UPDATE: 2.4l Tigershark Turbo.
I had to reroute the radiator hoses and one of the engine oil cooler hoses. Relatively easy, I just had to cut the original hose clamps and rotate them up and out of the way and installed new hose clamps, relocate one of the ďTĒ fittings that is in the upper radiator hose. The surge tank hose had to be modified. It is a plastic flex hose that doesnít flex, so I had to cut the ends off to reuse them and replace the middle section with some silicone heater hose (solenoid hose has better heat resistance).
On the upper charge pipe going into the throttle body, I had to have a Boss welded in for an additional injector and a Blow-Off Valve (BOV) (not my work, I donít know how to TIG weld aluminum. But the guy did a really good job).
Wired in the Piggyback Computer (PBC). It wires in to the wire harness coming out of the computer (lower connector) and intercepts the signal for the crank sensor, cam sensor, knock sensor, upper and lower o2 sensor, and the MAP sensor (Iím sure that I am forgetting something, or two). The PBC has two harness and a vacuum hose coming out of it. The Main Harness, for all of the sensor inputs and out puts, one harness going to the Additional Injector, and the vacuum hose that reads boost.
How this works: The Piggyback Computer takes the reading from the sensors and makes no changes under normal driving conditions, it does this by monitoring vacuum. Once the PBC starts to see boost, it starts to make changes to the timing (retarding the timing) and starts adding additional fuel as needed; it also is taking reading from the o2 sensors, knock sensors and the cam sensor.
The Piggyback Computer is programmed through software on a Laptop. There are two Maps that are adjustable. Map A is for Timing adjustments and Map B for fuel. Adjustments are made at 500 RPM increments and Vacuum & Boost in .5 pound (figurative) increments.
By monitoring the software you can see where the PBC is getting its information to make adjustments. I installed an Air/Fuel ratio (AFR) and a Vacuum/Boost gauge so that I can monitor the AFR and Boost and make adjustment to the PBC.
I got the turbo installed and ran the piping. Initially I used the 1 aluminum pipe at the Throttle Body because I needed a solid place for the Additional Injector and BOV. All of the other pipes I made from ABS (it is like black PVC) plastic 2.25 inch pipe. I used regular silicone inner cooler elbows and reducers to join the ABS together. And of course the oil feed and return lines had to be installedÖ
My first test drive (running the PBC tuned (Renegade specific) as I received it): 25 mile round trip to the gas station. I made it all the way to the gas station without any issues. I am driving conservatively, not getting into too much boost, I want the vehicles computer and the PVC computer to learn to get along. It is mostly downhill form home to the station, I get stuck behind somebody driving slower then I want to, when it is clear, I press on the accelerator, get up in to the 4 pound boost range and the little Renegade wentÖ My pass was effortless. Keep in mind, I didnít floor it, I am driving conservatively, I want to get at least 100 miles on it before I try to see what it is capable of.
I fill the Renegade with 91 octane, because that is the best we have available where I live. TWO reasons. I am running with boost, and the Trailhawk does not have room for an inner cooler. Add the fact that I have the AVID bumper and an 8000 pound Winch, I really donít have room for an inner cooler. So to compensate for this, I run 7.35 pounds of boost, MAX, and premium gasoline. An inner cooler isnít required until after 8 pounds of boost.
On the way back from the gas station (mostly uphill) the jeep runs really good, with the exception of an occasional hick up, like the engine is losing crank signal, but only for a fraction of a second. I stop for a red light and the jeep dies but starts right back up. The light turns green and I give it some gas and I hear a pop, sound like one of my hoses came off of one of the charge pipes. The jeep runs, but no boost and I can hear the air rush. I pull over and sure enough, one of the pipes came out of the hoses. So I bust out my little tool box and I start to out the pipe back in the hose and realize that the ABS pipe had gotten soft by the engine bay heat and shrunk at the hose by the hose clamp. While I am reconnecting the pipe I can smell something like plastic melting, but I donít see anything. I get the pipe reconnected and start the Renegade and have an engine light and a red screen stating Cooling Circuit FailureÖ the engine temperature is in the 200 range, but normal. So I head towards home, the engine starts to warm up and the A/C stopped working. I pull over, shut off the Renegade and pop the hood. The Turbocharger sits about a 1.5 inches from the cooling fan, and it gets hot! Melted the fan motor cover. The fan blades turn but it makes crunchy sounds. Call the wife to pick me up, bring the trailer.
So I order a new fan, a turbo blanket, and exhaust wrap. I have seen videos where a turbo blanket will retain the heat and send it out the exhaust reducing the engine bay temperature by 50%, add exhaust wrap for the headers and down pipe for additional insurance. I also ordered aluminum pipe to replace the ABS pipe because ABS canít withstand the heat in the engine bay. I also figured that aluminum pipe will help dissipate heat, especially since I am not using an inner cooler, any additional cooling would be a plus. I did learn that the ABS made for a good templet for the more expensive aluminum pipe.
Now, I put the turbo in a blanket, wrapped the headers and down pipe, replaced the radiator fan, replaced the ABS with aluminum and relocated the Additional Injector and BOV to the rear of the engine (appearances), and reprogrammed the PBC to get rid of the hesitation and fine tune the timing and air fuel ratio.
More test drives, and computer tuning and now Iím ready to take the big test drive.
I loaded up the Renegade and headed off to work, 75 miles one way.
It was a good drive. The computers are still learning, the engine temperatures are where they are supposed to be and the Renegade runs up and down the mountains like a regular car.
Before the turbo, but after I installed the Front and Rear Bumpers, Winch, Rock Sliders and 4 inch lift (approximately 500 additional pounds (reminds me, I need to get this thing weighed)), the little (not so little as for a Renegades go) really had to work hard to climb some of the mountain roads that I travel on a daily basis. I am still driving conservative because I want to get more miles on it before I play too hard, but there is a big difference in the way this Jeep runs. It isnít a hot rod my any means, but is now has the power to climb 6 % grade and pull, I can pass somebody with confidence. It now runs (in my mindís eye) like it should have from the factory.
Iím going to run this for a couple weeks and post another update, unless of course something goes terribly wrong, then I will post that as it happens.
Side Notes: estimated gains. Our 2.4l Renegades are rated at 180 Brake Horse Power (BHP (at the crank)) which is approximately 139 Wheel Horse Power (WHP). 23% loss through the Powertrain (Automatic and AWD).
7 pounds of boost is approximately 285 BHP = 216 WHP
A few Before and After pics.
Going fast is only half the fun... You get to build it first.