Ok to start off with the simple question. Can you slap a turbo on a stock 4.0l? and the answer is yes with a little bit of time and some fabrication. And yes it did help with top end power a lot considering I had an 8 inch lift and 35 inch tires. I ran a turbo on my 4.0 for about 4 months with no problems. But there are a few things you have to do to make sure your engine doesn't blow up. Now a stock 4.0L cant take that much boost. A safe level is under 8 psi. anything over 10 you run the risk of blowing a head gasket or worse your engine blowing up. Another question I get is do you need to tune the ECM? and the answer is it depend. the stock jeep ECM will adjust the air fuel by adding more fuel to about 8 psi anything more than that it will run lean. This will only work is the stock O2 sensor is not moved to a different spot.
Now the first step is to find yourself a turbo. You can do 2 things. 1 make your own kit/ do it yourself. or 2 buy a whole pre made kit for like $2,000? I chose the cheap route and went with an eBay turbo. I went with a t3/t4 hybrid turbo that had a .57A/R. When buying a turbo DO NOT buy the complete eBay turbo kits with everything they suck and a waste of money. Buy all the of parts separately like turbo, piping, BOV, wastegate (if you want to run 1), and oil feed lines. So after buying the turbo you will need access to a welder and have some knowledge on fabrication. Next you need to decide weather you want the turbo to be engine braced or frame braced. When you rev the engine, the engine will move in the mounts a little bit so if you run a pipe and weld it to your frame without flexible exhaust pipe to allow the engine to move the pipe will eventually break. I chose to do a frame brace since it was easier. The easiest spot to put a turbo is the passenger side of the engine bay at least in a YJ, so the exhaust needs to be run across the bottom of the engine back up to the passenger side with at least 1 small piece of flexible exhaust pipe to allow engine to flex. Once figuring out how to route the exhaust to the passenger side of the back up to where the turbo will sit you will need to brace that pipe going up to the turbo to support the weight of the turbo since they are not light. After mounting up the turbo to the exhaust to the passenger side you need to decide weather you want an intercooler or not to run one. I chose not to run 1 due to the more piping and welding involved. After the turbo I welded a pipe that connected the turbo to the throttle body that went over the valve cover. This is where I mounted my boost gauge and my BOV. I adjusted the BOV to be at a very low psi then hooked up to the intake manifold where there was an unused vacuum fitting this will allow the BOV to open when the throttle body shuts and creates a vacuum in the intake. I decided with my turbo build to not put a wastegate on due to I wanted simplicity and for it to be done in a weekend (just make sure when running no wastegate watch your boost so it doesn't go over 8 psi). After all that I ran the high pressure oil side of the lubrication system on a turbo to a fitting that was on the oil filter housing of the 4.0. For the oil drain of the turbo you will have to remove the oil pan and drill a hole where a oil drain fitting can be attached. I just used some 1 inch radiator hose to a 1 inch brass barbed plumbing fitting I got a Lowes (don't make the same mistake I did and put the fitting way to close to the starter). once the oil pan is back on and the oil fitting are connected you need to run the exhaust. You can do that many ways I chose a 6 inch hood stack with a 45 degree miter. The exhaust is up to you. After that your done. If running no waste gate make sure to watch your boost so it wont go more than 8. If running wastegate make sure its got the right spring that's rated to the psi and its mounter 45 degrees to the flow of the exhaust on the pipe for it to work properly don't mount it like a T you will have over boost problems. If you need anymore information or help let me know and I can.
Now the first step is to find yourself a turbo. You can do 2 things. 1 make your own kit/ do it yourself. or 2 buy a whole pre made kit for like $2,000? I chose the cheap route and went with an eBay turbo. I went with a t3/t4 hybrid turbo that had a .57A/R. When buying a turbo DO NOT buy the complete eBay turbo kits with everything they suck and a waste of money. Buy all the of parts separately like turbo, piping, BOV, wastegate (if you want to run 1), and oil feed lines. So after buying the turbo you will need access to a welder and have some knowledge on fabrication. Next you need to decide weather you want the turbo to be engine braced or frame braced. When you rev the engine, the engine will move in the mounts a little bit so if you run a pipe and weld it to your frame without flexible exhaust pipe to allow the engine to move the pipe will eventually break. I chose to do a frame brace since it was easier. The easiest spot to put a turbo is the passenger side of the engine bay at least in a YJ, so the exhaust needs to be run across the bottom of the engine back up to the passenger side with at least 1 small piece of flexible exhaust pipe to allow engine to flex. Once figuring out how to route the exhaust to the passenger side of the back up to where the turbo will sit you will need to brace that pipe going up to the turbo to support the weight of the turbo since they are not light. After mounting up the turbo to the exhaust to the passenger side you need to decide weather you want an intercooler or not to run one. I chose not to run 1 due to the more piping and welding involved. After the turbo I welded a pipe that connected the turbo to the throttle body that went over the valve cover. This is where I mounted my boost gauge and my BOV. I adjusted the BOV to be at a very low psi then hooked up to the intake manifold where there was an unused vacuum fitting this will allow the BOV to open when the throttle body shuts and creates a vacuum in the intake. I decided with my turbo build to not put a wastegate on due to I wanted simplicity and for it to be done in a weekend (just make sure when running no wastegate watch your boost so it doesn't go over 8 psi). After all that I ran the high pressure oil side of the lubrication system on a turbo to a fitting that was on the oil filter housing of the 4.0. For the oil drain of the turbo you will have to remove the oil pan and drill a hole where a oil drain fitting can be attached. I just used some 1 inch radiator hose to a 1 inch brass barbed plumbing fitting I got a Lowes (don't make the same mistake I did and put the fitting way to close to the starter). once the oil pan is back on and the oil fitting are connected you need to run the exhaust. You can do that many ways I chose a 6 inch hood stack with a 45 degree miter. The exhaust is up to you. After that your done. If running no waste gate make sure to watch your boost so it wont go more than 8. If running wastegate make sure its got the right spring that's rated to the psi and its mounter 45 degrees to the flow of the exhaust on the pipe for it to work properly don't mount it like a T you will have over boost problems. If you need anymore information or help let me know and I can.
