ranger magnum wrote:I want to build a hot tub car. Take a chassis from a toyota pick up, and mount a 4 person hot tub to it. The heat for the water would come from the engine. Instead of a radiator, water would flow from the block to the hot tub, then back into the motor.
The driver would sit in the hot tub while driving, using hand controls on the steering wheel. Much like a motorcycle.
The big problem is filling/emptying the hot tub
This can be done if you have good fabrication skills. Putting the driver in the water is the most complicated part, and I'm not really sure it's the best part of the plan.
About heating the water: You absolutely need to keep the radiator for the truck engine. DON'T actually run the engine coolant through the tub, for many reasons, not the least of which is you wouldn't be able to control the temperature of the tub very well. Instead, use the truck's heater hoses to run hot water to a heat exchanger to heat the tub water. The original tub heater is just a tube with an electric heating element in it that the water passes through... you can make a container that your tub water passes through, and plumb the truck's heater hoses through it, perhaps through some coils of copper tubing.
Even a four-person hot tub is awful heavy for any Toyota, you'll be fine cruising 5 MPH but you'll need to beef up the springs.
I don't see filling/emptying it as a big issue. A smaller tub like that is gonna be maybe 300 gallons or so. That will all fit in 6 55-gallon drums and you can get a reasonably inexpensive electric water pump from Harbor Freight. That much water will weigh about 2500 pounds. The rest of the vehicle will probably weigh about that, so maybe 5000 pounds. Any decent two-axle car trailer will handle this contraption.
If I were doing this, I'd get my electricity from the truck engine by using multiple alternators. They sell high-amp alternators for lots of money, but they require a lot of RPM and you'll be idling all the time - instead, go to the local Pull-A-Part or whatever junk yard and get some alternators from late '80s to early '90s GM small cars or S-10 pickups. That will be the "CS 130" unit that cranks out a ton of current at idle speed. You can combine their outputs directly in parallel. You can Google how to wire them, you need to hook up a few extra wires but it's not too complicated. Then run a big inverter. Unless you can get a big enough inverter and enough alternators to run it, you might need to go with a smaller, weaker hot tub water pump than the original one, maybe swap a smaller electric motor onto it or go with an entirely different pump, maybe the same little Harbor Freight unit you use to transfer the water from the drums to the tub. It won't give you the kind of pressure you need for massage jets but it will circulate the water. The start-up current of a standard hot tub pump might be pretty high.
Driving from IN the tub will make setting up the driving position a challenge, it seems you'd either be facing backwards or you'd have a steering column stretching right over the middle of your tub.
I can totally see this thing, all covered in cedar planking, with a nice deck over the engine in front, a big umbrella, etc.