Remote-mount turbos. The concept flashed through my mind when I saw Honda had moved its exhaust manifolds to the back side of the engine in my 2001 Civic. Plop a turbo on the far side of the cat and you don't have to worry about firing it off in a timely manner to pass CARB requirements.
For me this was an idle, passing thought, but Rick Squires made the concept a reality and has a patent on the process to prove it. Squires Turbo Systems (STS) is developing remote-mount turbo systems that position the turbo in the space previously occupied by the muffler. The company's initial foray into the market will feature applications for 1999-and-up GM pickups and SUVs, 1993-and-up F-Bodies (Camaro and Firebird) with LT1 and LS1 V8s, 2000-and-up Toyota Tundra pickups with the 4.7-liter V8 and 1996-and-up Toyota Tacoma pickup trucks with a 3.4-liter V6.
Spool-up and turbo lag issues in regard to the length of the piping leading to and from the turbo will probably jump to the forefront of enthusiasts' minds. These issues aren't as critical as one may think.
From my viewpoint, turbo lag is a term used to describe turbo systems with poorly sized turbine housings and their consequent incorrectly sized turbine wheels and poor tuning. Or it could be a combination of the three at work simultaneously. The velocity of exhaust gas and the fact that the STS design features a good deal of straight pipe, coupled with what exhaust gas does when it enters a turbo, should help negate any "lag" in the system.
The conical shape of the passage from the turbine inlet flange to the turbine wheel dramatically increases the velocity of the gases, which is how a turbo can spin at speeds of 80,000 to 120,000 rpm. Engine size, the trim of the turbine wheel and the turbine housing's A/R have much more impact on spool-up characteristics than the amount of pipe between the engine and turbo.
On the cool side of the turbo, it's no secret that sharp bends in the pipe create a pressure drop and can hinder response. An intercooler also creates a pressure drop, but the added density and the accompanying increase in power potential make this compromise a no-brainer; dial-in more boost to regain the "dropped" pressure.
The STS system uses that long length of pipe as an advantage. Just as the exhaust pipes are HPC-coated to keep heat in, the intake pipes are HPC-coated to assist heat transfer out of the pipe. The pipe is the intercooler, and STS reports 52-percent efficiency in its CARB-legal systems. Finned tubes and inline intercoolers can be employed, but STS has seen favorable results with standard piping and the HPC coating.
Installation of an STS remote-mount turbo system starts at the workbench-joining the turbo to the manifold, bolting on the provided TiAL wastegate and getting the turbo assembly together. It continues like an exhaust system installation; until it's time to hang the muffler section, the turbo assembly is used instead. The system uses all the O.E. hangers, further simplifying the install, which should be a 4- to 6-hour job. The intake piping is routed along the frame rail using as many factory bolts and holes as possible and enters the engine through the fenderwell.
The oiling strategy of the STS setup is another unique, easy solution. A scavenging pump is mounted on the frame rails, which draws oil from the engine via a filter-mounted adaptor. The return line is run to a special oil cap that has a fitting incorporated into it. The line acts as an oil cooler and the scavenging pump is designed to vary flow based on boost pressure, which helps reduce pump noise.
Tuning for CARB-legal kits is handled by Unichip in Toyota applications and Diablo Predator in GM kits. The CARB kits run about 4 to 6 psi and require no engine modifications. Those interested in turning up the wick can install a boost controller, get upgraded turbos or employ methanol injection and see some crazy power. Of course, as the boost goes up, so may the need for beefier rods and pistons.
Squires' Firebird has a built LS1 outfitted with a remote turbo system featuring an upgraded Garrett GT40 and a methanol injection system. STS estimates this combination will make 600 plus at the wheels at 10 psi.
I rode in an STS-turbo'd Tahoe and it felt good. The boost gauge was mounted at the turbo and not at the intake, so I couldn't observe any lag, but the truck seemed to respond quickly to throttle inputs.
The systems should retail for less than $4,000 and the Dodge Ram pickup is the next vehicle in the STS bull's-eye. We were impressed by the kits and the concept is tailor-made for many modern performance cars that seem to have shrinking engine bays these days.
Beyond the space challenge vehicles, having the system on the far side of the turbo should make it easier to gain CARB approval, something STS expects with all its kits. Import applications aren't on STS's radar, but we'd like to see some sort of universal remote-mount offering that enthusiasts from either side of the divide can graft onto their ride.
We commend Squires Turbo Systems for the innovation and integrity of the concept it put forth, and we also appreciate the enormous potential it represents. Now all we have to do is lobby the OEMs to design bigger mufflers.
STS Kit Components
Patented oil syste
mHPC intake tubing
HPC exhaust tubing
K&N air filter/pre-charger
Silicon connectors, fittings
Turbo System Options
Methanol injection system
Manual boost controller
Electronic boost controller
Gauges (boost, air/fuel, pyrometer, wideband)
GT Turbo upgrade
Fuel pressure regulator
Snorkel kit (air intake relocation for trucks)
Air filter shield (F-body)
Innovate and AEM widebands