With so many rear-wheel-drive LS swaps becoming common nowadays, it’s often very rare you see an LS4 swap performed on any car. While they’re not extremely popular due to the front-wheel-drive configuration and transaxle platform, enthusiasts like Brandon Furches, see the potential in the LS4 engine, and the W-body platforms they came in.
So why would someone like Furches want to build a W-body car like this ’05 Monte Carlo SS, which was originally powered by a 3.8 liter supercharged V6, anyways? We’ve always been taught by other enthusiasts that rear-wheel-drive platforms reign king of the drag racing world, so why would anyone challenge that knowledge? Furches explains the reasoning behind his choice to use the ’05 Monte Carlo SS as the platform of choice for this turbocharged LS4.
Furches comments with, “I’ve always been a fan of W-body cars. I’ve owned numerous Monte Carlos in the past: all powered by the GM 3800 series engine. The majority of the market in the LS swap community are rear-wheel-drive platforms, with these cars being avoided like the plague. One of the biggest reasons for that, is because the transmissions are an extreme weak point on these cars. They can’t handle the factory output of GM’s 3800 series engines, let alone a LS4 swap.”
We inquired with Furches regarding the possibility of installing the engine in the rear, he said, “The biggest thing that limits enthusiasts from modifying these cars is the transaxle. We just wanted to make a change with using a front-wheel-drive car. Every LS car you see out there is rear-wheel-drive, and for good reason. From a drag racing standpoint, they certainly have their advantages. However, the W-body platform has been proven in the past. We wanted to further that proof: these chassis’ can make power and are able to put it down to the ground efficiently, even in a front-wheel-drive configuration.”
Furches explains that everything wasn’t always clear skies in paradise during the build process. The first transmission the car had literally exploded. We think Furches can explain this one a little better, commenting, “We grenaded the first transmission. The biggest issue with using the 4T80E is the PCM software. These transmissions were only available on Cadillac vehicles. But unfortunately, any tuning software that has the ability to talk to a LS engine’s PCM, wasn’t able to license to a 4T80E equipped vehicle until 2007. What that means, is that we had to use an older ’04-‘11 style PCM. We chose an electrical harness and PCM from an ’06 cargo van, which utilizes a drive-by-cable setup.”
He continues with, “The tuning program that we’re using, was meant to be used on a 4L80E rear-wheel-drive transmission. Luckily, ninety-percent of the programing is the same, including the shifting mechanisms. The big difference between those two transaxles is the manifold pressure switch located in the transmission, which on ours, wasn’t receiving enough pressure at WOT. We believe that’s why the first transmission exploded. It was a completely stock unit from a ’01-’03 Oldsmobile Aurora, and we’re not sure how many miles were accumulated on that particular unit. On the second transmission, we were able to get it to work.”
Furches’ LS4 swapped Monte Carlo SS hosts a respectable amount of upgraded components: including a completely one-off custom turbocharger kit, a custom camshaft made specifically for his application, and more. He explains, “The turbocharger is a Bullseye S475-series. It’s a standard trim unit, and we haven’t modified anything on the compressor side of it. The turbine is a 83mm wheel, housed in Bullseye’s stainless steel V-band housing. It’s nothing crazy. It has a 4-inch down pipe, and a 3-inch V-band turbo inlet on the turbo side. Pertaining to the kit itself, it’s completely custom, which was done all in-house. The exhaust is completely TIG-welded in-house, and leads to an 18-inch long, 4-inch diameter stainless steel pipe which exits through the side of the front bumper. It also has two Turbosmart wastegates on it and uses a Turbosmart Race Port 50mm blowoff valve. We custom built and TIG-welded an air-to-air intercooler for the system as well.”
It’s obvious that the turbocharger setup is stout, but what about the new LS4 engine? How does it handle all of that power? Furches responds with, “The LS4 comes with 243 GM cylinder heads. They’re completely stock, with just a resurfacing performed on them. We upgraded the valve springs and pushrods with Brian Tooley Racing components.”
Furches continues, stating, “We disassembled the bottom end of the engine and replaced the rings and bearings after thoroughly having it looked at. We’re still using the stock crankshaft, rods, and pistons. We haven’t changed the compression ratio whatsoever, and we’re using factory GM head gaskets with ARP bolts. We did decide to use a factory GM LS2 intake manifold and 90mm throttle body, as the LS4 manifold wasn’t ideal for the new setup. We haven’t dynoed the car yet, but the car weighs 3700 pounds with me in it. We’re guessing it’s around 700 horsepower to the wheels.”
From what we’ve been told, the car has retained all of the factory functions it came with. All the way down to the air conditioning and the cruise control. Furches explains, “The car is a fantastic daily driver, and was relatively inexpensive to build. The goal for this build was to set the example, and that example was that it’s possible to have a fast, fun, and reliable front-wheel-drive application.” He continues with, “A special thank you as well to Geoff Skinner at Engine Power Systems in Baton Rouge, Louisiana. I couldn’t have done this project without Geoff. Thank you for putting up with all my questions and ramblings!”
We had a blast interviewing Furches and his one-of-a-kind turbocharged LS4 swapped Monte Carlo SS. Even though the car was put together extremely fast (just over three weeks from what Furches tells us), it’s already proven itself to be an absolutely animal at the strip. We can’t wait to see Furches break into the 10s with this turbocharged beast.
Furches has plans to race the Monte Carlo SS over the weekend, looking to break into the 10s with ease after some tinkering with the current setup.