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The F-Body Guide to Rear Mount Turbos
Build Your Own Rear Mount Turbo Kit
Introduction to Building Rear Mount Turbo Systems
The purpose of this web site is to give you all the of information needed to build your own rear-mount turbocharger system for any V8 F-body car. This includes both the LT1 and LS1 Camaros and Trans Ams. I will also cover a bit of turbo science, including turbo sizing, flow rates and turbo terminology.
In building your rear mount turbo system, you will need access to a welder, and of course basic welding skills, or someone who can weld up the tubing for you. You will also need a few other tools that I will cover in the section appropriately called Tools and Skills.
The debate is still burning on automotive forums whether or not the rear-mounted turbo systems actually work. It has been proven again and again on drag strips that this type of system works, and works well. A quick search on LS1Tech.com or any of the other well known F-Body forums will put the debate to rest. You will find a 12 second full sized Chevy truck, a 10 second LS1 GTO, a 12 second V6 Cavalier and many 11 second Camaros all running remote-mount turbo systems.
I also know from experience that this system works. I have built my own rear-mount turbo system for my 2002 Camaro Z28 for under $1000 and it works great. I have not track tested my car since the install, but I can tell you that I have added at least 100 rwhp to my Z28. I am not new to the turbo and supercharger scene, as I have owned many other boosted vehicles such as a supercharged C4 Corvette and a single turbo 347ci stroker 04 Mustang GT. My turbocharged Z28 is the fastest vehicle that I have owned.
One of the greatest features of this type of system is the ease of installation. With minimal fabrication skills, you can be up and running in a weekend. Once your system is on, it can be removed and your car can be returned to stock in a few hours.
Let’s get started!
So how much boost can a stock LT1 or LS1 handle? I would not run more than 4 psig on a stock LT1 or LS1 without fuel and timing modifications. You are combining a high-compression engine that has cast pistons with boost pressure. Play it safe!
Please consider getting a dyno tune once you have completed your system. Not only will it save you from replacing broken pistons, it will maximize your engine’s power and efficiency.
Special considerations in A/R need to be taken into account for remote mount turbo systems. Since heat, acoustic pulses and exhaust gas pressure supply the energy to spin the turbine, and these pressures are reduced as the distance increases from the source, adjustments in A/R need to be made.
Keeping the turbine A/R at .84 or smaller will keep the turbine spool time to a minimum. Anything larger than that will not spool quickly, and the infamous turbo-lag will be very apparent.
Turbos to consider using are the 60-1 HiFi, T61, T64, T66, T68-1, T70, T72 and T76. Remember to keep the turbine A/R lower than would normally be used on a conventional turbo system.
Garrett offers ball-bearing cartridges that help keep friction to a minimum. This helps the turbo to spool much quicker. These turbos tend to be a bit pricey, but may be worth it if you are not on a budget.
Look at the Garrett GT series with the ball bearing cartridge. The GT30 and the GT35R would make great rear-mount turbos if sized correctly.
Tools and Skills
Before you begin your build, you will need a few basic tools and some fabrication skills. At bare minimum you will need some sort of tubing cutter and access to a welder. If you do not have a welder, or any welding experience, you will need to find a shop (or a friend with a welder) that can weld up the tubing for you.
I use a chop saw for cutting tubing. They are cheap and cut through metal quickly. The down sides are lots of noise, lots of dust from the abrasive cutoff wheel, and cleanup of the edge of the tubing.
For welding I use a 110V MIG welder. My first build was done with flux-cored wire. Flux-cored welding has of splatter and cleanup, but it gets the job done. I have since converted my small welder to MIG, and I will never go back to flux cored wire again. The welds are much cleaner, and the beads tend to have fewer leaks to touch up.
A chop saw and welder are invaluable tools for turbo fabrication.
(Photo © 2006 JunkyardTurbos.com)
You will also need the basics such as a measuring tape, wrenches, screwdrivers, a sharpie for marking tubing, various taps etc.
Always wear eye protection when cutting or grinding. I cannot count the number of times my safety glasses have kept shards of metal out of my eyes. Always wear safety glasses when performing tasks that spew metal at high rates of speed!
While welding, wear welding gloves, a welding shield and long sleeves and pants. Welding without protection will lead to burns from splatter, or UV burns from the arc. I’ve learned this the hard way!
In this section, I will cover all of the parts needed to build your system. I will discuss all of the parts, what they do, and where to get them. Most of the parts are common to all turbo systems, however some are remote-mount specific.
The heart of the system is of course, the turbocharger. We discussed different turbo options and sizing in the Turbocharging 101 section, but I will offer some more information here.
When I built my first system, I used an old Holset H2D turbo that I purchased on ebay for around $100. Although it was not the best suited turbo for a rear-mount system, it did spool and it did produce more boost than my LS1 could handle without modification.
The Holset H2D Turbocharger. (Photos © 2006 JunkyardTurbos.com)
The Holset line of turbochargers is a popular line for the DIY turbo crowd. They can be had for a steal, and they are plentiful on ebay. These turbos are used on Cummins diesels (Dodge trucks) and are often found to be in great shape.
Dodge truck owners will often upgrade their turbo, and offer their stock turbo for sale. The common Holset turbos found for sale are the HX35, HY35 and HX40. These are widely used by the DIY Mustang turbo guys. Please be aware that the turbine inlets for the HX and HY35 turbos are not standard, and will require a custom inlet flange.
Also, some of the HX and HY35 turbos have an internal wastegate that can not be used on the LT1 and LS1. The wastegate is designed for use on diesel engines, and will not bleed enough boost to slow down the turbine on a gas V8 engine. A ‘W’ denotes that a Holset has an internal wastegate. (HX35W for example) Most people weld up the wastegate actuator and use an external wastegate instead.
Another consideration when looking at Holset turbos is that the A/R is not measured like other turbochargers. Holset uses another convention. They simply use volume for specifying turbine housing size. Common sizes are 16cm3, 18cm3, 19cm3, 20cm3 etc. If you do use a Holset turbo, use a 16 or 18cm3 turbine housing.
The graphic below shows supported horsepower for common Holset turbochargers.
Master Power Turbochargers
Master Power is a brand of turbochargers that grew from the Garrett line of turbos. Engineers from Garrett left the company and started their own business. Their turbochargers are top quality and comparatively inexpensive.
Master Power turbochargers use standard T3 and T4 inlet flanges for ease of fabrication. A source for these turbochargers is http://www.partsexpressonline.com .
A source for Garrett turbochargers is http://www.precisionturbo.net .
Ebay can be a great source for turbochargers, however, beware of deals that seem to good to be true. There are lines of turbochargers on ebay that have questionable reliability. I do not have any personal experience with these turbochargers, but I have read many a post about these turbochargers failing shortly after installation. I will note them here.
Please purchase these at your own risk. Turbos by SSAutochrome and XSpower have come under fire for reliability and poor workmanship. These turbos are Chinese knockoffs. Buy them at your own risk.
When considering buying a turbo on ebay, ask the seller to double-check the end play, that is the side to side movement of the shaft. If the shaft moves too much from side to side, or up an down, it may be an indication that the bearings are worn. Worn bearings will require a rebuild.
Also ask the seller to check that there are no chips or cracks on the compressor or turbine blades. If so, they will need to be replaced. Running a turbocharger with cracked blades is dangerous. The turbocharger will explode at high speeds, throwing projectiles at high velocity much like a hand-grenade.
The wastegate is a very important element in a turbo system. Without it, the turbine would spin increasingly faster, over boosting your engine and causing a catastrophic failure. The wastegate is used to bleed off exhaust energy before entering the turbine inlet, thus controlling the turbine speed.
A TiAL 38mm wastegate. (Photo © 2006 JunkyardTurbos.com)
Wastegates come in different inlet sizes and spring pressures. For my project, I used a TiAL 38mm .25Bar wastegate. These can be purchased at http://www.nolimitmotorsport.com/tial/ for around $250.
You should also search on ebay for OBX wastegates. OBX makes high quality components for a great price.
So what about sizing? Go with a 38 or 40mm inlet. The spring pressure is up to you. They are measured in bar. 1 bar = 14.5psi so a .25bar wastegate will keep boost at 3.63psi.
Of course you can always add a boost controller to increase the boost pressure. The boost controller will allow you to adjust the boost pressure above the boost setting of the wastegate. More on those later.
Charge and Exhaust Tubing
You will need lots of tubing. You will need straights and bends galore. I used 2.5” aluminized tubing for everything. It can be purchased from Summit Racing. Buy about 6 4’ lengths of straight tubing, and a bunch of J or U bends.
Aluminized exhast tubing (Photo © 2006 JunkyardTurbos.com)
Take some time to measure where you will place the tubing to get a rough estimate of what you will need, then buy a few extras just in case.
With aluminized tubing, it is important to grind the areas that are to be welded to ensure weld purity. Also, breathing the fumes from welding aluminized tubing can be hazardous. Weld in a well ventilated area.
You will also need a steel transition for the hot pipe. It should be 2 ½” to 2 ¾”. The stock exhaust pipe is about 2 ¾” and it needs to connect to your 2 ½” hot pipe. You can also have a muffler shop stretch the end of your 2 ½” hot pipe. They should be able to do that for a couple of bucks.
For the cold pipe, I used a 2 ½” to 3” steel transition when going to the MAF sensor. I then used a 3” to 3 ½” silicone connector from that to the MAF.
You will need an oil pump to return the oil back to the engine after it flows through the turbocharger. A pump is not usually used on conventional systems, but because of the distance, and the fact that oil does not flow uphill, you will need a pump capable of pumping large quantities of hot oil back into your crankcase.
The Mocal 12v Oil Pump
The best pump for the job is the Mocal 12v differential oil pump. It can handle hot oil up to 300 degrees F and flows enough to keep up with the demands of a turbo.
This pump can be purchased for around $180 at http://www.RacerPartsWholesale.com
I tried to save some money and bought a less expensive ShurFlo pump that was not temperature rated for hot oil. It lasted for about 10,000 miles before it kicked the bucket. ShurFlo makes a great product, and I use their pumps for my alky injection system, but for this application, go with the Mocal for the temperature rating.
A blowoff valve bleeds boost pressure in the charge pipe when the throttle blade is shut. If pressure remains between the turbo compressor and the closed throttle blade, bad things can happen.
Blitz Blowoff valve
Once the throttle is closed, remaining boost pressure needs to escape somewhere. It will either blow off couplings to escape, or if it can’t do that, it will back out through the compressor causing strain on turbo bearings, seals and blades. Over time this will ruin your turbo.
A blowoff valve or BOV, will pop off the built up pressure to prevent this from happening. It is referenced to manifold pressure, and when it senses that the manifold pressure is less than the charge pipe pressure, it is forced open to release pressure. You can hear a BOV working between shifts on a turbo car. It’s that really cool psssshhhh sound.
What about cars with automatic transmissions? I’ve heard lots of people say that cars with automatic transmissions don’t need a BOV because you don’t release the throttle when shifting. My opinion on this is that it is a part of any complete turbocharging system, and should be used.
Search ebay for good deals on blowoff valves. There are plenty of them available at any given time. A 50mm BOV is sufficient for an LT1 or LS1. Try to get the flange with the valve. It makes it easier than tracking one down later.
Silicone Couplings and Transitions
You will need a few silicone couplings to connect various charge pipes together. After you decide where your charge pipe will run and measure everything out, you will need to determine where pipes will be welded together, or connected using silicone connectors.
Silicone transitions by HTS (Photo © 2006 JunkyardTurbos.com)
Count on buying at least four 2.5” couplers and two transitions. The transitions go between the charge pipe and MAF sensor, and the MAF sensor and the throttle body.
You will need a 3” to 3.5” transition, and a 3.5” to 4” transition. The couplings and transitions can be purchased at ExtremePsi.com http://www.extremepsi.com/store/customer/home.php?cat=338 .
As usual, check out ebay and search for “silicone couplers”.
Don’t use hardware store worm gear clamps to clamp down those nice new silicone couplers! They are not strong enough and will eventually blow off, and they will tear up your nice couplers. The worm gear notches dig into the silicone and rip it.
Buy T-Bolt clamps to secure your couplers and transitions.
These clamps can be found on ebay, or at places like ExtremePsi.com
You will need different flanges for connecting the turbocharger, wastegate, oiling systems, BOV etc.
Turbo Inlet Flange
Mild steel T4 inlet flange (Photo © 2006 JunkyardTurbos.com)
You will need an inlet flange to match your turbine housing inlet. Common sizes are T3 and T4. You may need to do some fabrication for Holset turbos, as they use a proprietary inlet for some turbos. Some Holsets do however use a standard T4 flange like the H2D.
Make sure to buy the correct type of flange for your application. If you are using stainless steel tubing, buy a stainless flange. For aluminized tubing, go with mild steel.
You will also need a gasket to go between the turbo and flange.
A flange is needed to bolt the wastegate onto your feed pipe.
38mm wastegate flange
I used a 38mm wastegate, so I purchased a 38mm mild steel flange and welded it to a 1.5” pipe, which I then welded to my exhaust pipe just before the turbo. As with all flanges, you will need the gasket that goes between the wastegate and flange. Gaskets are usually supplied with the wastegate when purchased.
The BOV is connected to the charge pipe via a flange. Different BOVs use different flanges. Try to get the flange with the BOV when you purchase it.
TiAL 50mm BOV flange.
You need to drill an appropriately sized hole in your charge pipe, then weld in the flange. The BOV clamps to the flange.
The turbo requires lubrication via your engine’s oiling system. Flanges are required to connect the oil inlet and return hoses.
Aluminum oil inlet and return flanges with hose connectors.
(Photo © 2006 JunkyardTurbos.com)
The inlet flange bolts onto the top of the turbo’s center section, and the return flange bolts onto the bottom. You will also need the gaskets to go with the flanges.
Oil inlet flange and hose connector on a Holset turbocharger.
(Photo © JunkyardTurbos.com)
A flange is required to connect a downpipe (exhaust pipe) to the turbine outlet. This will vary depending on the type of housing your turbo has. The common type are bolt on and V-Band. Try to find a V-Band type of housing. V-Bands and flanges are available in many different sizes, and offer easy installation and removal of the downpipe.
V-Band flange and clamp.
You will also need a matching V-Band clamp to go with the flange. The flange welds to your downpipe, and the downpipe clamps to the turbocharger’s V-Band flange.
If your turbocharger has a bolt on type housing, you will need to find the matching flange. These can be purchased where you buy your turbocharger.
Bolt-on turbo discharge flange.
Oil Feed and Return Lines
Don’t skimp here. Buy stainless steel braided hose for the oil feed and return lines. Rubber heater hose will break down over time, become brittle and crack. You will spend a little bit more on the good stuff, but it will save you a lot of trouble in the long run.
You can get all different types of stainless steel braided hose at Summit Racing. Get -4 or -6 AN for the feed line, and at least -10 AN for the return.
You should also use AN fittings rather than simply using a hose clamp on the hose. AN fittings will provide a tight seal that will not come loose like hose clamps will.
Stainless steel braided hose and AN fitting.
Check valves are one way valves. They let fluid enter from one direction only. You will need two different check valves in your system. One valve to prevent boost pressure from entering through the PCV system, and one to prevent oil from draining into the turbo when the engine is shut off.
Female 7775k52 check valve with hose-barbs attached
You will need a 7775k52 and a 7768K51 1/8" female Viton seal. You can get them from McMaster-Carr, http://www.mcmaster.com .
You will want to install a boost gauge in your dash somewhere to keep track of boost levels. I purchased mine from Summit Racing for around $30. You can buy a boost gauge at almost any automotive parts dealer.
Autogauge boost/vacuum gauge.
(Photo © 2006 JunkyardTurbos.com)
You will need a few miscellaneous items to complete your system. You’ll need some pipe connectors, vacuum hose, t-barbs etc. All of these items can be found at your local automotive or hardware store.
Depending on what type of oil feed and return lines you are using, you will need some sort of fittings to connect them to the turbo oil inlet and return flanges. Standard NPT type pipe fittings from Lowes or Home Depot can be used here in most cases.
You will also need pipe fittings for your oil pump. Once again, head to your local hardware store for these.
You will need some nylon t-barbs for vacuum reference lines. Get a ½” and 5/8” nylon t-barb for the main manifold pressure reference point.
You will need two ¼” NPT to hose barb fittings for your PCV check valve. All available at your local hardware store. This will connect your PCV check valve to the PCV hose.
Now that you know all of the tools and parts that you will need to complete your turbo system, it’s time to make some sparks fly. Let’s get started building that rear-mount turbo system!
The Hot Side
The best place to start on your system is the hot side. This is where the turbo connects to your exhaust system. We will begin by building the 24” pipe that connects to your tail pipe, and has the turbo inlet flange on the other end.
This is made from a J or U-bend pipe that is 2 ½” in diameter. Begin by cutting the pipe at a bend so that a flat oval shaped outlet is formed. See illustration 1.
Illustration 1. Cutting the hot pipe at the bend.
You can now weld the inlet flange to the hot pipe as shown in illustration 2.
Illustration 2. Weld the inlet flange to the hot pipe.
After you have cut the pipe, and welded on the flange, you should have something that looks like this.
Turbo inlet flange welded to the hot pipe. (Photo © 2006 JunkyardTurbos.com)
Next you will need to weld the 2 ½” to 2 ¾” transition to the other end of the pipe as shown in illustration 3.
Illustration 3. Weld the transition to the end of the hot pipe.
Next you will need to need to weld in the wastegate tube and flange. Drill a hole in the hot pipe to fit the size of your wastegate tube. Welde the tube into the hot pipe, then weld the wategate flange to the tube. See illustration 4.
Illustration 4. Weld the wastegate tube into the hot pipe, and the wastegate flange onto the tube.
You can now bolt your turbo and wastegate to the hot pipe. Make sure to use the gaskets between the flanges for the turbo and wastegate.
You must now cut the exhaust pipe where it meets the muffler, and remove the muffler and tail pipes from the vehicle.
After the muffler system is removed, you can attach the hot pipe to the exhaust system. I chose to weld my hot pipe to the exhaust rather than clamp it. The choice is yours.
Before you hoist your turbocharger into place, make sure that it is “clocked” correctly. That is, the compressor outlet facing forward and the oil inlet directly on top with the oil return directly on the bottom. You can do this by loosening the bolts that hold on the compressor and turbine housings and rotating the center section and compressor housing to their correct locations.
After the turbo is clocked, you can hoist the hot pipe with turbo into place, and weld or clamp it with the turbocharger facing the front of the car as shown in the photos below.
Hot pipe and turbo welded into place. (Photo © 2006 JunkyardTurbos.com)
Turbocharger facing the front of the vehicle.
(Photo © 2006 JunkyardTurbos.com)
Turbocharger detail. (Photo © 2006 JunkyardTurbos.com)
You will need to run a reference line to your wastegate. If your turbocharger has a hose barb on the compressor, you can use it. Run a vacuum line from it to the reference port on your wastegate. If your turbocharger does not have a tapped hole with a barb, you can tap the cold pipe and screw in a barb there.
You are now ready to work on the oiling system. Let’s get the oil feed set up first. The LT1 and the LS1 will get their oil feed from different places. On the LT1, you will run the feed from the ¼” NPT port above the oil filter, and on the LS1, you will get your feed from the oil block off plate near the oil filter.
For LT1 cars, remove the plug above the filter and screw a ¼” NPT fitting into the hole. Connect your oil feed line there. For LS1 cars, you need to remove the block off plate that is next to the filter so that it can be tapped. Once you have tapped the port, insert the fitting and attach the oil feed line.
LS1 oil block off plate tapped for 1/8” NPT to -6 AN
Once you have you oil feed line connected to the engine block, route it back to the turbocharger, keeping out of the way of the driveshaft and other moving parts. You will want to use tie-wraps to keep it in place.
Once you have routed the line back to the turbocharger, you must connect the check valve with the part number 7768K51. This valve has a cracking pressure that allows oil to flow into the turbo while the engine is on, but stops the oil from flowing when the engine is off.
If you do not place this check valve in the oil feed line close to the turbo, oil will flow from your engine downhill into your turbo causing lots of smoke and oil puddles the next time you fire up your engine.
Put the check valve close to the turbo and with the direction of flow toward the turbo. You can tell the flow direction by the arrow on the side of the check valve.
Once the check valve is connected inline, connect the check valve to the fitting on the oil inlet fitting on the turbo. Make sure that the AN fittings are tight, or if you do use hose clamps, make sure that they are all tight. Do not use Teflon tape anywhere in the oiling system. The tape will get into the turbo and crankcase and could cause damage.
You can now start working on the oil return system. The first step is to find a location to mount the oil pump. I opted to keep mine out of the way of water and dirt, and mounted it in the rear section of the trunk. You may opt to mount yours under the car to keep the noise inside the down.
Oil return pump mounted in the trunk. (Photo © 2006 JunkyardTurbos.com)
Once you have found a suitable place to mount the oil pump, you can wire it up. I wired mine to the ACC so that it turns on whenever the key is on. Be sure to place a fuse inline as with any other electrical device.
I did not place an oil pressure gauge or alarm in my oil return. I could hear my pump working since it was mounted in the car. It is a good idea to place some sort of oil pressure warning system in the return just in case the pump does fail. A common warning system is an oil pressure switch that is tied to a warning light or buzzer on the dash.
If the pump stops working, pressure will build between the pump and the turbo, causing oil to backup in the turbo. You will see plumes of smoke coming from the turbocharger if this occurs. Shut down immediately if you ever see this!
Connect your return line to the turbo and route it to the inlet side of the pump. Next route the return line from the output side of the pump to the front of the car, and up into the engine bay on the passenger’s side. You are going to feed the oil back into the crankcase through the oil filler cap.
Remove the oil filler cap and place it into a vise. Tap the top of the cap as shown below.
Tapping the oil filler cap for the oil return line. (Photo © 2006 JunkyardTurbos.com)
You can now connect the oil return line to the oil cap with hardware store fittings as shown below.
Oil return detail. (Photo © 2006 JunkyardTurbos.com)
Once you have verified that all fittings and clamps are tight, and your oil pump is mounted and wired, you can start your engine and check for oil flow and leaks.
Fire up the engine and remove the oil cap, but keep it pointed into the filler neck. You should hear a gurgle followed by oil flowing out of the bottom of the oil filler cap. If you do not get any oil, check over your feed and return systems. Make sure that the pump is working, and that you have the in/out pump ports connected correctly. Also make sure that the check valve near the turbo is pointing to flow toward the turbo.
Once you have your oiling system done and have made sure that it is flowing freely and leak free, you can move on to the cold tubing.
The Cold Side
It’s time to tackle the cold side tubing. It will run from the turbocharger under the car and up the MAF sensor and throttle body. You will need to get the car up safely on jack stands, and map out the route from the turbo to the intake. There are many different ways to go, and you will have to decide what is best for you. If you have subframe connectors, you will take a different route than those without them. Your fabrication skills will be put to the test here.
You will need to decide whether to go over or under the axle with the tubing once the charge pipe leaves the turbo. I decided to go under the axle for ease of fabrication. I would suggest that you take the extra time to loop over the axle. It will improve ground clearance, and prevent problems when jacking up the rear of your car.
You will also need to decide where you will use silicone connectors, and where you will weld the pipes together. I would recommend starting at the turbo and working your way forward. Connect a pipe to the turbo using a silicone connector, then build the hoop over the axle. Once the axle is cleared and you are ready to continue going toward the front of the car, start with another silicone coupler. This makes it easy to remove the hoop over the axle if you need to.
Cold piping goes over the axle.
Cold piping along the edge of the rocker panel.
Cold piping with a subframe connector.
Cold piping before installation. (Photo © 2006 JunkyardTurbos.com)
Cold pipe detail.
Once you build up the cold pipe to the front of the car. You must route the pipe up to the MAF and throttle body.
I made a cut in the cross member to route the pipe. I welded on some supports to strengthen the cross member.
Routing the cold pipe to the MAF sensor
Photos © 2006 JunkyardTurbos.com
Connect the cold pipe to the MAF sensor using the 3” to 3 ½” silicone transition, and the MAF sensor to the throttle body using the 3 ½” to 4” transition. Once the cold pipe is secured, you will need to install your BOV.
Find a suitable place to mount the BOV and cut a hole in the cold pipe for the mounting flange. Weld the flange to the cold pipe and attach the BOV.
Before you run your car, be sure to remove the pipe and clean out the drill shavings. You don’t want that going through your engine!
BOV mounting location.
You will need a boost and vacuum reference to run the BOV and boost gauge. The best place to get this is from the brake booster vacuum line as shown below.
T-barb in the brake vacuum hose.
Cut the brake vacuum hose and insert a plastic ½” T-barb into it. Place a hose on the T-barb. That hose will be your boost and vacuum reference.
Attach a fitting on the end of the reference hose for feeding the BOV and boost gauge.
Boost reference fitting.
Once the boost reference line has been installed, we can move on to the PCV system. I used a simple check valve before the PCV valve to keep boost from entering the crank case.
You will need the check valve with the part number 7775k52. It is a one way check valve with a light cracking pressure. Screw in ¼” NPT hose barbs to each end of the check valve.
7775k52 check valve with hose barbs.
Disconnect the PCV valve from the hose that goes to intake manifold. Attach a new hose onto the PCV valve and attach it to the check valve. Run a hose from the other side of the check valve back to the nipple on the intake manifold as shown in the picture below.
PCV detail. This prevents boosting the crank case. (Photo © 2006 JunkyardTurbos.com)
That’s all there is to the PCV system. You can of course install a catch-can instead of this simple modification. It will require a little more fabrication, but it is a better system. The catch-can installation is beyond the scope of this guide.
You will need to attach an air cleaner to the inducer side of the compressor. I suggest routing it up out of the way and into the cavity where the driver’s side tail pipe went. Use a 3 ½” pipe to route your air cleaner up out of the way. A cone type K&N filter is your best bet.
Down Pipe/Exhaust Pipe
You must attach a down pipe from the turbine housing outlet flange out the back of the car. No muffler is needed with this system. The turbo uses acoustic energy to spin the blades, and noise is converted into boost energy.
This is where you will weld a pipe onto the V-band or bolt-on exhaust flange. Route a 3” or 3 ½” tail pipe out the back of the car.
See the next photo for intake and exhaust routing.
A rear mounted turbocharger system showing intake and exhaust routing.
The Boost Gauge
The boost gauge is the final step in your build. Run the supplied vacuum line from the boost reference that you made through the firewall and into the location where you will mount your boost gauge. I removed the vent on the driver’s side and place my gauge there.
Boost gauge location.
Run the vacuum line to the back of the gauge and install it using the supplied hardware.
I wired my gauge to the dashboard lighting system so that the light turns on if the dash lights come on. My gauge automatically lights up at night. How you wire your gauge is up to you. I suggest using the proper wire connectors rather than twist and tape.
Boost gauge wiring.
Congratulations! Now you have all of the information you need to build your F-body rear mount turbo system.
Once you have finished your build, start your car and look for oil leaks. Take it easy on the maiden voyage. Don’t get too heavy into the boost. Watch the gauge closely. Make sure that your wastegate is installed correctly. Roll on the throttle gently and listen for detonation.
Park your car and check again for leaks. Give everything a once over before taking your car back out on the road. Once you feel comfortable that everything is working, you can get on it a bit.
Make sure that you do not exceed 4 psi on a stock LT1 or LS1 without a tune or you will be doing this!
Pulling an LS1 out the top. (Photo © JunkyardTurbos.com)
Do yourself a huge favor and get a dyno tune before you get on your car. It is well worth it, and it will save your engine!
Enjoy smoking those pullied Cobras with your new boosted F-body!
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