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by Mike Holler
Turbochargers use the normally wasted heat energy from the exhaust to help engines make more power. That’s how Stephane Beauregard can go 8.04 at 174.30 mph in a 2.2 liter Shelby Charger! It will be a key component in helping Bob achieve his “modest” goals as well. Converting to a blow through intake manifold, Bob has decided to use a TII Garett T3 turbo (.42 A/R intake, .48 A/R exhaust).
These turbos were used from ’87 to ’89 on the Shelby Daytonas, and the used varieties typically have been around the block a couple of times too many (and too fast). To help Bob achieve his goals and to spawn material for another exciting article on Allpar, we will rebuild and improve upon a garden variety (albeit an upscale garden) factory TII turbo.
The chosen turbo has some shaft play, but has not yet had the turbine blades get intimate with the housing. For this rebuild we will be using a basic rebuild kit from www.gpopshop.com. G-Pop’s kits are about ½ the price of the exact same pieces from Turbo City. G-Pop rebuilds turbos and offers various upgrades as well, so they are reputable. The kit includes the gasket, seals, floating bearings, and clips needed to spool new life into our tired huffer.
Step one is to remove the coolant and oil lines, associated fittings, wastegate can, oxygen sensor, and all the other doo-dads. Next the intake housing is removed, followed by the swing valve. The exhaust housing gets the next eviction notice. You might want to soak the bolts for a couple of days with PB Blaster to loosen them up. Even after soaking, they may still be uncooperative. I have 2 housings here that would require drilling and tapping to salvage due to snapped bolts (and both were soaked for days).
We are left with the center section. Before removing the impellers, mark a blade on the exhaust side and intake side so it can be put back together exactly as it came apart. This preserves the balance. With a ½” wrench and 7/16” 12 point socket, the intake wheel can be removed. The whole shaft will now slide out the exhaust side (perhaps with a bit of persuasion from a modest sized hammer). Four bolts get the last piece off the center cartridge, exposing the seal and thrust washer. Lift the washer and slide it out.
Really small snap ring pliers are needed to remove the bearing retaining clip. Once removed, the bearing can be removed. I used a pick with a curved tip. Remove the clip from the exhaust side and pull that bearing out. You will see that there are 2 more snap rings deeper in the cartridge. It is not necessary to remove these. They can be a nightmare to reinstall later.
With the whole shebang now in parts and pieces, it’s time to improve. The Stock ’87-’88 exhaust outlet, aka swing valve, is called a 2.25” but actually measures 2.1” across the choke point. With a die grinder and carbide bit, this opening can safely be ported to 2.4”. For comparison, the ’89 Shelbys got a 2.5” swing valve that only measures 2.3” across.
The next upgrade is to open the wastegate hole as much as possible, yet leaving 1/8” margin for the puck to seal against. When the volumetric efficiency of a turbocharged engine is increased dramatically, there is a whole lot more exhaust gasses coming out of the engine. The tendency is for the wastegate to max out forcing too much exhaust gas across the turbine. The result is “boost creep”. What this means is that the wastegate can no longer control boost and the engine pulls like crazy then goes into over-boost shut-down. Porting the wastegate hole larger allows it to flow more, compensating somewhat for the added volumetric efficiency.
All of the parts will receive some sort of coating. The exhaust housing and swingvalve will get Tech Line’s Cermit ceramic thermal barrier coating on the inside, and Tech Line’s Color Guard Titanium high temperature coating on the outside. Coatings are applied with an air brush. Infared thermometers show about 400 degrees F lower surface temperatures with these coatings combined. Since the intake manifold all but touches the exhaust manifold and turbo, this can only help power. The center cartridge will get coated with the Titanium to preserve that new look.
Before the coatings can be applied, everything needs sand blasted. The intake pieces get powder coated, first with Super Chrome, then with Translucent Gold. (Watch for upcoming article on powder coating.) The bolts, wastegate can, and oil drain tube are painted with black engine enamel. New 316 stainless steel bolts replace the rusted factory ones on the exhaust side, so they won’t need painted.
After all the parts are reconditioned, they will need a final and thorough cleaning. We just bombarded everything with sand. We don’t want sand in the freshly rebuilt turbo scratching it’s name on the walls. Bolt holes should be chased with a tap to clean out all the old rust and sand. Aluminum parts can be cleaned with water, but the steel and cast iron parts will rust. I use brakleen to remove the sand and dust without causing rust. The shaft gets a thorough cleaning by spinning it in the drill press while scrubbing with Scotchbrite.
Going back together begins with the center cartridge. Check your old parts against your new kit to be sure you have the right kit. It will go back together in the reverse order it was taken apart. The oil seal on the exhaust side will pull in as you tighten the shaft nuts. Notice there is a taper in the cartridge just for that. Be sure to oil everything as you go so there won’t be a dry start. A new E-clip secures the wastegate arm to the canister rod.
It looks so gosh-darned good, I would love to place it over the mantle, replacing some family photos. But alas, it will be shipped to Bob where it will be installed in his ’86 C/S Daytona.
Also see our 2.2 turbo page.
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