Hauss, power shifting is disengaging the clutch, changing gears, and reengaging the clutch as rapidly as possibly but not re-engaging the clutch prior to completing the gear change. The power shifting definition you are embracing is not powershifting it is mechanical abuse that in short order results in broken transmission parts.
Liberty Gears were the originator of the clutchless transmission for drag racing and nobody other than Liberty offers it, which might be because of expense, market size or intellectual property protections. Not sure which or perhaps something entirely different but Liberty is the only source.
This is a picture of the insides of a Liberty Clutchless transmission;
Aside from the dual countershafts to reduce the torque and shock loads the countershaft is required to handle, in a race environment, the significant design issue here is the shape of the dog teeth on the individual sliders and gears.
Normally a manual transmission will have a single synchronizer sleeve to engage and disengage adjacent gears (first to second, third to fourth) gear changes. Liberty made two significant changes to their racing transmissions to allow clutches operation without abusing the transmission internals.
The first change was to split the slider into two independent sliders that operated independently of each other. The second was the use of ramped dog teeth on the sliders and gears for engagement, see the larger pic below;
When a gear change is executed the slider for the current gear is not moved by the shifter, only the slider for the next gear is moved. The large dog teeth allow quick and easy engagement. As soon as the next gear is engaged the lower gear speeds up. As the gear speeds up the ramp that has been built into the gear and the slider, kick the slider for the previous lower gear out disengaging the lower gear (see pic and arrows above).
The power delivery effect at the tire is indistinguishable from a gear change in an automatic transmission or a Lenco. This is a transmission that does not require a clutch disengagement to change gears. So why don't we all use these for our street driven toys?
The answer while intuitive is not immediately obvious. East time you let off the gas it is the equivalent of changing gears for the gear you are currently in. Once the vehicle momentum begins to drive the transmission gears through the tail shaft it kicks the current gear dog clutch into a disengaged neutral condition. This would be a nuisance factor in a street driven car. Same thing is true for a road race car. The driver is on and off the gas so frequently he would be hard pressed to keep the transmission engaged in the gear he was already in before letting off the gas.
So the urban legend / story of macho man just ramming the shifter from one gear to another without clutching, while a romantic rendition of power shifting, is just more urban legend. Ask anyone who has tried it, how difficult it is and also how damaging it was to their transmission.
Speed shifting (power shifting for the uninformed macho crowd) requires rapid clutch disengagement, rapid gear changing, and rapid clutch re-engagement. The hand / foot / eye (assumes you look at your tach) coordination requires a manual dexterity level that is a variable from driver to driver. Physically able drivers can do very well. Not so physically able — well not so well.
Contrast that to the Liberty clutchless design where the power transmission to the tire is never interrupted even on a gear change — no matter your physical dexterity because it is a mechanical process executed entirely within the transmission.
BTW, check out the
Second Strike Gearing Calculator <= clickable, to get a sense of where you vehicle is speed wise at 5500 rpm for your "Power Shift" into overdrive.
If you use a 295 x 55 x 15 rear tire and a 3.55 R&P you will be North of 120 mph at your 5500 rpm gear change into overdrive (check the calculator).
A couple of observations are worthwhile here;
- If you haven't won your contest by 120 mph you're not going to!
- Racing these cars at or above 120 mph on the street is irresponsible,
- Racing these cars at or above 120 mph without appropriate prep and safety equipment is irresponsible,
- Overdrive transmissions were designed for fuel economy not racing,
- "Power shifting" overdrive wil virtually always over stress your transmission.
The use and operation of a TKO as you describe is what I would classify as abusive and I tend to use that terminology conservatively. Just surrender the contest if you have not won by the top of fourth gear. — because you are not going to!
Enjoy the car for all the fun it is capable of providing. Don't abuse it and it won't abuse your wallet not to mention it will reduce the number of times you need to endure TKO removal, repair and re-installation — and, big bonus, it will be less likely to kill you or some innocent bystander.
Ed
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