Intro to car construction methods and planning for side impact

One of the weak points of many kit cars is side impact protection. This is something that’s hard for kit cars to replicate like it exists in production cars due to the vastly different construction method. This requires a brief introduction into basic car construction methods.

Most modern cars are built as a unibody where large portions of the body are actual integral and stressed parts of the chassis. This is in contrast to body-on-frame construction, where as the name suggests, there’s a frame which holds the load and the body just rest on top, unstressed. Body-on-frame is still a common construction method for trucks and buses. To compare, here’s a picture of the body of a Lamborghini Aventador and the chassis of a Toyota Tundra:

Lamborghini Aventador chassis (unibody construction)
Toyota Tundra chassis (body-on-frame construction)

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Brake system updates

Time to update the blog. Sorry for the delays, folks. Going to do this one post at at time, so there should be a few flowing through in the next couple of days. First topic: brakes.

This isn’t a finished project yet because I haven’t mounted the pedals, but it’s done other than that. I’m holding off on the pedals until I can move the telescoping steering column (requires wiring & power), can mount the seat and can mount the pedals. All three work in unison to create a comfortable driving position, so they need to be fitted as one. Plus, I want to fit Stengelita-sized people all the way up to about 6’2″ drivers.

I’ve been able to get most of the rest of the brakes set up though. The brake lines came pre-bent, requiring just a small amount of work to achieve the proper fitment. The front brakes run through the aluminum monocoque which makes for a natural point to create the junction from hard lines to the braided lines between chassis and caliper. In the rear, things are more open, so I had to build some clips which would allow the hard brake lines to mount to the braided lines. Here’s a shot of one of those brackets (on the right):

Rear brake line clip

In the front, I created the connection between the fluid reservoirs for brakes and clutch to the master cylinders. The cylinders are mounted on the pedals inside of the monocoque, so the lines have to go through it. The lines are just a regular hose, so they’re simple to work with, but it did requireda huge drill bit and some very specific grommets to get through the monocoque, be sealed snugly and not rub under vibration. The grommets were the trickiest part in some ways. I spent an ungodly amount of time tracking down a part which costs $12 for a pack of 50. Ugh.

Brake and clutch lines through monocoque

I got the final pieces of the brake hardware, but in the rear the fitment of the braided line to the calipers wasn’t great with the parts I got. Instead, I ordered some new fittings which worked out really well. In the picture below, you can see the bracket I made on the very left, the braided line running to the right and then a shiny 90 degree fitting mounted to the caliper on the very right (the caliper is the dark thing). That piece in the kit came as a straight fitting, not 90 degrees, so the fitment was a bit wonky. 90 degrees worked out much better.

Final rear brake line mounts

In some ways this isn’t the most special thing the world, but what it did mean is that I now have a fully plumbed brake system short of the final mounting of the pedals. It’s only 15 minutes of actual work to drill and mount the pedals from here, but I want to be sure I get the fitment right before I do that.

Replacing the water pump housing

This was a big job. A real big job. A job that seemed so easy and obvious, like they all do, but turned out to require two guys, 6 hours, air tools, ingenuity, brute force, drilling holes out in a $700 part, cuts which were sanitized and fixed with electrical tape (!) to stop the bleeding, beers of elation and much more. All worth it of course.

So how to explain it. Let me give it a shot: the front of a GT3 engine (which sits in the rear of a Porsche due to the unique rear-mounted motor) has a housing on it which pumps water around the engine. The heads are water cooled on this engine (the block is not due to its air cooled car heritage), as are the transmission and the engine oil. This requires a lot of plumbing and that’s basically what this water pump housing does. It connects all of those pieces and the water pump and coolant overflow tank together. It looks like this when installed without the engine carrier in front of it – the shiny piece on the front with the four studs running through it:

New housing installed

When I bought the engine, this had a crack in one of the mount holes as pictured here:

Cracked water pump housing

I initially thought this was due to the impact of the crash that the engine endured, but it may not have been. It turns out that contrary to my thinking that this was a stressed mounting point, the engine bolts actually just go through the holes from the block to the mount instead of the housing being the mount itself. Those bolts then mount to an engine carrier which is mounted to the frame on both side of the car right behind the driver compartment. Here’s a picture of that from inside the driver compartment, i.e. the front of the engine:

Front engine mount of Porsche GT3

The two black uprights on either side of the engine have a horizontal arm on which the metal engine carrier with the three holes on it sits. What that means for replacing the pump housing is that you have to dismount the engine from the chassis and brace it with jack stands and then unbolt that brace. I think we did two jack stands and some wood and later realized that in a worst-case scenario, the engine is actually too wide to fit through the chassis, so the heads just land on the chassis. Not great for the engine probably, but at least it’s basically impossible for the engine to drop onto the floor. Still, there was no way either of us would get under the car.

With the engine properly secured, the engine carrier is easy to remove. The housing is a very different story though, largely due to the various hose connections to/from the pieces it cools. We worked our way through it and in the end we had to remove the starter, an oil line under the engine (fun!) and two braces on top of the engine to even have a remote chance of sliding the old housing off. “Sliding” is a relative term here, meaning that it took screwdrivers, hammers, wood and anything we could use for leverage. The key problem was that the unit doesn’t slide off horizontally as you’d think and even with all of those pieces removed or loosened, you have to somewhat angle it off. I think it would only slide of horizontally if you have a basically bare engine block.

Once removed, we got beers and celebrated, thinking that installation of the new unit will be a piece of cake. Obviously, right? WRONG. The new unit proved very hard to install due to the same non-horizonal path to slide it on. After a few failed attempts, we decided that we had to make two of the mount holes slightly larger to accommodate installation. It’s a bit scary on a $700 part, even if I got a credit for most of that cost from the engine’s seller meaning my net cost was very low. We took three rounds of making the hole larger until we had it just right to slide it on. New gasket went on, water pump, oil line reconnected and motor brace back on and we were back in business!

Engine brace with a shiny new water pump housing behind it

And because you really wanted to see it, here’s my redneck (genius?) band-aid:

Busted finger fixed with electrical tape

And of course once again thank you Ryan for all that help!

Ryan and Tim with their nemesis

Better ground effects

Enzo approves of the ground effectsOr just making it look cleaner by installing an undertray. I have no basis for knowing whether I’m truly helping ground effects with this addition to the car, but it does make for a cleaner look in my opinion.

Here’s whats going on. The car essentially has a flat bottom all the way from the very front of the to where the engine bay begins. This includes the front splitter, the area under the driver compartment and the area under the fuel tank which is between the driver compartment and the engine. As a side note, I had a special order done on my car to have the same 1/4″ aluminum that’s the monocoque under the driver also welded under the fuel tank. Typically this is a thinner gauge (1/8″), but I figure it’s a good safety measure at a $150 total cost to make it 1/4″ welded aluminum.

Looking further towards the back of the car, I wanted to have the flat floor “undertray” go as far as possible so I decided to add a roughly 22″ square panel in front of each rear wheel well. The reason for not doing a full side-to-side panel is that you want to leave the part under the engine open to allow for air flow around the engine.

Off I went to research how to buy custom cut aluminum and as it turns out what looks to be San Francisco’s premier metal supply shop, Bayshore Metals, is less than 5 minutes from my place. Two hours and $80 later I what I needed: custom cut 1/4″ 6061 aluminum. 6061 is colloquially “aircraft aluminum”, i.e. the stronger variety that isn’t bent as easily. It was recommended by fellow builders to save money and go with a thinner gauge here since it’s not structural, has no safety implications and since it has a greater chance to be banged around a little, replacement is easy. That’s also part of the reason I screwed it in with 3 through-bolts on each side with a layer of silicone between the frame rails and the plate to prevent vibration noise.

That was all. Pretty simple job. Now I have an even longer and cleaner car floor. And zero clue whether this is helping ground effects in any way, but it looks cool, right?

Driver side undertray panel

Insulating the driver compartment (part 1 of many)

I’m going to start updating in smaller increments, largely with complete projects as opposed to “this is still in flight”. Fortunately, I’ve been able to somewhat increase the number of those completed projects, though I’m still blocked on quite a few due to missing parts. Here’s one quick one that I was able to complete: putting sound deadening and heat resistant layers on the firewall between engine and driver compartments.

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SLC Week 2: Lots of cleaning

Week 2 has so far been basically consumed with cleaning the engine and also dealing with lots of logistical items. The engine came from a salvage car and they most certainly don’t clean it before they give it to you. Wishful thinking, but I now have much greater appreciation for what ~20k miles does to an engine’s cleanliness. To the right is an example of some TLC given to an intake to bring it back to more or less original form. The one on the left has about 20-30 minutes of hand polishing with a ScotchPad-like pad vs. the one as it came on the right.

Here’s a quick run-down of that project and some of the other current sub-projects.

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SLC Day 5 Report

I’m on day 5 of having the SLC in house and have had a great time putting a bunch of stuff together. I sort of have a number of projects going at the same time since I a) like variety but more importantly b) am close or already stuck on a bunch of them due to missing parts.

After getting all the bodywork off on Sunday, we were able to get the front and rear clip stored below the decks in our yard, out of sight to us and basically out of sight to our neighbors as well. The various other small panels all made their way into the basement as well. The only section which we could not get out there is the center section, which you can see standing upright in the back right in the picture. There’s just no way it would even come close to fitting through the door frames like the one on the left in the picture. Calisthenics are now required to do laundry, but hey, not my problem, right? (kidding, it definitely is!)

So anyway, here’s a quick rundown of what I’ve done so far.

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The SLC Arrives!

Alright, the day has finally come and the SuperLite Coupe has safely made it into the garage. Very exciting of course and it wasn’t as tough to get it in there as it could have been. I did get pretty lucky though and I have some really great friends who I can’t thank enough.

The truck came around 8 am and after quickly looking up at the hill towards the general direction of my house, they called me and say “no way we’re gonna make it up there”. I was prepared for that to happen and due to a stroke of luck, my friend Ryan had the keys to our other friend’s Matt’s Ford F-150 Raptor who in turn had borrowed a flatbed trailer from Chris who we race Lemons with. How lucky. Unbeknownst to Matt’s slumbering self, Ryan commandeered the truck and trailer and met me at the shipper’s truck. Fortuitously, the trailer was about as flat as can be and had a very low Porsche on it the prior day, so we knew we could get a car that was sitting at best 2″ off the ground onto the trailer.

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A working IVI system prototype

I’ve written about the IVI system for the SLC before here, but since then I’ve made a few changes, added a few things and put together a live demo of it. Before you check out the demo below, here is a quick overview of the progress I’ve made:

  1. I bought an embedded computer with the right Intel Crown Bay chipset, but had to return it of a variety of reasons to with hardware support and functionality. Instead I will be using the Nexcom VTC 1000 system, which is the Tizen IVI reference platform. Couple of questions around the display which I need to work out before I order, but that will be the one.
  2. I rewrote the front end from scratch to use jQuery mobile and a different gauge library. This allows various gestures and much more customizable gauges.
  3. I bought a Tire Pressure Monitoring System (TPMS) hub that connects via USB to provide both pressure and temperature of the tires.

Check out the video below – a live demo of what I’ve put together so far. I would really appreciate any feedback you might have on current functionality, features to build, data to visualize (and how), logical organization/flow, etc. Note that things like nav and audio are part of a base system and this app is just meant for the car data. Either comment below or send me an email at Thanks!

Fuel Surge Tank Assembly

A fuel surge tank (a.k.a. swirl pot, reservoir) is an integral part of a modern electronic fuel injected race car. Many modern high performance cars have them as well, especially once with turbocharged engines. Its purpose is to ensure the engine has a constant and uninterrupted supply of fuel even while the car is in a corner which is pushing all the gas in your main tank to one side. When that happens, the main tank pump can’t pick any fuel up and starts pumping air, which is not good and in a worst-case scenario can blow your engine. Continue reading