3.08 to 4.10 question

i love 4.10's for n/a.i wouldnt go with anything else.just my .2

Thats kind of a generic chart,its close,but not exact. I have 410's in my AOD. Believe it or not my 373's were 2 tenths faster at the track..Granted,410's are a total blast for around town driving,makes everyday driving alot more fun! They limit you on the highway though unless you dont mind revving your motor and getting crappy gas mileage. I have my motor set up to breathe better now at higher RPM's (Thumper Heads,1.7 RR's,and soon added cobra intake and catted X-pipe) Im gonna get to the track in March see how it runs.But Im pretty sure Im gonna put the 373's back in. For better highway mileage and 1/4 mile ET's!! If you have a 5spd theres no way I'd put 410's in!!
The old rule of thumb is 373's in a 5spd is the same as 410's in an AOD.JMO

4.10s should put you around 2300-2400 or so at 65. my 3.90s put me at around 2200.

The chart's helpful but there's a pretty easy way to figure this. Any speed, any gear --- the change in engine speed is simply the engine speed you're seeing on your tach (assuming it's accurate --- a big assumption if it's a stock Stang tach) X the ratio of the gears you're changing to -- 4.10/3.08. So, if you're cruising down the highway in 5th at 1800 rpm with 3.08's, when you put the 4.10's in the new rpm will be 1800 X 4.10/3.08 = 2396, or 2400 rpm. It's just simple ratios.

Blake - what rear tire size was the chart based on?

Michael Yount said:

The chart's helpful but there's a pretty easy way to figure this. Any speed, any gear --- the change in engine speed is simply the engine speed you're seeing on your tach (assuming it's accurate --- a big assumption if it's a stock Stang tach) X the ratio of the gears you're changing to -- 4.10/3.08. So, if you're cruising down the highway in 5th at 1800 rpm with 3.08's, when you put the 4.10's in the new rpm will be 1800 X 4.10/3.08 = 2396, or 2400 rpm. It's just simple ratios.

Blake - what rear tire size was the chart based on?

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Blake - what rear tire size was the chart based on?[/QUOTE]


This is what I was referring to when I said it was generic!!

The rpm at any given speed will be 4.1/3.08 x whatever it is right now with the tire size you have. Plain old ratio. Tire size is the most annoying number to find or figure out accurately.

Its best to just bite the bullet and crunch the numbers.

My 82 runs about 2500 at 45 mph with about a 26 in tall BFG 275-50-15 Drag Radial, with 4.10 gears. So 90 is 5000, and 104 at the finish line is about 5700. Allowing for converter slippage, and the stock tach, it seems to finish at 6000-6100.

willys - that's why I provide the formula.....instead of just saying 'it's generic'.....

It's actually not generic -- it's for just one tire height, otherwise it's not accurate.

willys1 said:

..I have my motor set up to breathe better now at higher RPM's (Thumper Heads,1.7 RR's,and soon added cobra intake and catted X-pipe) Im gonna get to the track in March see how it runs.

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Well, the X-pipe puts a new factor in there, but if you have before dyno (I know you have track data) and are going to get after dyno/track data - I'd love to hear the results on the intake switch.

willys1 said:

Blake - what rear tire size was the chart based on?

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chart is bace on the stock tire height.

tmoss said:

Well, the X-pipe puts a new factor in there, but if you have before dyno (I know you have track data) and are going to get after dyno/track data - I'd love to hear the results on the intake switch.

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Im pretty curious to see the results also..Im looking for a dyno in my area.Tom the closest dyno's are at some really good Mustang shops,Larocco's,Crazy Horse,and a few others,but they are wayyyy south for me.2 hours minimum. Im pretty sure theres a Turbo shop not too far away with a dyno.I just have to find them which shouldnt be hard.

LOL,,Mr Yount you gotta lighten up!!

and i got it from jrichker, he uses it also.