UPDATE FD 3.54 ....Awesome!!!!..
#61
05-11-2011, 11:22 PM
#62
05-12-2011, 12:27 AM
https://g35driver.com/forums/drivetr...tial-swap.html
#63
05-12-2011, 09:46 AM
You can definitely overgear a car to the point that it's slower. Basically too much gear causes the motor to go thru the powerband way too quickly. This is also partly the reason for why adding a deeper gear causes a slight reduction in topend acceleration. What ends up happening, like you said, is maximum speed in each gear is reduced. In the taller gears, this can be problematic because they're simply too tall, even with the deeper rear gear set. It also forces an extra shift in the 1/4 mile which isn't exactly ideal. With the 3.3 gear set, 3rd is good to around 101mph. With the 3.54 gear set, it's good to about 94mph. Since these 5AT easily get 94mph in the 1/4 mile (mine does nearly 100mph), that means a shift into a much 4th and acceleration does tail off a bit. In a highway roll from 60mph, the 3.3 car would probably pull the 3.54 geared car to 105mph. However, from a stop to 105mph, the 3.54 car might have a slight advantage because it would likely be quicker to 50mph. It's hard to explain without showing a bunch of math with calculations for torque multiplication, gear ratios, and wtq/whp. In the end, one must be careful when choosing gear ratios. There's a fine line between too little and too much.
#64
05-12-2011, 11:27 AM
You can definitely overgear a car to the point that it's slower. Basically too much gear causes the motor to go thru the powerband way too quickly. This is also partly the reason for why adding a deeper gear causes a slight reduction in topend acceleration. What ends up happening, like you said, is maximum speed in each gear is reduced. In the taller gears, this can be problematic because they're simply too tall, even with the deeper rear gear set. It also forces an extra shift in the 1/4 mile which isn't exactly ideal. With the 3.3 gear set, 3rd is good to around 101mph. With the 3.54 gear set, it's good to about 94mph. Since these 5AT easily get 94mph in the 1/4 mile (mine does nearly 100mph), that means a shift into a much 4th and acceleration does tail off a bit. In a highway roll from 60mph, the 3.3 car would probably pull the 3.54 geared car to 105mph. However, from a stop to 105mph, the 3.54 car might have a slight advantage because it would likely be quicker to 50mph. It's hard to explain without showing a bunch of math with calculations for torque multiplication, gear ratios, and wtq/whp. In the end, one must be careful when choosing gear ratios. There's a fine line between too little and too much.
P.s. dave not to get off topic but how was the update on the sprint booster kit? did you have to change the pedal or what, im looking into a Blitz throttle controler.
#67
05-13-2011, 05:48 PM
Registered User
You can definitely overgear a car to the point that it's slower. Basically too much gear causes the motor to go thru the powerband way too quickly. This is also partly the reason for why adding a deeper gear causes a slight reduction in topend acceleration. What ends up happening, like you said, is maximum speed in each gear is reduced. In the taller gears, this can be problematic because they're simply too tall, even with the deeper rear gear set. It also forces an extra shift in the 1/4 mile which isn't exactly ideal. With the 3.3 gear set, 3rd is good to around 101mph. With the 3.54 gear set, it's good to about 94mph. Since these 5AT easily get 94mph in the 1/4 mile (mine does nearly 100mph), that means a shift into a much 4th and acceleration does tail off a bit. In a highway roll from 60mph, the 3.3 car would probably pull the 3.54 geared car to 105mph. However, from a stop to 105mph, the 3.54 car might have a slight advantage because it would likely be quicker to 50mph. It's hard to explain without showing a bunch of math with calculations for torque multiplication, gear ratios, and wtq/whp. In the end, one must be careful when choosing gear ratios. There's a fine line between too little and too much.
Sorry Dave I'm just not seeing it... (don't get offended, I love constructive conversation).
Yes I certainly agree you can overgear a car, just like you can undergear one. But all things being equal (weight, torque, temp, driver skill, traction, etc..)on a G35, concerning the factory gear ratios available (3.3-3.9) for our cars, the shorter geared car will accelerate faster than one with taller gears. Both from a stop and on a roll. For sake of argument let's say up to 120mph.
Most people who have done the swap seem to acknowledge this. And this holds true on paper as well.
Consistent real life experience is always best for those that care to chime in.
#68
05-14-2011, 12:00 AM
Sorry Dave I'm just not seeing it... (don't get offended, I love constructive conversation).
Yes I certainly agree you can overgear a car, just like you can undergear one. But all things being equal (weight, torque, temp, driver skill, traction, etc..)on a G35, concerning the factory gear ratios available (3.3-3.9) for our cars, the shorter geared car will accelerate faster than one with taller gears. Both from a stop and on a roll. For sake of argument let's say up to 120mph.
Most people who have done the swap seem to acknowledge this. And this holds true on paper as well.
Consistent real life experience is always best for those that care to chime in.
Yes I certainly agree you can overgear a car, just like you can undergear one. But all things being equal (weight, torque, temp, driver skill, traction, etc..)on a G35, concerning the factory gear ratios available (3.3-3.9) for our cars, the shorter geared car will accelerate faster than one with taller gears. Both from a stop and on a roll. For sake of argument let's say up to 120mph.
Most people who have done the swap seem to acknowledge this. And this holds true on paper as well.
Consistent real life experience is always best for those that care to chime in.
I've got a set of 23.5" tall drag radials which give my car an effective gear ratio of around a 3.55 (car had the 3.34 gear set at the time). On same day at the strip, I did four runs with the 26.3" tall OEM 17s and 3 runs with the DRs, which were also 15lbs lighter each than the 17s. The car did consistent higher 14.4s and lower 14.5s@97-98mph with low 2.2 60 foots with the 17s. With the DRs, the car did consistent lower 14.5s at higher 96mph with mid 2.1 60 foots. It never could break into the 14.4s. The car was quicker off the line, in the 1/8 mile, just the same as the 17s at the 1000' mark, but the killer was the forced shift to 4th about 150 feet short of the finish. It crippled both ET and MPH.
Years ago, my friend had a 90 LX 5.0 nothback 5MT. It was basically stock except for a catback, pullies, and hacked airbox. It came stock with 3.27s. It did 14.0s@98mph with the stock gears. He then added 3.73s. The car totally woke up and felt awesome in 1st, 2nd, and 3rd. After that, acceleration tailed off. With the 3.73s it did 14.2s@97. 60 foots were better, it was quicker in the 1/8th, but since he had to run through a lot of 4th, the car slowed down. The 3.73s were just too much gear for that 5.0 that peaked at around 5000rpms. No problem though, he added a heavier breathing cam, intake manifold, valvetrain stuff which extended power to around 6500rpms and it was doing mid 13s. With extra breathing allowed the motor to fully use the deeper gears.
The only reason I went with the 3.54s in my G was because I wanted snappier daily driving, more gearing would help in the auto-x (sub 65mph racing), and I wanted the LSD (huge help in the auto-x). I haven't been to the strip in 2 years. I may try it again with my DRs which would effective gear the car to a 3.75.
Some cars come from the factory woefully undergeared. The 98-00 Cobras are prime examples. They come with 3.27s, but the motor makes good power in the mid to upper rpms and revs out 7000rpms. The long gear don't allow the motor to get into the meat of it's powerband quickly nor fully exploit the powerband. Adding a 4.X series gear will easily shed .3 seconds and add 1-2mph in the 1/4 mile. The G and Z aren't those cars, at least with stock cammed VQs. Nissan did a pretty good job gearing these cars for strong acceleration while trying to maintain some MPG sanity. There aren't many other V6 sport luxury sedan/coupes out there that perform as with just 260-280hp. Since these cars are already decently geared stock, they don't make significant gains when adding deeper gears. They definitely feel quicker since there's more torque multiplication therefore seat of the pants acceleration 'feels' more impressive. Put that feel under the clock and you'll see that the two don't necessarily agree. My friend's 5.0 felt downright brutal in every gear. It felt far quicker than 14.2s. All that torque multiplication mislead the mind.
Last edited by DaveB; 05-14-2011 at 12:00 PM.
#69
05-15-2011, 01:11 AM
Agree to disagree
I've got a set of 23.5" tall drag radials which give my car an effective gear ratio of around a 3.55 (car had the 3.34 gear set at the time). On same day at the strip, I did four runs with the 26.3" tall OEM 17s and 3 runs with the DRs, which were also 15lbs lighter each than the 17s. The car did consistent higher 14.4s and lower 14.5s@97-98mph with low 2.2 60 foots with the 17s. With the DRs, the car did consistent lower 14.5s at higher 96mph with mid 2.1 60 foots. It never could break into the 14.4s. The car was quicker off the line, in the 1/8 mile, just the same as the 17s at the 1000' mark, but the killer was the forced shift to 4th about 150 feet short of the finish. It crippled both ET and MPH.
Years ago, my friend had a 90 LX 5.0 nothback 5MT. It was basically stock except for a catback, pullies, and hacked airbox. It came stock with 3.27s. It did 14.0s@98mph with the stock gears. He then added 3.73s. The car totally woke up and felt awesome in 1st, 2nd, and 3rd. After that, acceleration tailed off. With the 3.73s it did 14.2s@97. 60 foots were better, it was quicker in the 1/8th, but since he had to run through a lot of 4th, the car slowed down. The 3.73s were just too much gear for that 5.0 that peaked at around 5000rpms. No problem though, he added a heavier breathing cam, intake manifold, valvetrain stuff which extended power to around 6500rpms and it was doing mid 13s. With extra breathing allowed the motor to fully use the deeper gears.
The only reason I went with the 3.54s in my G was because I wanted snappier daily driving, more gearing would help in the auto-x (sub 65mph racing), and I wanted the LSD (huge help in the auto-x). I haven't been to the strip in 2 years. I may try it again with my DRs which would effective gear the car to a 3.75.
Some cars come from the factory woefully undergeared. The 98-00 Cobras are prime examples. They come with 3.27s, but the motor makes good power in the mid to upper rpms and revs out 7000rpms. The long gear don't allow the motor to get into the meat of it's powerband quickly nor fully exploit the powerband. Adding a 4.X series gear will easily shed .3 seconds and add 1-2mph in the 1/4 mile. The G and Z aren't those cars, at least with stock cammed VQs. Nissan did a pretty good job gearing these cars for strong acceleration while trying to maintain some MPG sanity. There aren't many other V6 sport luxury sedan/coupes out there that perform as with just 260-280hp. Since these cars are already decently geared stock, they don't make significant gains when adding deeper gears. They definitely feel quicker since there's more torque multiplication therefore seat of the pants acceleration 'feels' more impressive. Put that feel under the clock and you'll see that the two don't necessarily agree. My friend's 5.0 felt downright brutal in every gear. It felt far quicker than 14.2s. All that torque multiplication mislead the mind.
I've got a set of 23.5" tall drag radials which give my car an effective gear ratio of around a 3.55 (car had the 3.34 gear set at the time). On same day at the strip, I did four runs with the 26.3" tall OEM 17s and 3 runs with the DRs, which were also 15lbs lighter each than the 17s. The car did consistent higher 14.4s and lower 14.5s@97-98mph with low 2.2 60 foots with the 17s. With the DRs, the car did consistent lower 14.5s at higher 96mph with mid 2.1 60 foots. It never could break into the 14.4s. The car was quicker off the line, in the 1/8 mile, just the same as the 17s at the 1000' mark, but the killer was the forced shift to 4th about 150 feet short of the finish. It crippled both ET and MPH.
Years ago, my friend had a 90 LX 5.0 nothback 5MT. It was basically stock except for a catback, pullies, and hacked airbox. It came stock with 3.27s. It did 14.0s@98mph with the stock gears. He then added 3.73s. The car totally woke up and felt awesome in 1st, 2nd, and 3rd. After that, acceleration tailed off. With the 3.73s it did 14.2s@97. 60 foots were better, it was quicker in the 1/8th, but since he had to run through a lot of 4th, the car slowed down. The 3.73s were just too much gear for that 5.0 that peaked at around 5000rpms. No problem though, he added a heavier breathing cam, intake manifold, valvetrain stuff which extended power to around 6500rpms and it was doing mid 13s. With extra breathing allowed the motor to fully use the deeper gears.
The only reason I went with the 3.54s in my G was because I wanted snappier daily driving, more gearing would help in the auto-x (sub 65mph racing), and I wanted the LSD (huge help in the auto-x). I haven't been to the strip in 2 years. I may try it again with my DRs which would effective gear the car to a 3.75.
Some cars come from the factory woefully undergeared. The 98-00 Cobras are prime examples. They come with 3.27s, but the motor makes good power in the mid to upper rpms and revs out 7000rpms. The long gear don't allow the motor to get into the meat of it's powerband quickly nor fully exploit the powerband. Adding a 4.X series gear will easily shed .3 seconds and add 1-2mph in the 1/4 mile. The G and Z aren't those cars, at least with stock cammed VQs. Nissan did a pretty good job gearing these cars for strong acceleration while trying to maintain some MPG sanity. There aren't many other V6 sport luxury sedan/coupes out there that perform as with just 260-280hp. Since these cars are already decently geared stock, they don't make significant gains when adding deeper gears. They definitely feel quicker since there's more torque multiplication therefore seat of the pants acceleration 'feels' more impressive. Put that feel under the clock and you'll see that the two don't necessarily agree. My friend's 5.0 felt downright brutal in every gear. It felt far quicker than 14.2s. All that torque multiplication mislead the mind.
#70
05-15-2011, 01:54 PM
Registered User
#72
05-15-2011, 02:14 PM
Registered User
#73
05-15-2011, 02:26 PM
#74
05-15-2011, 03:31 PM
Yes, just did it last night. Went from an open 3.3 to the VLSD 3.54 and I am very happy with the results. Well worth the $300 spent.