Engines

[soeharyo]

could someone with enough knowledge about engines educate me. I drive a 03 Z4 3.0i

03 Z4 3.0i's engine
3.0 litres
231 hp
221 ft·lbf (300 Nm)


S2000's engine (2000-2003)
2.0 litres
240 hp
153 ft·lbf (208 Nm)


I was about to put in Porsche Boxter's engine specs, but i am not sure of them.

My question, hence, is that why is our Z4 3.0i engine not achieve a higher hp given that a 2.0 litres can achieve so much hp.

I also noticed that honda's engine achieves a significantly lower torque.

Does the honda engine trades off torque for horsepower?

Could BMW achieve more horsepower if it has lower torque?


thank you in advance.

[epbrown]

The standard Z4 engine has a much lower rev limit than the S2000's engine. Typically, lower revving cars make more toque while higher revving cars make more horsepower. The US specs for the S54 engine in the Z4M, for instance, are 330hp and 262lb-ft. Torque helps your off-the-line speed for acceleration, while horsepower at higher revs gives you more flexibility while you're already moving. For instance, you know how you have to down-shift to get more oomph for overtaking? Not as big an issue when you're already running at 5000 rpm and have another 3500 rev available.

This is why the Z4 3.0si has a different final drive ratio than the 3.0i and 2.5si (available in other markets). Because the 3.0si is not far behind the S54 in torque, the 3:38 diff in the other cars would put its 0-60 times pretty darned close to the Z4M; the 3.46 diff would put it closer still - within tenths of a second. However, that same gearing means the Z4M would still kick its but as far as top speed and high-speed acceleration, due to the latter's higher rev limit.

[PhilDZ4]

Nice explanation.

[ZEEFOUR]

Also the stoke of an engine plays a big part also, longer stroke produces more torque, while a short stroke motors can rev higher (kinda like a tall and short person racing).

You didn't give all the specs so its hard to tell, but i'm sure that the Honda has a much shorter stroke to acheive those high rpms. Torque is really what you feel, thats what pushes you back in the seat. There was an old race saying that "torque wins races, while horsepower sales cars" it still holds true, most people will usually ask how much HP does it put out. There really is no true measurement for HP, HP is a product of torque.

[Vroomer]

The numbers for the 2003 M54 engine are at 3500 RPM.

Not sure about the Honda's

[inTgr8r]

Originally Posted by Vroomer

The numbers for the 2003 M54 engine are at 3500 RPM.

Not sure about the Honda's

Just to take that a little further...
peak numbers are absolutely FN meaningless.

The curves tell the tale.
Peaks can be just a blip & the rest of the curve sucks wind. = piss poor performance

[ZEEFOUR]

Originally Posted by inTgr8r

Just to take that a little further...
peak numbers are absolutely FN meaningless.

The curves tell the tale.
Peaks can be just a blip & the rest of the curve sucks wind. = piss poor performance

Your absolutely right, to take it 1 step further, a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Most people don't understand it, but peak horsepower is meaningless other than bragging rights. its usually so far away from the torque peak that your just spinning the engine faster not making power. Thats why most manufacturers brag about HP its much easier to make in a small displacement motor than torque, thats probably why BMW went to a twin turbo, its putting out 300HP and 300TQ out of the same 3 liter motor with 80% of the TQ at 1800 RPMs. That motor in the Z4 would be faster than the ///M.

[pbdm4k]

That motor is already in the Z4.. Go check out Hartge, they already swapped the twin turbo engine in there I believe...

Along with the 5.0 V8 from the M5.. ACS did that as well...

But wouldn't mind finding a donor 335 engine to shove under my hood!

[AlanL]

The Honda engines can lay down some pretty amazing power given the displacement, but it is in a very specific rev range - starting at 5500RPMs. Below that the AP1 S2000 motor (MY00-03) is pretty much a dog and has no torque at all.

I traded in a 2005 S2000 for my Z4 and by then Honda had upped the displacement by adding a longer stroke which gave mine a lot more lower end power but chopped off the redline to 8200RPMs. This is known as the AP2 engine. It was still the case that the real power band didn't start until about 5300-5500 RPMs, so you really had to rev it to get any power out of it. A very buzzy and noisy engine I might add too.

My 3.0si has a huge torque range in comparison, much smoother, and far more quiet for cruising out on the highway. I'll keep the Zed thanks....

[epbrown]

Originally Posted by pbdm4k

That motor is already in the Z4.. Go check out Hartge, they already swapped the twin turbo engine in there I believe...

Along with the 5.0 V8 from the M5.. ACS did that as well...

But wouldn't mind finding a donor 335 engine to shove under my hood!

Rumor has it the 3-liter twin turbo was designed for the Z4M, when some bean-counter noted that they already had a surplus of S54 engines lying around from the M3 run-out. If it makes it into the Z4 - or is announced - my order is in. I like the S54, but the lower maintenance requirements (okay, theoretically) and better fuel economy will steer me towards the N54.

[ZEEFOUR]

Originally Posted by epbrown

Rumor has it the 3-liter twin turbo was designed for the Z4M, when some bean-counter noted that they already had a surplus of S54 engines lying around from the M3 run-out. If it makes it into the Z4 - or is announced - my order is in. I like the S54, but the lower maintenance requirements (okay, theoretically) and better fuel economy will steer me towards the N54.

Your preaching to the choir, i'll be order number 2!

[ZEEFOUR]

Originally Posted by pbdm4k

That motor is already in the Z4.. Go check out Hartge, they already swapped the twin turbo engine in there I believe...

Do you have a link to that? I only saw the 5.0 V8 and the 3.0 Compressor (which is a supercharger)

[inTgr8r]

Originally Posted by epbrown

Rumor has it the 3-liter twin turbo was designed for the Z4M, when some bean-counter noted that they already had a surplus of S54 engines lying around from the M3 run-out. If it makes it into the Z4 - or is announced - my order is in. I like the S54, but the lower maintenance requirements (okay, theoretically) and better fuel economy will steer me towards the N54.

Not saying it isn't so,,,,
Just find it hard to understand why they'd develop anything for a low production vehicle like the Z4M.
Development for the 3er makes total sense because of high volume.

[PhilDZ4]

I love the folklore.

[inTgr8r]

How 'bout rumorlore....

[epbrown]

Originally Posted by inTgr8r

Not saying it isn't so,,,,
Just find it hard to understand why they'd develop anything for a low production vehicle like the Z4M.
Development for the 3er makes total sense because of high volume.

If it were me trying to explain it to the BMW board room, the proposal would be along the lines of: let's debut the new twin-turbo in the Z4 before we release it in the 3-series. The new engine will draw more attention to the lagging Z4 line, get the car back on magazine covers, and the enthusiast/techno-junkies/early-adopters will scoop up Z4s just to get the engine before everyone else. The twin turbo will also give the tuners something to play with, which will drag out the publicity. Tuners go to extremes to make standard cars look exotic - the Z4 shape looks exotic right out of the box. If you were Dinan looking to get a new car on magazine covers, would you want a tarted-up commuter car or a red Z4 coupe scowling at you hunkered down on 19" rims?

Later, we add the engine to the 3-series line as just another model. The 3-series is our best-selling model, so it's not like it needs the publicity, and by delaying the debut until after the new M3 is announced, we don't cannibalize sales from our impatient high-performance market when tuners start churning out 400-bhp 335s just as we get the M3 to market.

[inTgr8r]

I suppose it would have made sense to get it out in more limited numbers to debug as well.

[Godspeed]

Originally Posted by ZEEFOUR

Your absolutely right, to take it 1 step further, a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Most people don't understand it, but peak horsepower is meaningless other than bragging rights. its usually so far away from the torque peak that your just spinning the engine faster not making power. Thats why most manufacturers brag about HP its much easier to make in a small displacement motor than torque, thats probably why BMW went to a twin turbo, its putting out 300HP and 300TQ out of the same 3 liter motor with 80% of the TQ at 1800 RPMs. That motor in the Z4 would be faster than the ///M.

Exactly. It's all about torque at the axel. The wheels don't know a thing about horsepower. The higher in the rpm band you can maintain torque, the later you have to shift, and, hence, you will maintain wheel torque at a higher road speed.

[pbdm4k]

Originally Posted by ZEEFOUR

Do you have a link to that? I only saw the 5.0 V8 and the 3.0 Compressor (which is a supercharger)

Sorry, I saw it in European Car magazine, it was a tiny blurb about the Geneva Car Show.

Although the ACS Topster V8 and the Hartge 5.0 V8 Z4's are already quite popular.

[pbdm4k]

http://www.germancarzone.com/z4-road...-z4-coupe.html

Ooh, I found it. They released it at the Essen Motor show, not Geneva.. my bad.

Officially they call it the Z30 Biturbo, making 380hp.

http://www.worldcarfans.com/features...or-show-part-2

More info. It's not a 335 swap, its a 3.0 twin turbo. Apparently they couldn't get a 335 engine to swap in time for the show.