posted on January 13, 2014 13:31
Project Silvia's Girlfriend Part 1: Engine and Stuff
I've been holding out on you. While years were going by between updates on Project Silvia, I was actually spending time on Project Silvia's girlfriend. This project is all past tense, and is based entirely on whatever pictures I could find and whatever details I could shake loose from the dusty recesses of my brain.
The project started in 2006, when my girlfriend, Sarah, wanted a Silvia of her own. As a daily driven track car, she wanted the versatility of a hatchback, the under-the-radar style and color of an adult's car, and working air conditioning. This would end up making her car substantially different from mine.
This car showed up on Craigslist with an S14 SR20DET already installed. In fact, the seller said he had built the car after reading my original Project Silvia series in Sport Compact Car, and claimed to have followed my advice throughout the build. Really, he had used the same radiator, fans and boost controller as I had, but otherwise seemed to have completely missed the point. Sadly, he overheated the car while sitting in traffic and the engine had no compression when we bought it.
Not owning a trailer, we pushed the car down the street and called AAA to get it home. After digging into the engine, we learned just how bad that overheating had been. The coils (SR20DETs have coil-on-plug ignition) were melted into the head and the knock sensor had liquified and dripped down to the oil pan flange! This would be a great place for a picture of those melted parts...
Sadly, this will not be the last time in this project series that I apologize for misplacing a photo. Found it!
The previous owner had no idea why the car had overheated, so the teardown had to be a search for the root cause. Pretty quickly I found an aftermarket fan controller that was supposed to be triggered by a probe-shaped temperature sensor that was jammed between the radiator fins. Shitty design to start with, but the bonehead who installed it had left the sensor dangling behind the radiator in the relative cold, so the fans would never turn on.
That would seem to be reason enough to overheat in traffic, but further disassembly revealed a hairline crack in the water supply line to the turbo. A leak here would evaporate immediately and was so buried that there would be no visible sign of leakage. That's a wicked combination that would make it very easy for a person to be left with no idea why they were losing coolant.
More than a year later, when the car was losing coolant anyway, we found a third problem. The Koyo aluminum radiator has a thin aluminum cap flange, and that flange had warped, lifting the cap so it would no longer seal against the high pressure seal in the base of the flange. The low-pressure seal on top still held, so water didn't leak out the cap, but with the lower seal not doing its job, pressure was bled out into the overflow tank whenever the engine warmed up.
This trifecta of failure meant the water level was low from the hairline crack, the boiling point was low because of the lower pressure, and there was no cooling flow across the radiator when sitting still in traffic. The engine was doomed.
With overheating that severe, nothing on the old engine could be trusted for a rebuild. It was just a stinky pile of scrap metal.
With the help of an eagle-eyed friend, we scored a low-mile Japanese import S13 engine for only $300. The engine was missing the turbo manifold and had a silver non-turbo valve cover on it (only difference is the bosses for the coils and coil cover haven't been drilled and tapped), and nobody seemed to notice that someone had scribbled "turbo" on the valvecover in junkyard paint pen, so it was mistakenly priced as a non-turbo engine. There is exactly zero demand for rear-drive non-turbo SR20DEs, so the price was incredible.
All Japanese import engines claim to be low mileage, but this one really did seem to be. It was a later S13 engine built when S13s and S14s were being produced at the same time. These are nearly identical to the red-top S13 engines, but had a black valve cover, so they're often known as black-top red-tops. Our black-top red-top happened to have a silver top...