reaching 120 mph slower? with 4:10
#12
I got mine about the same time as the OP. I feel like my car is pulling harder past 120. It also seems like my power is more available in ALL gears. Many people will say they aren't the best for highway miles. But I just drove my car on a 900 mile road trip. Loved every minute. Passing cars easily in 5th, plus great launches.
#13
Over 120? My car came with 3.31 and now with 4.10 has a higher top speed. People are misled into thinking 4.10s make you lose top speed but it's around here somewhere that the hp you need to top out that gear is pretty dang high. My car cannot hit redline in 5th with 4.10s so I doubt you will.
edit: some searching points to 180ish but thats a speed nobody here should ever go without an ambulance standing by
edit: some searching points to 180ish but thats a speed nobody here should ever go without an ambulance standing by
Last edited by Ricardo; 07-16-2013 at 10:31 PM.
#14
Over 120? My car came with 3.31 and now with 4.10 has a higher top speed. People are misled into thinking 4.10s make you lose top speed but it's around here somewhere that the hp you need to top out that gear is pretty dang high. My car cannot hit redline in 5th with 4.10s so I doubt you will.
Where the 4.10s really shine is in the low end pull getting you up to speed sooner as well as allowing you more use of the power band.
#15
So my take on whether your slower with 410s could be true. I have had this talk with some friends and our conclusion was that you basically need more hp to get to it quicker. As was stated earlier there is s reason why people run 410s at the track. When ur car hits fourth you just need more power to keep her picking up speed
#16
ok guys before i installed my 4:10s from 0-120 it seemed faster with my 3;55 gears? yesterday i opened it up from 0-120mph now with my 4:10 gears and it seamed when im passing 90 or 100mph it been slower reaching 120? i might be wrong but can anyone confirm this please. thanks guys
I recall in 1979 we had Chrysler Newports with 360 engines and 3.23 rear gears, then in 1980 we got Plymouth Gran Fury s with exact same engine in same body with same trim, but 2.94 rear gears. The '79s were faster accelerating and would run a good 5-7 mph faster on top because the '80s hit that wall of not making enough RPM when resistance reached a certain level about 120 .... where the '79s would push 125-127 .... but engine turned faster .... and the '80s got slightly better gas mileage.
Last edited by tbear853; 08-04-2013 at 11:09 AM.
#17
higher gears (4.10s) = faster acceleration, lower acceleration over 60 mph.
lower gears (3.31s) = normal acceleration off the line, linear acceleration over 60.
The reason: 4.10s pull harder off the line because they keep your engine in the main power range (3k to 6k) more of the time. But at speeds above 60/70 your engine will be running much higher RPMs, but doing more work because the torque require to make the car go faster at that speed is greater with 4.10s vs 3.31s. Therefore your car is faster than stock 3.31s (stock) from 0-60/70mph, but slower from 70-120+
lower gears (3.31s) = normal acceleration off the line, linear acceleration over 60.
The reason: 4.10s pull harder off the line because they keep your engine in the main power range (3k to 6k) more of the time. But at speeds above 60/70 your engine will be running much higher RPMs, but doing more work because the torque require to make the car go faster at that speed is greater with 4.10s vs 3.31s. Therefore your car is faster than stock 3.31s (stock) from 0-60/70mph, but slower from 70-120+
#19
I think maybe this is some kind of Keynesian math, and I think we all know how good that stuff works.
Maybe with luck Norm will step in and set things straight, till then.
#20
For a few mph immediately following the speed at which you upshift the 4.10-ratio car, the 3.55-geared car will have slightly stronger acceleration. This is because the 4.10-geared car loses more due to the taller overall gearing than it gains by dropping back to around the torque peak rpm. I haven't ever tried to determine what this might amount to or if it'd be enough to clearly notice.
Take the speed limiter away and I think I found that the 4.10's actually pull an extra mph or two on the top end (there's a fairly fussy mathematical simulation for determining real-world top speed). Basically, 4.10's put the engine closer to peak HP rpm in 5th at the high 140-ish/150 range than you would be with 3.55's. With 3.55's and a stockish 4.6L, you don't have enough power at enough revs to pull ~150 in 4th with stock tire sizes.
Norm
Take the speed limiter away and I think I found that the 4.10's actually pull an extra mph or two on the top end (there's a fairly fussy mathematical simulation for determining real-world top speed). Basically, 4.10's put the engine closer to peak HP rpm in 5th at the high 140-ish/150 range than you would be with 3.55's. With 3.55's and a stockish 4.6L, you don't have enough power at enough revs to pull ~150 in 4th with stock tire sizes.
Norm
Last edited by Norm Peterson; 08-04-2013 at 10:01 AM.