Power transfer to the rear wheels?

[2013SHOpp]

As ive been reading in the forums ive noticed that some people will say that thay have 400 or 500 AWHP. All wheel horse power im assuming. Am i missing something because i was under the impression that only 150 hp was the max power sent to the rear. And if they really are all wheel power how are they doing that?
when i was younger and into hondas when we would convert a honda to awd we would use a crv rear end but drill and pin the clutch packs to lock them in awd full time. Is that something we can do with this setup on the SHOs?

 

[Zpak]

Negative

 

[Ta2dResqr]

As ive been reading in the forums ive noticed that some people will say that thay have 400 or 500 AWHP. All wheel horse power im assuming. Am i missing something because i was under the impression that only 150 hp was the max power sent to the rear. And if they really are all wheel power how are they doing that?
when i was younger and into hondas when we would convert a honda to awd we would use a crv rear end but drill and pin the clutch packs to lock them in awd full time. Is that something we can do with this setup on the SHOs?

AWHP is a measurement achieved with an all wheel dyno. It is a total power measured at all 4 wheels. It does not matter the split. While their may only be 150 RWHP, it is still the sum of both. (Not a direct 1+1 sum.) In an all wheel drive or 4 wheel drive, they do not measure RWHP or FWHP, they measure AWHP and state the amount of power put to the ground. Depending on the split, there may be more or less to each axle or equal.

 

[2013SHOpp]

Oh. So it's not that it's a 50/50 split front and back and all wheels are getting equal power. It's the sum of the front and back? It could be 70/30 but the total is 500 or 600 or whatever ot may be.
So if a person says it's 500 awhp taurus sho it would still be 500 hp if the power was only going to the front wheels? Can awd dynos not tell the power distribution between front and rear? Or is that why it's a measurement of awhp? So it could be a 600 awhp car with 600 at the front and only like 200 at the rear? To me the statement All Wheel HP implies that all the wheels are getting g the same amount of power. It's deceiving. Or am I just stupid?

 

[Joshw0000]

AWHP will have a greater transfer loss than front or rear wheel. At the end of the day it's just a number. Some are building race cars or are trying to break records. Others just like a big number to brag about, in which case I'd stick with the factory crank # (365) plus estimated from mods unless you've actually had it dyno'ed.

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[Ta2dResqr]

Oh. So it's not that it's a 50/50 split front and back and all wheels are getting equal power. It's the sum of the front and back? It could be 70/30 but the total is 500 or 600 or whatever ot may be.
So if a person says it's 500 awhp taurus sho it would still be 500 hp if the power was only going to the front wheels? Can awd dynos not tell the power distribution between front and rear? Or is that why it's a measurement of awhp? So it could be a 600 awhp car with 600 at the front and only like 200 at the rear? To me the statement All Wheel HP implies that all the wheels are getting g the same amount of power. It's deceiving. Or am I just stupid?

The issue becomes how do you state the numbers. FWD is easy, it is FWHP. RWD is easy, it is RWHP. Both are usually just called WHP. Now when it comes to AWHP, how would you describe it/write it? The split is dynamic, it may go from 100/0 to 70/30 to 50/50 etc. From a stop, there is more sent to the rear axle then when you are rolling or cruising. What about cars with a manual control? What about RWD cars with an open differential, you don't rate each wheel. Do you give a RWHP and FWHP number and then let people add them? Do you separate 4WD from AWD? It just becomes complicated. The biggest thing is that an AWD, FWD, and RWD have different drivetrain loss. Many people assume a generalized number. Often I have seen 1.1 FWD, 1.15 RWD, and 1.2 AWD.

As far as can the dyno tell where the power is coming from, that depends on the dyno. Some places use a wheel dyno. There is a device mounted in place of each wheel and it is calculated from the total of 2 or 4 devices depending on the number of drive wheels. Some use a single drum for a single axle and a dual drum for a dual axle. Some have a dual drum but one is linked to the other and transferred through the primary drum.

 

[802SHO]

Its going to activate all wheels driving you need it on an awd dyno……sounds like you’re over analyzing. You’ve never seen this car in gear on a lift or jack stands have you? All 4 wheels spin in drive. Whatever you do and wherever you take it it needs to be on an awd dyno and your numbers are awhp numbers. Nothing to debate.

 

[kryptto]

Its going to activate all wheels driving you need it on an awd dyno……sounds like you’re over analyzing. You’ve never seen this car in gear on a lift or jack stands have you? All 4 wheels spin in drive. Whatever you do and wherever you take it it needs to be on an awd dyno and your numbers are awhp numbers. Nothing to debate.

Yeah awd dyno or they take out the drive shaft to the RDU if it's a dump for single axle. I agree awd dyno is the way to go and no reason to overthink this. @Ta2dResqr said all that could be said and thanks for that explanation.

 

[2013SHOpp]

I appreciate everyone's input. A while back when I read that the car made awhp i though i had missed something. did someone find a way to push more power out back and I missed it. to me, awhp sounds like equal power to all wheels. while were on the subject, has anyone found or come up with a way to send more power out back?

 

[Joshw0000]

I appreciate everyone's input. A while back when I read that the car made awhp i though i had missed something. did someone find a way to push more power out back and I missed it. to me, awhp sounds like equal power to all wheels. while were on the subject, has anyone found or come up with a way to send more power out back?

Does that really matter? Our cars are primarily front wheel drive. I believe it's a 60/40 split. Under hard acceleration or when the front wheels lose traction, the rear wheels will supply more power.

I don't understand why you feel like the rear wheels need more power. Is there some concept that I'm missing? Would the car somehow be faster if it was 50/50 instead of 60/40?

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[kryptto]

I appreciate everyone's input. A while back when I read that the car made awhp i though i had missed something. did someone find a way to push more power out back and I missed it. to me, awhp sounds like equal power to all wheels. while were on the subject, has anyone found or come up with a way to send more power out back?

Not that I am aware of - no reason too - you can use LSD - make the power in the front apply to both front.

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[2013SHOpp]

theres no practical need. but being able to slide the rear end around a bit would be fun. I thought the car would handle better if it was able to put more power out back. my coworker has an audi s7. the power bias is to the back. like 60/40 or 70/30. that car handles like a champ. i assumed that the bias was helping out

 

[76FoMoCo]

theres no practical need. but being able to slide the rear end around a bit would be fun. I thought the car would handle better if it was able to put more power out back. my coworker has an audi s7. the power bias is to the back. like 60/40 or 70/30. that car handles like a champ. i assumed that the bias was helping out

the drive train is front bias so the LF tire comes out of the L side of the trans and the RF and rear wheels come out of the R into the PTU (power transfer unit). So there is no way to send power out back without driving the RF tire.

 

[kryptto]

the drive train is front bias so the LF tire comes out of the L side of the trans and the RF and rear wheels come out of the R into the PTU (power transfer unit). So there is no way to send power out back without driving the RF tire.

thank you for explaining for my correction.

 

[Ta2dResqr]

theres no practical need. but being able to slide the rear end around a bit would be fun. I thought the car would handle better if it was able to put more power out back. my coworker has an audi s7. the power bias is to the back. like 60/40 or 70/30. that car handles like a champ. i assumed that the bias was helping out

The S7 is a longitudinally oriented drivetrain while ours is a transverse oriented. The S7 is also marketed has a higher end luxury sport sedan. If you are looking for better handling, I would look into the Gen 4 performance section and try things like H&R Springs on PP Struts, Whiteline Sway Bars, AD mounts, different tires, etc. As far as sliding the back end around, this is not the platform for that easily. A big part of the AWD setup is trying to eliminate slip, both sideways and launching.

 

[SM105K]

The S7 is a longitudinally oriented drivetrain while ours is a transverse oriented. The S7 is also marketed has a higher end luxury sport sedan. If you are looking for better handling, I would look into the Gen 4 performance section and try things like H&R Springs on PP Struts, Whiteline Sway Bars, AD mounts, different tires, etc. As far as sliding the back end around, this is not the platform for that easily. A big part of the AWD setup is trying to eliminate slip, both sideways and launching.

Yep hit it on the head. The SHO is completely ass backwards when it comes to the "better handling" department. It will not stack up against RWD bias AWD systems. That is also why those manufacturers have added drift mode to their platforms.

 

[2013SHOpp]

I wonder if it's possible to swap in a forum rs rdu. That would be kinda cool

 

[Ta2dResqr]

I wonder if it's possible to swap in a forum rs rdu. That would be kinda cool

Again, if those are your desires, this is the wrong platform. Can it be done? With enough time and money, anything can be done. Is it feasible? No. First are the fitment issues, you are trying to take the RDU from a 4 cylinder C-car platform and adapt it to a PTU V6 D3 platform. The RDU is between the rear wheels, the PTU is between the front wheels. Once you figure out all of the mating and fitment issues, then you have to move on to control. The torque-vectoring control from the RS takes in information from all the cars sensors over 100 times a second and then uses that data to determine how to distribute the power. It also has 4 electronically controlled modes. So now you have to make sure all the sensors you need are on the SHO. Then you either need to develop an entire CAN based network to run your custom mix of sensors and modules or figure out how to reprogram the existing modules. Then after you finally get it running, you get to find out if it holds together. You just took a piece of driveline from a 3500lb car and put it in a 4500lb car and are desiring to "abuse" it. So again, can it be done? Yes, but no.

 

[kryptto]

Again, if those are your desires, this is the wrong platform. Can it be done? With enough time and money, anything can be done. Is it feasible? No. First are the fitment issues, you are trying to take the RDU from a 4 cylinder C-car platform and adapt it to a PTU V6 D3 platform. The RDU is between the rear wheels, the PTU is between the front wheels. Once you figure out all of the mating and fitment issues, then you have to move on to control. The torque-vectoring control from the RS takes in information from all the cars sensors over 100 times a second and then uses that data to determine how to distribute the power. It also has 4 electronically controlled modes. So now you have to make sure all the sensors you need are on the SHO. Then you either need to develop an entire CAN based network to run your custom mix of sensors and modules or figure out how to reprogram the existing modules. Then after you finally get it running, you get to find out if it holds together. You just took a piece of driveline from a 3500lb car and put it in a 4500lb car and are desiring to "abuse" it. So again, can it be done? Yes, but no.

I believe the OP should continue challenging us to come up with more hash induced hallucinations, I keep learning more and more how patient @Ta2dResqr is in playing along - however I have two thoughts - I am appreciative since I am learning more and more how the powertrain works and how those fools for engineers only spend their entire careers figuring out as complicated as AWD is, to learn how we can switch the power differential to 40/60 power to the rear.

If anyone else on these boards ever says the folks here are too arrogant and short fused for their efforts to answer a "simple" question, I am bookmarking this thread to repost as a reply...

 

[Tbird6]

Thanks for added details! Lot's of deep knowledge on this forum.

We have an MKS Eco-Boost but I am into Jaguars too. Those AWD versions are built like the Audi described above. RWD and longitudinal drive lines are standard. Then they added the FWD portion as an added cost option. Just a way different design starting point and even though both are called AWD they operate much differently.
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