Forced Induction Primer - Mazda MX-6 Forum
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Exclamation Forced Induction Primer

Forced Induction

There are really two different forms of forced induction.
The turbo charger, and the supercharger
Things you will need to know about forced induction.

1. Forced Induction is not very everyone, so make your choice wisely.
2. It is very expensive.
3. Yes it does provide you with mass gains, but that also means more things can break.
4. If you get in a wreck, without informing your insurance company that your vehicle has a forced induction system on it, you're screwed more than likely.
5. It does require more maintenance.
6. You absolutely must build up your vehicle to hold the set up. Having a few minor modifications won't cut it.



Detonation, Knock and Pre-Ignition



There is a very little difference between Detonation and Pre-Ignition. Detonation is actually fuel combusting from the heat and pressure of the combustion chamber. Pre-ignition is an alternate source igniting the fuel (a hot spot in the combustion chamber, a sharp point, etc). Pre-Ignition is very much like an over advanced timing. Both of these could occur before or after the spark, it doesn't really matter.




Knock and detonation is the same thing. The actual sound of knock is the pressure waves inside of the cylinder, piston, and valves. If you hear a knock, you have a problem.

The only way to solve this problem is to adjust the mixture. If you add more air, you need to add more fuel at the proper ratio.

Compression

The pistons inside of an engine all compress the air and fuel at a certain rate. The higher the compression rate is, the more power the motor will make, but this also means the internals are under more strain, and are performing with more heat. A high compression engine does not make for a very well force induction system. The added strain of a force induction system, and the increased pressure in each cylinder can create enough stress to damage the motor. A lower compression engine on the other hand, can handle far more boost because it is under less stress and the compressor does not have to work as hard to push the air into the cylinders since less air in there to begin with.



How they Work

The Super Charger and the Turbo Charger both work with the same theory and rules of science; the only real difference in how they work is the power source. The Super Charger is a belt driven unit, and the Turbo Charger uses a turbine and shaft that is spun by the exhaust stream to increase the rpm's of the blades
Comparison
Turbocharger
Little extra strain on the motor

Boost lag
Takes no power to make power
Obtains power from exhaust stream
Usually Harder Installation
Usually costs less
Causes back pressure on exhaust
More common (easier to find parts)

Supercharger
Does add extra strain on the motor

Instant Boost
Has to take power to get power
Obtains power from a belt pulley
Usually easier installation
Usually more expensive
Less common (harder to find parts)
Far less piping

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Last edited by Goatcrapp; 3-14-08 at 1:29.
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post #2 of 25 (permalink) Old 4-6-04, 15:16 Thread Starter
 
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Turbochargers

Turbo Chargers

Very few people actually know how a turbocharger works, so below is the best basic description I have ever read. If you don't feel like reading this, and you don't already know you should probably go back to the Basics Modifications page. Because building a forced induction set up will require a lot of patience, money, time, and above all you must understand exactly how they work. So to do this, just click on the link below.





Remember, turbochargers only work under load.



Different Types of Turbo Chargers




Ball Bearings-Some turbochargers use ball bearings instead of fluid bearings to support the turbine shaft. These bearings are made of very light, but strong material to handle the speeds and temperature of the turbo. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers. They also allow a slightly smaller and lighter shaft to be used. The lighter the shaft is compared to it's size will help the blades accelerate more quickly, which helps to reduce turbo lag.

Ceramic Turbine Blades-Ceramic turbine blades are lighter than the steel blades used in most turbochargers. Again, this allows the turbine to spin up to speed faster, which reduces turbo lag. The down side is that a ceramic turbine is significantly more prone to shattering.






Twin Turbo




This type of set up uses two turbochargers instead of one. Some of these are often known as a sequential turbo set up. One turbo is smaller, which accelerates quickly in lower rpms, and the larger turbo will take over to produce boost at higher rpm's. Sequential set ups do not always use one very small turbo, and one very large turbo. Sometimes the only difference is one turbo is clipped, or they have different trim levels. Although not all twin turbo set ups are sequential. Some use two identical turbochargers just for the added boost.









Boost Lag




One of the largest downsides of having a turbocharger is boost lag. That means when you step on the gas, the turbo is not instantly creating power. The turbine must speed up to higher rpm's before it starts to create boost. One way to reduce this is to make sure your exhaust flows very well. You can also get properly sized piping.









Properly Sized Piping




Each turbocharger and intercooler use a certain amount of air, you should always try to set up a close ratio of each. One way you have to do this is to have piping that is properly sized. If your pipes are too large, you will have more boost lag because the turbo cannot build the pressure up as quickly. The smaller piping will reduce boost lag, and increase velocity. The problem with smaller piping is that it can choke the engine. You must research this and find a nice medium. The largest concern with the piping is the length. A one by one inch pipe will flow thousands of cfm, but if it's 12 inches long it will only flow a few hundred at most. For the intercooler piping, in general most people use piping thatís 25% larger than your compressor output. One of the largest limitations is the throttle body, make sure the throttle body can keep up with amount of air flowing into the engine.









Clipping the Turbo Charger




Clipping the blades on a turbo will allow air to flow through the blades easier, in turn it increases the breathing of the turbo. This means two things, the turbo will breathe into higher rpms, but it will have more boost lag.







Picking the right turbo

Picking the right turbo makes is probably the biggest difference in the way you want your turbocharger set up to work, and how it will actually work. The smaller turbochargers boost up quicker, since there is lass mass there and consumes less air. But, a smaller turbocharger will not make the mass gains in the higher rpm's like a larger turbocharger would. The smaller the turbo, the less boost it makes. The less boost it makes compared to it's potential, the less strain. You have to figure out the proper sized turbo for your car. Remember, sometimes a smaller turbo is not a good choice. The smaller the exhaust side is, the more backpressure there is, which causes more stress on the engine internals. Also, because of the added back pressure there is more heat on the motor. Take in to account how fast you would like to boost, how much power you want to have, if this will be a street set up or a race only car, and your budget. Make sure you consult with someone to this if you do not understand the different trims and turbos, and how they would work with your engine.

Here is list of pretty much everything you will need to have a full turbocharger set up ready to install. I got all of this information from Raf (FRCFD6 on probetalk.com, a turbo God, and a FI Moderator at probetalk.com)



Collector pipe: pipe that merges front and rear exhaust manifolds and feeds into turbocharger
Turbocharger
Wastegate
Intercooler
Intercooler piping: from turbocharger to IC, from IC to VAF
Blow off valve or compressor bypass valve
Silicone couplers and clamps for intercooler piping
Down pipe: pipe expelling exhaust from turbocharger to cat
Oil lines: Feed line, -4AN; Drain line, at least 1/2Ē
Tapped oil pan: preferably have a ĹĒ female fitting onto the pan
Oil drain flange/gasket: flange that bolts to turbocharger oil drain outlet
FMU: rising rate fuel pressure regulator used to increase fuel pressure according to boost levels
Spare fuel high-pressure hose/clamps: factory size used to connect FMU
Fuel pump: Preferably a 255lph Walbro in-tank pump. Less desirables are the Walbro 190lph and any in-line fuel pump
Vacuum lines, vacuum block/several Tís
O2 sensor bungs (if you replace the log-manifolds with header primaries)

Now here's a basic list of the tools required for a installation.
Piping in a variety of sizes, including elbows, U bends, and straight sections
Chop saw for cutting pipes
Welder for exhaust piping and flanges
Drill with large drill bits for drilling out waste gate, o2 sensor, and blow off valve flange holes
Couplers and clamps for IC piping, oil drain, and fuel lines
Standard and metric sockets, variety of wrench sizes, and standard wrenches
Large scale cutting tools for cutting through front wall and modifying front bumper. (Sawzall, etc)
Other miscellaneous automotive tools for removing and installing basic components


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Last edited by Superman; 4-6-04 at 15:20.
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Superchargers

Superchargers
Types of Superchargers
Roots -positive displacement units, which means every rev of the blower pumps out a fixed volume of air, regardless of the blower's rpm. Result is that boost comes on instantly. Most applications will produce full boost at 2000-2500rpm. Boost can be increased or lowered by changing pulley size. Best to under drive larger unit than to overdrive smaller one.
Centrifugal- Most popular type for fuel injected engines. Provides airflow proportional to blower rpm, thus full boost comes as high rpm.
Twin-screw- positive displacement, similar to roots. The difference is that this type uses twin screws instead of lobed rotors to compress air, works best when overdriven.


Properly Sized Intercooler Piping
Each Supercharger and intercooler use a certain amount of air, you should always try to set up a close ratio of each. One way you have to do this is to have piping that runs from the intercooler, if chosen to use is properly sized. If your pipes are too large, The smaller piping will mass flow, and increase velocity. The problem with smaller piping is that it can choke the engine. You must research this and find a nice medium. The size of the piping a Supercharger uses is not as delicate as that of the turbocharger, but the velocity must more finely tuned with a Super Charger. The largest concern with the piping is the length. A one by one inch pipe will flow thousands of cfm, but if it's 12 inches long it will only flow a few hundred at most. For the intercooler piping, in general most people use piping thatís 25% larger than your compressor output. The largest limitations is the throttle body, make sure the throttle body can keep up with amount of air flowing into the engine.



Picking the right Super Charger

When considering your Supercharger, you must first decide which of the types you would like to have. This will alter the set up of the unit. Don't pick a Supercharger that is too small or too large. But it is better to under stain a larger unit that it is to overstrain a smaller unit. Also look at how much boost each of the different units creates on a low, and on a high boost pulley. The larger and the heavier the pulley is, the slower it spins, which in turn creates less boost.


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post #4 of 25 (permalink) Old 4-6-04, 15:23 Thread Starter
 
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If there is any wrong information please inform me

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post #5 of 25 (permalink) Old 4-6-04, 16:43
 
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ill update this as i go along, but just a few minor things i notice:

youre going to have to be wleding in a lot of filler with a chopsaw, its not nearly as precision as it needs to be.. unless you are building it on the car (where you can make a million cuts and not worry about it) a thin blade band saw works well in this capacity. IF using a chopsaw, i found that the "brick" cutting blades work best,/produce the smoothest cut.

rE: the knock issue theres a whole multi page thread on PT talking about it. Youre pretty much spot on, but an alternate cause, aside form the incorrect mixture one, is the octane one.. if you are running too low of an octane fuel for the boost you are pushing, you WILL detonate, regardless of quantity of fuel (so in this case the only saving grace would be some sort of timing retard, or just get better gas but fattening up the mix wont help in this particular example)

the compression issue is a little understood one i would expand on it to include base (static) compression plus effective compressions once youre running boost into the same engine. also to be noted.. an engine built with a higher static compression is going to produce more hp per lb of boost than the same engine running lower boost, at the expense of less room for error in your fuel tuning.

ill add more later but excellent write up

94 mx6 - you name it - I did it, came up with it, tried it and rejected it, trapped 108mph with it, or just plain still have it. **Now in the caring hands of Chef**
98 jeep GC - 5.9L with every bolt on + tune. My street jeep. 30" all terrains, but runs deep 13's
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post #6 of 25 (permalink) Old 4-21-04, 15:27
 
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forced induction typically refers to something that creates positive manifold pressure.. nitrous IS a power adder, but doesnt fall in this category, except recently when its been lumped in.

best bang for buck? tell me that after 100 runs down the strip. your bottle refill costs would be bringing you close to or exceeding that of a decent turbo setup.

i like juice.. i've run juice before.. but realistically, it doesnt REALLY belong in a forced induction discussion, nor is it REALLY any cheaper.. only in initial costs and setup.

94 mx6 - you name it - I did it, came up with it, tried it and rejected it, trapped 108mph with it, or just plain still have it. **Now in the caring hands of Chef**
98 jeep GC - 5.9L with every bolt on + tune. My street jeep. 30" all terrains, but runs deep 13's
2004 Subaru WRX - The laggin wagon. FOR SALE.
2006 Subaru Legacy GT Spec.B - #37/500 - Anything that can be done, has been done. Fully built motor, Fully built transmission, big turbo, built axles, a 500hp daily driven fire breathing instrument of death (but you wouldn't know it if we went for a ride)
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post #7 of 25 (permalink) Old 5-6-04, 10:28 Thread Starter
 
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Current Manufacturers of kits...

EDIT

heh..all the ones I posted don't make tham anymore!

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post #8 of 25 (permalink) Old 3-10-05, 19:08
 
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when i turbo my 6, i heard i should up grade my rods...is this true? or jus the injectors...what else should i do for uprgrades before i add the turbo??? someone please pm me
thanks all
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post #9 of 25 (permalink) Old 3-10-05, 20:18 Thread Starter
 
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Techinically, you need simply to put the things required. Turbo, manifold, FMU, bypass valve

Suggested: Exhaust, injectors, fuel pump, gut out VRIS, intercooler, MSD ignition, spart plugs, plug wires, boost controller, turbo timer

Would be nice to have: Standalone (to run higher # injectors and have more precise tuning), opened up intake manifold, cams, pistons, rods, crank, valves, a good tranny, a nice looking girl in the passenger seat, and two in the back. Get the idea?

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post #10 of 25 (permalink) Old 5-10-05, 0:03
 
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Nood question
Why do Superchargers like the Eaton M45 cost more than a custom turbo setup?
I always thought SuperChargers costed less
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post #11 of 25 (permalink) Old 5-10-05, 0:13 Thread Starter
 
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Damn, you're such a Noob you cant even spell "Noob".

The turbocharger can be made by more simple welds, while the supercharger must be mounted, have a custom shaft (for the mx3/mx6 generally), and some way to get the compressed air into the manifold which can be done in various ways (although usually only two ways are done). Turbocharger accessories can generally also be found at a lower cost simply because more cars are stock turbo as opposed to stock supercharged. Supercharger units themselves can cost less than turbochargers sometimes, but it all varies.

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post #12 of 25 (permalink) Old 8-6-05, 17:48
 
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Question, can you explain to me what you mean by gut out the VRIS, and why you would need to do this with a turbo setup, or rather why is it recommended? I know what the VRIS is and how it works, just explain to me whats involved in taking it out, and why would you need to do this, and what would happen if you didnt. Thanks

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post #13 of 25 (permalink) Old 8-16-06, 18:35
 
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If you turbocharge the MX6 what engine internals do you need to strengthen?
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post #14 of 25 (permalink) Old 8-16-06, 22:50 Thread Starter
 
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Please, use the search feature. This has been addressed more times than you can concieve.

BUT, no turbocharger is a bolt on for this car. It takes a lot of work to get one to fit well. You do not buy turbochargers for a car. You buy one you think will work well, and give you what you desire. Be it a fast spool torque monster, or a high horsepower lag machine.

By gutting the TVIS you simply make sure that the TVIS does not operate, make sure all butterfly's stay open at all times. You do this for pure performance. It's much like VTEC, look at their dyno's. When VTEC engages, the turbo'd motors lose power for about a thousand RPM.

You do not need to upgrade any internals for the motor, you can run a set up on a completely stock motor. If you give yourself some tuning capabilities, you will notice a huge difference in power and longevity.

-Andrew

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post #15 of 25 (permalink) Old 11-30-06, 23:04
 
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none of the links provided to turbo resources work any more. can you or someone find any working ones? (sorry if u have to waste your time to delete this)
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