From where did you get the idea I want to put bigger tires? and this car not meant to be a drag car it’s a sand dune offroad car. I don’t mind trying at the drag strip to see what she put down, but it’s purely an offroad. I might fit lighter wheels that are bigger than stock, but the overall size will be the same as I want to ensure speedometer/RPM reading correctly, so does that entitle me for running bigger tires?
Whats the point of 800 hp and stock sized tires? I have a hard time believing a stock tire size fj will do any better with 800 hp then with 400hp on sand. Wider tires will give you better flotation, at the cost of eating power. However your talking 800 hp and thats more then enough power to run a much wider tire for much better flotation.
I know torque and loss of traction have a big impact on transmission life, but I mentioned the hp goal since I am going twin turbo and it’s very hard to predict torque until you put the car on a dyno....torque will definitely be +600 since we are talking about the 4.7L V8 which will generate lots of torque. by the way I have a turboed Honda civic too and it uses the stock tranny with coated synchros and added mechanical LSD......I broke a 500hp axle before and the tranny is still surviving....that’s why I asked about the stock RA61F and A750F trannies, cause I wanted to know if there is any sort of way to modify those trannies to reach my goal without breaking them....I know honda engines have small displacement and put down lower torque numbers compared to V8s, but the torque on those stock honda trannies pretty much last for that 3x-5x torque numbers that is originally made from stock .you are making me sound as if I want to put down those high hp numbers using a stock tranny.....lol
The stick shift has very simple limitations. If you don't power shift (shift without letting off the gas) your limited to how much power the inputshaft and gear teeth can handle. If your not dumping the clutch in high traction situations, the stick shift will handle a lot of power. The same modifications can be done to the toyota stick as any other stick shift. Cryo treatment of parts, machining the gears for different syncros, and if enough money is floating around even a custom gearset. However like I said stick shifts don't cushion the blow from a dumped clutch very well.
The auto I am sure can be built to handle a lot of power. Heavy duty clutch plates, big electric fan trans coolers, aftermarket hard parts, the works. With a turbo motor the auto will be better since the slippage within the torque converter will help build boost better because the motor will be artificially loaded. A good example would be stepping on it from a lower rpm with the tires bound up in dirt/sand/mud. The auto will allow slippage to the torque converters stall speed (and I would imagine you would run a 2,200 to 3K stall speed converter depending on engines rpm potential) which means the motor will have more starting rpm to work with, and thus more power. With the stick shift the only way to build power through higher rpm is to go with a lower gear, or slip the clutch. Both of those are problems since lower gear=less wheel speed and the need to shift to keep floatation. Slipping the clutch isn't good either and will quickly eat the clutch and flywheel. Not to mention the auto will shift faster thus keeping forward momentum. I wouldn't want to speed shift the manual trans under 500 hp (let alone 800hp) to try to keep the wheel speed high. Its not ment for that.
I don’t think its ridiculous to run a stock tranny if its built to handle the target tq/hp. diesel engines make a lot of torque (more tq than hp) and that’s something I am not interested in. I have seen those diesel cars struggling in the steep sand hills cause there isn’t enough speed to keep the car going. believe me I have driven both on steep sand hills. For my application you will need a 4x4 that can keep up its speed all the way to the top....and I know torque is important to maintain it, but not 1000ft/lbs for me. I understand some of your theories, but my attention here is to reach +600tq and ~800hp. We don’t do crawling here where I live so a dual case or even higher gear ratios is something we don’t install
The point of going with higher gear ratios is to keep the torque in the driveline lower. Running 5+ ratio gears will lower the torque load in the driveline. The transmission will have less of a torque load. Think about the difference between dumping a clutch with a truck with big slicks on a sticky track, vs a truck with street tires on snow. The torque load on the transmission would be tremendous with slicks, and hardly anything on snow since the tires will just spin. Yes arguably by going with higher gears your putting the stress on the axle shafts, but thats a much better place then the trans/driveshaft/pinion.
did put some consideration for the TH400 or SP400. what do you think?
The th400 is availible over the counter to handle 1,000 hp all day. IF your serious about power why screw around? Rebuilding the toyota transmission to last could work, but what is there to gain over a th400? Sure a couple extra gears wouldn't hurt. But thats a couple extra gears that could fail.