The big HOMEMADE TURBO guide

[JDMFantasy2k]

Alright, all i ask is that before you read this that you browse through thermal's "turbo tech files" (click the back button) because there's a lot of good info in there. Especially if you're new to the turbo scene.

First lets cover what a good turbo setup should have:

turbo (duh)
manifold
downpipe
intercooler
charge pipes
oil lines
blow off valve
engine management


Basically, the turbo will add more air into the engine and you need to add the fuel so you don't see your rods all over the road. DETONATION and HORSEPOWER kills motors, not boost. Detonation causes extreme pressures in the motor and sounds like rattling bb's in a coffee can. This can just grenade your motor. When an engine makes more power than it can physically handle, then the motor will break. Usually in hondas the rods let go first (d-series anyway, it seems b-series tend to break ring lands first). As a rule of thumb, a D motor shouldn't run more than 200 whp, and and b-series vary (most LS motors will handle 250-275, and about the same for b18c and b16 but don't hold me to it) Also, realize that 12psi on one turbocharger may be completley different on another. Now an intercooler is not required, but is highly recommended, even for low boost levels. An intercooler can greatly lower intake air temps which will reduce the risk of detonation and make more power.

So lets see how to make a homemade turbo set up.

Manifold

Obviously the exhaust gasses go through this to the turbo. Manifolds vary in shape ( log style, ramhorn, inverted ramhorn, top mount, and other custom designs) and in price (from free to around 800-1000). Now the key to making a Homemade turbo set up is MONEY. Which means if you're going to do it CHEAP then do it good. try not to pay more than 200 for a manifold, and whatever you do DO NOT BUY SSAUTOCHROME. Any and all of the stuff they make (also known as XS POWER) is absolute SHIT, their stuff is that cheap for a reason, it WILL break. Log style manifolds are usually good because of their durability and some can even allow you to retain your AC (don't be a pussy, take it out, it'll be easier). The most cost effective solution for a D series motor is to use a manifold off an old D series motor which had a catalytic converter mounted to the manfold. Then you only need to fabricate an adaptor plate to mate the turbo to the manifold, and you can get the plate and manifold cheap. Another big difference is flow. Obviously a stock honda or log style manifold won't flow as good as a ramhorn will, but price is the limiting factor.


Turbo

Ah the turbo. This will be the largest factor in deciding what power goals you will achieve, and when they will happen. Turbos come in a plethora of sizes and brands. Most turbos are identified as being garrett based, and of using a T3 or T4 frame. Turbos are classified by A/R ratio, trim , and a few other measurements. One factor with turbos is the flanges. Any turbo that is a true T3, will have the same inlet flange, as long as it isn't brand specific. Many car manufactures will equip a T3 turbo on a car and change the inlet flange bolt pattern, in which case you'll need an adaptor plate. Also T4 is a different flange (it's larger) and you can't run a T4 anyway because they're massive. Now a very common T3 tubo that many D series enthusiasts use is the Garrett .48/.60 60 trim. Garrett is the manufacturer ( i think they're the same as airresearch, correct if wrong), but there's also companies like turbonetics, precision, and others, however most of them will follow the T series. Now the .48 is the A/R of the turbine or hot side. .48 is a common size and spools nicely on a d series and is good on a b-series if you have small power goals. The other common size is .63 which is a little laggier, however it will flow more air. A great analogy is picture spraying a pinwheel with a garden hose. If you spray with a nozzle the wheel will spin fast, spray with the open hose, you get a lot of flow. Same thing. A .63 housing is usually a good choice on a b motor cause they are larger displacement (aside from the b16 but it's powerband makes up for that) and will allow better power goals. Turbine wheels also come in trim sizes but for the most part many of them are the same.

The compressor side is much different. Like the turbine side the the housing can be changed out, and is designaged by an A/R ratio (in our example, the housing is a .60). The turbine wheel corresponds with the housing. For example another common turbo to run on a D series is a .48/.42. That turbo will run the exact same exhaust side as the .60, however the compressor side of the .42 will be smaller. Consequently this will also reduce spool time, and the turbo will not flow as much air. Therefore 10 psi out of a .42/.48 is not the same as having 10 psi out of a .60/.48. Compressor wheels also have trim. A common trim size is 60 but there's also 50 and a few others. I'm not exactly sure what the trim measurement is, however i believe it's just an adjustment of the wheel which manipulates airflow.

So what does all this mean? Well if you're boosting a D and you throw on someting like a .63/.60, it'll take longer to spool than a .48/.42, but when the .63/.60 hits full boost it's gonna feel like you fell off a building. The .48/.42 will feel cool too, but won't be as rough. It'll feel more like a little burnout turbo. Spools quick, like to lay tire. So when you chose your turbo, think of your power goals and what you're looking for. Do you want something that spools quick and is awesome in the city, or do you want a laggy 4000 RPM kick in the balls that will make your passengers cry?

Now i've only covered T3's here. Surely there are hundreds of other turbos but i feel T3's are very common turbos and are easy to convert to different spece (which can allow room for growth). A lot of people run mistubishi turbos out of old eclipses and what not. Usually 14B's and variants. Great turbos, but they usually don't flow as much on top. Also if you run one you'll need an adaptor plate. Now be very careful when you buy a turbo. Your best bet is find a nice one from a junkyard if you want to be cheap. Shaft play is the enemy and make sure it doesn't much (in any direction). Otherwise they're pretty simple. If you're going to buy one, ask lots of questions. Make sure you know the size, and ask if it's been rebuilt, if it smokes etc. They have seals and they will blow if they're subjected to high oil pressures or other forms of abuse (compressor surge). Try not to spend more than 200 for a used turbo (pristine). If you spend 250-300 on a remanufactured one you're doing good. Also depends on the size a T3/T4oe is obviously going to cost more than a .42/.48. If you wanna go the junkyard route (no shame in that) then just get something that looks good and start haggling.

Downpipe

This is pretty self explanatory. If you wanted to you could literally run your car open turbo (although it would be stupidly loud, illegal, and make a huge mess). Basically you're gonna need a flange to bolt to the turbo and then just fab the downpipe so it meets up to your exhaust. Luckily T3 flanges are very prominent, and if you look you can find 14B flanges as well. As a rule you don't want a downpipe that is smaller than 2.25 inches. You could make it 2 inch, but don't expect and phenomonial power output. I highly suggest a 2.5 inch downpipe and if you're going to run a good ammount of power then run a 3". Your downpipe will also affect your spool time so don't make it look like a maze. Simple smooth mandrel bends are the best. Check napa for the bends, they have some nice stuff. Also you could pay a local muffler shop to do it for you.

Intercooler

Now the intercooler is optional, but highly recommended. Factory turbo'd cars come with either a top, side or front mount intercooler. The front mount is the most efficient and most common to buy as an aftermarket part. A lot of times you can find cheap front mount intercoolers on ebay for around 200. You can use a used intercooler long as it's in good shape. Hardest part is making sure it fits, so take your bumper off and take some measurements. Lots of people will use DSM sidemount intercoolers and front mount them, some even mount them underhood. This works, but nothing beats having a nice 3x6x30 front mount to cool the boost. Just look around for good stuff and unless you're running a high HP setup which needs some rediculous intercooler, don't spend more than 250. Used dsm sidemounts can be had for 30 bucks so look around.

Charge Pipes

The charge pipes are on the same idea as the down pipe, self explanatory. As a rule of thumb you want the pipe comming out of the turbo to be the same size as the turbo outlet (usually 2") and going into the intercooler. From the there the pipe comming out of the intercooler should be the same as the outlet size and then routed to the throttle body. So most setups will have a 2" pipe out of the turbo then the intercooler and then a 2.5" pipe to the throttle body. Now basically pipe is pipe. Although if you use pvc you can run into problems because i heard it stinks when it heats up and charge temps can reach well over 200*. I used regular stainless steel pipe from advance auto and then i used rubber plumbing couplers from home depot. Although the plumbing couplers work great, they tend to deteriorate after a few months. Eventually you should save for some nice silicone connectors. Ebay piping kits work too, but i think they're too expensive and require just as much work as making your own pipe. Also, rubber elbows make life easy so you only have to work with straight sections of pipe. If you've ever played with Legos, then that skill will come in handy here.

[JDMFantasy2k]

Oil Lines

More important than the turbo itself. If your turbo doesn't get the oil it needs, it will break; the end. Turbos spin upwards of 100,000 RPM and ride on oil lubricated bearings. Now the oil feed line should be stainless steel and have -AN fittings. -4 and -3AN are both common sizes. However you need to run an oil restrictor in the oil line, otherwise you will blow the seals in your turbo (trust me i've done it). Hondas have around 90 PSI of oil pressure and as a rule of thumb turbos don't like more than 35 ish (but don't go below 20). So in that repsect, it's a good idea to get an oil pressure gauge. Now you need to get your oil source from where the oil pressure indicator switch is on the back of the block. It's near the oil filter and has a wire comming out of it. You'll need a T fitting so you can have the oil pressure switch and your line. Also the block has BPST threads while almost all of your other hardware will have NPT threads. You can use an NPT T fitting in the hole, but you will likely crossthread the block and run the risk of leakage. Best bet is to find a T fitting that has a BPST male fitting, a BPST female fitting, and an NPT female fitting. Then run your oil line and another T fitting if you want the oil pressure gauge. Finally run the line to the turbo. The restrictor is just a simple ball valve which can be put near the turbo or block, whichever is easier. Now the return line is just as important as the feed line. If you get a kinked return line, it can kill your turbo just as badly as not having any oil (well, almost). The oil feed line should be at least 1/2". 5/8" heater hose works awesome and the line should be as straight down as possible. NO KINKS. The biggest causes of smoking turbos is kinked return lines and/or too much oil pressure. Now when you drill the oil pan, make sure the hole is in line with the turbo outlet. This was my big mistake as my hole in my oil pan is actually about 1.5 inches to the right of the turbo outlet, so my line is not completley straight, which may have cost me my first turbo. Also make sure when you drill the hole that it will sit above the oil and that it's not too close to the top of the pan. Use common sense, and make sure to clean it very good and take your time. Now if you don't tap and thread the pan you can weld it, however it can be difficult as many honda pans are alumminum ( get the tig out) and are usually very thin. A great alternative is JB weld, which is a welding epoxy. Mix it up, throw it on, and give it 24 hours to cure. Great stuff. Now ebay does have oil line kits, if you look around there are better ones too. Don't spend more than 100. You can also make your own. Just get the inlet or outlet flanges for your turbo and open up the summit racing catalog. They have every oil line part you need. Just research it a little and it'll make sense.

Blow Off Valve

This is more of a bling item. Yes the blow off valve serves an important purpose (venting boost pressure when the throttle plate is closed, thus preventing compressor surge and the demise of your turbo), however many people will spend upwards of 300 on it because of the brand or noise or whatever. All you need is a 20 used DSM blow off valve. But if you want to spend some money on a bov that you like then by all means do it. They all work the same way, and most have a tension adjustment, so play around with it. I paid 200 for my blitz dual drive and i absoluely love it. Even made one girl wet. So it's your call here. Also if you can't weld it in, then try to find a BOV that's alredy attached to a pipe and use connectors to plumb it inline. Lastly, there's always huge controvesy on where the BOV should be placed. Most people put them after the IC before the throttle body, however i feel that it should go directly after the turbo. The reasoning? The BOV's function is to vent the boost and protect the compressor from surge, so if you put the BOV near the turbo, then trapped boost pressure won't be able to reach the compressor. Plus porsche race cars actually have the BOV integrated into the compressor housing so that's reason enough for me.

Wastegate

Now the wastegate is very important. It regulates your boost pressure. Look at it this way, if your wastegate fails, you can very easily blow your motor. With that said, there are 2 styles of wastegates, internal and external. Some turbos come equipped with internal wastegates (mostly OE turbo'd cars) and they consist of a diagphram with a rod attached to it, which opens up a valve in a special housing. This in turn vents exhaust gasses around the turbine and stops the turbo from boosting any more. Internal gates are okay, and have a preset pressure (most are between 8-13 psi). Sometimes the rod is adjustable or you can bend it to change the boost. You don't really want to run an internal gate if you're looking for power because an internal gate will boost creep like a mofo. Basically the turbo will move so much exhaust gas that the gas venting around the turbine will be inadequate to slow the turbo's boosting, and the boost will continue to grow. The other type of wastegate is external. This wastegate gets mounted to the manifold and simply opens up and vents boost out of the manifold. With this style you will need a dumptupe to carry the gasses away from other components. You can let it vent openly (aim the pipe down away from everything) or you can plumb it into the downpipe. I suggest doing both. I had mine venting openly and then i plumbed it into the downpipe. 2 very different effects, and after you've done both you can decide which you like best. Although i love the smell of it open, i like the sound of it being vented into the downpipe, plus the enigne bay stays a little cleaner. Also be careful not to melt anything cause my dumb ass half melted a JDM headlight. External wastegates can be cheap or expensive. I HIGHLY recommend Tial. They make an excellent gate and it's pretty affordable (usually around 200) and they come in different sizes. The most common size is 38mm, but make sure it will fit your manifold because there are also 44mm gates and some have different flanges. A 38mm should suffice up to around 350 HP, around there you may experience some boost creep. There's also other brands like HKS which can go as much as 800 bucks. Not worth it in my opinion since many people pushing 5 or 600 horse still run tials. Try to buy new unless you see a used one in good shape. Also turbonetics makes a decent gate i'm told. Also external wastegates can come with different springs which will control the boost pressure they're set at. I think they may go as high as 22 psi. However it's a good idea do get a wastegate that will vent half of your targeted boost level. So say you want to run 20 psi. You get a wastegate with a 10 psi spring, and use a boost controller to raise the boost up to 20 psi. Running the wastegate by itself is fine too.

Boost Controller

This regulates boost obviously. You don't necessarly need a boost controller if you want to just let the wastegate do the work that's cool. But if you don't feel like changing out springs and want to change boost often, then pick one up. There's two types, manual and electronic. Electronic is far more expensive and probably over kill for anyone doing a homemade turbo setup. They're usually 300+. They cosist of a control box and a silenoid which regulates the boost. Manual controllers are great because they're cheap, simple to use, and basically all the same. I like the turbo xs controller personally, it's easy to use, sexy, and i picked one up for around 70. There are cheaper ones out there, though. Basically they all have a ball and a spring and when you twist the knob, the spring tightens up. When the boost hits the ball inside it has to push it agains the spring. Once the air has pushed the ball far enough the pressure will vent out a hole and the off to the wastegate which will open instantly (because the boost controller setting is higher than the wastegate). Otherwise, they're pretty simple, and don't get crazy with boost.

[JDMFantasy2k]

Engine Management

Engine management is the most important part of a turbo set up; period. If you don't have engine management your motor WILL BLOW. Now since you're adding air, you need to add fuel. There are 3 ways of doing this, using an FMU, using an AFC, or using real management. An FMU (fuel management unit) is a boost-dependent devide which increases fuel pressure per pound of boost. This is shitty because it overloads your stock injectors to flow more than they're supposed to. Plus there is NO way of tuning with a FMU. Your motor is just getting more fuel, not more fuel where it needs it. I feel if you're going to turbo that you NEED injectors. DSM 450's (blue tops) work quite nice, and can be had for cheap money. Now there are 2 types of injectors, saturated, and peak and hold. The difference is in the impedance (one is high, the other low). I'm not sure which ones you need because i always forget. However You'll more than likely need a resistor box to run them because they're a difference impedance from honda ones. Otherwise they should drop in with small modifications to the seals. Any other injectors made for a honda will work too as long as they're in the 450cc range. Basically any injector that is a top feed and fits will work, but you should research first. You could also get a set of RC engineering injectors if you want but they're like 100/injector. Now to controll the injectors you can use a safc or vafc (one is made for vtec engines the other isn't and both are made by apexi) which is a fuel controller. This is nice if you don't have someone who can tune an ecu for you. Basically you trick the ecu into adding more fuel. It's not the best way to run it, but it's better than an FMU in my opinion, and i believe Arnel ran a vafc for over 3 years without problems. I'm not going to get hardcore into the theory, but basically your ecu is sending an electrical pulse to the injectors which has different lengths. So if it sends a pulse to an injector that is more than twice the size of the stock injector, you're going to get way too much fuel. The vafc "hack" (see the step by step section to set up the hack) alters the MAP sensor voltage which in turn modifys the ecu's fuel and ignition tables. Essentially when you take out fuel it will advance your timing. To address this issue some people run an MSD BTM to retard the timing (per pound of boost), some people will change the timing at the distributor about 2 degrees, and some people like me don't give a shit and just drive it. The afc hack works sweet around 7 or 8 psi.

The last and best engine management solution is a piggyback/standalone. Now a standalone is something that totally replaces your ECU (like AEM EMS). The tuning capability is un-real, and so is the price, it's about 1K. A piggyback system is something like the greddy emanage series. I'm not entirely sure how it works but i've heard if you can find someone to tune it, it's not bad. However the best solution in my opinion is chipping a honda ECU. What you need to do is find a stock OBD1 ECU that can be chipped (and corresponds with your car, for example if you have a 99 GSR, then you'll want an ECU out of a 93-95 GSR, etc although there are exceptions to the rule). Next the ecu needs to be chipped. I'm not entirely sure what modifications this entails but there are plenty of places that will do this for you, or better yet you could always buy one chipped. What this does is allow you to burn your own program onto a chip and plug it into the ecu, effectively re-writing the honda program. A chipped ecu can usually be had for around 100 bucks and don't pay more than 140. Now to make it all work you need a program. I personally like CROME because it's easy to use and it's free. (check www.tunewithcrome.com) However, there's also uberdata, turbo edit, and a few others. Once you get a program you'll need to essentially tune your car. I'm not getting into that cause that's a subject in itself. But it is possible to find people to do it for you. Then you'll need a chip burner, burn the chip, plug it in, and see how it turns out. Idealy you'll want to tune your car with a wideband O2 sensor so you know what your air to fuel ratio is so you don't blow your shit up (and use an EGT sensor if you're a true gangsta). Dyno tuning is great, but street tuning will suffice too.

Miscellaneous
You'll want to get a fuel pump. You don't have to but just think of it as cheap insurance. I got a brand new walbro 255LPH for 100 bones and it took all of 10 minutes to install. Also, the stock honda MAP sensor will only read up to 11 psi of boost. After that, it'll trigger a CEL and if you're tuning with CROME or similar, you won't be able to tune effectively past that point. A GM 3 bar map sensor will work and there's also motorola 2.5 bar map sesors i believe. Also if you're running the vafc hack and you're OBD2, expect a check engine light. Although the hack prevents the MAP from seeing boost, the MAP has a barometric pressure feature integrated into it and it WILL sense boost, giving you the inevitable check engine light. Best way to prevent this is to get a chipped ecu. Also if you run an OBD1 ECU you'll need a conversion harness they can be had for about 100 bones as well. Another thing people say is when you throw the turbo on to "prime" it with oil by cranking the car over. Personally i think it's kinda horse shit because most turbos have oil in them when they're shipped, plus most turbos don't spin at idle anyway. All you need to do is pour some oil in the inlet before you hook up the oil line; done. If you're running a new or reman turbo then you should break it in. 100 miles is usually a good idea, just to let everything wear in properly. Also hook your vaccuum lines up at the intake manfold. If you hook them up to a compressor nipple (aside from an internal wastegate) you will lose some boost pressure because of the pressure drop caused by the intercooler. Another suggestion is to run one step colder spark plugs. You don't have to, but if you're running a vafc i recommend it. With an ecu, just tune it good. Also YOU MUST RUN HIGH OCTANE. That should be a no brainer but if you run shitty gas it WILL CAUSE DETONATION. Low octane gas cannot withstand the effective compression of the boost and will leave you with parts on the road. It's also not a bad idea to change your clutch out. Most clutches can handle the extra power, the question is, how long. Especially if they have a lot of miles on them. Also make sure you run SYNTHETIC oil. Don't be a cheap bastard, turbos demand good oil so it doesn't coke up in the lines and whatnot. Lastly if you follow all this a RESEARCH then you should be good. I can't emphasize enough how important the SEARCH button is on a forum and how invaluable researching stuff is. Make sure you know what you're doing before you attempt to do this. Lastly, GOOD LUCK!!!



List of Good sites:
www.tunertoys.com - everything homemade turbo related
www.stealthmodeperformance.com - oil lines/restrictor
www.lsdmotorsports.com - clutches, flywheels, pipes
www.johnnyracecar.com - awesome intercoolers
www.bmcrace.com - flanges, adaptor plates
www.xenocron.com - ECU chipping/tuning solutions
and lastly
EBAY- but beware, if it's too good to be true, it usually is.

[GT40FIED]

This is getting stickied simply because I gotta respect anyone who would spend that much time typing. Seriously...great write up Will. If this doesn't answer just about every question someone has, they shouldn't be slapping on a turbo.

[thermal]

Holy tits and asses! Great job bro. When I retire, you can have my moderator spot...lol! I still remember the days when I was schooling you with some of this stuff. That was not too long ago. You are a quick learner! I'll read the whole post later