Tech: Installing Hooker Headers On A Buick Grand National

buickgn-leadart
One of the first modifications performed on a performance car of any type is a low restriction exhaust, coupled with a high-flowing set of headers. No matter what you drive, headers are a relatively cost-effective way to add power, while laying the ground work for more engine modifications down the road.

Hooker Headers

1986-87 Buick Turbo Regal, GN, GNX, and T-Type Header Kit (PN 1115)Header Kit Includes:

  • Headers
  • Cross-Over Pipe
  • Turbo Exhaust Inlet Tube
  • Ceramic Coating

Hooker Headers is one of the most-trusted names in the game, and one of the very few manufacturers that market high-flowing headers for the 1986-87 Buick Grand National, T-Type, and GNX.

While it’s true that the factory exhaust manifolds on the ’86-87 Buick Turbo V6 (LC2) are incredibly well-engineered pieces of craftsmanship from GM, and that they can reportedly support around 600 horsepower or more, the Hooker Headers can help take the Turbo Buick enthusiast to the next level.

To get some behind-the-scenes insight, we contacted Hooker’s very own, Blane Burnett, to provide us with any additional help we might need for the install. The first thing he mentioned to us even before they arrived was that, “We understand the huge cult following the Buick Grand National has, and we would like to support that community as much as we can.”

Our Buick Test Mule/Establishing a Baseline

We’ve had an ’87 Grand National at our disposal for over four years now, and other than some casual tinkering or the few TLC items it required upon our purchase, it still remains largely stock. So when we had the opportunity to upgrade the factory exhaust manifolds on our GN, we took it. We previously brought you the teaser story showcasing Hooker’s Turbo Buick headers, but now we have the full installation here.

To give you an idea what we’re working with, the only modifications performed on our Buick is a Racetronix/Walbro fuel pump and hotwire harness, a K&N/Kirban cold air intake, and a Hooker catback exhaust. It’s otherwise stock, right down to the factory turbo, boost level setting (12 psi), and chip. It’s hard to find an example like this these days, as most of these cars have been either modified to extreme levels or are restored to concours show-quality.

We understand the huge cult following the Buick Grand National has, and we would like to support that community as much as we can. -Blane Burnett

This Grand National is an honest to goodness survivor, and although it’s not perfect, we’re going to reverse it’s aging process by not only refreshing its overall look, but to bring its performance to modern-day levels, and then some. Part of that includes replacing the old manifolds, and despite the fact that the OEM units flow really well, the driver’s side has a tendency to crack over time. This has to do with the constant range of temps from cool to hot with the turbo, and the torque that these engines put out.

Our Buick seemed to have a leaking driver’s side manifold, and although we could have just welded it back together like so many Turbo Buick guys do, we decided to install the Hooker Headers. Not only are they high-flowing and good looking pieces, but they come ceramic coated – a feature that would benefit any turbocharged or supercharged application like our Buick.

Prior to installation we took a baseline run on the dyno to see where we were at in terms of power. It turns out, the 67,000 mile Buick was putting down on our Dynojet a peak output of 200.50 horsepower and 246.10 lb-ft of torque to the rear wheels on 91 octane.

That might not sound like enough these days with 662 [flywheel] horsepower GT 500s running around, but you have to remember these things were rated at 245 horsepower at the crank for the 1987 model year. So 200 horsepower to the tires roughly translates to 253 crank horsepower, and given its age, mileage, and apparent exhaust leak, we’re OK with that as a good baseline. Now enough talk, let’s get started!

Header Installation

After a lengthy cool down period (turbo cars do run quite hot, after all) we lifted our ’87 GN up in the air and cued the music.

Installing these headers probably wasn’t the easiest thing we’ve ever done, but it wasn’t near as bad as we thought it would be. Hooker makes this kit as installation-friendly as possible, and although we have a lift and pretty much every tool fathomable in our Power Automedia garage, an experienced mechanic could install these at home with simple hand tools, a jack and jackstands, keeping in mind that exhaust work will need to be done.

Once on the lift and up in the air, we immediately noticed that the Midwest precipitation hasn’t been too kind to our Buick over the last twenty-six years, despite its 67,000 mile odometer reading. We plan on a restoration at some point with this car anyway, and most of the rust was on everything but the actual underbody, thanks to a dealer-installed undercoat back in the day. 

For a system that has literally been around for decades, the Hooker headers offer a lot of style and craftsmanship to the potential Turbo Buick builder.

We also realized almost immediately that swapping out the headers is much easier when you remove the two front wheels. It gains you much more access to all of the header bolts and other components that need to be removed during the process.

There were some other things that needed removal as well; the accessory bracket on the driver’s side, and obvious components like the spark plugs, wires, and the down pipe on the passenger side – which entailed removing the heat shield from the turbo and our aftermarket breather in the passenger side valve cover.

turboheaders

We lined up this comparison photo so you can see the difference in design from the driver’s side OEM manifold, to the header from Hooker.

We also had to remove the crossover pipe from underneath the Buick in order to swap out the manifolds. This piece is replaced by the ceramic coated pipe from Hooker that not only appears to flow better than the OEM pipe, but helps keep operating temps cool, and dresses up the undercarriage at the same time.

You’ll have to either rely on an aftermarket downpipe or you will have to modify the OEM piece to work with the headers.

The downpipe was removed from the turbo with only three bolts (hence the term, 3-bolt turbo), and we pulled it out from underneath the car. The OEM downpipe must be modified to fit the new configuration, and since the headers are slightly larger than the factory manifolds, expect some customization as you would with most header installs. Burnett even pointed this out to us when we discussed this on the phone with him, “You’ll have to either rely on an aftermarket downpipe or you will have to modify the OEM piece to work with the headers.”

With a little measuring, cutting, and welding, we were back in business. We bolted everything back together in the reverse order in which we removed them, and we had our car back on the ground by the end of the afternoon.

Removing the downpipe and passenger side manifold required the removal of the turbo heat shield to grant us access to the three bolts retaining the downpipe. We applied RTV sealant to the header prior to installation, and had to do a bit of 'cut and paste' to the OEM downpipe to make it work with our larger diameter headers.

Conclusion

After everything was buttoned up, we took our ’80s musclecar for a spin around the block. While we didn’t experience any squeaks or rattles, we did however, experience a bit of turbo lag on the low end. That’s because these headers are designed with 2-inch primaries, which are more ideal for a modified V6 that sees occasional dragstrip duty.

After the installation, and reconnecting parts that haven’t been disconnected in decades, we did run across a few minor issues, and they needed to be addressed to get the car running properly. We turned to our friends over on the TurboBuick.com forums to see if anybody was willing to lend us a hand over the weekend.

Luckily, our buddy, Neal S. (aka, 750H.P V6), was free that Sunday and was interested in taking a look. Neal’s been in the Turbo Buick hobby since the late-80s, has built a few very quick Regals in his time, and is a well-respected member on the Buick forums.

With the Buick strapped back down to the rollers, we were anxious to see the results…

As it turned out, our factory O2 sensor had been on its way out and decided that it was time to retire. Neal also took the time to test our ignition system, (spark plug wires, coil, distributor) with some high-tech hardware, and everything checked out OK. So after we installed a fresh set of AC Delco R44TS spark plugs (gapped at .035-inch) and a brand new OEM replacement O2 sensor, we were back in top form. Anyone who has installed performance parts has likely run into similar issues, so we were glad to figure ours out relatively quick.

Once back at the shop with some “break in miles” under the car’s belt, we strapped her back to the Dynojet dyno to see the fruits of our labor. After a few pulls, we were rewarded with 206.25 RWHP and 256.00 lb-ft of torque, good for an additional 5.75 horsepower and 9.90 lb-ft of torque to the rear tires. We saw an increase in both power and torque throughout the powerband. It might not sound like a huge difference to some of you, but considering the stock mechanicals and no tuning on our part, we were very pleased with the results.

Here you can see the before and after results of the Hooker headers to the OEM manifolds. We managed to get 206.25 RWHP and 256.00 lb-ft of torque, while seeing a rise in horsepower after 2,000 rpm.

Also keep in mind that this car isn’t a heavily modified race car, obviously. Although the headers are designed for a modified car, they will help build a foundation for much more significant modifications in the future – such as ported cylinder headers or a stroker motor. So keep this in mind if you’re interested in upgrading your OEM manifolds on your Buick to these headers from Hooker.

Not only that, but these are a direct bolt-on replacement, so if you ever want to return your soon-to-be classic Turbo Buick to factory specifications to ensure it’s collectibility, you can do so at any time. It really is the best of both worlds.

Happy spooling.

About the author

Rick Seitz

Being into cars at a very early age, Rick has always preferred GM performance cars, and today's LS series engines just sealed the deal. When he's not busy running errands around town in his CTS-V, you can find him in the garage wrenching on his WS6 Trans Am, or at the local cruise spots in his Grand National.
Read My Articles

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