A $1,600 Boxster and two projects

[Racer Boy]

I somehow missed this thread! I have some real concerns about the way you mounted the seat, 78F350. The brackets you are using may feel fine, but if you hit something laterally, they fold over and the seat will end up moving a lot, possibly enough that the belts wouldn't do a good job of restraining you in the seat.

Will the only event you'll be doing is the drag strip and autocross? If so, your brackets may adequate, but if you are going to do any other kind of competition, I'd make something a lot safer. You also need to make a brace that attaches on the seat back and goes to the chassis of the car so the seat won't bend as easily. In a real wreck the seat WILL bend. In any kind of real competition, that brace is a required item.

And one other thing - that seat is going to break your ribs at the very least if you hit something, because there is nothing to hold your shoulders in place. Everything above your ribcage will keep moving when the car stops suddenly; the seat hold your lower body in place, but everything above that keeps moving and your ribs break, and you could even have internal injuries.

I'm telling you this because I had a similar aluminum seat in my Spec Miata, and when I hit a wall laterally, my ribs broke, and my insides felt like I had been run over by a semi-truck. The seat was actually bent towards the center of the car about three inches. My seat was bolted right to the floor with a large sandwich plate the kept the bottom of the seat from going anywhere. I'm guessing your brackets would easily fold completely over or even tear, and that might allow the seat to move an unacceptable amount.

It's really cool that you are tackling this, but I really would like you to re-consider how you've got the seat mounted. I learned a very painful lesson, and just wanted to pass the wisdom I gained on to you!

[78F350]

That's great info. Thanks for posting. After reading it, I looked up some details at the manufacturer's page. At this point I plan to use a standard seat and seatbelt for the autocross portion and the initial drag race run. If the nitrous oxide drag runs look like they'll run in the mid 13s or lower, I may use the race seat bolted directly to the floor and rollbar. I expect that before this engine runs the car into low 13s it will make smoke and a rattling noise, then grind to a stop.

[78F350]

The 2019 $2000 Challenge is complete. I placed 18th out of 57 cars that made it through scoring. I had a great time and learned a lot. With the V8 installed next year I think this car can truly be competitive.

I didn't push the 2.5L engine to the breaking point, but I could tell it was weakening. After every run, it needed to cool down for 20-30 minutes to de-pressurize and refill the coolant tank. On my first drag run with the car floored the whole way, running to a 7k redline, it only got a 16.1 1/4 mile. With a 50 shot of nitrous it did 14.6 with the Tiptronic shifting at 8k rpm. The 150 shot would have been glorious, but I was worn out from a long day. My wife convinced me to let the engine live and we called it a night.

Later this week I'll detail the modifications to the car, to wrap this up as a 'build thread'. I'll post the build for next year under a new title. Here's a few pics from the Challenge.

Prep in the paddock:


Topping coolant. Extra plastic tank (Audi) catches the drainage.


Tight corner in the autocross.


Danny Shields completing a run in my car. Great to get feedback from a pro driver.

[78F350]

A few mod details.
I got rid of the heavy stock muffler and welded some pieces cut from a scrapped exhaust onto the 'C' pipes. I would have deleted the cats too, but considering the value vs the time available, I left them. It sounds great at high revs, but not too loud at idle.


For the single radiator, I cut the fork out of the long tubes and used hose to join the elbow on.


I had a problem with the Toyota radiator. The engine I have over-pressurizes the cooling system and the radiator cap was a weak point that leaked. I went to a single stock radiator. The way I have the radiator positioned it has good, direct airflow without bends and restrictions. The temp stayed on the '8' in 180, but I still lost coolant from the pressure relief valve in the tank.


I installed a lawnmower battery in the stock position with 3/8 rod to tie it down. It worked great, was light weight, and cost about $25.


The nitrous oxide system from Nitrous Express, was easy to install and worked great. Nitrous tank in the trunk and fuel from the fitting on the fuel rail. I had ordered a system with a mechanical wide-open-throttle switch, but they sent one that works 'fly-by-wire' with the throttle position sensor. The 'shark fin' fit perfectly where I removed the brake booster venturi from the intake tube. I may take the car to the drag strip in Tulsa and do some progressively stronger runs to finish off the engine.