Project Silvia's Girlfriend Part 1: Engine and Stuff

by Dave Coleman

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.


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...

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Mazda Phil
Mazda Phillink
Tuesday, January 14, 2014 6:42 AM
Any woman that asks you to build her a Silvia is a keeper. Good project, but I'm dieing to see Project Silvia come back together.
Tuesday, January 14, 2014 6:43 AM
This is such a typical Dave article. Heres the TLDR:

"Although you all thought I was making millions from constructing garages out of shipping containers, I was really just tinkering with another POS 240SX. But as usual, everything I touch turns to gold so I picked up a car that was built with project silvia as a model and super low mile nonexistent Red Black Silver top SR20. But I don’t have to follow the SR20 rule because I am Dave Coleman so here are some really random photos of the engine on a rally tire and a few anecdotes. Oh, and it has A/C."

(and if any of that was taken as sarcasm, know that this kind of stuff is exactly why I read MotoIQ)
Tuesday, January 14, 2014 7:25 AM
Here's to wishing Dave had more time to work on projects and write us articles in 2014.
Mike Kojima
Mike Kojimalink
Tuesday, January 14, 2014 10:30 AM
I am glad Dave is writing about stuff like this and not Lemons stuff!
Tuesday, January 14, 2014 10:57 AM
These kinds of articles are my favorite. I hope to see more from Dave this year.
Dan DeRosia
Dan DeRosialink
Tuesday, January 14, 2014 4:33 PM
The presumably-completed image makes me lust. I love the SilEighty style, for whatever reason, even if it's a weird mishmash of angular with rounded and stuff like that. I do sometimes feel like the only RWD fanboy in the world who isn't on the SR20 lovetrain, but still, waiting for more with interest.
Tuesday, January 14, 2014 7:48 PM
The photo of the melted knock sensor is in a Technobabble article that I just happened to stumble across the other day.

Tuesday, January 14, 2014 8:01 PM
When Dave doesn't post enough, I'm forced to read old issues of SCC for my fix. We love you, man.
Der Bruce
Der Brucelink
Tuesday, January 14, 2014 11:17 PM
I think that was a 510 in the background which might need some attention and spotlight in the future!?
Wednesday, January 15, 2014 6:19 AM
That should be the rally 510 there. I am hoping that Dave regains his love for that chassis on a new project (as if he doesn't have enough), as I'd love to see what he does with modern technology and his engineering skills he's developed. Not to mention it might get me off my butt and work on my 510 project :/
Dave Coleman
Dave Colemanlink
Wednesday, January 15, 2014 11:30 PM
Thanks for the kind words everyone. Mazda Phil, you are 100% correct. Rady960, you are some kind of genius! A borderline creepy genius... Anyway, story updated...
Thursday, January 16, 2014 3:38 AM
"Borderline creepy genius" was my nickname in high school.
Thursday, January 16, 2014 8:44 AM
That's an impressive overheating job. Surprised it kept running long enough to melt plastic like that. Thermoplastics like that probably don't melt until at minimum 248*F, and more likely somewhere in the 300*F range. SR20, strong like bull!

Friday, January 17, 2014 7:12 PM
wheres the miatabusa?
Dave Coleman
Dave Colemanlink
Saturday, January 18, 2014 7:40 AM
On my back porch...

Really, I'm surprised it took almost a week for someone to ask! Two of the four new parts have been machined. I'll make an update as soon as we start test fitting them on an engine.
Saturday, January 18, 2014 8:17 AM
Speaking of machined 'busa engine parts. Anyone here seen www.dpcars.net?

Palatov is freaking nuts and has been building his own race cars from scratch using hyabusa engines and Hartleys. I have a feeling he and Dave would get along well.
Saturday, January 18, 2014 6:08 PM
i think im the only reader left that still checks for it.
Saturday, January 18, 2014 6:19 PM
I registered just to say that I check this site every 3-4 weeks, hoping for a Miatabusa update. I've got a clean Miata with a seized engine in my barn, just waiting, waiting, waiting...
Sunday, January 19, 2014 6:45 AM
There are people who aren't anxiously waiting for Miatabusa updates?
Thursday, January 23, 2014 10:47 PM
Dave....excellent article!!! I bought an early edition SCC mag back in early 90's when I was a teenager that featured a 180SX in it from Japan. Always thought "why can't that engine get installed here in US?"

I eventually did an SR swap in 01 in my 92 S13 Coupe in central TX. Everybody at the time was saying "just use a Permacool fan with their between the fin controller and it will work great" Luckily, I installed a set of Defi gauges with warning and peak hold. On day 1 the temp meter got pegged. I drove around with the heater on full blast to no help. Really sucks in 95 deg heat with 80% humidity driving around with heater on full blast and the car STILL overheats.

Eventually got fed up and got together with 2 other ME friends and Kevin Vancleve from C&R Radiators and did an SR radiator and fan test. Over a weekend we tested 5 radiators (Stock, Copper Stock, Koyo, and 2 from C&R racing) combined with 5 different fans (Stock Clutch with Shroud, Flex-A-Lite 2 fan setup, Permacool, and 2 different FAL's). I had a Blitz LM intercooler and Blitz cone intake. Engine was otherwise stock. Using a chart recorder from work we simultaneously datalogged about 7 different temp channels (rad coolant in and out, temp at air filter, in front of IC, between IC and Condenser, between Condenser and Rad, and Behind rad). We also measured fan CFM using an handheld air monitor.

Testing events consisted of: 2 drag launch runs per setup, highway steady state cruising in no traffic, and idling the car in full sunlight with the AC on high to monitor how long it took the temp to reach 210 F where it couldn't be brought back down by cycling the fan.

Results for radiators were: 1st = C&R Double Pass, 2nd = C&R Single Pass, 3 = Copper stock, 4 = Koyo, and 5 = Stock). Discovered early on that the Koyo's had very weak stamped Al fill necks that started leaking before too long. The C&R had thick billet necks that were awesome.

Results for Fans were: 1st = High CFM Spal, 2nd = med CFM Spal, 3rd = Stock Cutch, Distant 4th = Flex A Lite (fan shrouds not deep enough to effectively move air), and virtually worthless was the Permacool.

We also discovered that the ducting over the tops, sides, and bottoms of the rads made about a 20 deg drop in temp. That was just simple cardboard ducting seals.

Eventual winning setup was cardboard ducting, C&R Dual Pass + Spal High CFM. I could sit hours in gridlocked traffic @ 100+ deg ambient with AC on full blast cold and the fans would cycle on and off every couple of minutes to keep it under 200 with no probs whatsoever. Would drive on highway with full AC at same 100+ ambient and the fans wouldn't even come on. Phenomenal difference!

Also discovered that the between fin temp probes were complete junk (tried 3 different types and ALL junk). Yeah, it's great to measure the temp of the outside of the radiator but ya know what's even better?.... measuring the temp of the actual water coming out the engine. Eventually discovered a $400 Greddy elect fan controller that I had imported with Japanese only instructions that used a probe in the upper rad hose. Rock solid and worked awesome.

In short, 1.) the SR's run hot 2.) don't underestimate the power of excellent radiator and fans and 3.) you get what you pay for.

Thanks again for the great articles. Keep them coming!
Dave Coleman
Dave Colemanlink
Friday, January 24, 2014 9:11 AM
Wow, I dare say this comment is more informative than my story!

Are you sure that "early '90s" Sport Compact Car story on the 180SX wasn't late '90s? Like 1997? April, perhaps? That's the earliest 180SX story I can find, and actually I think it was the very first story I wrote when I joined SCC. It was a 180SX and R33 GTR in one story, if that joggs anything...

If the shallow shroud was the issue with the FAL fan you tested, the one I used might have performed better, since it was the 2-fans in one shroud deal. Harder for air to leak around the sides when you have basically full coverage of the back of the radiator. The flip side of this 2-for-one arrangement (cost and convenience were what really attracted me to that setup) is that when one of the motors died, both got shitcanned. The car now runs factory Miata fans. Small motors, but deep shrouds...

And the Koyo now has a billet neck welded on.

I'm also a little curious how you compared the stock belt-driven fan to the electrics. Was that an idle test? Comparing velocity or total volume? I can certainly see the Spals beating belt drive at idle (and face it, that's where fans matter most), but a velocity measurement isn't necessarily telling you what you need to know, since an electric fan will have a ring of high-velocity air around the fan blades, but nothing around the corners of the radiator where the fan doesn't even go. A properly shrouded factory fan pulls air evenly across the whole radiator.

I'm not sure how I would measure that, though. You'd need a good low-speed flow meter to measure air getting drawn in the nose of the car to get a picture of the total flow across the radiator.

Don't take this nit picking the wrong way, though. Your test still kicked my test's ass.
Tuesday, October 20, 2015 4:32 PM
Reasons we know that this project is really old: You found an unmolested S13 that looks completely stock except for a few mild modifications, and is not painted with gray primer. Doesn't exist anymore.
Monday, October 26, 2015 12:46 PM
Just to throw a little more information on the cooling discussion. There are 2 factory temperature sensors on a redtop SR20 (probably others). One single wire that makes the dash gauge go up and down and a two wire that gets reported back to the ECU (one goes to an ECU pin and the other is ground). The 2 wire sensor is actually fairly accurate and an OEM piece. I used an HKS fan controller wired to ground 2 30amp relays powering a set of Flex-a-Lite fans bolted to a PWR radiator and it's worked great. The fan controller will display temps in C or F and I can set turn on and turn off temps for individual fans or both. You can even wire additional outputs based on temperature (like a warning light or water sprayer). I'm pretty sure it's discontinued these days but there has to be something similar out there.

I don't have any of my S13 pinout stuff with me but it wasn't hard to find the right wire to tap to feed signal to the controller. That solution makes a lot more sense than pushing a probe into the radiator fins or adding addition sensors. You've already got a perfectly good OEM sensor.
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