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Things I Always Wanted To Know...


CanadaCraig

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Hi Guys!! :)

I hope you're OK.

The following are but a few of the things I've always wanted to know.

Please answer one or more of the following questions.

QUESTION ONE:

The LS400 has a 4.0 litre engine.

That's 4.0 litres of WHAT?!

How is the SIZE of an engine measured?

QUESTION TWO:

The LS400 makes 250 horsepower.

IS that REALLY equivalent to the power of 250 HORSES?

QUESTION THREE:

When it comes to engine power - should we focus more on torque or horsepower?

QUESTION FOUR:

I've heard it said that the better an engine 'breathes' the more powerful it becomes.

But does an engine NEED at least SOME exhaust system back-pressure to make all the power it can make?

QUESTION FIVE:

Is there a 'formula' to figure out [or at least guesstimate] what an LS400's GROSS horsepower rating would be? [to compare with cars from the 1960's and earlier]

QUESTION SIX:

Where - exactly - does engine COOLANT GO?!

[what IS it 'cooling'?]

QUESTION SEVEN:

Is there any law that says a cars BRAKES must be able to stop a car from the cars TOP SPEED?!

QUESTION EIGHT:

Are cars designed to weigh MORE on the passenger side than on the driver's side?

[to compensate for the weight of the driver]

QUESTION NINE:

Is there any truth to the idea that an 8 cylinder engine will last longer than a 4 cylinder engine?!

QUESTION TEN:

If you lower your car - do you change its drag coefficient number?

That's it!! [for now]

Thanks,

Craig!! :)

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The LS400 has a 4.0 litre engine.

That's 4.0 litres of WHAT?!

How is the SIZE of an engine measured?

Its the total volume of air/fuel the engine can take in during one complete engine cycle.

QUESTION TWO:

The LS400 makes 250 horsepower.

IS that REALLY equivalent to the power of 250 HORSES?

Kinda. The term "horespower" came from the creators of the first steam engines as a way to communicate to people who were used to using horses for transportation and to do work, how much work the steam engines could do by the virtue of how many horses it would take to do the same work. Horsepower is simply a unit of measurement, but the founding blocks of the horsepower forumula, the idea that 1HP can pull 180lbs, comes from studying what one horse could effectively pull. So, it kinda is the equivelent power of 250 horses.

The hp figuire you cited, 250 is bhp or brake horsepower. Its whatever power is generated from the engine before losses in the drivetrain and transaxle. So, the amount of power the LS actually puts to the ground is less than that.

QUESTION THREE:

When it comes to engine power - should we focus more on torque or horsepower?

It depends, what really gets you going from a stop is torque, but what keeps you going through the RPM range is horsepower.

QUESTION SIX:

Where - exactly - does engine COOLANT GO?!

what IS it 'cooling'?

The engine coolant cools the engine block, it moves through the coolant lines and absorbs heat from the engine, it then runs through the radiator where it is cooled, so that it can move through the coolant lines again.

If you mean why do you need to add coolant, when things operate at high temperature there is always vaporization causing coolant loss.

QUESTION SEVEN:

Is there any law that says a cars BRAKES must be able to stop a car from the cars TOP SPEED?!

Absolutely its a DOT requirement.

QUESTION NINE:

Is there any truth to the idea that an 8 cylinder engine will last longer than a 4 cylinder engine?!

I don't know that theres any truth to it, and it probably doesn't matter to 99% of owners because they'll never have their car long enough to see the difference. But, V8s as a rule are far less taxed than 4 cyl engines, and they're also better balanced so theres not as much vibration which could make them last longer sure.

QUESTION TEN:

If you lower your car - do you change its drag coefficient number?

Absolutely.

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Hi Guys!! :)

Can anyone answer to the following questions?

QUESTION FOUR:

I've heard it said that the better an engine 'breathes' the more powerful it becomes.

But does an engine NEED at least SOME exhaust system back-pressure to make all the power it can make?

QUESTION FIVE:

Is there a 'formula' to figure out [or at least guesstimate] what an LS400's GROSS horsepower rating would be? [to compare with cars from the 1960's and earlier]

QUESTION EIGHT:

Are cars designed to weigh MORE on the passenger side than on the driver's side?

[to compensate for the weight of the driver]

Thanks,

Craig!! :)

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Hi Craig;

Breathing refers to the efficiency with which the cylinder fills during the intake stroke, and the more air which can be moved into the cylinder, the more fuel that can be burned. Although our engines are four litre displacement (total swept volume of all cylinders), they cannot induct four litres of air at ambient pressure. The closer to that volume they can induct, the more power. In short, the engine is an air pump.

Exhaust back pressure is a layman's way of describing "scavenging", which is a method of utilizing the departing exhaust gases to create a low pressure region in the cylinder during the valve overlap period. This helps to "bring in" the next intake charge. In street cars headers can be used to accentuate "resonant" tuning of the exhaust system. Top fuel dragsters use "inertia" tuning, which is a bit different.

The problem is that good scavenging at high RPM results in very poor scavenging at low RPM, with residual exhaust gases "diluting" the incoming charge. It's one reason why people like "big" engines because the apparent compromise between high and low RPM is masked by the flat torque curve a big engine can have.

Horsepower is not a single unit, although lately the SAE Net horsepower unit has become the most used. In the 1960's auto manufacturers used SAE Gross ratings, which were substantially most optimistic. Other horsepowers were DIN (German) and JIN (Japanese), amongst many more. The huge drop in rated horsepower between 1973 and 1972 ( I think that was the year) was not reflected in the actual output of the engines made in the USA, only that the unit value of a horsepower was different.

Horsepower remains a measure of the "rate of doing work". Work is measured in torque units, and horsepower is a simple computation that reflects the rate of doing torque. Engine dynamometers measure torque and calculate horsepower from it. Many people confuse these values and distort them beyond all recognition.

Most cars are designed to be level in the unloaded condition, with a specified fuel load and all lubricants on board. Race cars will use a ballast weight to simulate the weight of the driver when the suspension is adjusted to level and for all steering angles. Such accuracy is not normally used in street cars, although any alignment shop will happily align your car with a ballast in the drivers seat. It makes little difference to them.

Well I hope this helps a bit.

SRK

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Hi SRK!! :)

I hope you're OK.

"I hope this helps a bit."

I HOPE THIS HELPS A BIT?!

Are you kidding?!

I've never FELT so SMART!! lol

I really appreciate you taking the time to answer those three remaining questions.

Thank you!!

Craig!! :)

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