BBK shorty headers

Rickyll7 · Mar 9, 2010

40oz said:
If you increase the hp at any given rpm, you also increased the torque at that rpm. In other words, in order to increase horsepower, you need to increase torque at that rpm.

You cannot separate torque and hp as if they are independent variables.

Horsepower is simply a way to compare two similar engines.

All true, except for one thing. Tq can be manipulated by gearing. Knowing that Tq is the only thing that will increase acceleration (except for lowing mass), one could just use larger and larger gear ratios to get more acceleration. The problem with this is what I was getting at above. More gearing makes more acceleration, but at a lower speed.

Above I defined and proved why increasing hp is what you want to do if you are interested in increasing acceleration at any given speed.

Obviousely increasing engine tq at a given engine speed will increase engine hp. However, engine tq does not move the car. The tq at the wheels does, which is engine tq multiplied by overal gearing. This makes engine tq meaningless without knowing the engine speed that its made at (or, more importantly, vehicle speed).

Hp is different. Hp gets to the wheels the same no matter what the gearing is (ignoring insignificant changes in losses).

This is why hp is a better measure for acceleration if you want a specific vehicle speed operating range.

300 ehp, 250 etq will accelerate a car just the same as 300 ehp, 350 etq. You just have to set the gearing so that you get the same wheel tq for each car.

Rickyll7 · Mar 9, 2010

40oz said:
If you increase the hp at any given rpm, you also increased the torque at that rpm. In other words, in order to increase horsepower, you need to increase torque at that rpm.

You cannot separate torque and hp as if they are independent variables.

Horsepower is simply a way to compare two similar engines.

They are two independent variables. Max tq and max hp are almost never at the same engine speed. When do you shift, to maintain peak hp or tq? Think about it. If you shift to maintain peak ENGINE tq, you are now in a gear with less mechanical advantage, less wheel tq, less acceleration.

007 · Mar 9, 2010

Ricky is correct. Remember he is talking about wheel torque and not just the engine.

40oz · Mar 10, 2010

007 said:
Ricky is correct. Remember he is talking about wheel torque and not just the engine.

I agree with him. I just think it is important to understand that horsepower is *directly* related to torque. You can't increase horsepower without increasing torque. Pretending that isn't so is ignorant, not an insight.

Nobody gets a dyno graph showing the actual measurement of rear wheel torque. Gear ratio is always factored in. Horsepower is calculated from the math that gives engine torque at the wheels based on rear gear ratio. Installing 4.10's increases torque to the wheels, making the car faster through the gears, but horsepower hasn't changed. It actually drops since shorter gears eat up more power through friction.

The idea that changing rear gearing changes horsepower is ludicrous.

Nobody said you shift to maintain maximum torque. You need to do the math in each gear to find out the ideal shift point. Based on torque, NOT horsepower.

The relationship between torque and horsepower should be self-evident. The relationship between torque and acceleration vs. horsepower and acceleration is not so obvious. I needed to put an accelerometer in my car and test it on the highway to clarify it in my own mind. Botom line - peak torque is peak acceleration. Horsepower is a fabricated number that means nothing at the end of the day. Tourque at rpm and gear multiplication is all that really matters.

***

But all I really wanted to know is how much factory GT headers weighed compared to BBK shorties.

mogs01gt · Mar 10, 2010

fast97gt said:
for the money are the bbk shorty headers worht it, i dont like the look of the long tubes and dont like the ideas of the mid length. another reason for the shortys is i want to retain the factory style of the way they bolt up, i have the bassai o/r-x bolted to the stock manifolds, so i know these headers will bolt up as a direct bolt on. and is true the claim of ~8-12hp

I've had both Long Tubes and shorties. I currently am running the BBK shorties. I understand the power difference but I'd rather be able to remove my transmission if need be rather than trying to remove a long tube header than remove the tranny.

I trap the same MPH with the shorties as I did with the long tubes.

Rickyll7 · Mar 10, 2010

mogs01gt said:
I've had both Long Tubes and shorties. I currently am running the BBK shorties. I understand the power difference but I'd rather be able to remove my transmission if need be rather than trying to remove a long tube header than remove the tranny.

Can the transmission be removed from the bellhousing with the longtubes in place or do the long tubes get in the way? I understand that some transmissions cant be removed from their bell housings from the outside, but my t56 can.

mogs01gt said:
I trap the same MPH with the shorties as I did with the longtubes.

Interesting... any other changes?

Rickyll7 · Mar 10, 2010

40oz said:
I agree with him. I just think it is important to understand that horsepower is *directly* related to torque. You can't increase horsepower without increasing torque. Pretending that isn't so is ignorant, not an insight.

Nobody gets a dyno graph showing the actual measurement of rear wheel torque. Gear ratio is always factored in. Horsepower is calculated from the math that gives engine torque at the wheels based on rear gear ratio. Installing 4.10's increases torque to the wheels, making the car faster through the gears, but horsepower hasn't changed. It actually drops since shorter gears eat up more power through friction.

The idea that changing rear gearing changes horsepower is ludicrous.

Nobody said you shift to maintain maximum torque. You need to do the math in each gear to find out the ideal shift point. Based on torque, NOT horsepower.

The relationship between torque and horsepower should be self-evident. The relationship between torque and acceleration vs. horsepower and acceleration is not so obvious. I needed to put an accelerometer in my car and test it on the highway to clarify it in my own mind. Botom line - peak torque is peak acceleration. Horsepower is a fabricated number that means nothing at the end of the day. Tourque at rpm and gear multiplication is all that really matters.

***

But all I really wanted to know is how much factory GT headers weighed compared to BBK shorties.

4.10 gears will make you accelerate faster in any given gear, but your top speed in that gear will be less than if you had stock 3.27 gears.

No one said gears increase hp.

Shift to maintain max hp output, and I think you will find that you are maintaining max wheel tq.

Hp is not a fabricated number.

It is contradictory to state that hp is meaningless and that rpm and tq is important. Horsepower is rpm and torque!

Hp = rpm * eTq

Why do you think hp is used to compare engines? Why do you think power to weight ratios are used to compare vehicles? Why not etq to weight ratio?

Their is a good reason why it has been done this way and you are missing it.

mogs01gt · Mar 10, 2010

Rickyll7 said:
Can the transmission be removed from the bellhousing with the longtubes in place or do the long tubes get in the way? I understand that some transmissions cant be removed from their bell housings from the outside, but my t56 can.

Never tried it, I got fed up with the Mac long tubes and the other headers that allow the tranny to be removed are a complete rip off.

Interesting... any other changes?

Other than the BBK o/r X connected to the shorties that replaced the shorty o/r H pipe, no other changes.

Technically speaking, HP is a mathematically created number. It is not measurable. The only meaningful measurement taken from an engine is Torque. HP is a way to make people feel all warm and cozy about their cars.

Rickyll7 · Mar 10, 2010

mogs01gt said:
Technically speaking, HP is a mathematically created number. It is not measurable. The only meaningful measurement taken from an engine is Torque. HP is a way to make people feel all warm and cozy about their cars.

Would you buy an engine without knowing what its hp curve is?

You cant measure an engines performance without knowing it's hp.

Show me a calculation that shows an engines ability to accelerate a given weight through a 1/4 mile in a given time that only considers torque (and not engine speed) as a mesure of performance of the engine. Knowing tq and engine speed means you know hp by definition.

I dare you.

Rickyll7 · Mar 10, 2010

http://www.vettenet.org/torquehp.html

mogs01gt · Mar 10, 2010

Rickyll7 said:
Would you buy an engine without knowing what its hp curve is?
You cant measure an engines performance without knowing it's hp.
Show me a calculation that shows an engines ability to accelerate a given weight through a 1/4 mile in a given time that only considers torque as a mesure of poerformance of the engine.
I dare you.

What are you talking about? You cannot measure HP. You measure Torque. Hp is a conversion of Torque over time. HP is a selling point. Torque is what moves the vehicle, not HP.

You just posted a link that shows you are arguing with yourself.

Rickyll7 · Mar 10, 2010

mogs01gt said:
What are you talking about? You cannot measure HP. You measure Torque. Hp is a conversion of Torque over time. HP is a selling point. Torque is what moves the vehicle, not HP.

You just posted a link that shows you are arguing with yourself.

Read the whole thing before you respond.

And again... I DARE YOU to do what I asked in post 69.

Rickyll7 · Mar 10, 2010

mogs01gt said:
What are you talking about? You cannot measure HP. You measure Torque. Hp is a conversion of Torque over time. HP is a selling point. Torque is what moves the vehicle, not HP.

You just posted a link that shows you are arguing with yourself.

One more thing... Both tq and hp can move things. BUT, hp will tell you how fast you can do it (time) and at what speeds. Tq wont do either without knowing more information (such as rpm) which would actually define hp.

If you dont care about your ET or mph in the quarter, fine. The rest of us normal people do.

mogs01gt · Mar 10, 2010

Rickyll7 said:
Read the whole thing before you respond.
And again... I DARE YOU to do what I asked in post 69.

To do what???You cannot measure HP. This is like speaking to a woman.

What you do think spins the tires? Torque from the engine
What do you think spins the rollers on the dyno? Torque from the engine

What do you not get?

Rickyll7 · Mar 10, 2010

mogs01gt said:
HP is a selling point.

Let's keep the myths to ourselves.

mogs01gt said:
To do what???You cannot measure HP. This is like speaking to a woman.

What you do think spins the tires? Torque from the engine
What do you think spins the rollers on the dyno? Torque from the engine

What do you not get?

You can measure hp. You would know that if you read ALL of the link I posted. What I dare you to do is to prove me wrong with science. Show me an equation that proves your point(s). I've given enough already.

Rickyll7 · Mar 10, 2010

Here is something else for you to chew on. With the right gear ratios, a 500 ft-lb tq engine can put the same tq to the wheels as a 100 ft-lb engine. Do they both accelerate through a 1/4 mile the same? Maybe they do... Maybe they don't. You don't know without knowing the hp curve.

bboylobo · Mar 10, 2010

Rickyll7 said:
Here is something else for you to chew on. With the right gear ratios, a 500 ft-lb tq engine can put the same tq to the wheels as a 100 ft-lb engine. Do they both accelerate through a 1/4 mile the same? Maybe they do... Maybe they don't. You don't know without knowing the hp curve.

to answer the question of wich will cross the line faster, wouldnt you need to know the weight that is being moved by the torque? like if you moving 100 lbs with 100 pounds of torque over a quarter mile vs 5000 lbs with 500 lbs of torque, will the 100lbs be first?

i dont know the equations behind all this im just trying to logically understand it. all this argument on this thread is awsome information

mogs01gt · Mar 10, 2010

Rickyll7 said:
Here is something else for you to chew on. With the right gear ratios, a 500 ft-lb tq engine can put the same tq to the wheels as a 100 ft-lb engine. Do they both accelerate through a 1/4 mile the same? Maybe they do... Maybe they don't. You don't know without knowing the hp curve.

So you are finally understanding that engines only produce torque?

Rickyll7 · Mar 10, 2010

bboylobo said:
to answer the question of wich will cross the line faster, wouldnt you need to know the weight that is being moved by the torque? like if you moving 100 lbs with 100 pounds of torque over a quarter mile vs 5000 lbs with 500 lbs of torque, will the 100lbs be first?

i dont know the equations behind all this im just trying to logically understand it. all this argument on this thread is awsome information

Both would have to weigh the same for the comparison to be meaningful.

The point is that the question can't be answered without knowing what the hp is for each engine.

Rickyll7 · Mar 10, 2010

F = ma (definition)
a = F/m
F=eTq/r (definition)
eTq=Hp/rpm (definition)
a = Hp/(rpm*r*m)
rpm*r = v (definition)
a = Hp/(v*m) (acceleration is a function of vehicle speed, mass, and hp only!)
m = vehicle mass
Hp = horsepower
eTq = engine torque
F = thrust force at wheels
r = factor including total gearing and tire size to convert rotational movement into straight line movement or tq into force

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