Author Topic: Fabr's Car-VW/busa crossbreed  (Read 263074 times)

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Re: busa/VW crossbreed?
« Reply #45 on: October 21, 2008, 06:08:11 PM »
After some educating reading the last two hours, Punkur, you have to do some research here... ;D

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Re: busa/VW crossbreed?
« Reply #46 on: October 22, 2008, 12:05:53 AM »
Wrong,wrong,wrong.NOTHING is measured ever in HP.HP(something imaginary in reality) is a mathmatical function of TORQUE(something that is physically measurable), RPM and the constant 5252.  HP=torque x rpm/5252Chassis dynos measure torque at the REAR wheel times  RPM of the wheel divided by 5252 to get REAR WHEEL HP and TORQUE figures.Any claims of HP at the crank when measured on a CHASSIS dyno will be CALCULATED guesses at best.Wheel diameter is also included in the calcs but for simplicity we'll keep it to basics.

Thank you fabr!  The more posts I read the more I wondered if anyone would stop the mayhem!

Punkur......  Why do we even have transmissions and reductions at the ring and pinion?  According to your idea no matter what the reduction is the torque is always the same?

There is something that is always the same (minus parisitic losses), and that is the Horsepower.  It does not matter what gear your are in, the motor makes the same horsepower.  As you click through the gears, the torque at the rear wheel is greatest in first, then less in second, less in third, and keeps being reduced each shift until high.  That is why any vehicle accelerates fastest in first, because it has the most mechanical advantage in first gear, and by the time you get to high you have taken away the mechanical advantage, and it does not accelerate nearly as fast in high.

A motor dyno is simple because you are connected straight to the crank with no gear ratio.  On the motor dyno it simply measures how much torque is being applied by the crank and at what RPM.  Once these numbers are recorded, you simply use the HP formula to determine the HP based on the torque and RPM number.  Horsepower = (torque x Rpm) / 5252

A chasis dyno is a little trickier because there are gear ratio's, tire size, and parasitic losses involved.  I believe there are two basic styles of chasis dyno's, some measure torque applied by the tires, while others measure how fast a roller with a specific inertia is sped up.  On both styles if you don't enter the correct gear ratios and tire size, you will not come up with the correct HP and torque numbers.  For example on the inertia dyno, do you think if you put the vehicle in 1st gear it will accelerate the roller faster than if you put it in high......  Sure it will, but when you tell it that you had more mechanical advantage in the first gear run, it will correct back to the same numbers as the high gear run. 

The saying rear wheel horsepower is really deceptive.  It is really (Motor horsepower minus drivetrain parasitic losses measured at the rear wheel, and calculated based on transmission and rearend ratios and tire size)  It's just easier to say rear wheel Hp.

Let me give you another Example, how much horsepower does a good Semi have? 500-600 Hp.  Now lets say I have a hopped up 350 Chevy that also make 600 Hp.  Which has more power?  Neither, they both have 600 Hp.  The difference is that the semi has 600 Hp at 1500 Rpm, and  2100Ft/lbs of torque at 1500.  The Chevy has 600 Hp at 7000 Rpm giving it 450 ft/lbs at 7000 rpm.  Now if you connect a tranny to the chevy with a ratio of 4.667:1 it now puts out 2100 ft/lbs at 1500 rpm at the ouput shaft, while the motor is running 7000 rpm.

We have the same situation with the VW vs Busa in front of the transaxle.  Because the Busa makes its HP at 10,000 Rpm, it has less torque than the VW of the same HP, but it gets alot more gear reduction which in turn causes more torque.

Plkracer hit on the real problem which is we want to use the Busa tranny to shift with instead of the VW tranny.  If you left the Busa in High, it would not have that much more torque than the VW.

The ring and Pinion in the transaxle would not be the issue in my opinion, because if the busa is in 6th, and the transaxle is in low, the torque at the ring and pinion would be similar to the busa in low and the transaxle in high.  Where the rub comes in is if the busa is in low, the transaxle in high gear will see much more torque at the high gear set than the VW could ever put out becase the busa has so much reduction through the primary and tranny.

Ok.....  I am just going to stop, and wait for Punkur's reply  "Ignore the fact of the reduction".

 :b


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Re: busa/VW crossbreed?
« Reply #47 on: October 22, 2008, 12:33:47 AM »
Punkur.  I am sorry if my post sounded harsh....  I am really just teasing.  But seriously the reduction does make a difference.  If it doesn't make sense, keep asking questions until it does.  That is the point of being here. 

Besides..... Once Bug figures it out he will set us all straight....   ;)

Crap now I got to apologize to Bug to.......

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Re: busa/VW crossbreed?
« Reply #48 on: October 22, 2008, 01:29:33 PM »
Thank you fabr!  The more posts I read the more I wondered if anyone would stop the mayhem!

Punkur......  Why do we even have transmissions and reductions at the ring and pinion?  According to your idea no matter what the reduction is the torque is always the same?

There is something that is always the same (minus parisitic losses), and that is the Horsepower.  It does not matter what gear your are in, the motor makes the same horsepower.  As you click through the gears, the torque at the rear wheel is greatest in first, then less in second, less in third, and keeps being reduced each shift until high.  That is why any vehicle accelerates fastest in first, because it has the most mechanical advantage in first gear, and by the time you get to high you have taken away the mechanical advantage, and it does not accelerate nearly as fast in high.

A motor dyno is simple because you are connected straight to the crank with no gear ratio.  On the motor dyno it simply measures how much torque is being applied by the crank and at what RPM.  Once these numbers are recorded, you simply use the HP formula to determine the HP based on the torque and RPM number.  Horsepower = (torque x Rpm) / 5252

A chasis dyno is a little trickier because there are gear ratio's, tire size, and parasitic losses involved.  I believe there are two basic styles of chasis dyno's, some measure torque applied by the tires, while others measure how fast a roller with a specific inertia is sped up.  On both styles if you don't enter the correct gear ratios and tire size, you will not come up with the correct HP and torque numbers.  For example on the inertia dyno, do you think if you put the vehicle in 1st gear it will accelerate the roller faster than if you put it in high......  Sure it will, but when you tell it that you had more mechanical advantage in the first gear run, it will correct back to the same numbers as the high gear run. 

The saying rear wheel horsepower is really deceptive.  It is really (Motor horsepower minus drivetrain parasitic losses measured at the rear wheel, and calculated based on transmission and rearend ratios and tire size)  It's just easier to say rear wheel Hp.

Let me give you another Example, how much horsepower does a good Semi have? 500-600 Hp.  Now lets say I have a hopped up 350 Chevy that also make 600 Hp.  Which has more power?  Neither, they both have 600 Hp.  The difference is that the semi has 600 Hp at 1500 Rpm, and  2100Ft/lbs of torque at 1500.  The Chevy has 600 Hp at 7000 Rpm giving it 450 ft/lbs at 7000 rpm.  Now if you connect a tranny to the chevy with a ratio of 4.667:1 it now puts out 2100 ft/lbs at 1500 rpm at the ouput shaft, while the motor is running 7000 rpm.

We have the same situation with the VW vs Busa in front of the transaxle.  Because the Busa makes its HP at 10,000 Rpm, it has less torque than the VW of the same HP, but it gets alot more gear reduction which in turn causes more torque.

Plkracer hit on the real problem which is we want to use the Busa tranny to shift with instead of the VW tranny.  If you left the Busa in High, it would not have that much more torque than the VW.

The ring and Pinion in the transaxle would not be the issue in my opinion, because if the busa is in 6th, and the transaxle is in low, the torque at the ring and pinion would be similar to the busa in low and the transaxle in high.  Where the rub comes in is if the busa is in low, the transaxle in high gear will see much more torque at the high gear set than the VW could ever put out becase the busa has so much reduction through the primary and tranny.

Ok.....  I am just going to stop, and wait for Punkur's reply  "Ignore the fact of the reduction".

 :b



Nicely put. Now the question is would a 091 trans take the input torque of the busa in 5th or 4th,3rd? How much input torque can a VW 091 take?  Will a busa tranny take long term usage in 5th,4th,3rd?
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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LiveWire

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Re: busa/VW crossbreed?
« Reply #49 on: October 22, 2008, 01:56:35 PM »
If you use the original bell housing of an 091 to hold a support bearing and you you are flipping th 091 upside down, you will have the issue of the bell housing now being the low point of the drivetrain. If you replace the bell housing with a plate, the input shaft which was near the top of the 091 is now near the bottom. Will that now cause the entire Busa engine to be low in comparison to the drive flanges of the 091?

Offline fabr

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Re: busa/VW crossbreed?
« Reply #50 on: October 22, 2008, 02:55:32 PM »
If you use the original bell housing of an 091 to hold a support bearing and you you are flipping th 091 upside down, you will have the issue of the bell housing now being the low point of the drivetrain. If you replace the bell housing with a plate, the input shaft which was near the top of the 091 is now near the bottom. Will that now cause the entire Busa engine to be low in comparison to the drive flanges of the 091?

Good point,does anyone have an approximate distance from input shaft c/l to the top of an 091 trans case?  Even a close guess?
[/quote]
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Admin

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Re: busa/VW crossbreed?
« Reply #51 on: October 22, 2008, 03:04:37 PM »
the output cvs flange is just about damn near the center, so either way would be darn close...

Offline fabr

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Re: busa/VW crossbreed?
« Reply #52 on: October 22, 2008, 03:06:32 PM »
INPUT shaft bug not output shafts.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

Admin

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Re: busa/VW crossbreed?
« Reply #53 on: October 22, 2008, 03:08:33 PM »
ya, after comprehending what livewire said, flipped over the input shaft would be approximately 1/4-1/3 the distance from the bottom..

Offline fabr

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Re: busa/VW crossbreed?
« Reply #54 on: October 22, 2008, 03:14:22 PM »
I'm guessing the input shaft will be approx 2.5-3" lower than the output shafts if the trans is flipped over.Does that sound about right? If so how tall overall is the gearbox less bellhousing?
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

artie on edge

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Re: busa/VW crossbreed?
« Reply #55 on: October 22, 2008, 09:28:14 PM »
approx 10" from memory.

Offline fabr

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Re: busa/VW crossbreed?
« Reply #56 on: October 22, 2008, 10:16:10 PM »
Thanks.Am I right in thinking that the input shaft is2.5-3" off center?
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

artie on edge

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Re: busa/VW crossbreed?
« Reply #57 on: October 23, 2008, 03:53:12 PM »
again from memory Its dead centre.

artie on edge

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Re: busa/VW crossbreed?
« Reply #58 on: October 23, 2008, 03:54:11 PM »
this is the box i used in my full sized car days. Never broke one, ever! Abused them, always! I used Albins gear sets in all my boxes, that would be why Im thinking they never failed, to be truthful I only ever used modest hp, fairly low torque power plants (class rules).

artie on edge

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Re: busa/VW crossbreed?
« Reply #59 on: October 23, 2008, 03:58:53 PM »
Thanks.Am I right in thinking that the input shaft is2.5-3" off center?

Sorry Mast did you mean sideways or height ways? Yes it is a little higher than the centre line so therefore it would be lower once flipped, sorry didnt read your prev posts correctly ( now mast.... dont take that too personally!!!!)
« Last Edit: October 23, 2008, 04:00:50 PM by artie on edge »

 

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