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Discussion Starter #1
I read some, but not all of the "1st sticky" thread, but enough to want to TRY to explain the difference between street / road cars and race cars. 1st, higher cam lift and longer deration are not what makes your car a fast street car. If you are an all out race car driver, and your not, it 'can" be what you are looking for. There are trade offs. you can sacrifice all your low end torque for high end HP. That is a very bad trade off for street driving. If you plan to operate you motor between 5000 and 8500 RPM most of the time, it can be a good thing. BMW made some progress with this problem with the Vanos timing that changes deration according to rpm to try and give you "some" of the best of both worlds.

Next, super free flowing exhaust. More of the same as above. Great when in the very high RPM ranges, means very little for a daily driver, in fact, many motors preform better at normal speeds / rpm's with some back pressure to offset cam overlap. A case in point, many here may remember the PONTIAC GTO back in 1965, the father of all muscle cars in the US (though not really, the 1961 two ton PONTIAC Catalina 421 SD was turning 12sec quarter miles from the factory before John D. invented the GTO). How were they doing it, with huge racing cams and hooker headers? No, with low end torque mild cams (by todays standards) cast iron headers, low end gear ratios and lots of cubic In. Well we don't have the big cubes today, but the rest remains the same, torque gets you from stop light to stop light quick, and HP gets you from 130mph to 145mph fast. Which describes better how you drive?. If you are a NASCAR driver, then disregard this bit of wisdom.

A great example is BMW's own M roadster, the 2000 was a sad 240 HP, the 2001 was a huge 315HP!, yet, there 0 to 60 and quarter mile times were just tenth of a second apart???? That is because their torque ratings were almost the same. (and most of the gains for the 2001 and 2002 were gearing changes, not HP related) Well, now you know, or you don't know, It is up to you to understand, or not :)
 

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The saying in the Hot Rod world is torque wins races, horsepower sells cars.

Here's my take on the exhaust pipe size vs torque. Smaller pipe size, faster exhaust gas velocity at lower rpm making for more efficient exhaust scavenging up until the engines exhaust gas volume exceeds pipe size velocity.

Bigger pipe sizes, slower moving exhaust gas velocity at low volume/RPM and the cylinders have to work against the slower velocity to move the gasses. Higher volume and then the big pipe sizes can start to scavenge.

So really what I believe we are feeling as low rpm torque with smaller exhaust is actually better cylinder filling from scavenging in that RPM range, same with the big pipe at high RPM.

I'm actually getting pipes made for my 540i/6 this week. I previously had a dual 2.5" with H-pipe that dumped before the differential. This go round I'm going with a 2.5" y-pipe into single 3" all the way out the back

Compression is where power is made. You can go with as big of a camshaft as your heart wants as long as the static compression is raised to compensate for intake valve timing bleed off. Then dialing in the cam timing and you can have a dynamic compression that will make the engine feel very alive on the street.

I try to build my engines to have a dynamic compression of around 9:1 if they are meant to be on high test pump gas. Sometimes that means the static compression gets as high as 11.5-12:1 but then the 282-294 duration cams bring that dynamic compression down. The actually desired intake valve closing degree varies from engine to engine, stroke and rod length and altitude.

On my own BMW V8, M60B40. When I had the engine out of the car I decided to dial in cam timing to what I knew of a "performance" camshaft spec by bolting a degree wheel to the crank and twisting away at the cams. BTW, having independently adjustable DOHC is awesome.

Stock the M60B40's have 246° duration intake and 242° duration exhaust on a 109° intake centerline and a 108° degree lobe separation for cam timing events of: IVO 14°BTDC, IVC 52°ABDC. EVO 48°BBDC, EVC 14°ATDC

I changed mine to be a 106°ICL/106°LSA for IVO 17°BTDC, IVC 49°ABDC. EVO 47°BBDC, EVC 15°ATDC

My plan was to bump up dynamic compression with the earlier closing intake valve and also increase valve overlap for scavenging cylinder filling. The changes aren't drastic but so far me engine has responded positively.


I, myself, am more of a stop light to stop light fun kind of guy. However, it seems the racing world focuses on building high RPM torque thus all of these rolling starts.
 

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Discussion Starter #3
Well

Well, you clearly get it! I think your understanding of the effects of scavenging and deration are a bit beyond the normal reader here, no offence meant to anyone. I just get frustrated when I see guys putting tones of money into a motor thinking it will serve them well stop light to stop light, just to waste it all. Most BMW motors built in the past 25 years are sound concepts with great HP / Torque balance from very few CID / Liter, My 530I is a huge 183 Cid motor (LOL) where my muscle cars could be 6.6lt or bigger.

BMW has amazing torque pre liter. IMHO. I had lots of fun running light to light with V8 mustangs and Camaro's, even most Vett's, just to have them ask after having their as s handed to them by my 2001 roadster "what you got in that?" I would say a straight 6" What, turbo, supercharged, NOS?????. "No" I would say, just natural aspirated inline six, pure stock on pump gas (LOL)

Well, back in the day I did port and polish heads, leaving just the right amount of hump in the combustion chamber to increase scavenging at just the right RPM, I would also CC each combustion chamber to get max equal flow pre cylinder, set tolerance's to the exact level in rings and bearings, magnaflux and shot peen my rods, you get it, most don't. But the average guy could get way more stop light to stop light by just putting in a lower rear end LSD in, then all that racing crap, for the street.
When I was 17, my high school car was a 1966 GTO with 12 to 1 TRW piston's, balanced and blueprinted, ISKY roller cam, breathing through a modified (by me) 1400cfm Pontiac tri-power intake with 670 heads, bolted to a T10 Trans with a 488 posse track on 11" M/T cheaters, that would pull the front end off the ground and turn easy low 11's in the quarter mile on 1970's technology tires, and yes, I built it at home on a budget. I shifted a Pontiac at 8000 RPM! If you are who I think you are, you will get the 8000RPM thing on a Pontiac. The stroke on these motors was the torque monster, and why you need to know what you were doing to hit 8000rpm every time, or even once without having a piston up your as s (LOL)

Well anyway, it is nice to see a BMW guy that get's it and knows where to put your bucks and why. I have read your build thread and I am impressed, but I have to say if I still had the need for speed and your budget, I would put a 600+ HP crate Chevy motor in that beast and save myself a lot of BMW problems:)
 

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Discussion Starter #4
For those who care

I was reading mine and MYKK's post and realized that it might seem like mumbo jumbo to some who really care about increasing their motors performance. So, here goes, valve lift means how wide does your intake valve and exhaust valves open at max clearance. The good thing is, more air can get into each cylinder on intake and more spent gas can get out on exhaust the stroke, "in theory".

Overlap Duration means the amount of time each are open at the same time during a complete cycle of the motor, so a 290 deration means both intake and exhaust valves are opened for 290 degree's per engine cycle. Car manufactures and high performance part makers spend a lot of time and money to get the best performance for their planed end result for their products.

Here is what happens in the motor, the piston starts moving downward and the intake valve starts to open to let air and fuel in to the combustion chamber, then begins to close so it can be compressed. Compression ratio is determined by how much air fuel mixture is displaced from the bottom of the pistons movement to its top. To understand what Mykk meant by different compression ratio's in the same motor, understand the fact that we have a piston in motion as well as valves opening and closing with airflow and scavenging + resistance X cylinders and many other factors that determine the actual compression ratio at any given RPM - load considering altitude and other factors. So you can see how a 10 to 1 compression motor can be compressing at different ratios at different time in its cycle.

Now, on to deration, the intake and exhaust valves are both each opened for a specific amount of time during the 4 cycles of the motor rotation, the overlap deration is the amount of time both are opened to some degree. The intake is letting air and fuel into the cylinder during the intake stroke, then the compression and power stroke happen.

Then the exhaust valve has to open to allow the spent gasses to escape into the exhaust manifold, while the intake valve has to start opening to allow air and fuel to start entering the chamber again, so then happens, the "scavenging" effect mentioned before. If everything is timed correctly, the exiting exhaust gasses will actually pull more air fuel mixture into the cylinder then would have otherwise been pulled in.

You may ask, how does a smaller exhaust system do this? Well, the smaller pipes cause the exhaust gasses to move at a faster pace, thus causing a vacuum effect on the intake gasses :).
 

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Torque is what causes acceleration. Power is torque times rotational velocity (RPM times a constant). Power is what allows a car to still accelerate at higher speeds.

That late-2001 M Roadster and M Coupe had the S54 engine, the same one used in the E46 M3, although slightly de-tuned because of the limited room for the headers. Yeah, those engines had "headers." The cam lobes on the S54 were long duration. They had a fairly wide flat section on the lobe, not just a pointed lobe like most cams. The valves would open, stay open for along time, and then slam shut. This violent valve movement and the 7900 RPM redline are why the S54 had solid lifters and required periodic adjustment (about every 25k to 30k miles). The S54 also had six throttles, one for each intake runner, the runners were very short (resonates at high RPM) and had "trumpets" (velocity stacks) on them (concealed by the air cleaner box). The S54 produced so much torque that the block was actually made of iron, where every other BMW block was either aluminum or a mix of aluminum and magnesium.
 

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HP = Torque X RPM / 5252

So you really cannot separate horsepower from torque.
 

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HP = Torque X RPM / 5252

So you really cannot separate horsepower from torque.
You are correct.

Here's the spec' sheet from Road & Track's recent comparison of the 228i, M235, and M2. The M2 has an overboost function that increases the maximum torque for short periods of time. The R&T horsepower and torque graphs for the M2 showed the increase in torque from the overboost function. But, they forgot to show the corresponding increase in horsepower vs. RPM. The peak horsepower of the M2 doesn't increase, because the overboost function only works from about 1500 to 4500 RPM. I've sketch in what the corrected horsepower curve would look like.

http://www.roadandtrack.com/car-culture/a29245/bmw-2-series-comparison-test/

Tuning an engine for maximum torque at higher RPM's results in greater horsepower, but at the expense of drivability. The original Honda S2000, with a two-liter motor, had higher specific power output (horsepower per cubic inch of displacement) than any other naturally aspirated engine except for the V8 Ferrari of the time. But, they were difficult to drive gently. When they updated the car, they bumped the displacement up to 2.4 liters, but kept the maximum horsepower still at 240. They did this to make the car more drivable by tuning the engine to produce more torque at lower RPM's. I rented a two-liter S2000 from Budget Rental Cars of Marina Del Ray in LA back in 2000. I stalled the car about a half dozen times before I figured I needed to drive it like I stole it.
 

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Discussion Starter #8
Rpm

RPM has nothing to do with weather or not you have torque, that is why when full current is applied to an electric motor torque is achieved at 0 rpm and why a torque wrench can apply torque at 0 rpm also. Horsepower is a measure power as it relates to work:

•1 horsepower is equivalent to 746 watts. So if you took a 1-horsepower horse and put it on a treadmill, it could operate a generator producing a continuous 746 watts.
•1 horsepower (over the course of an hour) is equivalent to 2,545 BTU (British thermal units). If you took that 746 watts and ran it through an electric heater for an hour, it would produce 2,545 BTU (where a BTU is the amount of energy needed to raise the temperature of 1 pound of water 1 degree F).
•One BTU is equal to 1,055 joules, or 252 gram-calories or 0.252 food Calories. Presumably, a horse producing 1 horsepower would burn 641 Calories in one hour if it were 100-percent efficient.
 

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RPM has nothing to do with weather or not you have torque, that is why when full current is applied to an electric motor torque is achieved at 0 rpm and why a torque wrench can apply torque at 0 rpm also. Horsepower is a measure power as it relates to work:

.
:dunno:

Are you saying that torque is achieved when an electric motor is not turning?
 

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:dunno:

Are you saying that torque is achieved when an electric motor is not turning?
Yep. That's why high-performance hybrids engage the electric motors at low speed. It's also why locomotives use a diesel engine to power a big DC motor.

Do a YouTube search for electric dragsters. Nothing with an exhaust pipe can keep up with them off the line.
 

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Yep. That's why high-performance hybrids engage the electric motors at low speed. It's also why locomotives use a diesel engine to power a big DC motor.

Do a YouTube search for electric dragsters. Nothing with an exhaust pipe can keep up with them off the line.
I understand that electric motors can attain max torque immediately upon starting, but the way he described it, it was at max torque BEFORE it turned, while the revs were 0, and if there are no revolutions, to me, it means the engine is not turning at all.
 

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Discussion Starter #12
US M54 aluminum block

Torque is what causes acceleration. Power is torque times rotational velocity (RPM times a constant). Power is what allows a car to still accelerate at higher speeds.

That late-2001 M Roadster and M Coupe had the S54 engine, the same one used in the E46 M3, although slightly de-tuned because of the limited room for the headers. Yeah, those engines had "headers." The cam lobes on the S54 were long duration. They had a fairly wide flat section on the lobe, not just a pointed lobe like most cams. The valves would open, stay open for along time, and then slam shut. This violent valve movement and the 7900 RPM redline are why the S54 had solid lifters and required periodic adjustment (about every 25k to 30k miles). The S54 also had six throttles, one for each intake runner, the runners were very short (resonates at high RPM) and had "trumpets" (velocity stacks) on them (concealed by the air cleaner box). The S54 produced so much torque that the block was actually made of iron, where every other BMW block was either aluminum or a mix of aluminum and magnesium.
"The main differences between the M54 and its M52TU predecessor are the non-return fuel system, a fully electronic throttle[1] (without mechanical backup), an electronically controlled thermostat[2] and that the North American engines no longer use an iron block. The M54 uses an aluminium block and aluminium cylinder head with cast iron cylinder liners and, like the M52TU, the M54 features variable valve timing to both camshafts[3] (called dual VANOS by BMW) and a dual length intake manifold (called "DISA" by BMW)."

The aluminum block has nothing to do with horsepower or torque of a motor. 10,000 horsepower dragsters of today have aluminum blocks, as did the BMW US M54. the cast iron cylinder sleeves are needed as BMW no longer uses Nikasil liners due to the problems in the past from high sulphur fuel. The use of solid lifters is to avoid a condition called "pump up" or "floating" at higher RPMs and you get a true designed amount of lift at the valve as no lift is lost due to auto adjusting hydraulic lifters
 

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You can have torque without rotational motion.... with an electric motor anyway.

Internal combustion engines sort of achieve this with a torque-converter (the fluid coupling between the engine and an automatic transmission). Torque converters "convert" high-RPM, relatively low torque input into low-RPM, high torque output. That's why the Sherman tanks of WWII could crash though brick walls. The torque multiplication of a torque converter is proportional to the slip (input RPM/output RPM). So, the more slip, the more torque that is delivered to the transmission. The torque convert is applying torque to the transmission when the car is standing still (in Drive with the brakes on), even though very little torque is being produced by the engine at idle. That's because of the high-slip, high torque multiplication.
 

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"The main differences between the M54 and its M52TU predecessor are the non-return fuel system, a fully electronic throttle[1] (without mechanical backup), an electronically controlled thermostat[2] and that the North American engines no longer use an iron block. The M54 uses an aluminium block and aluminium cylinder head with cast iron cylinder liners and, like the M52TU, the M54 features variable valve timing to both camshafts[3] (called dual VANOS by BMW) and a dual length intake manifold (called "DISA" by BMW)."

The aluminum block has nothing to do with horsepower or torque of a motor. 10,000 horsepower dragsters of today have aluminum blocks, as did the BMW US M54. the cast iron cylinder sleeves are needed as BMW no longer uses Nikasil liners due to the problems in the past from high sulphur fuel. The use of solid lifters is to avoid a condition called "pump up" or "floating" at higher RPMs and you get a true designed amount of lift at the valve as no lift is lost due to auto adjusting hydraulic lifters
S54, not M54.... iron block.
 

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Discussion Starter #15
The point

S54, not M54.... iron block.
I guess you still don't get the point, if a 10,000 horsepower dragster can have a aluminum block, BMW did not have to use a cast iron block on any of it motors that are below 10,000 horsepower, and last time I checked, that included all the "S" and "M" motors;) they have used both kinds of blocks over the years, but not because the torque or horsepower where to great for a aluminum to handle.

If you don't think a electric motor can have torque without rpm, find a big one, hold the shaft still so it is unable to turn, thus unable to make any torque and then put the juice to it and feel the torque :)
 

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Discussion Starter #16
You get it

Yep. That's why high-performance hybrids engage the electric motors at low speed. It's also why locomotives use a diesel engine to power a big DC motor.

Do a YouTube search for electric dragsters. Nothing with an exhaust pipe can keep up with them off the line.
You clearly do understand torque as a unit of force and not a measure of work. I understand why some on here have a hard time of separating the two. Most don't understand why 18 wheelers are diesel instead of gas, they need torque, and the diesels make tons of it, not tons of horsepower.
I guess a way to explain it to others is to floor your car at 3000 rpm in 1st, then floor your car a 3000 rpm in 4th, you still are making the same amount of horsepower, but you have changed the torque ratio to the wheels.

"Horsepower sells cars, Torque wins races!" Jay Leno
 

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I guess you still don't get the point, if a 10,000 horsepower dragster can have a aluminum block, BMW did not have to use a cast iron block on any of it motors that are below 10,000 horsepower, and last time I checked, that included all the "S" and "M" motors;) they have used both kinds of blocks over the years, but not because the torque or horsepower where to great for a aluminum to handle.

If you don't think a electric motor can have torque without rpm, find a big one, hold the shaft still so it is unable to turn, thus unable to make any torque and then put the juice to it and feel the torque :)
The S54 was punched out to 3.2 liters, and they had to make the engine the same exterior dimensions to fit into the engine compartment. Pound for pound, aluminum is stronger than steel. But, cubic-inch-for-cubic inch, iron is stiffer (modulus of elasticity). Engine blocks don't normally fail from stress. Instead, their primary design constraint is rigidity. They need to maintain their original shape under stress. BMW engineers determined that an aluminum block of the same size would not have been rigid enough in the S54 application.
 

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Discussion Starter #18
BMW engineer

The S54 was punched out to 3.2 liters, and they had to make the engine the same exterior dimensions to fit into the engine compartment. Pound for pound, aluminum is stronger than steel. But, cubic-inch-for-cubic inch, iron is stiffer (modulus of elasticity). Engine blocks don't normally fail from stress. Instead, their primary design constraint is rigidity. They need to maintain their original shape under stress. BMW engineers determined that an aluminum block of the same size would not have been rigid enough in the S54 application.
I apologize, I didn't know I was talking with a BMW engineer. If you and the other BMW engineers had just studied the wall thickness to horsepower of the 10,000 horsepower aluminum block dragster I was talking about, you could have maybe saved yourselves some weight on those cast iron motors, JAT:)
 

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You clearly do understand torque as a unit of force and not a measure of work. I understand why some on here have a hard time of separating the two. Most don't understand why 18 wheelers are diesel instead of gas, they need torque, and the diesels make tons of it, not tons of horsepower.
I guess a way to explain it to others is to floor your car at 3000 rpm in 1st, then floor your car a 3000 rpm in 4th, you still are making the same amount of horsepower, but you have changed the torque ratio to the wheels.

"Horsepower sells cars, Torque wins races!" Jay Leno
Torque is specifically not a measurement of force. Torque is the first moment of force (force times perpendicular distance).

Trucks use diesel engines primarily because diesel engines are more fuel efficient. The superior efficiency (miles/gallon) of diesel engines come from the greater thermal efficiency due to higher compression ratios, and the fact that diesel fuel contains more energy (latent heat of combustion) than gasoline. It's the geometry of engines (bore vs. stroke) and the tuning of the intake, exhaust, and valve timing that determine at which engines speeds they produce their maximum torque (and fuel efficiency). Truck engines produce torque at low engine speeds because of these geometries.
 

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Discussion Starter #20
Fuel efficient

Torque is specifically not a measurement of force. Torque is the first moment of force (force times perpendicular distance).

Trucks use diesel engines primarily because diesel engines are more fuel efficient. The superior efficiency (miles/gallon) of diesel engines come from the greater thermal efficiency due to higher compression ratios, and the fact that diesel fuel contains more energy (latent heat of combustion) than gasoline. It's the geometry of engines (bore vs. stroke) and the tuning of the intake, exhaust, and valve timing that determine at which engines speeds they produce their maximum torque (and fuel efficiency). Truck engines produce torque at low engine speeds because of these geometries.
Thank you for clearing that up for me. Now I know why these dragsters below use diesel engines, it is because they are fuel efficient (LOL)

https://www.youtube.com/watch?v=ygbVUEn_mHc

The main reasons trucks run diesel engines is durability. If you put a gas engine in a 18 wheeler and drove it from NY to CA with the pedal to the metal, like you have to do in big rigs lots of the time, and still can't keep 55mpr up hills. Your would need a new motor very soon. You don't see many gas motors with a rebuild cycle of a million + miles
 
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