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| Re: Has anyone done the VL commo auto swap? |
Subject: Re: Has anyone done the VL commo auto swap?
by ddgonzal on 2017/1/14 6:57:09
It's the same effect with stock or custom converters
* At low RPMs the torque converter multiplies torque (maximum of 2:1 for the stock 1200 automatic), and as the revs come up you'll get less and less converter torque multiplication
* The automatic 1st is 2.458:1
* The manual first is 3.757:1
Without the converter's torque multiplication, less torque would get to the ground. So it's strong at initial takeoff, but less strong as the RPMs rise
Here's where a custom converter is beneficial. Let's say you order a custom 3000 rpm stall converter from KEAS (stock 1200 stall is a low, low 1875 rpm, compare to 2625 RPM for stock 300ZX Turbo)
* When taking off, the engine will immediately run up to 3000 RPM where the A12 makes 9.8 m/kg torque at full throttle (compared to 8.8 at 1800 RPM) -- that's 11% improvement right there. This is similar to a Manual where revving the engine while letting out the clutch results in faster acceleration
* An off-the-shelf 3000 RPM stall converter won't work exactly right. What is needed is a custom 3000rpm-behind-70ft.lb.engine stall converter. If you were to use the 300ZX converter behind an A12 it will stall at a much lower speed than 2625
You can make up for this torque shortage by fitting a higher number rear diff gear (if you want to match the manual's acceleration). If acceleration isn't important to you no need to change anything -- just live with the slower acceleration of the Auto. The automatic's only got 3 gears (overdrive is not used in 0-100 or 1/4 mile runs) and while the torque converter multiplication helps, it doesn't help as much as the extra gearing
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