My IveyTune Experience
In theory, that seems to be the optimal way, but I don't think we have any real world testing just yet.
Here is my take....
I still do not believe gravel is best for launching, however, with the limited mods it may prove to be better since there is no wheel spin. IF, you get to a power level where wheel spin might occur off the line, then I feel tarmac will provide better 60' results.
With that said, it does seem gravel mode puts less resistance on the drivetrain to get down the track slightly faster. As long as you don't spin this seems to be the best way. Once wheel spin occurs I think the results might be slightly dfferent.
I wanted to attempt this theory last Friday, but the track event got rained out.
Here is my take....
I still do not believe gravel is best for launching, however, with the limited mods it may prove to be better since there is no wheel spin. IF, you get to a power level where wheel spin might occur off the line, then I feel tarmac will provide better 60' results.
With that said, it does seem gravel mode puts less resistance on the drivetrain to get down the track slightly faster. As long as you don't spin this seems to be the best way. Once wheel spin occurs I think the results might be slightly dfferent.
I wanted to attempt this theory last Friday, but the track event got rained out.
Im gonna be going in a couple days on wednesday...but its supposed to rain. Hopefully it will clear up by then. Im gonna try and do some in gravel and some in tarmac for comparisons.
Ok this doesn't make any sense. If someone ran 13.0/13.1 in Tarmac mode and 12.7 in gravel mode that just doesn't make sense. That's a .3/4 loss on the 1/4!! For that to happen you need to gain 30+ HP (drag rule 10hp should lower you time .1) or if you lose 100LBS off of car. Only other factor is the launch. Is it yielding better 60' in gravel the Tarmac?
I bet it's only 1% or maybe 2% off of the drive tran loss
I bet it's only 1% or maybe 2% off of the drive tran loss
I got a better explanation on another forum, and it makes allot of sense. It all has to do with the drivetrain bias towards front or rear and does not have the do with locking the differentials.
Tarmac - more rear wheel bias
Gravel - equal or close to 50/50 front/rear
Snow - more front wheel bias
Not really sure how it equates to faster times other than the Gravel seems more evenly distributed, and depending on the way the car limits the bias to certain wheels, there may be a noticable difference.
Tarmac - more rear wheel bias
Gravel - equal or close to 50/50 front/rear
Snow - more front wheel bias
Not really sure how it equates to faster times other than the Gravel seems more evenly distributed, and depending on the way the car limits the bias to certain wheels, there may be a noticable difference.
Just to take a 'swing' at the gravel vs tarmac debate, here's my take.
Tarmac provides the best "launch" traction/adhesion based on the "locked" diff.... however, where the gravel mode takes over is DURING the pull. Since the smart guys at mitsu realized they could distribute more power to the wheels that needed it in this mode, it has a complimentary effect on 1/4 mile et. The drivetrain loss is reduced enough for you to see the increases of 2-3mph in the 1/4 mile... (kind of like shutting the awd off during the pass).
Just my .02
Tarmac provides the best "launch" traction/adhesion based on the "locked" diff.... however, where the gravel mode takes over is DURING the pull. Since the smart guys at mitsu realized they could distribute more power to the wheels that needed it in this mode, it has a complimentary effect on 1/4 mile et. The drivetrain loss is reduced enough for you to see the increases of 2-3mph in the 1/4 mile... (kind of like shutting the awd off during the pass).
Just my .02
Just to take a 'swing' at the gravel vs tarmac debate, here's my take.
Tarmac provides the best "launch" traction/adhesion based on the "locked" diff.... however, where the gravel mode takes over is DURING the pull. Since the smart guys at mitsu realized they could distribute more power to the wheels that needed it in this mode, it has a complimentary effect on 1/4 mile et. The drivetrain loss is reduced enough for you to see the increases of 2-3mph in the 1/4 mile... (kind of like shutting the awd off during the pass).
Just my .02
Tarmac provides the best "launch" traction/adhesion based on the "locked" diff.... however, where the gravel mode takes over is DURING the pull. Since the smart guys at mitsu realized they could distribute more power to the wheels that needed it in this mode, it has a complimentary effect on 1/4 mile et. The drivetrain loss is reduced enough for you to see the increases of 2-3mph in the 1/4 mile... (kind of like shutting the awd off during the pass).
Just my .02
Here's a quote for thought,,,
"The interaction between all the transmission and center diff modes is where the Evo MR gets complicated – but you’re going to like it. As with the previous generation, all new Evos offer you a driver-controlled center differential. You can set your front-rear torque split for tarmac, gravel, or snow driving. (Tarmac offers the greatest rear-bias, while snow mode splits torque evenly to all four wheels. Gravel is in the middle.) "
With this in mind,, does "snow-mode" offer an even lower et/higher mph? According to the info from here to Japan, this would offer the most "traction" with the most amount of limited-slip effect.
I try to imagine what the engineers where aiming for with this particular option. Obviously tarmac gave the evo the most freespirited driving on dry paved roads. This would be aimed more towards highspeed driving and steering response. Snow-mode offered the least amount of ecu "input" and just allows the power to go ***** to the wall, assuming the vehicle was to be driven on roads with 0 traction.
Gravel may verywell be the answer to the dragstrip. It lays between tarmac and snow offering enough pc interpretation of how to best "assist" the driver.
Maybe posting the timeslips between the passes may help to breakdown exactly where on the 1320 the car picked up it's greatest gains. This should solve the riddle.
Last edited by 4kinboost; Jun 4, 2009 at 10:07 PM.
You are entitled to your opinions of course,,,, but please explain how 50/50 is better for launching the car? Include weight transfer in your explanation--
Here's a quote for thought,,,
"The interaction between all the transmission and center diff modes is where the Evo MR gets complicated – but you’re going to like it. As with the previous generation, all new Evos offer you a driver-controlled center differential. You can set your front-rear torque split for tarmac, gravel, or snow driving. (Tarmac offers the greatest rear-bias, while snow mode splits torque evenly to all four wheels. Gravel is in the middle.) "
With this in mind,, does "snow-mode" offer an even lower et/higher mph? According to the info from here to Japan, this would offer the most "traction" with the most amount of limited-slip effect.
I try to imagine what the engineers where aiming for with this particular option. Obviously tarmac gave the evo the most freespirited driving on dry paved roads. This would be aimed more towards highspeed driving and steering response. Snow-mode offered the least amount of ecu "input" and just allows the power to go ***** to the wall, assuming the vehicle was to be driven on roads with 0 traction.
Gravel may verywell be the answer to the dragstrip. It lays between tarmac and snow offering enough pc interpretation of how to best "assist" the driver.
Maybe posting the timeslips between the passes may help to breakdown exactly where on the 1320 the car picked up it's greatest gains. This should solve the riddle.
Here's a quote for thought,,,
"The interaction between all the transmission and center diff modes is where the Evo MR gets complicated – but you’re going to like it. As with the previous generation, all new Evos offer you a driver-controlled center differential. You can set your front-rear torque split for tarmac, gravel, or snow driving. (Tarmac offers the greatest rear-bias, while snow mode splits torque evenly to all four wheels. Gravel is in the middle.) "
With this in mind,, does "snow-mode" offer an even lower et/higher mph? According to the info from here to Japan, this would offer the most "traction" with the most amount of limited-slip effect.
I try to imagine what the engineers where aiming for with this particular option. Obviously tarmac gave the evo the most freespirited driving on dry paved roads. This would be aimed more towards highspeed driving and steering response. Snow-mode offered the least amount of ecu "input" and just allows the power to go ***** to the wall, assuming the vehicle was to be driven on roads with 0 traction.
Gravel may verywell be the answer to the dragstrip. It lays between tarmac and snow offering enough pc interpretation of how to best "assist" the driver.
Maybe posting the timeslips between the passes may help to breakdown exactly where on the 1320 the car picked up it's greatest gains. This should solve the riddle.
Here is a more detailed tech info about how the ACD works... I hope it will help for the confusion about the ACD 
"
In short, the ACD unit hydraulically controls the limited-slip locking state of the center differential which ranges between full locked, full open, and every point in between these two states. It calculates what the optimum locking amount would be using real-time input from the previously mentioned sensors and which ACD mode is selected. The ACD is extremely fast in operation, bettering the performance of the standard VCU and Viscous units.
When the car is accelerating or decelerating rapidly, the ACD begins to engage the limited-slip locking on the differential. The harder you accelerate or decelerate, the more it locks. This is done to provide maximum lateral stability and wheel traction. (Cool
The ACD allows the differential to operate in more of a free state when steering movements are made. When turning, the wheels in the front have to travel a further distance than the wheels in the rear. This is because the wheels in the front travel using a larger turning radius than the rear wheels as you can see from this picture. (turning radius.gif) So in order for smooth turning, the center differential needs to become open to allow for the front set to turn at a different speed. If you were to leave the center differential locked, the wheels would skip and skid badly.
Despite popular belief, this switch DOES NOT change the torque split. The differential is geared at 50:50 and cannot be changed by the push of a button. What this switch actually does is quite simple. Each setting determines how long the ACD will delay in freeing the center differential after a steering input is made. In addition, it will determine how much locking force the ACD will exhibit on the clutch pack and center differential.
Tarmac is the setting to be used in dry, paved conditions. In this setting, the ACD will almost immediately allow the center differential to go into a free state upon detecting a steering input. Additionally, this mode provides the strongest limited-slip clamping force of the three modes.
.
Gravel is the setting designed for wet or loose roads. In this setting, the ACD will delay in freeing the center differential for a moment (possibly 2-3 seconds). Of the three modes, this one has the second strongest clamping force.
Snow is the setting designed for, you guessed it, snow. In this setting, the ACD will delay in freeing the center differential for much longer than the other two settings (possibly 4-5 seconds). Of the three modes, this one also provides the least amount of clamping power. "
"
In short, the ACD unit hydraulically controls the limited-slip locking state of the center differential which ranges between full locked, full open, and every point in between these two states. It calculates what the optimum locking amount would be using real-time input from the previously mentioned sensors and which ACD mode is selected. The ACD is extremely fast in operation, bettering the performance of the standard VCU and Viscous units.
When the car is accelerating or decelerating rapidly, the ACD begins to engage the limited-slip locking on the differential. The harder you accelerate or decelerate, the more it locks. This is done to provide maximum lateral stability and wheel traction. (Cool
The ACD allows the differential to operate in more of a free state when steering movements are made. When turning, the wheels in the front have to travel a further distance than the wheels in the rear. This is because the wheels in the front travel using a larger turning radius than the rear wheels as you can see from this picture. (turning radius.gif) So in order for smooth turning, the center differential needs to become open to allow for the front set to turn at a different speed. If you were to leave the center differential locked, the wheels would skip and skid badly.
Despite popular belief, this switch DOES NOT change the torque split. The differential is geared at 50:50 and cannot be changed by the push of a button. What this switch actually does is quite simple. Each setting determines how long the ACD will delay in freeing the center differential after a steering input is made. In addition, it will determine how much locking force the ACD will exhibit on the clutch pack and center differential.
Tarmac is the setting to be used in dry, paved conditions. In this setting, the ACD will almost immediately allow the center differential to go into a free state upon detecting a steering input. Additionally, this mode provides the strongest limited-slip clamping force of the three modes.
.
Gravel is the setting designed for wet or loose roads. In this setting, the ACD will delay in freeing the center differential for a moment (possibly 2-3 seconds). Of the three modes, this one has the second strongest clamping force.
Snow is the setting designed for, you guessed it, snow. In this setting, the ACD will delay in freeing the center differential for much longer than the other two settings (possibly 4-5 seconds). Of the three modes, this one also provides the least amount of clamping power. "
Gravel is fastest. Test it. It's true. staatz was at the track when I did the test. I have the timeslips to prove it. There were several others there as well whom I explained the test to. I encourage everyone to run Tarmac vs Gravel and post results. Well documented thus far that gravel is a couple tenths faster. Road & Track and Motor Trend also stated that they ran their straight line acceleration tests FASTEST/QUICKEST in Gravel setting.
Here is a more detailed tech info about how the ACD works... I hope it will help for the confusion about the ACD
"
In short, the ACD unit hydraulically controls the limited-slip locking state of the center differential which ranges between full locked, full open, and every point in between these two states. It calculates what the optimum locking amount would be using real-time input from the previously mentioned sensors and which ACD mode is selected. The ACD is extremely fast in operation, bettering the performance of the standard VCU and Viscous units.
When the car is accelerating or decelerating rapidly, the ACD begins to engage the limited-slip locking on the differential. The harder you accelerate or decelerate, the more it locks. This is done to provide maximum lateral stability and wheel traction. (Cool
The ACD allows the differential to operate in more of a free state when steering movements are made. When turning, the wheels in the front have to travel a further distance than the wheels in the rear. This is because the wheels in the front travel using a larger turning radius than the rear wheels as you can see from this picture. (turning radius.gif) So in order for smooth turning, the center differential needs to become open to allow for the front set to turn at a different speed. If you were to leave the center differential locked, the wheels would skip and skid badly.
Despite popular belief, this switch DOES NOT change the torque split. The differential is geared at 50:50 and cannot be changed by the push of a button. What this switch actually does is quite simple. Each setting determines how long the ACD will delay in freeing the center differential after a steering input is made. In addition, it will determine how much locking force the ACD will exhibit on the clutch pack and center differential.
Tarmac is the setting to be used in dry, paved conditions. In this setting, the ACD will almost immediately allow the center differential to go into a free state upon detecting a steering input. Additionally, this mode provides the strongest limited-slip clamping force of the three modes.
.
Gravel is the setting designed for wet or loose roads. In this setting, the ACD will delay in freeing the center differential for a moment (possibly 2-3 seconds). Of the three modes, this one has the second strongest clamping force.
Snow is the setting designed for, you guessed it, snow. In this setting, the ACD will delay in freeing the center differential for much longer than the other two settings (possibly 4-5 seconds). Of the three modes, this one also provides the least amount of clamping power. "
"
In short, the ACD unit hydraulically controls the limited-slip locking state of the center differential which ranges between full locked, full open, and every point in between these two states. It calculates what the optimum locking amount would be using real-time input from the previously mentioned sensors and which ACD mode is selected. The ACD is extremely fast in operation, bettering the performance of the standard VCU and Viscous units.
When the car is accelerating or decelerating rapidly, the ACD begins to engage the limited-slip locking on the differential. The harder you accelerate or decelerate, the more it locks. This is done to provide maximum lateral stability and wheel traction. (Cool
The ACD allows the differential to operate in more of a free state when steering movements are made. When turning, the wheels in the front have to travel a further distance than the wheels in the rear. This is because the wheels in the front travel using a larger turning radius than the rear wheels as you can see from this picture. (turning radius.gif) So in order for smooth turning, the center differential needs to become open to allow for the front set to turn at a different speed. If you were to leave the center differential locked, the wheels would skip and skid badly.
Despite popular belief, this switch DOES NOT change the torque split. The differential is geared at 50:50 and cannot be changed by the push of a button. What this switch actually does is quite simple. Each setting determines how long the ACD will delay in freeing the center differential after a steering input is made. In addition, it will determine how much locking force the ACD will exhibit on the clutch pack and center differential.
Tarmac is the setting to be used in dry, paved conditions. In this setting, the ACD will almost immediately allow the center differential to go into a free state upon detecting a steering input. Additionally, this mode provides the strongest limited-slip clamping force of the three modes.
.
Gravel is the setting designed for wet or loose roads. In this setting, the ACD will delay in freeing the center differential for a moment (possibly 2-3 seconds). Of the three modes, this one has the second strongest clamping force.
Snow is the setting designed for, you guessed it, snow. In this setting, the ACD will delay in freeing the center differential for much longer than the other two settings (possibly 4-5 seconds). Of the three modes, this one also provides the least amount of clamping power. "