy numbers, although usually it doesn't affect peak power since fuel economy tests aren't done under full load most of the time.

4. More accessories. While not as huge of an impact, adding more accessories to the engine's drive belt (or electric ones, necessitating a larger alternator, which is an accessory) will reduce the power at the flywheel.

KnowsAboutCars > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW.
08/30/2014 at 15:21

Despite the same displacement they are different engines. M273 is available for both cars and is less powerful while M278 is more powerful and only available in the S-class.

Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW. > carcrasher88
08/30/2014 at 15:28

Well, that makes sense. I know it's a detuned, but i'm sort of agree it's lies on either the boost or different cam.

Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW. > GhostZ
08/30/2014 at 15:31

Well, that makes sense. I know it's a detuned, but i'm sort of agree it's lies on either the boost or different cam.

Unless they're running the same boost then i believe it's the cam.

GhostZ > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW.
08/30/2014 at 15:38

Oh, right, I forgot about boost.

In that case, they are certainly running a different mapping on the turbo's wastegate, either reducing peak boost or letting it out at an earlier RPM. It would be far cheaper than having a different cam in there.

Likewise, you can change the exhaust shape to affect the boost, meaning that even tiny changes in the exhaust can make a huge different on the outcome of the power depending on how 'in balance' everything is on the peak RPM.

AMGtech - now with more recalls! > KnowsAboutCars
08/30/2014 at 22:09

Actually both of those engines were available on both of those chassis depending on year.

AMGtech - now with more recalls! > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW.
08/30/2014 at 22:11

It's all in the software.

Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW. > AMGtech - now with more recalls!
08/31/2014 at 06:23

Really?

So..
With a software tweaking you can get the same power?

AMGtech - now with more recalls! > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW.
08/31/2014 at 12:04

With software tweaking you can get a bit more power than the 5.5l version actually. But that might sacrifice a bit of long term reliability. They over build the engines and turn the power down from what they could handle for the sake of reliability and DD useability. I hear they handle the extra power quite well though I haven't seen any like that first hand.