Terry, Just to add what Jarrid notes, the Series III specs. report a
road speed of
21.4 mph at 1000 rpm ( 3.89 w O/D). So at 4800 rpm you could be
cruising at 102.72 mph -
I've tried mine up to 4200rpm and that's enough for me!!!
Tony Leeming
Jarrid Gross (Yorba Linda, CA) wrote:
>
> Terry,
>
> The 1592 engine makes peak torque at around 3800 RPM. This is
> the point at which the power deminishes. When the power deminishes
> at a greater rate over an RPM range than the increase in RPM ratio,
> the engine begins to produce less horsepower. This occurs on an
> alpine 1592 at around 5200 RPM.
>
> The Laycock OD unit has a final drive ratio of ~.800 or a 25% ratio
> increase.
>
> Not the 20% increase that you specified. ( 1.25 = 1 / .800)
>
> This will make the speed 25% higher in OD with a given engine RPM.
>
> Look at the tag on your OD trans, if it starts with 25, the OD ratio is
> .800
> if it starts with 32, the ratio is about .757, which is a lot taller.
>
> Assuming the tire circumference is about the same as it rolled out of
> the factory (80 series 155 tires), the figures are as follows.
>
> AND that the 83 MPH (at)4800RPM in non OD top is also correct.
>
> Speed at 4800 in OD with 3.89 = 4.22 / 3.89 * 1.25 * 83
>
> = 112.6 MPH.
>
> A stock motor in a stock Alpine will not pull that kind of speed.
>
> This is pretty tall, and I doubt that the motor will pull above 4500
> with
> this tall of a setup.
>
> Your actual top speed would be about 100 MPH (at)5700 RPM, in
> NON OD top.
>
> Your acceleration will suffer, and believe it or not, the OD will not
> gain
> you any fuel milage increase.
>
> The OD just saves wear and tear on your motor.
>
> Jarrid gross
>
> >I am driving a 1960 Series I with a 1592 engine, 3.89 rear end, and a
> late
> >series (25 spline) overdrive. The speedo and electrics for the
> overdrive
> >are not hooked up yet. I am running standard 13 inch tires.
>
> >I can accellerate to 4800 r.p.m. in top gear (good accelleration up to
> >then), at which point it will go no faster. I can maintain this speed
> with
> >only an inch or so of throttle depressed, and mashing the pedal to the
> >floor makes no difference. I am assuming that 4800 r.p.m. is the
> maximum
> >the car is capable of in top gear, due to wind resistance, etc.
> According
> >to my owner's manual, 4800 r.p.m. is equivalent to about 83 m.p.h.
>
> >I have the following questions:
> >Assuming I can get the same 4800 r.p.m. in top overdrive, how fast will
> I
> >be going? The manual says 4800 r.p.m. in top overdrive is 95 m.p.h.
> with a
> >4.22 rear end. Since I have a 3.89 rear end, I should get 8% more
> turns of
> >the wheels (4.22/3.89) or 102.6 M.P.H. at the same revs.
> >
> >or:
> >
> >Since the overdrive will drop r.p.m. by about 20%, will the speed be 82
> >m.p.h. X 1.20, or 98.4 m.p.h.
> >
> >Will I be able to get up to 4800 r.p.m. in o.d.?
> >Which of my calculations are correct, if any?
> >The answer is out there somewhere.
> >
> >Terry McKitrick
> >1960 Series IB9006321LRX
> >St. Albert, Alberta, Canada
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