Are all 16V engines non-interference?
09-02-2003 | 01:07 AM
#1
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From: Fema region 6
Are all 16V engines non-interference?
Well, the title pretty much says it, I read somewhere that all the 16V engines were NON-interference, just wanted to clarify. TIA!
09-02-2003 | 01:29 AM
#2
Burning Brakes
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As far as I've seen, all the US-spec motors are non-interference (YMMV). The high-comp RoW 4.7 is a different matter - I'm afraid I didn't check the last time I had one apart, but I would suspect the high-comp engine's valves could hit - especially if the belt lets loose at speed.
Greg
Greg
09-02-2003 | 02:13 AM
#3
Drifting
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From: Owasso, OK
The factory service manuals does not require prepositioning of the cams on the 16 valve engines like they do on the 32 valve (interference) engines due to their being non interference. BUT if the heads have been machined more than the maximum (approx .4mm) and a thick headgasket isn't used they could sustain valve damage. If in doubt about your heads, measure the L shaped indicators on each corner. If they are less than 23.6 mm consider your engine interference.
Dennis
Dennis
09-02-2003 | 10:46 AM
#5
Drifting
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From: southern new england
Here is an example of what sometimes happens here on the list, many authoratative sounding yet completely conflicting views. I have talked to an "expert" who does kits for sharks who says non-interference, another guy on the site said his belt broke with no damage done, others claim there would be damage. Can't anybody get in touch with a porsche factory engineer who can give a definitive answer? Nicole?
Tom
1985 928s2
Tom
1985 928s2
09-02-2003 | 11:40 AM
#7
Burning Brakes
Joined: Mar 2002
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From: Skokie, IL
Is there any debate if the S4 is non-interference? I'm assuming no as all I've heard is that if it snaps you're in trouble. Has anyone on this board sustained serious damage in a snap? I've read the "my timing belt snapped but luckily all is ok" posts but never the "it snapped and my engine is dead" ones. Could it be that the ones that snap their belts and walk away ok aren't so "lucky" after all?
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09-02-2003 | 11:47 AM
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From: New York
Can you afford to be wrong?
tv: This has been discussed here many times. It would be nice to have an authority put the question to rest. I think Jim Bailey put it best. Unless you, the owner, are POSITIVE, it is non-interf., treat it as if it were an interference engine. If it is non-in, and you are wrong, you haven't really lost anything. But if it is an interf. and you jump or snap a belt or if you turn the crank w/the cams positioned incorrectly, you may have a very expensive problem on your hands.
09-02-2003 | 01:13 PM
#9
Nordschleife Master
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From: Gilbert, AZ
I asked this same question when I first came aboard onto Rennlist.
The answer I recieved was to treat alll engines as if they were interference engines. If you really want to know - Pull a plug, grab a flashlight,take your breaker bar w/a 27 mm socket and turn the crank to look inside the cyclinder. (Obviously, it would help if you had someone helping!).
The answer I recieved was to treat alll engines as if they were interference engines. If you really want to know - Pull a plug, grab a flashlight,take your breaker bar w/a 27 mm socket and turn the crank to look inside the cyclinder. (Obviously, it would help if you had someone helping!).
09-02-2003 | 02:01 PM
#10
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From: Southern New England
Gosh, Drew...
Re/ your max acceleration statements; I understand the second one, but the first statement doesn't seem to make a lot of sense. Given that the maximum HP is produced at a certain speed, then what are you saying?
Re/ your max acceleration statements; I understand the second one, but the first statement doesn't seem to make a lot of sense. Given that the maximum HP is produced at a certain speed, then what are you saying?
09-02-2003 | 02:08 PM
#11
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From: Gilbert, AZ
The comments were taken by an article I viewed on the OT board . Here is that article - This strange term....don't shoot the messenger and BTW - O&N, your not the first one who has questioned my title signature. It's all good!.
Sorry Sharky - don't meant to hijack your thread:-).
This strange term, horsepower, has caused many people to wonder exactly what the meaning of the term is. We all know that more horsepower is a good thing and the term is commonly assigned to car engines, bench grinders, vacuum cleaners, lawnmowers, etc. But how we ascertain exactly what horsepower is and how we measure it remains a mystery to many.
Let's start by placing the credit/blame on a fellow by the name of James Watt. This Scottish engineer/inventor was credited with many inventions during the mid to late 1700's, especially with his work relating to improvements of steam engines. Watt was determined to provide a way of measuring the rate at which an engine could produce mechanical work. While observing horses being used to haul coal from mines, Watt had the idea of using them as a measurement of work performed. The term Horsepower was coined and is usually abbreviated hp. One Horsepower is the electrical equivalent is 746 watts, and the heat equivalent is 2545 British thermal units per hour.
One horsepower was originally defined as the amount of power required to lift 33,000 pounds 1 foot in 1 minute, or 550 foot-pounds per second. This strange way of measuring work enabled Watt to explain to buyers of steam engines how much work the engine could do for them. In Watt's judgment, one horse can do 33,000 foot-pounds of work every minute. So imagine a horse raising coal out of a coal mine. A horse exerting one horsepower can raise 330 pounds of coal 100 feet in a minute, or 33 pounds of coal 1000 feet in one minute, or 1,000 pounds 33 feet in one minute, etc. It was this original relationship between horses and mechanical devices that led to a system of measurement that continues to be used today. Three different horsepower values are used to quote the power output of an engine: (1) Indicated horsepower is the theoretical efficiency of a reciprocating engine, which is determined from the pressure developed by the cylinder(s) of the engine; (2) brake or shaft horsepower is more commonly used to indicate the practical ability of the engine, or the maximum power, which is the indicated horsepower minus the power lost through heat, friction, and compression of the internal workings of the engine; (3) rated horsepower is the power that an engine or motor can produce efficiently for sustained periods of time.
Typical HP vs. Torque curve
The problem with measuring horsepower these days comes when trying to translate that linear motion of the work performed by the horse, to rotating motion performed by the internal combustion engine. Since the crankshaft of an engine is spinning, there needs to be a way of measuring the force of this rotation. To do this we apply a load to the crankshaft in an attempt to slow it down. This force against the load produces a measurement called Torque. Torque, or turning force, can be understood easily by thinking of a socket and handle (breaker bar) at work. Imagine a socket with a 2 ft long handle attached and a force of 50 lbs applied to the end of it. The torque at the nut or bolt would be 100 ft lbs. Likewise, if you applied 1 lb of force at the end of a 100 ft long handle you would achieve the same 100 ft lbs of Torque at the nut.
To measure the amount of torque (twisting force) an engine will produce we use a dynamometer. The dynamometer utilizes a water brake to apply a load to the crankshaft while the engine is running. With the engine running at full speed the load at the crankshaft can be increased to slow the engine and measure the amount of torque the engine is capable of producing. By doing this a technician can create a computer generated graph which shows a curve indicating the Torque output throughout the engines operating range. So far we have measured the speed of the engine (RPM) at the crankshaft and the Torque (lb ft) output at those various speeds. So how do we end up with horsepower?
To determine a horsepower rating we do a simple calculation. We simply multiply the torque by RPM / 5252. For example: If a given engine produces 300 lb ft of torque at 5,700 RPM we simply multiply 300 X 5,700 and then divide by 5252, we end up with 325.59 horsepower at that speed. Here's an interesting bit of trivia; below 5252 rpm any engine's torque will always be higher than its horsepower, and above 5252 rpm any engine's horsepower will always be higher than its torque.
Using a data acquisition computer connected to a dynamometer we can plot a curve indicating the horsepower output at all engine speeds. We now have a graph showing engine speed, torque curve and horsepower curve. Another thing you can see from a car's horsepower curve is the place where the engine has maximum power. When you are trying to accelerate fast, you want to try to keep the engine close to its maximum horsepower point on the curve. That is why you often downshift to accelerate, by downshifting you increase engine RPM, which typically moves you closer to the peak horsepower point on the curve.
How this all relates to the average driver can be observed in the torque output of an engine and less in the horsepower output. At slower engine speeds the torque output of the engine will be higher than the horsepower output and you will feel this when the car accelerates. For those of you that remember the big displacement engines so commonly found in some of the Detroit cars of the 60's will recall how easy it was to turn the tires into burning rubber at the stoplight. These engines, in some cases, produced in excess of 400 lb ft of torque at very low RPM levels. Since an engines horsepower output typically increases as engine speed increases we need to get the engine turning faster to utilize the horsepower (work) output.
As engine speed continues to increase, the torque output will start to fall off and the horsepower output will continue to rise. However, a vehicle's acceleration rate will closely follow it's torque curve. From this we can understand why we would want an engine to produce the maximum amount of torque at the highest possible RPM level. Here is a simple way to understand this relationship: If you take your 10 speed bike and try to start up a steep hill in 10th gear you will barely be able to start peddling. On the other hand, in first gear you can easily get started. The problem is that in first gear you are peddling like mad and not going very fast, so you start switching gears at the appropriate times to optimize your power/speed output. If you shift up too soon you will begin to slow and if you shift too late your speed will stabilize and your friends will start to pull away. This is why automotive engineers will try to match a vehicles gearing to it's torque curve in order to optimize the acceleration rate of the vehicle. Remember 3 on the tree? then came 4 on the floor, followed now by 5 speed and 6 speed transmissions.
Just remember, we don't measure horsepower, we measure torque and calculate horsepower from it. So remember to look at those torque figures and gear ratios when you consider your next vehicle and what you expect from it. Maybe we can do a little comparison shopping for you in the future. We hear there could be a new S2000 in our future, maybe we will take a look at a few of the Honda tricks of the trade.
Maximum acceleration at any speed occurs at the HP peak.
Maximum acceleration in any gear occurs at the torque peak
Sorry Sharky - don't meant to hijack your thread:-).
This strange term, horsepower, has caused many people to wonder exactly what the meaning of the term is. We all know that more horsepower is a good thing and the term is commonly assigned to car engines, bench grinders, vacuum cleaners, lawnmowers, etc. But how we ascertain exactly what horsepower is and how we measure it remains a mystery to many.
Let's start by placing the credit/blame on a fellow by the name of James Watt. This Scottish engineer/inventor was credited with many inventions during the mid to late 1700's, especially with his work relating to improvements of steam engines. Watt was determined to provide a way of measuring the rate at which an engine could produce mechanical work. While observing horses being used to haul coal from mines, Watt had the idea of using them as a measurement of work performed. The term Horsepower was coined and is usually abbreviated hp. One Horsepower is the electrical equivalent is 746 watts, and the heat equivalent is 2545 British thermal units per hour.
One horsepower was originally defined as the amount of power required to lift 33,000 pounds 1 foot in 1 minute, or 550 foot-pounds per second. This strange way of measuring work enabled Watt to explain to buyers of steam engines how much work the engine could do for them. In Watt's judgment, one horse can do 33,000 foot-pounds of work every minute. So imagine a horse raising coal out of a coal mine. A horse exerting one horsepower can raise 330 pounds of coal 100 feet in a minute, or 33 pounds of coal 1000 feet in one minute, or 1,000 pounds 33 feet in one minute, etc. It was this original relationship between horses and mechanical devices that led to a system of measurement that continues to be used today. Three different horsepower values are used to quote the power output of an engine: (1) Indicated horsepower is the theoretical efficiency of a reciprocating engine, which is determined from the pressure developed by the cylinder(s) of the engine; (2) brake or shaft horsepower is more commonly used to indicate the practical ability of the engine, or the maximum power, which is the indicated horsepower minus the power lost through heat, friction, and compression of the internal workings of the engine; (3) rated horsepower is the power that an engine or motor can produce efficiently for sustained periods of time.
Typical HP vs. Torque curve
The problem with measuring horsepower these days comes when trying to translate that linear motion of the work performed by the horse, to rotating motion performed by the internal combustion engine. Since the crankshaft of an engine is spinning, there needs to be a way of measuring the force of this rotation. To do this we apply a load to the crankshaft in an attempt to slow it down. This force against the load produces a measurement called Torque. Torque, or turning force, can be understood easily by thinking of a socket and handle (breaker bar) at work. Imagine a socket with a 2 ft long handle attached and a force of 50 lbs applied to the end of it. The torque at the nut or bolt would be 100 ft lbs. Likewise, if you applied 1 lb of force at the end of a 100 ft long handle you would achieve the same 100 ft lbs of Torque at the nut.
To measure the amount of torque (twisting force) an engine will produce we use a dynamometer. The dynamometer utilizes a water brake to apply a load to the crankshaft while the engine is running. With the engine running at full speed the load at the crankshaft can be increased to slow the engine and measure the amount of torque the engine is capable of producing. By doing this a technician can create a computer generated graph which shows a curve indicating the Torque output throughout the engines operating range. So far we have measured the speed of the engine (RPM) at the crankshaft and the Torque (lb ft) output at those various speeds. So how do we end up with horsepower?
To determine a horsepower rating we do a simple calculation. We simply multiply the torque by RPM / 5252. For example: If a given engine produces 300 lb ft of torque at 5,700 RPM we simply multiply 300 X 5,700 and then divide by 5252, we end up with 325.59 horsepower at that speed. Here's an interesting bit of trivia; below 5252 rpm any engine's torque will always be higher than its horsepower, and above 5252 rpm any engine's horsepower will always be higher than its torque.
Using a data acquisition computer connected to a dynamometer we can plot a curve indicating the horsepower output at all engine speeds. We now have a graph showing engine speed, torque curve and horsepower curve. Another thing you can see from a car's horsepower curve is the place where the engine has maximum power. When you are trying to accelerate fast, you want to try to keep the engine close to its maximum horsepower point on the curve. That is why you often downshift to accelerate, by downshifting you increase engine RPM, which typically moves you closer to the peak horsepower point on the curve.
How this all relates to the average driver can be observed in the torque output of an engine and less in the horsepower output. At slower engine speeds the torque output of the engine will be higher than the horsepower output and you will feel this when the car accelerates. For those of you that remember the big displacement engines so commonly found in some of the Detroit cars of the 60's will recall how easy it was to turn the tires into burning rubber at the stoplight. These engines, in some cases, produced in excess of 400 lb ft of torque at very low RPM levels. Since an engines horsepower output typically increases as engine speed increases we need to get the engine turning faster to utilize the horsepower (work) output.
As engine speed continues to increase, the torque output will start to fall off and the horsepower output will continue to rise. However, a vehicle's acceleration rate will closely follow it's torque curve. From this we can understand why we would want an engine to produce the maximum amount of torque at the highest possible RPM level. Here is a simple way to understand this relationship: If you take your 10 speed bike and try to start up a steep hill in 10th gear you will barely be able to start peddling. On the other hand, in first gear you can easily get started. The problem is that in first gear you are peddling like mad and not going very fast, so you start switching gears at the appropriate times to optimize your power/speed output. If you shift up too soon you will begin to slow and if you shift too late your speed will stabilize and your friends will start to pull away. This is why automotive engineers will try to match a vehicles gearing to it's torque curve in order to optimize the acceleration rate of the vehicle. Remember 3 on the tree? then came 4 on the floor, followed now by 5 speed and 6 speed transmissions.
Just remember, we don't measure horsepower, we measure torque and calculate horsepower from it. So remember to look at those torque figures and gear ratios when you consider your next vehicle and what you expect from it. Maybe we can do a little comparison shopping for you in the future. We hear there could be a new S2000 in our future, maybe we will take a look at a few of the Honda tricks of the trade.
Maximum acceleration at any speed occurs at the HP peak.
Maximum acceleration in any gear occurs at the torque peak
09-02-2003 | 09:50 PM
#15
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From: Southern New England
Drew,
There's lots of good & interesting info in that article, of course. I'm just trying to figure out what the author was trying to say about the relationship between acceleration/speed/HP.
I would figure that one might say, "The maximum HP is produced near the maximum speed" or something similar.
There's lots of good & interesting info in that article, of course. I'm just trying to figure out what the author was trying to say about the relationship between acceleration/speed/HP.
I would figure that one might say, "The maximum HP is produced near the maximum speed" or something similar.
