Guys, (mods, i have found that most of the links are going dead after some time. so i thought of copy pasting the basics here)
I have got some material on turbo basics. I am doing a initial feasibility study on doing a turbo and doing lot of google and ebay and various other sites. So have to take it from google cached pages. So thought might be useful trying to get some knowlege on turbo. Ok now the long read.
[FONT=Arial]Let's have a frank discussion about turbochargers as a system. A lot of street guys want turbos for their cars for however many reasons exist… you want the hardware under the hood because it's cool; you want a turbo timer because it's cool; you want the "psssssh" sound from a blowoff valve because girls throw their panties at your car when they hear it. Lots of us like to drive Hondas, Mitsubishis, Volkswagens; whatever you prefer, it probably has a small engine and even if you think it will, revving it to 9,000 RPM isn't going to magically catapult you ahead of that Corvette LS-1 next to you at the red light. Fast cars take torque, and a turbo system is arguably the best way to get mondo torque on pump fuels. Let's say you have a healthy Integra LS with all the bolt-ons. About 165 hp @ 6500 RPM and 137 ft-lbs @ 5750 RPM. You could spend the $5,000 or so swapping to a 195 hp Type-R engine, a cost of about $167 per horsepower. Or you could spend $3,200 on a DRAG turbo system and get 255 hp and 211 ft-lbs. of torque. A cost of $36 per horse. (By the way, that's not a hypothetical situation; we've seen several 1994+ Integra LSs with DRAG kits, 91-octane fuel and 10 psi making those numbers.)[/FONT]
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What's In A Turbo?
First thing's first, let's acquaint you with the three major pieces that make up a turbocharger; the center section, the housing over the turbine (usually made of cast iron) and the housing over the compressor (usually made of cast aluminum). You can call these the "turbine housing" and the "compressor housing," respectively.
The Theory
Let's waste little time and cut right to the part where we jump out of the tree wearing underwear attached to bungee cords. A turbocharger is about the simplest air pump that can be designed. A venturi-type air pump is the absolute simplest (it has no moving parts), but can't be used for an automotive forced induction application since it would mix a great deal of exhaust gas into the incoming fresh air charge. A turbocharger has one moving part and this one moving part (the turbine shaft) is powered by exhaust gases streaming down the exhaust system. The effect is not unlike a water wheel. When using a water wheel to power your wheat-grinding mill, no water gets into the mill because it is separate. The same goes for a turbocharger. No exhaust gas bleeds to the intake charge because the power source is separate from the portion of the turbo that does the work. In the photo we drew some arrows indicating where the exhaust gases enter and exit turbine enclosures; gas goes in radially, turns a wheel and exits axially. Air moves a shaft and that's about it.
On the other side of the turbo, work gets done in the exact opposite direction; the shaft moves air, and the air enters the center (axially) and exits the side (radially). So a turbocharger simply helps us use some of the leftover power in exhaust gas to pump more air, and we can pump that air directly into the engine for a self-sustaining reaction of sorts.
A Few Considerations
The shaft that conjoins the turbine to the compressor needs lubrication and cooling, and both are supplied by the oil and coolant already in the engine. Turbocharger center sections usually have a number of holes in them for fluids. This particular turbo has only two holes; one for an oil feed and the other for an oil drain. Other turbochargers have two additional holes for coolant, but the coolant is only to protect the turbo after the engine is shut off. Cutting the engine doesn't make heat in the turbo go away. It certainly does make oil pressure go away so having a bit of water nearby helps to keep things cool. This is why a turbo timer is a good accessory to have on a turbocharged car, because it keeps the engine running for a set amount of time after the key is turned off, allowing the turbo to cool. Water gets to the turbo by connecting it in-line with any coolant source, such as throttle body coolant lines. Oil can be fed to the turbo from just about any oil source, such as a tee on the stock oil pressure switch on the engine block. Most turbochargers use gravity to drain their oil so the drain hole
must be pointed down. From the turbo, oil usually drains directly back to the oil pan through another hose.
Practical Application
Now for the fun part. Do you want a TD04-14B, a K04-001 or a T3/T04E hybrid turbo? Well let's not allow the undecipherable strings of alphanumerics scare us. First of all, three different manufacturers make those three turbos we just mentioned. The TD04-14B is made by Mitsubishi and is used in the factory turbocharged Talon/Eclipse/Lasers built from 1990 through 1994. The K04-001 is made by BorgWarner and is used in the higher-powered European version of the Audi A4. (A side note: BorgWarner purchased the original manufacturer, which had a name that meant something entirely different in Europe: KKK. You got that, hillbilly boy? –OVB) Hybrid turbochargers are something designed entirely for the performance aftermarket and are based on Garett turbochargers. It's called a T3/T04E because the turbine section comes from the T3 Turbo, which was designed for gasoline-powered cars. The compressor comes from a much larger T4 turbocharger, which was designed for heavy trucks. So you get a small-engine-friendly T3 turbine driving a big-power-friendly T4 compressor. (A 1.5L engine probably wouldn't make enough exhaust gas to even get a true T4 turbo spinning, let alone making power.) Generally speaking, each brand of turbocharger will perform similarly if similar specs are selected. About the only difference is where the bolts go. So if you have a Volkswagen running a BorgWarner K03 turbo and you want an upgrade, the easy route is a larger K04. Sure, you could use a TD04-14B, and it would make power, but then you're left with figuring out how to bolt up the turbo. If you're switching a non-turbo car over to turbo status the sky's about the limit. For Hondas, most of the parts you can buy from shops are geared toward using Garrett-type turbos. The turbocharger in the photos above is made by Turbonetics, but fits Garrett applications. It is a T3/T04E trubo and will flow to about 500 hp. Note the compressor housing is stamped "E50," which indicates T04E compressor with a "50" trim. The exhaust housing is stamped "63," which means the turbine housing has an aspect ratio, or a/r, of .63. Generally speaking, the higher these numbers, the higher in the RPM band the turbo will be comfortable making boost and the more power they can ultimately make. A T3/T04E-50 is generally considered high-performance standard for four-cylinder engines because it makes boost in a wide range of engine RPM and makes a lot of power. (At 10 pounds of boost this thing'll make 260 horse with a good intercooler.)
Which Turbo to USE
So once you've decided which brand of turbo is the one you want to use, which model do you select? We can't cover that answer in its entirety in a single article but usually you'll be looking for a kit. With kits, the engineering equations are done for you and all you have to do is select which kit you like and slap it on. If no kits are available, we'd have to say go for the Garrett-based hybrids. Availability of parts means a wider selection of turbos for your engine and easy availability of support parts such as flanges and gaskets. Here's a short list of automakers and the Garrett brands they use in the factory. When shopping for a bolt-on upgrade, these are the brands to stick to:
Audi: KKK/BorgWarner K0-series
Dodge: Mitsubishi TD-series and Garrett T25
Mazda: Mostly proprietary; kits include custom exhaust manifold(s)
Mitsubishi: Mitsubishi TD-series and Garrett T25
Nissan: Garrett T25
Subaru: IHI
Toyota: Toyota CT-series and Mitsubishi TD-series
Volkswagen: KKK/BorgWarner K0-series
While not a hard and fast list, this should get you pointed in the right direction so you don't go chasing a KKK turbo for your 1990 Toyota Supra. Note that many of Mitsubishi's TD turbos are interchangeable with the Garrett T25, so don't be surprised if you see a Mitsubishi turbo on a Dodge or a Nissan.
As far as hardware is concerned, getting a turbocharger into a car involves little more than positioning the turbine into the exhaust stream, attaching the exhaust system to the turbo, and attaching the compressor to the intake system. The three major parts of the turbo are bolted together so you can freely rotate the turbine, compressor and center section to get the plumbing where you like it. Of course, there are fuel and spark concerns...
References:
Link 1 Link 2
23rd February 2007, 04:36
