According to Eyesore Racing, one of the participants of last weekend's 24 Hours of LeMons race at Thunderhill, turbocharging can be easy. And this team puts their money with their mouth is, considering their entry, a first-generation Miata known as the FrankenMiata, was bought, prepped and turbocharged for less than $500.
Sound too good to be true? Hit the jump for some pointers to keep in mind when turbocharging on the cheap.
1. Start with a car that can handle boost.
Don't bother with a carbureted engine. Perhaps paradoxically, it's easier to turbocharge a later-model car with multi-port electronic fuel injection than some jalopy with an old-school fuel mixing bowl. It turns out that the later engines are more flexible when it comes to suppling the additional fuel required by the turbo.
First-generation Mazda Miatas (1990-1997) are a great starting point since their engines were derived from the turbocharged Mazda 323GTX. From the factory, Miatas came with forged rods, low compression pistons, oil squirters for said pistons, and a rugged closed-deck iron block. You won't find a more boost-ready stock engine. Heck, the early Miata engine blocks were still machined (and plugged) for the turbo's oil and coolant supply ports.
Alternative: bring spare engines to the track with you.
2. Don't be greedy.
Boost is great, and, yes, you must respect the mechanical and thermal load it places on an engine. Curiously, boost also has a debilitating effect on one's judgement. It's so tempting to make power with a turbo that you must force yourself -- like Odysseus and the Sirens --to run low boost.
Eyesore Racing ran just 3.5-psi of boost, which is enough to give them a useful 40 horsepower compared to not having a turbo, but not enough to risk a spectacular engine failure.
Keeping your expectations low is the best way to ensure you aren't disappointed. Sort of a metaphor for life, really.
3. Use crappy, obsolete parts that nobody wants anymore.
Scour craigslist.org and model-specific car forums. If you're racing, tell folks you're racing. People will ransack their garages for old parts they'd nearly forgotten about if it means some tenuous association to motorsports. Yes, racing in LeMons actually counts as motorsports.
Eyesore Racing landed a rising-rate fuel pressure regulator and a spark-retard black box for a total of $42 including shipping. In Miata-land, these parts are on the bottom rung of craptitude, making them easy pickins for the broke racer-wannabe.
Turbos are free when they look like this:
Also, factory turbo cars provide a plentiful source for cheap intercoolers. This one came from a blue Ford Probe and cost $40:
4. Fashionistas need not apply.
A turbo car needs a turbo exhaust manifold. This is usually the biggest stumbling block for the cheap racer.
But wait--your car came with an exhaust manifold already. Why not just use that one? A simple adapter will mate the stock manifold to any turbo. Here's Eyesore's implementation:
Thin-wall manifolds like the Miata's will self-destruct in minutes if the weight of the turbo isn't supported elsewhere. Consider comprehensive bracketry to lighten the manifold's load:
Using the stock manifold to turbocharge your car also gives you the sweet roof as seen in Step One, and encourages drivers to look through the turn the way they're taught in driving school:
5. Don't skimp on your tow vehicle.
Turbocharging a car can be cheap, but that doesn't mean it'll be reliable. In fact, it almost assuredly won't be.
To hedge their bets, Eyesore Racing used this 2008 Toyota Tundra Limited to haul their stuff to and from the track. With 381-horsepower and a tow rating of 10,500 pounds, it never even breathed hard towing a Miata-laden trailer and a full bed of spare parts.
6. Learn to weld.
When your exhaust bracket breaks in the middle of an endurance race, thereby hanging the entire exhaust's weight on your turbo, you'll be glad you spent ten minutes learning how to use a hot metal glue gun, aka a MIG welder.
7. Congratulations, you've ghettocharged your car. Your engine is about to blow up.
If you're turbocharging your engine in the manner described here, chances are that that you're not the sharpest knife in the drawer. You had better hope you were blessed with good ears instead.
You will need to listen for detonation, that rattly sound that precedes pending engine failure. If you hear this noise, back off the throttle. Well, finish passing that Plymouth Belvedere first. Then get in the pits and retard your spark timing until you don't hear the rattle anymore.
You can also add fuel to douse the detonation, but this isn't as effective as pulling timing.
The third solution? Revisit Step 2 above, Senor Boost Junkie.
--Jason Kavanagh, Engineering Editor and Eyesore Racing Team Member
estreka says:
04:29 AM, 01/ 3/09
Awesome article. A big kudos to you.
bbechtel16 says:
11:14 AM, 01/ 5/09
Awesome! Nice info I wasn't aware of about the Miata engine too.