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Discussion Starter #1 (Edited)
Forced Induction. What is the meaning of this term when working with the combustion engine?

This thread will strive to cover every aspect required when properly using forced induction on a engine. And if your talking about buying a kit, then move on and don't post. This thread is for the rare few who want to: Engineer, Design, and Fabricate their own forced induction system to get some more ponies under the hood. Besides, this is the Hard Core section. NO BOLT ONS ALLOWED!

So what is needed for forced induction? Basically a air pump that is driven by the engine using a pulley system(SuperChargers) or using the exhaust system(Turbo's). Whatever one is used both has its own pro's and con's.(I personally prefer Turbo's) We will get deeper in this later.

Yes, I always get the, "Its easier to throw in a Cheby 350", or the "Just go find a LS series with the ECU" Swap. We all know that a quality engine swap is nice to see, but its getting boring:shaking: I personally think that fabbing up your own forced induction system and making it work "reliably" is awsome to see.

The Key word here is "reliable"! I don't want to see this thread filled up with engines that operate at max potential for about a quick one days work then needing the rebuild. I want to focus on reliable systems with longevity when proper maintenance is done. Besides, that is what we all strive for is the reliabilty factor when out enjoying our trails.

Lets just throw some basics out there required for forced induction:
1. Compressor
2. Engine Operating Range
3. A way to turn the Compressor
4. Fuel system requirements
5. Plumbing for compressed air to engine
6. Engine Management requirements
7. Exhaust system

Im pretty sure I covered the basic topics. Later we will take each topic and break it down. So before you go out and start buying parts or God Forbid that P.O.S. kit, lets do some research.
 

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Discussion Starter #2 (Edited)
Compressor

First off is the type of compressor to run.

1. Belt Driven:

A. First there is the old school Roots(Eaton, Whipple, Moonyham, etc)style that everyone can relate to. It usually sits on top of a V-8 motor that is driven by a belt off the main crank pulley. These types usually provide off the line boost and can give great results. The only problem is that they actually rob power from the engine to make power. Basically, if your motor is puttin out around 500 at the crank, thats after the 10-15 percent loss that is used to actually turn the compressor. Also, there is the heat generated by the incoming compressed air going into the engine before the combustion cycle is even started. More on Heat build up later.

B. There is also the "Belt driven Turbine"(think of Vortech and Paxton). These also are driven by a belt from the crank. That is correct on the term when I say a "Belt Drivin Turbine". These use a mounting style off to the side of the front of the engine similar style to that of a Air Conditioning Compressor, or Alternator. So you will have to fab a supporting bracket for this style.

It is a turbine type compressor that is supported inside a housing with a shaft to a pulley on the outside. The compressor is basically the same as a turbo, but they also rob horsepower to make the compressed air. These are easier to use external types of heat syncs (Intercoolers) to cool the incoming air charge before the combustion cycle. (more on intercoolers later and how they work).

The main connection between these two types, is that the amount of boost and RPM range is severly limited to the operating range of the engine itself. You can always swap out the pulleys to generate higher boost(which is a PITA) to help tune your system.

But this belt driven system is easier to build/fabricate, quicker to get up and running from a mechanical standpoint. But the tuning flexibility is fairly limited to what you get


2. Gas Turbine Driven Compresser (Turbo):

A. This type of compressor is attached to what is called a Turbine, which is bolted into the airstream of the exhaust gases of the engine itself. The force of gas enters the Turbine, which also starts spinning the Compressor. The compresser and turbine are connected via a solid shaft that is housed in what is called a Center Housing Rotating Assembly(CHRA: Pronounced=Tray) You also need to find a space in your engine bay to mount the turbo for everything to work(The hardest of the type of fabrication needed to work).

-The faster the engine can cycle(higher RPMS) the faster the turbine will turn the compressor. Therefore, boost is generated. You can alter the characteristics of the turbo by going to a smaller or bigger turbine to change the boost output of the compressor at different RPMS of the engine as well as to tune for optimal efficiency to match the engines best operating range. When a turbo is matched correctly, It can ALSO give off the line idle boost performance. Notice I say MATCHED CORRECTLY! We will go in more detail of matching turbines to compressors to engines later.

B. Turbo's have about a infinite of tuning range for about any type of situation. The draw back to turbo systems is that they are about twice as hard to fabricate/build and set up and tune. But if you do your homework, the first setup should be on target and using very little work to home in on a bulls eye performance result. Another draw back to Turbo's is that they can generate an enourmous amounts of Exhaust Gas Tempuratures(EGT's) that can kill an engine in less then a minute if you don't know what your doing!:eek: But you all shouldn't have to worry about Fawking this up because we know how to read, research, and do homework before we pick up a wrench, much less, go into the garage blind folded.


C. Both of these types of systems require an external pressurized oil source to keep the compressors lubed(I think Whipple was the only one with its own oiling system). That means you have to tap into the oil source of your engine. And just like the engine, you also have to provide a oil return dump back into the engine or oil pan. Some compressors even require you to also tap into the engines water cooling system to also cool down the compressor during its operation with a water return line. So thats another thing to think of. I didn't say this would be easy! Maybe that bigger engine transplant is looking more your like your style. But if it was easy, it wouldn't be fun!:p

So right now, put down the welder, torch and tools. Back away from your engine and go in the house. Go find a good calculator, pencil, a large notepad and get ready.
 

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Discussion Starter #3
Engine Operating Range

Another VERY important part of all this, is to define YOUR engines operating range. This is important in also deciding on how big or how small of a compressor you need.

1. max engine speed
a. This will be the upper limit of the compressor's operating range

2. engine cruising speed
-when cruising down the hwy or around town, you should be able to give it more throttle and you will be producing positive boost for more power if needed.

3. engine speed at all shift points
-when you shift from max RPM to the next gear, you will still be the compressors sweet spot and produce maximum boost at the lower RPM. We call this, keeping the engine and system in its power band.

You don't want a compressor thats to big for your engine. If its too big, you will experience a surge in the upper rpms close to your shift point. So when you shift, you will fall out of the compressors range and you will get serious lag. Think of trying to fill a 55 gallon drum with water, having drain the size of a 3 inch hole at the bottom, using a gallon size can. You will eventually fill it up to the top, but will take all day doing it.

In the other spectrum, you don't want to have your engine die out of pulling power when you still have about 1500-2000 rpms of upper range to your shift point. Think of filling that same size 55 gallon drum with water, having a small 1/4 inch drain hole at the bottom, using a 30 gallon bucket. You will fill it up quick and overflow the drum real fast. The idea is to match the incoming air to the outgoing air and keeping the 55 gallon drum full at the top so the drain empties with a constant pressure.

The majority of us here, operate our engines from idling in the rocks or trail to the mid to upper range during a short sand/mud climb to continue the trail. So its safe to say, we want a system that is user friendly from idle(or at least 1500rpm) to max. We are generally not dealing with race engines. Most of these applications are on stock from factory engines with stock internals.

But for the rare few, you can also take this info for the 8000rpm sand drag, mountain climbing screamer if needed.
 

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maybe you could explain this to me... i get why superchargers suck up power, what i dont get is how exhaust gas PUSHING (< key word there) a turbine to compress air doesnt add back pressure to an exhaust which would make more work for the engine to push the gases out of the combustion chamber and thus causing parastic power loss.... really i dont get it. i could see maybe how it wouldnt cause as much power loss but ive always been a believer that nothing is free.
 

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Discussion Starter #5
maybe you could explain this to me... i get why superchargers suck up power, what i dont get is how exhaust gas PUSHING (< key word there) a turbine to compress air doesnt add back pressure to an exhaust which would make more work for the engine to push the gases out of the combustion chamber and thus causing parastic power loss.... really i dont get it. i could see maybe how it wouldnt cause as much power loss but ive always been a believer that nothing is free.
This is a VERY good point to bring up. In some states, the turbine of a turbo is actually considered a muffler. It does provide enough backpressure for the engine to deaden the exhaust pulses. Yes, the backpressure does also add more restriction on engine breathing under "vacumn" conditions. But as you transition to boost, that boost also coming out of the exhuast after combustion is now turning the turbine to turn the compressor faster. Its an engine that feeds upon itself and grows bigger and bigger. The only way to stop the monster from growing is adding whats called a Waste Gate. More on this later. Its hard to picture and maybe understand. But it works and it really doesn't lose as much power compared to a belt driven compressor. (here comes the argument) Lets leave the argument in another thread please. But my personall and professional opinion is that Turbo's are more effeceint then Belt driven Compressors.

The next topic will enter into whats called Pressure Ratio, Density Ratio. The difference between the two and how both relate to each other.
 

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i get ya... so it would only have a marginal effect power under non-boost conditions? if your planning on getting to this later then ill just wait but is this another factor to lag?
 

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You should subdivide the belt driven "Roots" section into Roots and Screw types.

Roots styes are the 6-71, 8-71, and 14-71s that everyone is familiar with on the old school hotrods, muscle cars and drag cars. These are the Detroit, GMC, Littlefield, B&M, Holley, Moonyham, Weiand, BDS and The Blower Shop. Eaton, Magnacharger are still considered Roots type but they twist the lobes.

Screw types work on a little different principle. These are the Whipple and Kennebell

Edit: I wanted to add a thank you for a nice start to useful and appropriate Hardcore thread.
 

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Discussion Starter #8
i get ya... so it would only have a marginal effect power under non-boost conditions? if your planning on getting to this later then ill just wait but is this another factor to lag?
Lag is all dependent on the size of the turbine related to size of the compressor its connected to. With today's technology with materials, lag is no longer an issue with today's systems.

You should subdivide the belt driven "Roots" section into Roots and Screw types.

Roots styes are the 6-71, 8-71, and 14-71s that everyone is familiar with on the old school hotrods, muscle cars and drag cars. These are the Detroit, GMC, Littlefield, B&M, Holley, Moonyham, Weiand, BDS and The Blower Shop. Eaton, Magnacharger are still considered Roots type but they twist the lobes.

Screw types work on a little different principle. These are the Whipple and Kennebell

Edit: I wanted to add a thank you for a nice start to useful and appropriate Hardcore thread.
Thanks:)

If you want to add some tech on belt driven compressors, The more of the tech the better. I will admit that I am a turbo person. I don't know in great detail of the different belt driven familys. If someone can add more detail in the different systems, please do. Heres a question for someone:

Which belt driven compressors have thier own oiling system, and which one's require to tap into the engines oiling system?

My current location in the world right now with certain fire walls set up, limit my research abilities:(
 

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Discussion Starter #9
The Math involved


Here is the following formulas and why they are used to get the best possible set up. First we have to set up some rules and known numbers to make this all work out. These numbers are just ideal and do not garrentee the outcome of the final product. Use these numbers as a guideline only.

These are the following numbers I used.

Compression Ratio for the engine: 8.75:1
Red line RPM: 5300
Using a ambient Temp of 85 degrees
-This is the standard when running calculations on assumption. If you have a known tempurature in your own environment, use that number. You will also notice later that a slight change in intake tempurature to the compresser will have a dramatic change in power output. Its no wonder why all the pro draggers that run forced induction are always retuning their system at every track at least 3 times or more a day, on every race day, to reflect change in temp to get the optimal power output.

Engine size is 281.33 C.I. Inline 6 (4.7 liter)
-This is just the dream engine that I am working with. It is also the same size as a rare few on this board work with. Yours will be different. Even the number of cylinders comes into effect with the calculations.

Base off of 10 PSI of boost from turbo
-This is about the max safe pressure on stock OEM replacement componants for MY ENGINE. Other engines have different extreme levels. You yourself will have to research on what yours can handle. Go find a group of speed freeks and ask for their opinion. You might find this group at the local 1/4 mile drag strip or maybe the offroad race scene. Go hit up some other forumns that deal in hot rodding your particular engine.

Ambiant absolute air pressure is 14.7 psi
-This is the pressure of air that we breath at SEA LEVEL. It is the pressure exerted on our bodies when walking around. This Pressure also changes with altitude. Go to your local airport to get this pressure in your local area to get better findings. It was amazing the change of my system when I went from Barstow CA, to Farmington NM(13.7 A-psi to 12.5 A-psi)! My performance changed huge! I lost about maybe 20 HP just with change in Pressure. Not to mention the change in Air Density(this is also referred to Density Ratio).

Compressor effiency is 75.8%
-This is another assumption that a turbo will operate at IF THE PROPER ONE IS USED FOR YOUR APPLICATION.

Quote:
"Designing a turbocharger system requires a basic understanding of pressure, temperature, and flow of gas."(Honeywell Turbo Technologies)

First equation is to find the pressure ratio(PR). We use PR later when we look at compressor maps to properly size the turbo to the application. This PR is for the compressor side. We will call this EQ1(equation one)

-note: I cannot say for sure if Belt Driven superchargers have Maps available to the public. Hopefully someone on here can confirm this and post up some info.

PR=(boost + ambient pressure)/ambient pressure
PR=(10+14.7)/14.7
PR=1.68(or 1.61 using a intercooler)
This is based on at sea level. This can change with the use of intercoolers. It is important to try and get an ideal PR of the entire system. Using a intercooler will usually drop the system around One psi (or 10%) and you can just add this into the above equation Just take 10 psi and subjract one which will give you a PR of 1.61.(we will also dive into the math associated with I/C's) You can use this equation every time you change the output PSI of the compressor (5, 5.5, 7, 13) Use these numbers and play with the above equation and see what you get when you change the boost.

Next step is to get our Density Ratio. First lets define DR. My definition:
The amount of oxygen particles in a given amount of pressure.

Tempurature can also dramatically affect the DR. Everyone understands that the colder the air going into the engine, the more performance. Now we will see the mathmatics involved and see why. If someone tells you that it does not matter or affect the performance of a forced induction engine of the incoming air temp charge is dead wrong!

So before we get the DR, we need to figure the Temps of the air we are working with.
 

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Discussion Starter #10 (Edited)
Air temps

Next is to find out the ideal temp out put going into the engine. You know that if you compress air, it gets hotter. You also now that the cooler the air the denser it becomes and better power. Remember, these are just ideal numbers. We will use the above given temp for Equation 2 (EQ2).

To,ideal: tempurature exiting the compresser to the engine.
Tin: The tempurature entering the compresser
PR : Pressure Ratio
^ : raised to the power of. .

To,ideal=[(Tin+460) x PR^0.283]-460

=[(85+460) x 1.68 ^0.283]-460
=(545x1.16)-460
= 172.2 degrees

Play with the intake charge and see the end number jump all over the place. Also if you adjust PR, the temps will rise with an increase in PR and vice-versa.

Do you all see that in the winter cold months that your engine runs like a race horse and in the summer time(120+ at the Hammers) the engine runs like a donkey!

But this is assuming that the compressor is operating at 100 percent efficiency which is never true. Compressors run between 70-80% on the average. So we take the above number to another equation (EQ3) to get the more realistic number. We will use the given efficiency as above.( that number I will show you later in another equation)

Efficiency is given as a decimal of less then one. A value of 1 would represent 100%

To,actual=[(To,ideal - Tin)/efficiency] + Tin
=[(172.2 - 85)/ .758] + 85
=(87.2 / .758) +85
=200 degrees

Now we can take this and move on to find out our Density Ratio( DR) and how it relates to Pressure Ratio( PR ), at the same time showing the huge difference between the two and not mixing it up.

I have to go back to work. we will break for now. In the meantime, your homework assignment is to take your dream engine and specs and do the same calculations for your future system. Any questions will be answered ASAP. Any one willing to share with the class and discuss, PLEASE DO AT THIS TIME. See you all back here soon.
 

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Wanted to add this info to the forced induction thread.

http://www.pirate4x4.com/forum/showpost.php?p=7746939&postcount=221

It is the reason that forced induction powerplants are able to do so much more with less.

A 400 HP engine (assuming equal RPM / displacement / VE) requires a certain MEP (referred to often as BMEP). That is the average (Effective) pressure acting on the piston during the whole cycle. Since that pressure happens only during the power stroke, the peak is very high, and the rest of the time it is very low, but it averages out to that MEP number.

A naturally aspirated application makes most of it's MEP gains by making the peak higher. (Assuming constant RPM remember).

A forced induction application can make the curve MUCH fatter AFTER the peak. Drop the peak pressure a little, but make the pressure curve in the cylinder after peak MUCH fatter, and the MEP goes up much faster than just increasing the spike. (much much easier on parts too.) The octane requirement is determined by the temperature and pressure value just before controlled ignition is to begin. (temp x pressure = max, as long as those 2 add up to MAX or slightly under MAX you have no detonation, regardless of pressure AFTER peak)
Also note, forces increase linear with power, but at the square of RPM. RPM kills parts faster than HP ever will.
 

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Discussion Starter #12
Rusty, thanks for that info. If you ever get the chance, can you come back and break that info down. Formula's would be nice if your willing to share. Some of us know how to control detonation, but what is the mathmatical definition you are describing.

Detonation is another topic I was going to hit on. Just not yet. But it was brought up. I do know in a nutshell, Detonation is the mulitible small explosions in the combustion cycle that kills instead of one single explosion we all want. High intake tempuratures are a major contributing factor to this evil killing cycle. This is why some of you have seen destroyed engines from forced induction applications in the past. It has to do with lack of tuning or proper parts from the builders part.
 

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Discussion Starter #13 (Edited)
Density Ratio (DR)

Now we can find out the Density Ratio (DR) of the system. Remember that density is the AMOUNT of oxygen particles in a given intake stroke of the engine.

PR: Pressure Ratio from before
Tin: Tempurature entering the compressor
Tout: Tempurature output from compressor

DR= PR x[(Tin + 460) / (Tout + 460)]
= 1.68 x (545 / 660)
= 1.39


Now lets change Tout to 120 degrees. This is because we are using a intercooler as stated above. We will also use the PR of the intercooler and we will see the DR increase. This is a good thing.
DR = 1.61 x (545 / 580)
= 1.51
So if you can cool the air enough and keep the PR as high as you can you will get a denser charge of air in the engine equaling more power.
Do not confuse the PR and DR. PR is the efficiency of the turbo. DR is the amount of OXYGEN MOLECULES entering the combustion chamber.

The reason we need to convert from PR to DR, is because using DR will give a much more accurate and truthfull out come in the system. When ever I see a forced induction system with no type of IC installed, I question the efficiency of the system. I am really amazed that I do find some engines getting intake temp charges well above 220 Degrees F.:eek: Now you see than when ever I design a system, I do everything I can to cool that final intake charge going into that engine. Remember I said this before, If anyone says that the temp intake going into the compresser has nothing to do with H.P. output is spouting wrong info they probably heard from a stupid ass magazine.

Next installement: calculating possible horsepower output using more math:p
 

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FYI

Vortech, Paxton and Procharger all offer centrifugal superchargers with self-contained oiling systems. No need to tap the pan with any of them if you have the right model.
 

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My Magnacharger is self contained. Most of the X-71 style blowers are self contained in the respect that the nose cone and/or rear bearing housings have oil in them but they are not plumbed to the engines oil system. The bearings ride in an oil bath much like most transfer case bearings.

Turbos just produce so much more heat from both the exhaust gasses and the ultra high rpms that they spin at that they need a constant source of cool oil. Their compact designs don’t lend well to a large enough oil bath to sufficiently lubricate and dissipate the heat. A lot of the turbo seals are designed to use the engine oil pressure to help maintain the sealed barrier between the two impellers. The oil pressure helps push the seal up against the sealing surface thus increasing its sealing characteristics.

Whipple is getting away form the side mounted superchargers that used the stock intake manifold and moving toward the more traditional intake replacement mounted systems. One of the major reasons I went with the Magnacharger on my Jeep was because of the lower profile of the intake mounted system even with the intercooler. My next one will probably be a Whipple. The performance advantages of the screw type superchargers are unreal, especially in some of their marine application stuff.

The Vortech brand is mostly centrifugal systems but they have a new screw type out for the Mustang motors.

From Whipple’s site, slightly edited:

The major difference between the positive displacement superchargers (Roots and Screw type) and centrifugal superchargers is the rate of boost. Positive displacement superchargers create boost the instant the throttle is touched usually reaching full boost by 2000 to 2400 rpm. The centrifugal supercharger is a belt driven turbo that has a lag time while it "spools up." The centrifugal commonly does not come into boost until 2600 to 3000 rpm and they commonly do not reach full boost until max rpm. Whenever the positive displacement supercharger has more boost, your engine has more power giving you far more net power.

The instant boost gives you far better throttle response whenever you call on it, far greater acceleration, and incredible drive-ability. A good example is when you’re towing up a hill at 3000 rpm and you need more power. If you give it some throttle with a positive displacement supercharger, you’ll get full boost, if you have a centrifugal, then you can’t get that full boost unless you’re at full rpm.
 

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For the record:

Since this is the hardcore Jeep forum, I believe it is pertinent to post up the turbo-charger models that myself and others have had success with on the 4.0L engine.

* For 4.0L (stock) of displacement, giving much mid-upper power, excellent all around turbo:

I'll let Martin fill this one in

** For 4.0L with cam/head work/etc etc, giving top end power:

T04E 50-trim with 0.60 A/R compressor and turbine is .48 AR with Stage III wheel.

*** For a 4.X stroker engine, giving mid-upper power. Great for street and trail:

T04E 60-trim 0.60 A/R compressor with .63 A/R turbine. This is again a T3/T4 hybrid, ball bearing turbo. Combine with a mild aftermarket RV cam for best results.

**** For a high-end 4.X stroker motor, giving all upper end power (full on race turbo):

T-61 with GT40 compressor (same compressor wheel as GT35R aka GT3540R), .70 a/r with T4 turbine housing. Ported head, large exhaust, intercooler = must.
 

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Discussion Starter #17
Before we can get to the HP calculations, and picking a compressor, we need some detailed info on the engine and whats called flow rates:

A common formula for engine size.
Disp = [(#cyl)(stoke)(Bore^2 )] / 1.27
= [(6)(3.413)(3.91x3.91)] / 1.27
= 281.33 cid

These numbers are what I want to build my engine to. Your numbers will be different. So you need to plug your specs in place of mine to get your application.

The next thing we need is the Volumetric Flow Rates (VFR). But before this we need to talk about Volumetric Efficiency (VE). VE is basically the percentage of output vs. the input of any given engine. The method of intake/exhaust designe, the Head of the engine, size of exhaust, bends in intake and exhaust. There is so much to take into account. A fully race car engine can be upwards of 98-105 percent compared to your basic stock can be as low as 65 percent. So lets assume I will use a larger throttle body, high flow intake, large 2.5 inch exhaust, with cat, the head on MY engine is already efficient from the factory. So lets say I can achieve a VE of 80%. I don’t have an equation to get this number. Its just an assumption. If you would use straight stock intake and exhaust, I would use 65%. I will also use the redline RPM in this. So we are actually calculating the MAX VFR or our engine. This equation will be used again at different RPMs when we look at compressor maps. This number is expressed in CFM. So our next equation is as follows (EQ6):


VFR= [(disp x rpm) / 3465] x VE
= [ (281.33 x 5300) / 3456] x .8
= 366.72 CFM

Change the VE and see your VFR change.

(Personally, I am running a 3" exhaust with no CAT presently, and no bends in the routing. Its pretty much straight back with a dump just in front of my rear axle. My power dramitically improved from before. It was night and day difference. I also experienced a dramatic decrease in Engine Temps/EGT's. So in the future, try and run the largest exhaust you can without sacrificing low end torque. The Turbine provides enough back pressure in vacumn conditions for that.)

Moving on to the next equation. Lets find out the air density that is possible. This leads into another equation. This is expressed in pounds per cubic foot . This is also dependent on Absolute pressure at a given tempurature. This is also the same thing we breath on a day to day basis. Absolute pressure changes with change in altitude as well. So if you really want to get specific, find out your psia at your altitude to get more concrete numbers. All these equations are based at sea level (EQ7).


PSIA: This is the absolute pressure at sea level. This WILL change with altitude, EVEN WEATHER! So make sure you use the correct number for your application.
Temp: This is the incoming air temp going into the compressor. Again, this is always different.
The other numbers are given as part of the formula.
Air Density = [(2.703)(PSIA)] / (Temp + 460)
= [(2.703)(14.7)] / (85 + 460)
AD = .073 pounds per cubic feet

You will see where we use this Air Density for future Calculations. If you play with the values of what can change, you can see the AD change as well. Obviously, the larger the AD, the more power can be made.
 

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Discussion Starter #18 (Edited)
My Magnacharger is self contained.
. . snip. .

Turbos just produce so much more heat from both the exhaust gasses and the ultra high rpms that they spin at that they need a constant source of cool oil. Their compact designs don’t lend well to a large enough oil bath to sufficiently lubricate and dissipate the heat. A lot of the turbo seals are designed to use the engine oil pressure to help maintain the sealed barrier between the two impellers. The oil pressure helps push the seal up against the sealing surface thus increasing its sealing characteristics.


. . snip. .
And you are Correct on this about turbo's. As stated before, to combat the high EGT's, you need to go to a larger then normal exhaust with little backpressure. I recommend the muffler from magnaflow:

http://www.magnaflow.com/02product/02race.asp

or

http://www.magnaflow.com/02product/shopexd.asp?zone=main&id=8021

Its what I am running on mine. Zero temp issues, straight through design without any baffles in the muffler. YOU DO NOT WANT TO USE A BAFFLED MUFFLER IN FORCED INDUCTION APPLICATION!! THIS EXPECIALLY INCLUDES FLOWMASTER!!! Ask me how I know:shaking:

As for oil, I suggest switching to a NON-SYNTHETIC 20-50W. Im currently using Castrol NON-SYN 10-40w and I will switch to a 20-50w. The thicker oil combats the higher temps associated with turbos and the CHRA. On a historical note: My family had a 1985 Chrysler Leberon GTS that had the 2.2 turbo. My father always used 20-50w of the same oil I reccomend. That motor lived beyond 190K(when he sold it) and still pulled hard with ZERO issues, no smoke, equal compression test. He changed the oil every 3000miles.

Also, when running a turbo hard continously, you need to give the engine at least 15 minutes of cool down time running at least 8in/hg to allow the engine oil to cool down the bearings and itself. This will also give the engine to cycle normal level EGT's (about 650-800F) into the turbine to cool it down as well.

For the record:

Since this is the hardcore Jeep forum, I believe it is pertinent to post up the turbo-charger models that myself and others have had success with on the 4.0L engine.

* For 4.0L (stock) of displacement, giving much mid-upper power, excellent all around turbo:

I'll let Martin fill this one in

** For 4.0L with cam/head work/etc etc, giving top end power:

T04E 50-trim with 0.60 A/R compressor and turbine is .48 AR with Stage III wheel.

*** For a 4.X stroker engine, giving mid-upper power. Great for street and trail:

T04E 60-trim 0.60 A/R compressor with .63 A/R turbine. This is again a T3/T4 hybrid, ball bearing turbo. Combine with a mild aftermarket RV cam for best results.

**** For a high-end 4.X stroker motor, giving all upper end power (full on race turbo):

T-61 with GT40 compressor (same compressor wheel as GT35R aka GT3540R), .70 a/r with T4 turbine housing. Ported head, large exhaust, intercooler = must.

Thanks for that offer on filling in the blank. And I will surprise many here on my current application I am on. :p
 

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Thanks for that offer on filling in the blank. And I will surprise many here on my current application I am on. :p
Martin, when you know what turbo that "other" Jeep motor needs, post the tech and I'll add it to the above list of recommended turbos for Jeep engines.
 

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Discussion Starter #20
Well its been a few days. Been busy. Its actually busy at the work place. So its hard to get this article done. As for that other super secret jeep motor:grinpimp: I havn't started any calculations on that. Corey, I will start sending you PM's

So now class is in session:

This is where we start pluggin in the past equations and we see things coming together. The next one we calculate is the Mass Flow Rate (MFR) . This number is used in conjunction with PR to look at compressor maps to find the best turbo application for your engine. But we are not done yet. So here is EQ8:

MFR = VFR x Air Density OR:
MFR= [(2.703)(psia)(VFR)] / (Tin + 460)
= [(2.703)(14.7)(366.72)] / (85 + 460)
= 26.74 pounds per minute

This is the output of a 4.7 stroker with NO turbo. So the next one is very simple to figure the out put of a turbo running 10 psi of boost. All we do is multiply the above number by the DR.

MFRturbo = (MFRna)(DR)
= 26.74 x 1.51
= 40.38 pounds per minute

Now this calculation is based on running the engine at 5300 rpm. So, run the calculations for 1500 rpm (we want the turbo to start spooling), again at 3000 rpm (the range we want the turbo to be at its highest efficiency). These are numbers I wanted to work with. Use your own numbers for what you want. It is important you do this because we will use these numbers as a reference later in the article.

The reason I like to work with DR, is it gives you a more real world true effect of the out come. I feel that using PR will give a false outcome. This could lead to a bad decision on the design/build process. But other people/shops may work with PR even I may disagree with that process.

So lets punch some numbers at different RPMS assuming a max 10 lb/boost across the range.

MFR @ 1500 rpm = 11.43 lb/min
MRF @ 3000 rpm = 22.85 lb/min

To get your numbers first calculate VFR at the given RPM. Then take that number and plug into the MFR equation to get your flow at the given rpm. These numbers are guidelines that we must stay within to get the best possible results.

Now lets talk about possible horsepower output of this engine. Remember to plug your numbers in place of mine since they may be different. We will use the Brake Specific Fuel Consumption equation (BSFC). An average turbocharged gas engine will burn between 0.55 - 0.65 pounds of fuel every hour for each horsepower developed. We will use 0.6 pounds because this is a safe and fuel efficient area. We know our boosted MFR. We must come up with a Air/Fuel ratio now. We know that we never want to go above 14:1 to avoid to lean and burning up the motor. Under boost, a safe ratio is 12:1. This is all in the programming of the ECU fuel system. I have talked to some of the drag race crowd, and they tune as low as 10:1 under full boost. But these are full on race set ups. Some will even go with a lower ratio. But we are working with a daily driver. So lets just use 12:1 in the equation.(EQ9)

HP = [(MFR)(60)] / [(A/F ratio)(BSFC)]
= [(40.38)(60)] / [(12)(0.6)]
= 2422.8 / 7.2
= 336.5 horse power.

Using this equation, you can play with the numbers to see what is possible. This form of equation is your normal Bench top dynoing. This is only a tool. Real world outcome can have a drastic difference. But I have ran this exact same numbers for a buddy. He went and did a real world dyno and I was off maybe 2% of his actuall output number.:smokin:

This above result is also very conservative for a Daily Driven motor. I also stumbled onto a website that works with what needed injector size for horsepower output.

http://www.injector.com/injectorselection.php

This is just a guideline as well. We might dig deeper into fuel injectors later. Again, just use this as a guidline as well. There is much more to fuel injector set ups that must be understood.

Next class, looking at actual compressor maps and understanding how to read them with the tech info we have calculated.
 
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