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What Is The Proper Way To Bolt On Turbo(BOT)

You probably know how a turbo works already, the energy from the engine's exhaust spins a turbine wheel which is connected by a shaft to the compressor wheel. The compressor wheel compresses/charges air into the engine - increasing air density (more air and fuel = more power). The first step is to get the exhaust gas from your exhaust manifold to a turbo. You can either keep the stock collector and fabricate a custom pipe that will go from the collector to the turbo. Or you can fabricate or buy a turbo manifold. You'll hear/read about "equal length" manifolds - this means that all the manifold pipes coming off of each cylinder up to the turbo are equal length. Reason being is you want your turbo to spin up as quickly as possible. The exhaust "pulses" have a big impact on how efficiently/quickly it spools up. An equal length manifold will "time" the exhaust pulses in a way that they hit the turbine evenly and spin it up quicker than a traditional manifold. You may see the turbo spool up as much as 500rpm sooner with a well-built manifold. If your engine has more than one exhaust manifold (a "V" motor), you'll need a y-pipe for a single turbo set-up that joins the exhaust flow from both manifolds, or you can have twin turbos - one turbo per manifold. The exhaust then has to be routed from the turbo outlet to the back of the car. Turbos are great sound suppressants, so you won't need as many mufflers/resonators to quiet a turbo car down. A turbo car with a straight pipe all the way back can sound very nice. Key thing here is your manifold - you want it to flow well enough, be equal length if possible (though be ready to dump lots of $ on an equal length) and be STRONG. Big turbos with everything hooked up can weigh 50 pounds+. You don't want a cracked manifold. Invest in strong manifold head studs, you don't want your head studs breaking either.

Boost Pressure Control
You'll want to control boost pressure. Too much boost can cause detonation (if you don't have enough fuel to support) which leads to melted or blown pistons. Boost pressure is controlled by a wastegate - which can either be internal to the turbo or external. A wastegate simply diverts exhaust gases through another path that is outside of the turbo - effectively "slowing" the turbo down. Internal wastegates are common on "stock" turbos, larger turbos generally use external wastegates. External gates can divert more exhaust than their internal counterparts (less boost creep), are more precise, and also allow for a wider range of mounting options. Wastegates can be actuated mechanically or electronically. Wastegates have a spring that are matched to a certain boost level. You can connect a boost line to the wastegate, and when that boost level is reached (say 10 psi) your wastegate will open and allow exhaust gases to bypass the turbine, and reducing your boost pressure. Once your pressure drops (to say 9.5 psi), the wastegate spring forces the gate shut, and it does this very quickly and repetitively to keep the boost flat at that 10psi level. External gates are generally more effective at doing this - internal gates can boost creep due to the smaller valve size and internal gate design. Electronically actuated gates are the same, except there is an electronic valve that releases the boost pressure to the gate only when it hits a predetermined level that is set electronically (so you can have it at 10psi and then increase it to 15psi at the touch of a button). You want to make sure that the "mechanical" limit of the wastegate - set by the spring - is lower than that of the electronic controller, or else the electronic controller will try to open the gate but the higher spring limit will keep it closed and you will boost up to the spring's limit.

Mounting Options
To mount the turbo, you want to think about exhaust flow and fitment. Depending on where you mount it, you'll have to "clock" the turbo to make it work in that location. The turbine and compressor housings can be loosened and rotated. The center rotating assembly (with your oil and coolant line connections) can also rotate. You want your oil feed to be facing upwards and your oil drain to be no more than 15 degrees off of vertical (straight down) so you don't build up oil pressure in the turbo and risk leaking oil through the seals. Turbos without wastegates (external wastegate set-ups) are easier to clock because you're not limited by the wastegate actuator that sits on an internally gated turbo. Your compressor housing should point towards your intercooler so you can route your charge piping efficiently.

Oil and Coolant Lines
Some turbos (journal bearing and others) are just oil cooled while ball bearing turbos may be oil lubricated and water cooled. For a non-turbo car, you need to essentially create these lines. You'll need an oil feed line and an oil drain line going back into your oil pan (take your pan off, drill and tap a hole). Same for coolant lines if needed. You want to be careful with oil pressure and volume, make sure you're feeding your turbo the correct oil volume. If you feed too much, the oil will blow by the seals and you will be burning oil in your exhaust as well as charging oil into the engine. Most turbo manfuacturers will tell you if you need a restrictor in your oil feed line depending on your car's max oil pressure.

Charged Air
You will likely want to cool your charged air through an intercooler. There are various mounting options, but the most popular is front-mounted vertically. Be aware of the size of piping you use, bigger is not always better. The bigger the piping the more lag you will have (the turbo has more volume of space to pressurize). If you have twin turbos, you'll need a 2 into 1 intercooler design to route both turbos into one end and have a single charged air inlet pipe going to the engine. Make sure your clamps are on tight and that your pipes have a "lip" on the end to keep the couplers and clamps from blowing off. Boost leaks suck, you'll likely run into one at some point - and your piping will most likely be the cause.

Blowing-off Excess Charged Air
Blow off valves (that make the "pshhhh" sound) release charged air when you get off the throttle and the turbo is still spinning/charging air. These valves can vent to the atmosphere or they can divert the air back into the system. This will be determined by the type of air-reading sensors your car has (read more about this in the tuning section below).

You could write a whole book about tuning alone. You want to be aware of what sensors your car has - is it MAP or MAF based (or both)? MAP reads absolute pressure in the intake system whereas MAF reads air flow. MAP is preferred for forced induction and is generally easier to tune. Your blow-off valve can vent to atmosphere (and make the nice sound) only if you have a MAP sensor. The car will read the pressure and the valve has to blow-off to get an accurate pressure reading. For MAF, when the valve is blowing off - the turbo is still pulling air in through the system - so your MAF sensor will read that the engine is actually using this air. The ECU will add fuel to compensate for that air reading and your engine will run very rich under these conditions. So for MAF set-ups you route that excess air back into the turbo compressor so that the turbo pulls in that blown-off air instead of pulling in fresh air through your filter (and through the MAF sensor). You want to make sure the air is routed back in after the MAF sensor so it doesn't read that recirculated air.

Generally for a turbo application you want control of your fuel maps but also your timing maps. You can play around with ignition timing to help optimize your exhaust pulses and get the turbo to spool better. Bad timing can definitely increase turbo lag. Your common piggyback air/fuel controllers will not cut it for ignition tuning. There are some free open-source systems for complete ECU tuning capabilities for certain manufacturers. Nis-tune for nissans and Trionic Suites for Saabs come to mind. In general, manufacturers make it difficult for you to get complete access to the ECU "image" - which would be ideal since you wouldn't need an external controller "tricking" the ECU to read different air/ignition readings by intercepting the sensors. A good external/standalone tuner that has full ignition/fuel control will run you around $800. The Apex'i Power FC comes to mind. In addition you should factor in a couple hours on the dyno assuming you don't have any exhaust or boost leaks to get the tune done properly.

You can get away with a piggyback fuel tuner, but being able to tune your ignition timing is very valuable and can help you run a much safer and higher-performance tune.

Engine Internal Upgrades
Some engines can support turbos without much lower-end upgrades required. You mentioned pistons and sleeves - this will depend on the stength of your stock pistons and block. Aluminum blocks will have a lower boost limit than an iron block - and iron sleeves can help increase that limit. Without knowing what engine you're using I can't determine whether sleeving is necessary, but it generally isn't required. Pistons and rods are the most common upgrades since thinner/lighter components used in naturally aspirated applications are less likely to hold up to high boost levels. Forged pistons and rods are generally a good upgrade in this case. You also want to think about air and exhaust flow through the engine head. Upgrading your camshafts - epsecially on the exhaust side - can help you reduce turbo lag.

Forgot to talk about compression ratio - so here's a touch on that. Naturally aspirated engines may have higher compression ratio (the amount the piston compresses the volume in the cylinder through its entire movement). You can reduce your compression ratio with different pistons - but a quicker/easier way is to install a thicker head gasket. The head gasket sits between the head and the block - and the head is the "top" of the cylinder that the piston is moving in. So you space the head, add more volume, and decrease the compression ratio. Lower compression ratios help you run higher boost with less risk of detonation. Detonation occurs when the air/fuel mixture "explodes" inside the cylinder instead of combusting (more of a slower burn). Lower compression ratio also reduces the stress on the rotating assembly under forced induction.

You will likely need to upgrade your clutch and potentially your transmission. Check to see what the power rating is for your transmission.

Overall - for best bang for the buck - I recommend starting with a car that has:
- Iron block and strong pistons/rods from factory (some engines are known to hold 500-600hp in stock form - the nissan RB series, Toyota JZ engines, Saab B204, etc.; but these are all engines that came turbocharged from factory). Again Naturally Aspirated engines will likely have light-weight and more fragile components to reduce drag and make the engine more efficient, whereas forced induction engines have heftier components to handle boost - start with a something designed for what you want to achieve.
- MAP sensor instead of MAF - just better suited for measuring pressurized air
- A solid transmission
- ECU control/access through an open-source tuning program - will save you thousands, and a car on a stand-alone unit will never run as smoothly as a car on an OEM ECU (plus having to pass inspection, etc.)

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