The goal of this project is to build a "modern" rat-style hotrod. By modern, I mean that I'm going to use the components that are readily available today, rather than period-correct, hard-to-find parts. The end result will be in the spirit of the original hotrods: take a vehicle that's readily available, remove anything that isn't necessary, and add horsepower.
This is going to be a low-budget project as well, and I intend to use what I have and what I know. The frame and body are from an '85 GMC S15. The power will be supplied by a Volvo turbo 4-cylinder.
The S15 is currently stripped down to its bare essentials. The frame has been mostly painted black, and the cab has been channeled to sit down over the frame.
I've finished the gas tank, as you can see from the pictures below. It's made from an old beer keg. I removed the original bung and welded a plate over the hole. I added a bolt for a drain at that location. The S15 filler neck was welded onto the side. On the bottom, a 3" diameter section of exhaust pipe was used to weld in a sump. The tank will feed an external pump from that location. On the side of the tank, there are two barbs to allow a clear section of fuel line to be used as a sight gauge. The fuel return line feeds back in near the top of the tank. Currently, there are two tabs that bolt the tank to its cradle, but I'm going to add straps across the body of the tank as well. I've decided to forgo any sort of pickup bed, leaving the rear end pretty bare except for the springs and differential.
For interior style, I've obtained some inexpensive, plastic bucket seats from Summit Racing. I've finished the steering wheel, which is welded out of a length of chain and painted black. The gauges will all be Volvo or other junkyard gauges, set into a new custom dash. I'll install a heater core and small fan for defrost duty.
My original plans included chopping the top and suiciding the doors. I think I'm going to hold off on those parts of the project until I've got the hotrod running. Modifications like that can always come later, and I'm excited to hear this thing roar.
The intercooler is already installed--it's an Isuzu NPR unit painted black. The Volvo radiator will go behind that, with a junkyard electric fan.
I plan to weld the stock differential, which has whatever gear ratio came in this S15. (I believe it's a 3.42:1 rear.) I may upgrade to a stronger rear differential in the future with disc brakes, but the stock drums will do for now on a budget.
The stock output of the Volvo B230FT is 160hp. That's pretty fun in a 760, and should provide plenty of grunt in a much lighter hotrod. The boost has already been turned up, which should increase output. The 760's engine also has an underdrive pulley installed. In the hotrod, this will only need to run a water pump and alternator. The mechanical fan is being traded for an electric fan, and the power steering pump isn't needed. Of course, no air conditioning on a rod like this. Using the stock engine management will save some tuning hassles that Megasquirt presents, such as cold start. Also, there are fuel chips available for Bosch LH-Jetronic 2.2 which are sufficient up to 300 horsepower.
Among the other upgrades that will transfer from the 760 is a 3" exhaust system. I will re-weld things to make it fit the S15 chassis, and probably use less restrictive muffling. I also have a 1990+ exhaust manifold, which flows enough more to provide approximately 10 more horsepower. For future upgrades, I also have a exhaust manifold flange so that I can start welding up my own tubular manifold.
I also plan to stick with the stock AW71 automatic transmission from the Volvo, which will get a 240's output shaft in order to allow for a mechanical speedometer. This transmission has been holding up so far in the 760. If it dies, the big money upgrade would be a TH350 using an adapter plate.
The S15 suspension needed some work. I just recently finished redoing the entire front suspension. It got new Ground Force lowering springs, new shocks, and all new ball joints. The brakes also got replaced with new rotors, new calipers and new pads. I still have two new shocks to install in the rear, which already has lowering blocks.
Electricals, outside of the stock Volvo engine management, will be fairly simple. Up front, some custom buckets will hold a pair of headlights. For the front turn signals, rear turn signals and brake lights, some Harbor Freight specials should work. The 760 has a Optima redtop battery to donate.
I've just finished fabricating engine and transmission mounts, and the drivetrain is now installed in the hotrod.
Here are some fairly current pictures:
Buy:
windshield $250 installed
outer tie rod ends
brake lines
12v electric fan for defrost
speedo gear 17 tooth (380978, cream color)
To do:
fix leaking tire
fabricate upper intercooler and radiator mounts
install front fenders
finish body paint
finish rearview mirror install
cut wood, 1” by 1.5” by 35.25”
bolt down gas tank platform
install fuel pump and plumb fuel lines
bend new brake lines
install door poppers
fabricate seatbelt mounting
install outer tie rod ends (and get alignment)
install new windshield
reposition steering and fabricate shaft
weld in handle bar for passenger
fabricate parking brake using 760 components
fabricate dash with gauges from square tubing
wire OEM EFI
weld up extra firewall holes
install new door seals
put spikes on headlights
install headlight buckets with 2-foot min. height
install reverse light
install front turn signals
install horn
