Video.. My G vs GT mustang.
Originally Posted by Klubbheads
Aston Martin Vanquish:
The electrohydraulic gearshift is basically the same Magneti Marelli system used in the Ferrari 360 Modena F1 -- two pedals only,
Ferrari 575: SMG tranny
Notice non of them are autotragic?
The electrohydraulic gearshift is basically the same Magneti Marelli system used in the Ferrari 360 Modena F1 -- two pedals only,
Ferrari 575: SMG tranny
Notice non of them are autotragic?
Dave already had that info. So it looks like you have to cut the ave manual shift time by more than 1/2
The JATCO 5AT in the G/Z can complete an upshift in about 200 milliseconds assuming you're a WOT. Shift speed is usually based off of line pressure which is based off of engine vacuum, throttle position, load, etc. The higher the line pressure, the quicker the shift. The JATCO 5AT doesn't behave like your Mom's Grand Caravan 4AT. I'll agree that there are many lazy autos out there, but the JATCO isn't one of them.
Here are some of the advantages of an auto:
1) Quick shift speed. Thanks to the design, the next gear is always engaged so the upshift can be completed almost instantly. This is why you don't get the rocking motion/load shift on each shift like you do with a manual. The DSG trannies behave basically the same way. Newer autos are now able to execute upshifts and downshifts as quickly as 50 milliseconds. I imagine the upcoming JATCO 7AT will be able to this because the current 5AT in the 2nd gen G is almost there.
2) Torque converter. A TC is a torque multiplication device and can increase wtq on the initial launch (0 to 5mph) be around 2.5X to 3X. This is what is commonly refered to as stalling up the TC. The TC in the G is very efficent and has a high stall rpm (~2,800rpm). Both of these are good traits for drag racing.
3) TC locking. All TCs will lock at part throttle and will have a direct connection to the engine (like a manual) at cruise. This improves MPG. The JATCO 5AT takes it one step further by locking 2nd (top of 2nd gear only), 3rd, and 4th gears at WOT. This greatly improves acceleration in the upper rpms. This is why the 5ATs typically see similiar traps speeds to the 6MT.
4) Gearing. The 5AT is ideally geared for maximum acceleration. Lots of autos are geared for MPG and cruising. The JATCO 5AT in the G is not.
5) Weight. The compact 5AT weighs about 35lbs less than the 6MT.
Here are some of the advantages of an auto:
1) Quick shift speed. Thanks to the design, the next gear is always engaged so the upshift can be completed almost instantly. This is why you don't get the rocking motion/load shift on each shift like you do with a manual. The DSG trannies behave basically the same way. Newer autos are now able to execute upshifts and downshifts as quickly as 50 milliseconds. I imagine the upcoming JATCO 7AT will be able to this because the current 5AT in the 2nd gen G is almost there.
2) Torque converter. A TC is a torque multiplication device and can increase wtq on the initial launch (0 to 5mph) be around 2.5X to 3X. This is what is commonly refered to as stalling up the TC. The TC in the G is very efficent and has a high stall rpm (~2,800rpm). Both of these are good traits for drag racing.
3) TC locking. All TCs will lock at part throttle and will have a direct connection to the engine (like a manual) at cruise. This improves MPG. The JATCO 5AT takes it one step further by locking 2nd (top of 2nd gear only), 3rd, and 4th gears at WOT. This greatly improves acceleration in the upper rpms. This is why the 5ATs typically see similiar traps speeds to the 6MT.
4) Gearing. The 5AT is ideally geared for maximum acceleration. Lots of autos are geared for MPG and cruising. The JATCO 5AT in the G is not.
5) Weight. The compact 5AT weighs about 35lbs less than the 6MT.
Jeff92se I just timed myself with a stop watch when i was granny shifting on my way to home for lunch and my average grannyshift was 0.90 seconds. This is when i shift smooth and without jerking the car at all. The way i counted was the timer started i pressed the clutch and stopped when i released the clutch after getting into the next gear.
I would love to see where DaveB got that info from and the credibility of his source because i find it hard to believe that 30k family sedan shifts faster than ferrari 575 having regular automatic tranny with TC.
I would love to see where DaveB got that info from and the credibility of his source because i find it hard to believe that 30k family sedan shifts faster than ferrari 575 having regular automatic tranny with TC.
.9 sec = 900 milliseconds. Give or take depending on how you timed yourself. I can't really say you would be conservative. Cutting your time by 50% would give you 450 ms.
But yeah, I looked for a time for a TC auto but I couldn't find it. I know I've discussed it before on another forum.
But yeah, I looked for a time for a TC auto but I couldn't find it. I know I've discussed it before on another forum.
Originally Posted by Jeff92se
.9 sec = 900 milliseconds. Give or take depending on how you timed yourself. I can't really say you would be conservative. Cutting your time by 50% would give you 450 ms.
But yeah, I looked for a time for a TC auto but I couldn't find it. I know I've discussed it before on another forum.
But yeah, I looked for a time for a TC auto but I couldn't find it. I know I've discussed it before on another forum.
The reason i did not time myself while shifting agressively is because i would like to have atleast one hand on the wheel and for that i will have a friend time me when im shifting as i would while drag racing.
Originally Posted by Jeff92se
Are you stating that for something like a built turbo 400 equipped muscle car is going to be at a disadvantage to a muscle car with a 4 speed?
If both are stripped, weigh the same, using slicks, etc, then I'd probably bet on the Auto (or better yet, hydraulic/sequential/etc) tranny.
Being turbo, the Auto has no spool-up delay.
E.g. the 997TT auto is faster than the MT in a straight line.
Originally Posted by Jeff92se
More power is not really the way you want to describe it. Put both engines on an engine dyno and measure it. I think you want to say the manual has less driveline loss. But once the auto locks, there should be no more losses vs the manual.
Right in that the LOSS is the same when the auto locks.
The auto NEVER locks at WOT.
Only for cruising and LIGHT acceleration.
Originally Posted by Mike@RiversideInfiniti
That would depend on how exactly the cars are equipped.
If both are stripped, weigh the same, using slicks, etc, then I'd probably bet on the Auto (or better yet, hydraulic/sequential/etc) tranny.
Being turbo, the Auto has no spool-up delay.
E.g. the 997TT auto is faster than the MT in a straight line.
If both are stripped, weigh the same, using slicks, etc, then I'd probably bet on the Auto (or better yet, hydraulic/sequential/etc) tranny.
Being turbo, the Auto has no spool-up delay.
E.g. the 997TT auto is faster than the MT in a straight line.
How are you still trying to argue that an Auto tranny in a mildly modded G35 is better then MT...
were not talking about 1000rwhp supras...were talking about slow g35's
were not talking about 1000rwhp supras...were talking about slow g35's
Originally Posted by UFmark
How are you still trying to argue that an Auto tranny in a mildly modded G35 is better then MT...
were not talking about 1000rwhp supras...were talking about slow g35's
were not talking about 1000rwhp supras...were talking about slow g35's
Originally Posted by Mike@RiversideInfiniti
Right and Wrong.
Right in that the LOSS is the same when the auto locks.
The auto NEVER locks at WOT.
Only for cruising and LIGHT acceleration.
Right in that the LOSS is the same when the auto locks.
The auto NEVER locks at WOT.
Only for cruising and LIGHT acceleration.
Wow, this has really turned into a heated debate. Yes, the 5AT will complete the upshift in about 200 milliseconds which is pretty damn slow when you realize the 7AT auto (read TORQUE CONVERTER) in the Lexus IS-F completes the same freaking feat in 8 milliseconds. Yes, 8. Why can't you guys understand that autos tend to execute shifts faster than even the most trained driver performing powershifts? Like I've said, time and time again, the tranny is already in the next gear so when the accelerating gear is disengaged, the next gear is there. Why do you think there's no bobbing of the chassis when the shift is completed? Need I make a video of me in the car executing the shifts? I use to drag race manual cars and I've probably got a few hundred extra passes on 99% of the guys on this site and I'm pretty certain that I cannot complete a powershift upshift in 200ms.
I am in no way saying that the auto is better than the 6MT for drag racing or road racing, but a lot of you 6MT drivers don't give it any credit and I constantly read how doggishly slow it is which is absolutely false. Yes, the quickest NA G is a 6MT. That's no suprise to me because I've told the driver (Trey) for years that his car had the potential to run those times with drag radials and a high rpm launch. And right there is why the 6MT has the biggest advantage at the drag strip, assuming NA bolt-ons. The 6MT can increase it's torque multiplication by simply raising launch rpm, assuming you've got the traction. The auto is limited by the brake/acceleratior nanny and the 2800rpm stall TC. Add a 4000rpm stall and the 5AT would leap off the line harder than Trey's 6MT. Why? Because the TC is a torque multiplication device and can multiply torque by 2.5X. That's huge. Throw a turbo into the mix and the turbo G is going to be quicker.
I have raced my G at the strip 4 times and made about 20 passes. Two of the times I was there (stock except for a Z-tube), a coupe 6MT and a 6MT sedan were there. Our ETs and MPHs were within a couple tenths (going back and forth against each other) and MPHs were within .5mph. Any gearhead knows that you can't really f-up trapspeed. ET is heavily influenced, but not trap. I fail to see how stock or mildly modded 6MT is going to pull away decisively in the 1/4 mile if the 5AT driver has a clue. Racing the auto isn't hard and neither is racing a manual, but you have to know what you're doing with both trannies. Launching off idle and letting the tranny shift itself, results in mid 2.3 60 foots and 14.6-14.7@96mph. If I flash the TC to around 2400rpms and manually shift the 2-3 and hold 3rd, the car will do low to high 14.3s at 98-99mph. Additionally, my track is nothing special at all. It's average. Yes, some tracks are quicker than others. When I had my 94 Z28, it ran 13.7s@101mph here in Kansas City. I then ran at an F-Body event at Houston Raceway Park (sea level, basically coastal) and the car was running 13.4s@103-104mph in hotter weather. Yes, some tracks are quicker than others.
As for gearing, the stock 5AT is pretty damn ideal for the 1/4 mile and the 6MT is not. If you don't believe me, do the calculations yourself. i've experimented with different gearing in my G. I took my 23.8" tall BFG DRs mounted on 15" rims and ran at the strip. The short tires effectively geared my car like it had a 3.55 gear. I made a few passes with the 26.2" OEM 17s (49lb combo) and then my 225/50R15 DRs (34lbs). My car was .2 second and 2mph slower with the DR. Why? Because the tires forced a shift into 4th gear a few hundred feet short of the finish. The tall gearing of 4th plus the extra shift hurt my times and ET.
I'll end by saying don't let your butt fool you into thinking the 6MT is significantly quicker or faster. The additional torque multiplication and shorter gears gives the sensation of going much faster, but you're not. Go ride in a stock 5.0 with a OEM 3.08 gear and then one with a 3.73 gear. You'd swear the 3.73 equipped car was worlds quicker because it revs out so quickly. However, the timing lights will tell the truth. About .1 second and 1mph. You'd swear it felt 1 second quicker.
I am in no way saying that the auto is better than the 6MT for drag racing or road racing, but a lot of you 6MT drivers don't give it any credit and I constantly read how doggishly slow it is which is absolutely false. Yes, the quickest NA G is a 6MT. That's no suprise to me because I've told the driver (Trey) for years that his car had the potential to run those times with drag radials and a high rpm launch. And right there is why the 6MT has the biggest advantage at the drag strip, assuming NA bolt-ons. The 6MT can increase it's torque multiplication by simply raising launch rpm, assuming you've got the traction. The auto is limited by the brake/acceleratior nanny and the 2800rpm stall TC. Add a 4000rpm stall and the 5AT would leap off the line harder than Trey's 6MT. Why? Because the TC is a torque multiplication device and can multiply torque by 2.5X. That's huge. Throw a turbo into the mix and the turbo G is going to be quicker.
I have raced my G at the strip 4 times and made about 20 passes. Two of the times I was there (stock except for a Z-tube), a coupe 6MT and a 6MT sedan were there. Our ETs and MPHs were within a couple tenths (going back and forth against each other) and MPHs were within .5mph. Any gearhead knows that you can't really f-up trapspeed. ET is heavily influenced, but not trap. I fail to see how stock or mildly modded 6MT is going to pull away decisively in the 1/4 mile if the 5AT driver has a clue. Racing the auto isn't hard and neither is racing a manual, but you have to know what you're doing with both trannies. Launching off idle and letting the tranny shift itself, results in mid 2.3 60 foots and 14.6-14.7@96mph. If I flash the TC to around 2400rpms and manually shift the 2-3 and hold 3rd, the car will do low to high 14.3s at 98-99mph. Additionally, my track is nothing special at all. It's average. Yes, some tracks are quicker than others. When I had my 94 Z28, it ran 13.7s@101mph here in Kansas City. I then ran at an F-Body event at Houston Raceway Park (sea level, basically coastal) and the car was running 13.4s@103-104mph in hotter weather. Yes, some tracks are quicker than others.
As for gearing, the stock 5AT is pretty damn ideal for the 1/4 mile and the 6MT is not. If you don't believe me, do the calculations yourself. i've experimented with different gearing in my G. I took my 23.8" tall BFG DRs mounted on 15" rims and ran at the strip. The short tires effectively geared my car like it had a 3.55 gear. I made a few passes with the 26.2" OEM 17s (49lb combo) and then my 225/50R15 DRs (34lbs). My car was .2 second and 2mph slower with the DR. Why? Because the tires forced a shift into 4th gear a few hundred feet short of the finish. The tall gearing of 4th plus the extra shift hurt my times and ET.
I'll end by saying don't let your butt fool you into thinking the 6MT is significantly quicker or faster. The additional torque multiplication and shorter gears gives the sensation of going much faster, but you're not. Go ride in a stock 5.0 with a OEM 3.08 gear and then one with a 3.73 gear. You'd swear the 3.73 equipped car was worlds quicker because it revs out so quickly. However, the timing lights will tell the truth. About .1 second and 1mph. You'd swear it felt 1 second quicker.
Last edited by DaveB; May 6, 2008 at 09:06 PM.
Registered User
Joined: Jan 2006
Posts: 394
Likes: 0
Um, the bobbing is not there in the AT because the torque converter is a fluid connection and thus the revs are "blended" together much like slowly feathering the clutch would do.
We have both an Infiniti 5AT and a 6mt in the family and there's no way the 5AT in *OUR* infiniti comes anywhere close to shifting as quickly as I can in our other infiniti.
Can you explain how the tranny is "in the next gear already" in detail? I fully understand how that happens in a DSG-type transmission but with planetary gear + torque converter-based trannies, I've actually not heard anyone claim they are in the next gear already.
The GTR has a true DSG-style (dual clutch computer-controlled) transmission and it shifts in 100ms or less, which is about as fast as any human is going to shift a manual tranny.
We have both an Infiniti 5AT and a 6mt in the family and there's no way the 5AT in *OUR* infiniti comes anywhere close to shifting as quickly as I can in our other infiniti.
Can you explain how the tranny is "in the next gear already" in detail? I fully understand how that happens in a DSG-type transmission but with planetary gear + torque converter-based trannies, I've actually not heard anyone claim they are in the next gear already.
The GTR has a true DSG-style (dual clutch computer-controlled) transmission and it shifts in 100ms or less, which is about as fast as any human is going to shift a manual tranny.
Registered User
Joined: May 2008
Posts: 31
Likes: 0
From: EARTH
This is funny, especially about manuals being faster in 1/4 track than auto w/ equal mods done to each car because it has more HORSEPOWER.
My other car (Z28~4L60e)dynoed w/ the best of 317 rwhp/316 but ran at the track 12.2 @ 110 MPH. My GM slow piece is weighing at 3540lbs w/ me in it (half tank of gas, full weight w/ 18s on the front and 17s on the back fitted w/ drag radials). This is also still on stock suspension.
Mods: lid, intake, full exhaust, Yank converter, 3.42 rear and a tune.
My other car (Z28~4L60e)dynoed w/ the best of 317 rwhp/316 but ran at the track 12.2 @ 110 MPH. My GM slow piece is weighing at 3540lbs w/ me in it (half tank of gas, full weight w/ 18s on the front and 17s on the back fitted w/ drag radials). This is also still on stock suspension.
Mods: lid, intake, full exhaust, Yank converter, 3.42 rear and a tune.