I made a table like the others posted containing the ratios of the A340E, A650E, and R154:
_____ _ 1st ____ 2nd __ 3rd ___ 4th ___ 5th
A340E _ 2.804 _ 1.531 _ 1.0 ___ 0.705 _ --
A650E _ 3.357 _ 2.180 _ 1.424 _ 1.0 ___ 0.753
R154 __ 3.250 _ 1.955 _ 1.3 ___ 1.0 ___ 0.753
Kai;1478403 said:
(...)
Looking at that table, the A650E looks like it's a close match for the R154 in terms of gearing - so surely the 3.73:1 diff would be okay to use?
IJ.;1478404 said:
With an auto you want a bit deeper gearing to make full use of the torque multiplication from the converter, you'd also be raising the cruising RPM so economy will suffer, the 650 with it's low 1st can give you the best of both worlds if you use the right diff ratio.
If not may as well stay with the 340 as it will be far cheaper in the long run.
... and then I went on to find a diff ratio that would make the most of the A650E. I figured I would try to match the overdrive in both autos, by doing this:
.705 * 3.73 = .753x, x = 3.492
Using the above, I came up with a formula that'll figure out how the ratios in the A650E would compare to the A340E with the 3.492 diff:
(ratio of A650E on butt-dyno) = (new diff ratio) * (A650E gear ratio) / (old diff ratio)
I substituted 3.492 for "new diff ratio", 3.73 for "old diff ratio", and evaluated the equation for each ratio (I didn't round off to the end). I made the table again, but with the "new ratios" for the A650E:
_____ _ 1st ____ 2nd __ 3rd ___ 4th ___ 5th
A340E _ 2.804 _ 1.531 _ 1.0 ___ 0.705 _ --
A650E _ 3.143 _ 2.041 _ 1.333 _ 0.936 _ 0.705
R154 __ 3.250 _ 1.955 _ 1.3 ___ 1.0 ___ 0.753
Kai;1478406 said:
Aaah, right, i think i know what you're getting at - sorry for asking so many questions, but trying to learn something here
With the ratio's tabled above, would there be any benefit to an A350E over an A340?
IJ.;1478409 said:
If you had a little engine yeah but for a torquey 7M nope it's a WOTM.
So I'd like to ask Kai's question again, would the A650E be worth it?
I have the R154 right now because I settled and, although it's really fun sometimes, I miss having an auto. But the only way that I'll have no regrets is if I swap a 5-speed in. According to the staged modification list that I found once my car has ~280bhp, and I'd like to raise the boost to 11psi once I get an aftermarket boost and coolant gauge. Is that little enough? Lol