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Old 01-15-2005, 06:50 AM   #16
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Quote:
Originally Posted by DSMer
The ecu moniters the engines rotational speed through sensors located usually on the crankshaft. Although there are many other places to measure RPMs.

Im talking about the RPM thats on the gauges in the drivers seat next to the speedometer and the steering wheel. They dont measure that RPM on the crank. Is it the belt.
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Old 01-15-2005, 06:56 AM   #17
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Quote:
Originally Posted by CarEXPERT
Im talking about the RPM thats on the gauges in the drivers seat next to the speedometer and the steering wheel. They dont measure that RPM on the crank. Is it the belt.

No it monitors the RPM of the engine. Thats the only tachometer there is. Why would a gauge monitor a belt?
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Old 01-15-2005, 07:03 AM   #18
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Quote:
Originally Posted by DSMer
No it monitors the RPM of the engine. Thats the only tachometer there is. Why would a gauge monitor a belt?

RPM= rotation per minute so which part of the engine are you talking about.
The tachometer.. yes. It cant be the crank because thats where they measure horsepower and if it is the crank why does when the car shift the RPM go down.
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Old 01-15-2005, 06:57 PM   #19
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Quote:
Originally Posted by CarEXPERT
RPM= rotation per minute so which part of the engine are you talking about.
The tachometer.. yes. It cant be the crank because thats where they measure horsepower and if it is the crank why does when the car shift the RPM go down.

If you're going to sit here and argue then stop asking for advice. Why does measuring horsepower at the crank make it impossible to also measure RPM from the crank?

Theres things called engine speed sensors or crank shaft sensors. These sensors or the ignition coil create an electronic pulse everytime the crank spins. This pulse is then picked up at the ECU module and converted into a voltage signal that moves the needle of a tachometer. On newer cars the sensors do it all electronically and the ecu just sends the right current to the tachometer to move the needle.

Every engine has an optimal RPM range where it is the most efficient. You wan't to stay in that range. So when a car shifts it either moves to a smaller or larger gear to stay in the optimal RPM range. The shifting from one gear to another is where you get you RPM "loss"
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Old 01-15-2005, 08:45 PM   #20
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Originally Posted by DSMer
If you're going to sit here and argue then stop asking for advice. Why does measuring horsepower at the crank make it impossible to also measure RPM from the crank?

Theres things called engine speed sensors or crank shaft sensors. These sensors or the ignition coil create an electronic pulse everytime the crank spins. This pulse is then picked up at the ECU module and converted into a voltage signal that moves the needle of a tachometer. On newer cars the sensors do it all electronically and the ecu just sends the right current to the tachometer to move the needle.

Every engine has an optimal RPM range where it is the most efficient. You wan't to stay in that range. So when a car shifts it either moves to a smaller or larger gear to stay in the optimal RPM range. The shifting from one gear to another is where you get you RPM "loss"

i didnt mean to argue with you and i appriciate the advice and information but if you shift gears at high RPM then you lose RPM so it means the crank slows down when you shift gears? So are you saying that the RPMs on the tachometer is measured at the crankshaft?

If you want max performance from your engine should you redline? I know it messes up the engine when you redline but would it give you that extra boost?

Last edited by CarEXPERT : 01-15-2005 at 08:52 PM.
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Old 01-16-2005, 12:33 AM   #21
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Quote:
Originally Posted by CarEXPERT
i didnt mean to argue with you

I don't think that can be avoided when talking to DSMer . Oh and when are you going to change your name to carNOVICE?
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Old 01-16-2005, 12:49 AM   #22
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Quote:
Originally Posted by CarEXPERT
If you want max performance from your engine should you redline? I know it messes up the engine when you redline but would it give you that extra boost?

Now about that question, like DSMer said you have to keep the car in it's rpm 'range', as an example you see the some japanese race drivers teasting out cars and they usually use a racing technique called Heel and Toe, now this technique is all about keeping the car in it's rpm 'range' when down shifting especially in NA cars.
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Old 01-16-2005, 01:10 AM   #23
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Quote:
Originally Posted by GreekWarrior
Now about that question, like DSMer said you have to keep the car in it's rpm 'range', as an example you see the some japanese race drivers teasting out cars and they usually use a racing technique called Heel and Toe, now this technique is all about keeping the car in it's rpm 'range' when down shifting especially in NA cars.

Yes i knw that but it still doesnt answer my question with the redlineing!
Im talking about in a drag race too. do people redline to get more horsepower?
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Old 01-16-2005, 08:27 AM   #24
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Originally Posted by CarEXPERT
Yes i knw that but it still doesnt answer my question with the redlineing!
Im talking about in a drag race too. do people redline to get more horsepower?

Drag racing is a completly different gearing scneario from road racing or daily driving. Redline shifting is something you see in video games. In reality you shift at the proper RPM that will give the next gear optimum RPM range or close to it. IT all depends on the car, I can't really tell you other than what I've actually drag raced.
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Old 01-16-2005, 01:49 PM   #25
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Why do I keep picturing an eagle circling an unsuspecting rabbit?

To say I'm flabbergasted would be an understatement.

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Old 01-17-2005, 12:20 AM   #26
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Quote:
Originally Posted by DSMer
IT all depends on the car.

That pretty much sums it up, there is not point revving lets just say for example 1992 Mitsubishi Lanser GSR now this is a graet little car that is virtually lag free thanks to its small turbo but does run out of puff near the top end of the rev range at about 5500rpm so there is no real point in revving this to redline.
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Old 01-17-2005, 12:26 AM   #27
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Thanks everybody...
This question has been bugging me and hopefully someone that is sure and answer this for me
In your car, there is a tachometer(RPM meter) near the stearing wheel. Where do they measure that RPM at? When I rev a car, the engine goes louder and the belt shakes a little and spins faster. DSMer said they measure it at the crank but why when i rev my engine the belt spins faster? So does this mean they measure the RPM at the engine belt? PLEASE help me
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Old 01-17-2005, 12:32 AM   #28
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As far as i know the RPM is measured at the flywheel/flexplate. But I might be wrong.
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Old 01-17-2005, 12:48 AM   #29
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As far as i know the RPM is measured at the flywheel/flexplate. But I might be wrong.

How sure are you? Cuz like I said when i rev the engine and look at the engine belt it spins faster and when i rev it faster the belt spins faster. Where is vwhobo? I bet he can answer this.
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Old 01-17-2005, 04:58 AM   #30
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Ughh, at the flywheel! NO. The flywheel does'nt spin as fast as the crankshaft thats the point of its existance!

Dammit CarEXPERT. Its measured at the crankshaft. The belts spins faster because the crankshaft spins the belt. Wich in turn spins the gears that spin the cam that open and close the valves.
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