Project Corn Star: Our Fourth-Gen Goes Turbo With Huron Speed Part 1

These days it often feels like you’re not one of the “cool kids” unless your ride is sporting a power adder. Nitrous, superchargers, and especially turbochargers have become the norm when prowling the streets or track. And with modern fuels, such as E85, at your disposal, it’s more cost-effective and safer than ever to run one. And while we’ve played with just about every power adder under the sun, we’ve never done a boosted, E85 build—until now that is.

Recently, we introduced you to Project Corn Star, our resident E85-powered fourth-gen Chevy F-body, and showed you a lot of the components that we selected for our build. You can read all about it here, but to refresh your memory we decided to go with a turbo kit from Huron Speed. Their kit is a work of art and will greatly cut down on the amount of fabrication necessary to fit it to our 2002 Camaro. In fact, the only fabrication necessary for the entire build were things we chose to do ourselves, such as hooking up the stock-style exhaust—but we’ll get to that later.

The Kit

In case you missed our previous article, where we introduced Project Corn Star, we decided to go with a Huron Speed turbo kit for our build. This will prevent unnecessary fabrication and will allow us to run any T4 turbo we want, all while retaining our A/C for those hot Southern Californian afternoons.

As you can see here, the Huron Speed turbo kit is gorgeous to look at and all of the welds and flanges are sturdy and ready to be heat cycled. Constructed from 304 stainless steel, the tubes are all .120-inch thick to ensure the weight of the turbocharger and immense heat will never crack them. While Huron has never seen a failure, the hot side is covered by a lifetime warranty.

Our kit also retains our front sway bar, a component that is often ditched when switching to a turbo. Our Huron Speed kit is virtually bolt on and will have us back up and running in no time. All of Huron’s kits are made right here in the U.S.A. and come with a lifetime warranty against defects. Jon Ojczyk, owner of Huron Speed, says he’s yet to see any of their welds fail and with such a fantastic reputation for customer service and build quality we knew we were making the right decision.

It seems a shame to cover up the beautiful stainless steel pipes. Hewn from .120-inch thick material, these systems can take a beating and keep right on going. Everything we needed to get the turbo on the car can be ordered with the kit or put together piece-meal, depending on your budget and plans for your car. 

The kit comes with a massive 4-inch thick intercooler and all of the cold side piping as well. Oil feed lines, couplers, turbo blanket, and exhaust heat wrap are also included.

Our Components

For our turbo, we turned to the guys over at Precision Turbo & Engine who recommended a PT7675 Gen 2 CEA for our setup. The turbo features a .96 A/R, V-banded turbine housing which will allow our engine to spool the turbo pretty quickly, yet still give us enough breathing room not to choke the engine in the higher RPM range.

It comes with Precision’s Competition Engineered Aerodynamics (CEA) compressor wheel machined from forged 2618 aluminum. It also uses a dual ceramic ball-bearing center housing rotating assembly. This will also increase how quickly our turbo reacts to dynamic changes in exhaust flow and will cut down on lag and offer faster transient response.

Here you can see the CNC-machined 2618 forged aluminum inducer as well as the Competitive Engineering Aerodynamic technology on both the compressor and turbine wheel.

The compressor housing is a “Ported H” style housing that helps to eliminate compressor surge and features a 4-inch inlet and a 3-inch outlet. The turbine wheel also uses the CEA technology and measures in at 75mm.

To keep our boost under control, we went with a Turbosmart 50mm Race Port blow-off valve that flows up to 330 cfm, ensuring that our boost has a place to go once the throttle shuts. This will prevent compressor surge that could damage our Precision turbo. Compared to most blow-off valves on the market, Turbosmart’s is 50 percent lighter and 25 percent smaller making it perfect for the tight real estate we are working with.

As you can see here, our turbo was designed to work with a non-divided T4 flange. You can also see the investment-cast 310 stainless steel V-banded turbine housing.

To keep boost pressures under control, we selected a Turbosmart 45mm HyperPort wastegate. Again, the compact design of the HyperPort is crucial on our build due to the compact design of the turbo kit. If you’ve ever been under the hood of a fourth-gen, you’ll know that space is at a premium and the ingenious way Huron Speed has packaged everything allows all the components to work flawlessly.

The Install

With the kit and all our supporting components in hand, it was time to get dirty. We started by pulling the engine on Corn Star; however, this step isn’t required. We decided to do so since we wanted to check in on our newly installed SPEC clutch and because we were installing a BMR turbo crossmember at the same time.

With everything disconnected from the chassis including fuel lines, electrical connections, and hard mounts, the engine was ready to drop out of the car. We also had to remove the torque arm and transmission crossmember. After that, it was just a matter of unbolting the car's cradle from the unibody and lifting the car off its engine.

The crossmember allows us to keep our A/C intact by routing the downpipe down the driver’s side. The tubular crossmember provides us with enough room to clear all of the new hot side piping without having to make any compromises. The BMR piece also helped us offset some of the additional weight we are gaining by installing the turbocharger kit. BMR also sent us a set of their tubular lower control arms to match our crossmember. This will give us greater control over our Camaro’s suspension settings and again help reduce weight creep.

Dropping the engine was a relatively straightforward process, we won’t go over it in detail here, but suffice it to say that we had it out of our F-body in just a few hours. As we mentioned, this step isn’t technically necessary, but since we had the time—or so we thought—and the means, we decided it would be best.

A Crack In Our Plan

As we were lowering the engine and transmission out of the chassis, we happened to notice some dried coolant on the side of the block. This seemed to indicate that the head gasket on the passenger side had been leaking, confirming that we made the right decision to remove the engine.

Since we would now be removing the heads to replace the leaking gaskets, we opted to improve things while we were at it. ARP sent us over a set of LS1 Pro head studs and Cometic gave us a set of MLS head gaskets (P/N H1295SP5051S). The head studs and gaskets will ensure that all our additional cylinder pressure will be transferred to the rotating assembly instead of vented to the cooling system instead—something we’d really like to avoid.

After unbolting the transmission, the engine headed for the stand so we could remove the heads and install our ARP head studs. With the LS6 intake off the motor and the valve covers, pushrods, and rockers removed, we loosened the head bolts and removed the stock 241 casting heads. After the heads were removed, we blew the coolant out of the thread bosses—an important step as you can crack your block if you compress the coolant under the head bolts while reinstalling the heads, advice we wished the previous owner would have taken.

Everything seemed fine as we pulled the stock heads off the block. However, we noticed dried coolant on the side of the engine and figured the head gaskets may have been leaking. What we discovered was much more serious. The previous owner had cracked the block when they didn't remove the coolant from the head bolt bosses.

With everything out of the way, we proceeded to hand-thread the ARP head studs into place. While we were doing so, we noticed coolant seeping down the side of our stock LS1 block. Upon closer inspection, we realized the block had been cracked by the previous owner when they removed the heads to install a cam and bolted the heads back on without removing the coolant from the thread bosses. This was made evident by thread sealer already in the cracked bosses which were allowing the engine to “get by” with a cracked block.

Back To The Drawing Board

Turbo Kit By The Numbers

  • Huron Speed V3 A/C T4 Single Turbo Kit
  • Precision PT7675 Gen II CEA (PN PTB605-7675)
  • Turbosmart Race Port blow-off valve (PN TS-0204-1102)
  • Turbosmart HyperGate 45 wastegate (PN TS-0204-1104) (This is for the gate with the HKS/Tial style flange)
  • BMR Turbo Crossmember (PN KM014)
  • Derale Pusher Fans (PN 16925)

As some of you may know, we ran into this surprise as we were rushing to get the car ready for LS Fest West. The plan was to have Corn Star lead the cruise to Hoover Dam and participate in the show’s activities. Since we really didn’t want to let you down, we quickly turned to one of our partners, Summit Racing, to see if they could help us out of a bind.

Obviously, since the LS1 block was completely unusable, and we didn’t have time to build a completely new engine, Summit recommend a 364 cubic inch short-block from one of its partners BluePrint (PN BPLS364). Naturally, we said yes as fast as we possibly could and Summit went to the added effort of having the engine express shipped to us in order for us to continue to try to make LS Fest West. We received the engine just two days later, a true testament to the speed and capability of Summit’s network of suppliers.

To keep our turbo project moving forward, Summit Racing stepped up to the plate and really saved our bacon. They express shipped us a 370 cubic inch short-block from their partners BluePrint (PN BPLS3640). While the iron block is slightly heavier than the aluminum piece it replaces, it is also more rigid and will be better able to cope with the boost we intend to throw at it.

We will cover the build of the engine in another article, but here are a few of the specs in case you were curious. The engine is an iron-block 6.0L that has been punched out .030 inch making it a 370 cubic inch mill. It is fitted with forged aluminum pistons from Mahle and the rest of the rotating assembly is stock GM equipment. We topped it off with a set of Edelbrock CNC-215 heads we happened to have on hand which we secured with a new set of ARP head studs. Since the engine is newer than 2003, the head studs are all one length instead of the multiple-length bolts used in the previous year LS engines, including our wounded LS1.

After our new short-block from BluePrint arrived, we quickly set about getting it ready to go back in the car. We topped it off with a set of Edelbrock CNC-215 heads secured by ARP head studs and sealed by Cometic MLS head gaskets.

Used in conjunction with the Edelbrock heads and the Cometic gaskets, with a compressed thickness of .051, we were left with a livable 10.4:1 compression ratio. While that might be a little high for a boosted application, it’s not much higher than the LS1’s stock 10.1:1 compression ratio, and since we’re using E85, it won’t be too prohibiting.

Full Steam Ahead

While we were waiting on the engine to show up, we went ahead and removed the front fascia of the car to give us room to install the 4-inch thick intercooler included in the Huron Speed kit. The mounting brackets are provided and mount where the crash bar used to (the crash bar has to be ditched to mount the intercooler). We simply drilled two holes in the F-body’s “frame rails” to help mount the intercooler. After that, it was as simple as bolting the intercooler in place.

After removing the bumper cover and foam support, it was only a matter of drilling a couple holes and bolting the intercooler into place with the brackets provided by Huron.

Now that we had the new engine, and the heads were installed, we could continue our test fit of the turbo hot side. After temporarily bolting all of the hot side together with the provided V-band clamps, we noticed that the power steering lines would come much too close to the exhaust and would have to be rerouted.

Huron Speed sells a kit that includes braided steel lines that make it much easier to do this, but we decided to re-bend our stock lines. If we had to do it over again, we would definitely opt for the kit. We snaked our lines on the opposite side of the power steering pump down past the water pump and alternator.

As you can see in the picture, the power steering lines come much too close to the hot side. They have to be rerouted to go to the inside of the power steering pump. We simply re-bent our lines by hand, but it would have been much easier with the optional braided steel power steering line kit offered by Huron.

Once the power steering lines were dealt with, and the hot side piping was mostly in place, we could now temporarily mount our Precision turbo to make sure everything would clear and that we wouldn’t have any surprises when bolting the turbo on with the engine in the car. At this point, we also loosened the bolts on both the compressor and turbine housing in order to clock our turbo correctly.

Here we re-clocked the turbo by loosening the bolts on the turbine and compressor housings. This allowed us to position the oil feed and drain straight up so the turbo will drain properly when in operation.

Keeping oil running through the turbo at all times is of the utmost importance as is making sure it is draining properly. Since we are only using a gravity-fed drain line, it’s important that our feed line and drain are completely vertical without any angle in them.

Getting them in the right position was easy enough and we lightly snugged the bolts back down, leaving enough wiggle room to reposition them in the car later if necessary.

With the hot side bolted up and the BMR crossmember attached we were beginning to get a clear picture of whether or not everything would clear.

With the turbo bolted in place, we continued by attaching the downpipe to ensure proper fitment. We also bolted the BMR tubular crossmember to the motor to make sure the downpipe would clear everything. Once we were happy that everything was looking good, it was time to give our turbo a blood source.

Feeding Time

Before we were ready to stab the engine back in the car, and continue with our install, we had to make sure the turbo was fed fresh oil at all times. This involved drilling and tapping a pre-existing oil adapter on the oil filter mount. We also need to drill and weld in a turbo drain back so that the oil fed to the turbo had a way to get back to the oil pan.

To keep our turbo fed, we drilled and tapped the pre-existing oil filter adapter to allow us to us a -4 AN feed line. Huron provides the line and all of the necessary fittings for this process.

The feed line is a straight-forward process. We simply drilled the pre-existing fitting and tapped it to accept a -4 AN fitting. The pan on the other hand was a more involved procedure. While we decided to weld our -10 AN fitting to the oil pan for the turbo drain, this isn’t absolutely necessary.

Many simply drill and tap the pan on the passenger side directly above the drain plug. In this area, the pan provides enough material for the tap to cut enough threads to adequately secure the drain. We decided to weld ours simply because we already had the engine out and accessible, providing us with a less leak-prone solution.

With the location for the drain marked on our pan, we began the process of drilling it and tapping it for use with the provided -10 AN turbo drain. You want to be sure to pick a location well above the oil level as to not back feed the turbo. This can cause oil to push through the seals in the turbo and cause it to smoke.

While this part of the install can arguably be the most daunting for the average wrench turner, if you take your time and go slowly, it shouldn’t be a problem. We even know a few people that have drilled the pan with it still on the vehicle, though we wouldn’t recommend it. If you’re switching out the crossmember like we are, there is no reason not to drop the pan and make sure no shavings get pushed into your oil pan.

Once we had the fitting in, it was ground down even with the inside of the pan and Tig welded in place.

To Be Continued 

Though this isn’t the end of our Huron Speed turbo kit install, you will have to wait for the conclusion in part two in the Corn Star saga next week.

In the next installment, we’ll get the SPEC clutch installed on the new motor and re-couple it to the T56, we’ll get the motor back in the car, and finish showing you how we got our new turbo system up and running in our fourth-gen Camaro. So stay tuned.

About the author

Chase Christensen

Chase Christensen hails from Salt Lake City, and grew up around high-performance GM vehicles. He took possession of his very first F-body— an ’86 Trans Am— at the age of 13 and has been wrenching ever since.
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