3.3 vsld vs 3.5
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From: curl lookin boy
3.3 vsld vs 3.5
Sorry if this is a dumb post, but what is the difference if both are redlined to 7500rpm. Would the speeds be different? And what kind of top end difference would there be between the two.
http://www.f-body.org/gears/
plug in your tire size
the final drive ratio (3.357, 3.538, 3.917, or 3.7xx? - not sure what the 3.7 is exactly)
then the redline and gear ratios which are
3.794
2.324
1.624
1.271
1
.794
the top speeds at 7500 rpms with 295/35/18 tires with these final drives are:
3.357 FD:
46
75
107
137
174
219
3.538 FD:
43
71
101
130
165
207
3.917 FD:
39
64
92
117
149
187
long story short, in most cases with a turbo for most types of driving, the stock 3.5 FD will be the more ideal choice in terms of accelleration from different speeds. The 3.9 will give you way better accelleration at higher speeds but you'll be more likely to lose traction in lower gears with turbo setups because of the high amount of torque. The 3.3 will give you better gas mileage, less shifting under certain distances (in some cases with the 1/4 mile you won't have to shift into 5th gear which has improved people's 1/4 mile times by roughly 0-.1 seconds faster and gain around 2mph in trap speed). The 3.3 will obviously give you the highest top speed if your car has enough power to reach it (219 mph at 7500 rpms) Otherwise IMO with two otherwise equal cars, the 3.9 FD will just about always reach 160-180mph before the other FD's but after that the 3.3 and 3.5 will continue to slowly go faster onto their higher top speed
The 3.3 will give you more traction though since less power is going to be muliplied to the ground and some people are desperate for any traction they can get so they'll choose the 3.3 anyway
The 3.9 also has an advantage with a centrifugal supercharger like the vortech or ATI procharger because it will bring the rpms higher which means you'll be higher into the boost and also put down more gear torque. The 3.3 likewise will lower your rpms at a given speed and reduce your gear torque accelleration.
I have a text file somewhere full of some averages between the 3.3, 3.5, and 3.9 FD and then from different speed ranges like say you raced someone from 40-120mph, or 80-140, or 0-100, or 0-125, etc etc and then figuring the rpm/gear you'd be starting and ending in and adding up all the gear ratios that you'd go through, and multiply them by the FD, then divide by the number of gears used, and then seeing which scenerios would generate the most total gear multiplication assuming there was 100% traction.
I did something like 15 different scenerios and the 3.9 actually edged out the 3.5 FD by a couple scenerios but was generally very close to the 3.5 FD except for races that involved really high speeds like say 0-160, then the 3.9 really killed the other two because there were the same amount of gear changes total between the two. The 3.3 only had one race out of 15 where it had the advantage over the 3.5 and 3.9 FD. It was strictly gear ratios being calculated, so the type of FI had no bearing on my results which in the real world they would ....yeah I was bored at work
plug in your tire size
the final drive ratio (3.357, 3.538, 3.917, or 3.7xx? - not sure what the 3.7 is exactly)
then the redline and gear ratios which are
3.794
2.324
1.624
1.271
1
.794
the top speeds at 7500 rpms with 295/35/18 tires with these final drives are:
3.357 FD:
46
75
107
137
174
219
3.538 FD:
43
71
101
130
165
207
3.917 FD:
39
64
92
117
149
187
long story short, in most cases with a turbo for most types of driving, the stock 3.5 FD will be the more ideal choice in terms of accelleration from different speeds. The 3.9 will give you way better accelleration at higher speeds but you'll be more likely to lose traction in lower gears with turbo setups because of the high amount of torque. The 3.3 will give you better gas mileage, less shifting under certain distances (in some cases with the 1/4 mile you won't have to shift into 5th gear which has improved people's 1/4 mile times by roughly 0-.1 seconds faster and gain around 2mph in trap speed). The 3.3 will obviously give you the highest top speed if your car has enough power to reach it (219 mph at 7500 rpms) Otherwise IMO with two otherwise equal cars, the 3.9 FD will just about always reach 160-180mph before the other FD's but after that the 3.3 and 3.5 will continue to slowly go faster onto their higher top speed
The 3.3 will give you more traction though since less power is going to be muliplied to the ground and some people are desperate for any traction they can get so they'll choose the 3.3 anyway
The 3.9 also has an advantage with a centrifugal supercharger like the vortech or ATI procharger because it will bring the rpms higher which means you'll be higher into the boost and also put down more gear torque. The 3.3 likewise will lower your rpms at a given speed and reduce your gear torque accelleration.
I have a text file somewhere full of some averages between the 3.3, 3.5, and 3.9 FD and then from different speed ranges like say you raced someone from 40-120mph, or 80-140, or 0-100, or 0-125, etc etc and then figuring the rpm/gear you'd be starting and ending in and adding up all the gear ratios that you'd go through, and multiply them by the FD, then divide by the number of gears used, and then seeing which scenerios would generate the most total gear multiplication assuming there was 100% traction.
I did something like 15 different scenerios and the 3.9 actually edged out the 3.5 FD by a couple scenerios but was generally very close to the 3.5 FD except for races that involved really high speeds like say 0-160, then the 3.9 really killed the other two because there were the same amount of gear changes total between the two. The 3.3 only had one race out of 15 where it had the advantage over the 3.5 and 3.9 FD. It was strictly gear ratios being calculated, so the type of FI had no bearing on my results which in the real world they would ....yeah I was bored at work
Last edited by sentry65; Nov 24, 2006 at 03:05 PM.
. Thanx for the info guys.
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ok well I took a look back at my text file I made at work and after looking it over there's a few things that I guess should generally be pointed out from my findings anyway (people are free to disagree if they want, but I'm pretty sure this sorta thing is how a lot of race teams decide on what final drive they want for a particular track given the average speed ranges for that track)
Overall it looks like the 3.3 FD is the ideal choice for races that start in the 80-100 mph range and go up from there. It can start accellerating in 3rd gear where the other FD's would have to use the 21.3% weaker 4th gear which far outweighs the 3.3's weaker FD ratio.
The 3.9 seems to have the advantage (by 10.7%) when it starts at any speed between 0 and 50 mph and goes up to any speed after that.
The stock 3.5 is pretty much a compromise between the the 3.3 and 3.9 - not really being the best at any range or by much the few times that it is
but obviously your dyno and boost curves, traction, and budget will ultimately dictate what you should get, not just raw overall gear torque
I picked speed ranges where I'd choose the ideal gear for starting and ending for the given speed range. I tried to base things off of what you'd do in the real world in a race. Most people don't mind reving to 6800-7000 rpms in 1st-3rd gear, but usually won't do that in the upper gears unless maybe it's that last final gear you're in during a 1/4 mile run. I used 295/35/18 as the tire size that I based everything on. If your tires are taller, you'd have a higher top speed in each gear so you might possibly do better on 1 or 2 of these speed ranges. And if your tires are a lower profile, then your top speed in each gear would be less and you might do slightly worse in 1 or 2 of these speed ranges.
Like I said earlier, all I'm doing is calculating the gear multipliers with the final drive. The hp/tq that the engine makes or the weight of the car or drivetrain parts have no bearing on these results - either does how fast you can shift. Actually time isn't even really factored into any of this, but you can probably bet that if you have 100% traction and can make use of all the gear torque for whatever scenerios, the higher gear torque will accellerate you faster. So anyway, this just adds the gear ratios uses divided by the number of gears used in then multiply that by the final drive. Things can be made more accurate if you factored in exactly what % of these speed ranges you're in each gear etc, but meh that's pretty tedius and I don't really think it'll change the results a whole lot anyway...
one of the things that some people might be interested in is that the 0-125 mph scenerio where everyone with FI has gone to the 3.3 has ran faster times and if you calculate the gear ratios, that shows the same result, however the 3.9 is actually supposed to be the faster method to get down the 1/4 mile @ 125mph if you can manage to pull off 100% traction, however since the 1/4 mile is timed the time it takes for the extra shift probably won't make the 3.9 worth it over the 3.3 FD
The first image is the simple table that shows which final drive came in 1st, 2nd, and 3rd place for that particular speed range as far as total overall gear torque being put to the ground
the second image is a more detailed version of the first table showing the difference in % that one setup has over the setups with less total gear torque. For instance one car that got 1st place might be by a huge % or just barely was better than the 2nd place car
Overall it looks like the 3.3 FD is the ideal choice for races that start in the 80-100 mph range and go up from there. It can start accellerating in 3rd gear where the other FD's would have to use the 21.3% weaker 4th gear which far outweighs the 3.3's weaker FD ratio.
The 3.9 seems to have the advantage (by 10.7%) when it starts at any speed between 0 and 50 mph and goes up to any speed after that.
The stock 3.5 is pretty much a compromise between the the 3.3 and 3.9 - not really being the best at any range or by much the few times that it is
but obviously your dyno and boost curves, traction, and budget will ultimately dictate what you should get, not just raw overall gear torque
I picked speed ranges where I'd choose the ideal gear for starting and ending for the given speed range. I tried to base things off of what you'd do in the real world in a race. Most people don't mind reving to 6800-7000 rpms in 1st-3rd gear, but usually won't do that in the upper gears unless maybe it's that last final gear you're in during a 1/4 mile run. I used 295/35/18 as the tire size that I based everything on. If your tires are taller, you'd have a higher top speed in each gear so you might possibly do better on 1 or 2 of these speed ranges. And if your tires are a lower profile, then your top speed in each gear would be less and you might do slightly worse in 1 or 2 of these speed ranges.
Like I said earlier, all I'm doing is calculating the gear multipliers with the final drive. The hp/tq that the engine makes or the weight of the car or drivetrain parts have no bearing on these results - either does how fast you can shift. Actually time isn't even really factored into any of this, but you can probably bet that if you have 100% traction and can make use of all the gear torque for whatever scenerios, the higher gear torque will accellerate you faster. So anyway, this just adds the gear ratios uses divided by the number of gears used in then multiply that by the final drive. Things can be made more accurate if you factored in exactly what % of these speed ranges you're in each gear etc, but meh that's pretty tedius and I don't really think it'll change the results a whole lot anyway...
one of the things that some people might be interested in is that the 0-125 mph scenerio where everyone with FI has gone to the 3.3 has ran faster times and if you calculate the gear ratios, that shows the same result, however the 3.9 is actually supposed to be the faster method to get down the 1/4 mile @ 125mph if you can manage to pull off 100% traction, however since the 1/4 mile is timed the time it takes for the extra shift probably won't make the 3.9 worth it over the 3.3 FD
The first image is the simple table that shows which final drive came in 1st, 2nd, and 3rd place for that particular speed range as far as total overall gear torque being put to the ground
the second image is a more detailed version of the first table showing the difference in % that one setup has over the setups with less total gear torque. For instance one car that got 1st place might be by a huge % or just barely was better than the 2nd place car
Last edited by sentry65; Nov 27, 2006 at 03:48 PM.
then here's data I was going by with the gears used and what the final multiplication ratio is overall as well as the number of shifts
format is the final drive being used
gear ratios for that speed range divided by number of gears multiplied by FD
= final multiplication torque
and number of shifts for that speed range with that final drive
0-30 mph
3.538
3.794
=13.423
0 shifts
3.917
3.794
=14.861
0 shifts
3.357 3.794
=12.7364
0 shifts
0-45 mph
3.538
3.794
2.324
=10.8227
1 shift
3.917
3.794
2.324
=11.982
1 shift
3.357
3.794
2.324
=10.269
1 shift
0-60 mph
3.538
3.794
2.324
=10.8227
1 shift
3.917
3.794
2.324
=11.982
1 shift
3.357
3.794
2.324
=10.269
1 shift
0-80 mph
3.538
3.794
2.324
1.624
=9.13
2 shifts
3.917
3.794
2.324
1.624
=10.1084
2 shifts
3.357
3.794
2.324
1.624
=8.6632
2 shifts
0-100 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.971
3 shifts
3.917
3.794
2.324
1.624
1.271
=8.8259
3 shifts
3.357
3.794
2.324
1.624
=8.663
2 shifts
0-105 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.9719
3 shifts
3.917
3.794
2.324
1.624
1.271
=8.8259
3 shifts
3.357
3.794
2.324
1.624
1.271
=7.5641
3 shifts
0-112 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.9719
3 shifts
3.917
3.794
2.324
1.624
1.271
1
=7.844
4 shifts
3.357
3.794
2.324
1.624
1.271
=7.5641
3 shifts
0-118 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.9719985
3 shifts
3.917 3.794
2.324
1.624
1.271
1
=7.8441842
4 shifts
3.357 3.794
2.324
1.624
1.271
=7.56416025
3 shifts
0-125 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
1
=7.08519
4 shifts
3.917
3.794
2.324
1.624
1.271
1
=7.8441
4 shifts
3.357
3.794
2.324
1.624
1.271
=7.56416
3 shifts
0-140 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
1
=7.0851988
4 shifts
3.917
3.794
2.324
1.624
1.271
1
.794
=7.05514372
5 shifts
3.357
3.794
2.324
1.624
1.271
1
= 6.7227282
4 shifts
0-160 mph
3.538
3.794
2.324
1.624
1.271
1
.794
=6.3725
5 shifts
3.917
3.794
2.324
1.624
1.271
1
.794
=7.055
5 shifts
3.357
3.794
2.324
1.624
1.271
1
.794
=6.045
5 shifts
40-100 mph
3.538
2.324
1.624
1.271
=6.1549
2 shifts
3.917
2.324
1.624
1.271
=6.8142
2 shifts
3.357 2.324
1.624
=6.626
1 shift
40-125 mph
3.538
2.324
1.624
1.271
1
=5.5007
3 shifts
3.917
2.324
1.624
1.271
1
=6.0899
3 shifts
3.357
2.324
1.624
1.271
= 5.84
2 shifts
60-120 mph
3.538
1.624
1.271
=5.12
1 shift
3.917
1.624
1.271
1
=5.0856
2 shifts
3.357
1.624
1.271
=4.859
1 shift
80-140 mph
3.538
1.271
1
=4.017399
1 shifts
3.917
1.271
1
.794
=4.00186
2 shifts
3.357
1.624
1.271
1
= 4.358
2 shifts
100-150 mph
3.538
1.271
1
=4.017399
1 shift
3.917
1
.794
=3.513549
1 shift
3.357
1.271
1
=3.8118
1 shift
format is the final drive being used
gear ratios for that speed range divided by number of gears multiplied by FD
= final multiplication torque
and number of shifts for that speed range with that final drive
0-30 mph
3.538
3.794
=13.423
0 shifts
3.917
3.794
=14.861
0 shifts
3.357 3.794
=12.7364
0 shifts
0-45 mph
3.538
3.794
2.324
=10.8227
1 shift
3.917
3.794
2.324
=11.982
1 shift
3.357
3.794
2.324
=10.269
1 shift
0-60 mph
3.538
3.794
2.324
=10.8227
1 shift
3.917
3.794
2.324
=11.982
1 shift
3.357
3.794
2.324
=10.269
1 shift
0-80 mph
3.538
3.794
2.324
1.624
=9.13
2 shifts
3.917
3.794
2.324
1.624
=10.1084
2 shifts
3.357
3.794
2.324
1.624
=8.6632
2 shifts
0-100 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.971
3 shifts
3.917
3.794
2.324
1.624
1.271
=8.8259
3 shifts
3.357
3.794
2.324
1.624
=8.663
2 shifts
0-105 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.9719
3 shifts
3.917
3.794
2.324
1.624
1.271
=8.8259
3 shifts
3.357
3.794
2.324
1.624
1.271
=7.5641
3 shifts
0-112 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.9719
3 shifts
3.917
3.794
2.324
1.624
1.271
1
=7.844
4 shifts
3.357
3.794
2.324
1.624
1.271
=7.5641
3 shifts
0-118 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
=7.9719985
3 shifts
3.917 3.794
2.324
1.624
1.271
1
=7.8441842
4 shifts
3.357 3.794
2.324
1.624
1.271
=7.56416025
3 shifts
0-125 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
1
=7.08519
4 shifts
3.917
3.794
2.324
1.624
1.271
1
=7.8441
4 shifts
3.357
3.794
2.324
1.624
1.271
=7.56416
3 shifts
0-140 mph 1/4 mile
3.538
3.794
2.324
1.624
1.271
1
=7.0851988
4 shifts
3.917
3.794
2.324
1.624
1.271
1
.794
=7.05514372
5 shifts
3.357
3.794
2.324
1.624
1.271
1
= 6.7227282
4 shifts
0-160 mph
3.538
3.794
2.324
1.624
1.271
1
.794
=6.3725
5 shifts
3.917
3.794
2.324
1.624
1.271
1
.794
=7.055
5 shifts
3.357
3.794
2.324
1.624
1.271
1
.794
=6.045
5 shifts
40-100 mph
3.538
2.324
1.624
1.271
=6.1549
2 shifts
3.917
2.324
1.624
1.271
=6.8142
2 shifts
3.357 2.324
1.624
=6.626
1 shift
40-125 mph
3.538
2.324
1.624
1.271
1
=5.5007
3 shifts
3.917
2.324
1.624
1.271
1
=6.0899
3 shifts
3.357
2.324
1.624
1.271
= 5.84
2 shifts
60-120 mph
3.538
1.624
1.271
=5.12
1 shift
3.917
1.624
1.271
1
=5.0856
2 shifts
3.357
1.624
1.271
=4.859
1 shift
80-140 mph
3.538
1.271
1
=4.017399
1 shifts
3.917
1.271
1
.794
=4.00186
2 shifts
3.357
1.624
1.271
1
= 4.358
2 shifts
100-150 mph
3.538
1.271
1
=4.017399
1 shift
3.917
1
.794
=3.513549
1 shift
3.357
1.271
1
=3.8118
1 shift
Last edited by sentry65; Nov 27, 2006 at 02:47 PM.
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