Turbocharging your 7g for noobies.
Ok, things cant get any simpler than this. 7g 4g64 is a part of the DSM family and as you know the 4g63 engine is the best bang for your buck or in another words cheapest horse power out on the market. Although having a couple of differences from its turbocharged brother - SOHC head, distributor and no knock control, the 4g64 is almost the same engine.
Im going to explain about each component that has to be changed or upgraded, things that need to be added, and also the options of different components. Its your choice which one you want to use or if you want to use it at all. Im going to talk about gaskets, OEM upgrades and bolts/nuts and how things work in general and more specifically in your freshly turboed engine.
Because we are going to be turbocharging a stock 4g64 with "soft" pistons and most likely with a lot of miles on it with safe boost of 8-10psi, I will only talk about OEM components out of a DSM/EVO. What I mean is that I will be talking about 14b, 16g, stock manifolds and etc. Since this is very basic forced induction, T3, T4, V-bands, external wastegates and so on will be left out of the discussion.
Turbochargers
14b and 16g are probably the best turbos suiting our platform. Before you buy one, make sure it doesnt have any shaft play, chipped fins or if it has been smoking before removal. If you got one in a bad shape, its easy to throw a rebuild kit on it. I've rebuild all turbos that I've owned so far.
A common upgrade for the 14b is a 7cm2 exhaust housing. Why? The 7cm2 housing was originally found on Evo3 which was matched to 2.5'' manifold outlet for better flow and less back pressure. 7cm2 housing will give you a slightly slower spool, but you have to keep in mind that spooling a turbo is never a problem for 4g64, ok!
6cm vs. 7cm ported
http://img101.imageshack.us/img101/6198/0305001959.jpg
http://img52.imageshack.us/img52/6516/0305001954.jpg
6cm vs. 7cm unported
http://i28.photobucket.com/albums/c2..._/e146a48d.jpg
Manifolds
You basically have 5-6 options - 1g, 2g, EVO3, tubular and other cast and tubular manifolds.
1g - I will not suggest using it unless you're really broke and cant afford 2g manifold, but if you're broke then maybe you shouldnt be turboing your Galant in first place. It has 2 1/8'' outlet.
2g and Evo3 - 2g has a good manifold, but not as good as Evo3 one. The 2g manifold has 2.25'' outlet while the Evo3 outlet is 2.5''. You can try and port the 2g manifold to 2.5'' and you'll get the same results as if you have had Evo3 manifold.
Evo3 vs. 2g
http://www.roadraceengineering.com/p...man-2gman2.jpg
1g vs. Evo3
http://i28.photobucket.com/albums/c2..._/1b6619ca.jpg
Tubular manifolds - the cheapest you can find is the ebay ones, but remember that you get what you pay for. If you happen to get one, you might want to reinforce the welds and then reinforce the whole structure of the manifold.
This is what you're going to get from ebay:
http://www.unionperformance.com/prod...12678_zoom.jpg
There other more expensive manifolds out there, both cast and tubular, but for simple reason to have a turbocharged car on a budged, I will leave them out.
O2 housings
This the part where the exhaust gases pass through after they have gone through the turbo housing and spun the turbine wheel. The o2 housing is mounted to the turbo housing with 3 bolts and 1 stud and nut. It guides the gases coming from the turbo housing to the actual exhaust system. It's called o2 housing because this is where the DSMs have the front o2 sensor. On 7g, depending what year it is, the front 02 sensor can be on the header or right before the catalyc converter. To relocate your stock o2 sensor to the o2 housing you will have to extend the wires.
Again, there are 4-5 options for these o2 housings.
1g - again, unless you're broke or getting it for free, I'd suggest not to use this one. It's very restrictive even for 1g.
2g - a little better than 1g housing. It has 2.25'' outlet and the good thing about it is the all ebay downpipes are made to fit 2g O2 housing.
Evo3 - the best OEM upgrade. It has 2.5'' outlet, but the bolt pattern is different/wider than 2g o2 housing. The stock 2g and the ebay downpipes are not a direct bolt affair with this one.
Stainless Steel/Ebay housings come in two options - with recirculated wastegate or open dump. They both have evo3 downpipe bolt pattern and are not bolt on to the stock or ebay downpipes.
2g vs 1g housing
http://i100.photobucket.com/albums/m...mSpring002.jpg
Stainless vs. 2g housings
http://i28.photobucket.com/albums/c2..._/5ad367f7.jpg
http://i28.photobucket.com/albums/c2..._/2693b6a0.jpg
2g vs. Evo3 housing
http://www.extremepsi.com/store/images/d_980.jpg
http://www.roadraceengineering.com/p...erentangle.jpg
Downpipes
The options here are limited. You either go buy some metal and put it together yourself or just buy the well proven ebay downpipe for 2g GST. It's a great piece and it works with 2g o2 housings. The only thing is that the neck after the flange and the first bend has to be extended 1.5 -2'' because it is meant for 2.0 and not for 2.4L engine. Its not a bolt on to the stock cat, although it could be made to, but since we are talking turbos here, Im hoping that you've decided to upgrade the exhaust to at least 2.5'' or 3'' even better.
This is what you're going to get
http://importevolution.com/images/gst.jpg
J-PIPES
There are so many j-pipes out on the market. Since we want to be cool and of course for better cooling of that hot air coming out of the turbo, we shall use the FMIC or front mounted intercooler. For that reason we want a j-pipe designed for FMIC, and not for a side mount or any other intercooler location.
This is the FMIC j-pipe.
http://ecx.images-amazon.com/images/I/31uQ-iLezZL.jpg
This is the stock j-pipe usually seen on 1g DSMs
http://img123.imageshack.us/img123/4294/outletlo9.jpg
1g vs. aftermarket
http://www.arctic-racing.com/media/jpipeold2.jpg
The thing about the aftermarket j-pipes is that they might interfere with the stock radiator fans. Some are designed no to, but all j-pipes, that I have used, required slim fans.
Now look at the stock J-pipe and you'll see it has a nipple sticking out of the pipe. This is you boost source for the wastegate. From that nipple, you run a hose line to the wastegate nipple of your 14b or 16g. The wastegate spring for these turbo happens to be 10psi which is right at the save boost limit for budget build and homemade tune. Now none of the aftermarket j-pipes have that nipple, so you're going to need to make your own boost source. I've seen people JB Welding brass fittings on the j-pipes, but the rule here is that it has to be sourced as close to the turbo as possible. I always JB welded fittings on the first pipe after the j-pipe and it has worked for me so far.
Intercooler and piping
Depending on the size of the intercooler you got, you might end up cutting into the bumper support. Sawzall work very well when it comes to that. Why? You dont want to have to cut the bottom part of the front bumper and have the intercooler sticking out from the bottom. Here are a few pictures of the cutting that you might have to do.
http://img716.imageshack.us/img716/5484/img7452d.jpg
http://img98.imageshack.us/img98/5958/img7458n.jpg
Next thing you want to do is to attach the IC to the bumper support. Usually the IC has bolt bungs welded to it on the top and the bottom. Mark the top bungs on the bumper support, drill thru the support and run bolts right thru it to the IC. If you IC isnt that tall you can fabricate some aluminum hangers out of $5 aluminum plank found in the hardware isle at Home depot.
Looks some like this:
http://i232.photobucket.com/albums/e...6/DSC00175.jpg
http://i232.photobucket.com/albums/e...6/DSC00176.jpg
There are different ways to run the IC piping. There is a short route, long route and there's a medium route.
Long route - this the simplest to do, but it requires most material.
This is the basic layout of the long route. The pipes go around the radiator support, right side to the j-pipe and the left side to the upper intercooler pipe (UICP).
http://www.tmobilepictures.com/photo...g81ur4r3ae3wv3
Short route - it requires cutting into the radiator support, precise measuring and welding of the bends. I mean it looks very neat, but its not worth the hassle.
Not very clear, but the IC pipes run on both sides of the radiator
http://t2.gstatic.com/images?q=tbn:A...7FeBEdHEvwdIzA
Medium route - is a mixed long and short routes. Right side goes around the radiator support and the left side goes through the radiator support. Im currently using this route and I'll tell you its very easy to put together and cheap as well.
http://vr-speed.com/store/images/IMG_3298.jpg
Either one of these routes can be accomplished by using straight pipes with silicone bends, or aluminum bends with straight couplers. T-bolt clamps are mandatory. Ebay couplers are OK to use, but do yourself a favor and dont buy ebay t-bolt clamps. I'll post the NAPA part number for 2.5'' t-bolts, a little expensive at $5 each, but they are well worthy.
Upper Intercooler Pipe (UICP) and blow off valve (BOV)
I'm gonna circle back to UICP in a minute after I explain the two main types of UICP and the difference between them
Ok, there are 3 types of forced induction air metering setups - draw-through, blow-through and speed density. The budget ones are the blow thru and draw thru.
Draw though setup - the factory setup is a draw thru. That means that the air is drawn thru the Mass Airflow Sensor(MAS or MAF) before entering the turbo. This setup utilizes the stock MAS and a Super Airflow Converter (SAFC) which intercepts the signal just before it enters the ECU. With this setup, the intake pipe that connects the rear end of the MAS and the inlet of the turbo, needs to have BOV recirculation tube and the breather nipple. Why? Because the air is measured before entering the system, and once in the system,and lets say the BOV isnt recirculated back to the intake pipe, or the valve cover breather is not hooked up to the intake pipe, all that measured air leaves the system and the MAS reads it as a post-mas boost leak that causes rich conditions and will trow your tune off. Here you see a typical draw thru setup where the UICP has the BOV only.
http://img344.imageshack.us/img344/8785/s10100789oo.jpg
http://img344.imageshack.us/img344/5416/s10101167sl.jpg
http://img344.imageshack.us/img344/763/s10100779vw.jpg
Blow through setup - its done by using a GM MAS and a Mass Airflow Translator (MAFT). What the MAFT does is to convert the GM signal to something that the Mitsubishi ECU would understand. Its called blow thru because the GM MAS is located on the UICP right before the throttle body and after the BOV and it measures the air that goes thru it. If the BOV is open and blows out to the atmosphere, it doesnt bother the MAS because the MAS is after the BOV and the BOV hasnt released metered air.
Why cant we use the Stock Galant MAS in a blow thru setup? The whole unit that we refer to as MAF, actually contains 3 sensors - The Mass airflow sensor (MAS or MAF), Baro (pressure) sensor and Air temperature sensor (AIT). The last two sensors determine how the ECU reacts when outside temperature changes and altitude changes. Now imagine what the ECU would think when the BARo sensor reads boost (positive pressure) or the IAT reads some temps that its not supposed to read and on top of the the MAS tells the ECU something very different than it's used to. Now you have a complete mess.!! What the GM MAS has is only MAS sensor, no BARO, no IAT and the MAFT itself is set to have constant values, for these two sensors, that are fed to the ECU at all time regardless outside temp or altitude changes.
This is how a blow-thru setup looks like and you see that the Upper intercooler pipe (UICP) is pretty much made of just GM MAS and BOV pipe.
http://i232.photobucket.com/albums/e...6/HPIM0729.jpg
