Building the Tom Henry RS
Part One: Easy Stuff First

It's late March, 2007.

It's been over a year since the fifth-generation Camaro Concept vehicle introduction and the toast of this year's Detroit Auto Show was the 2010 Camaro Convertible Concept. These cars' production versions arriving at dealers is still 2-3 years off, so even we hardcores at The Camaro Homepage are wondering if the buzz in the industry and the press is going to drop-off as we get into the middle of a  two-year wait for the Coupe.

A few Industry observers and and automotive media are beginning to sound like devil's advocates. Product Editor, Rick Kranz, wrote in Automotive News last October 9th, "(Camaros) are sharp-looking cars. But does that mean they are immune to the impact of fluctuating gasoline prices, especially the thirsty V8 models?

"Will the Federal Reserve cap (interest) rate hikes, or will rates continue upward? Each bump in the rate can translate into a higher monthly car payment. There are lots of Sam Malone's out there--remember the bar owner from "Cheers", who loved his Vette but sometimes barely had enough quarters in his pocket to buy a burger? Lots of Camaro enthusiasts fit that profile.

"The challenge: create a continual buzz for the Camaro beyond displaying concepts on the auto show circuit. Passing out posters and brochures until the cars arrive won't be enough, let alone directing potential buyers to dedicated Web sites."

Ouch! Kranz! You're killin' us, bud.

The V6 version of the 2010 Camaro is the product which will sell the most and needs to be done right. Image: GM Communications

Rick Jensen, Editor of GM High-Tech Performance, said in his November '06 issue, "While knuckledraggers traded the Fourth Gen's low seating position, firm ride and limited legroom for outstanding performance, non-enthusiasts avoided the '93-'02 F-bodies. And rightfully so: (mainstream customers) are not going to give a damn about the latest LSx underneath the V-8 Camaro's hood--they're looking for an attractive, V-6-powered sports coupe that's fun to drive and easy to live with. Give (that) to them and (GM will) sell a ton of those base models."

"Autoextremist", a web site read by industry insiders and hardcore enthusiasts, posts what it says is the "unvarnished truth". In mid-May of '06, Publisher, Peter DeLorenzo said in his issue #354 about the coming 2010, "The make-or-break business case for the new Camaro won't be the 400HP V-8, six-speed version, because GM can do that car in its sleep and make it great. The real issue is the V-6 version, a car that must be worthy of the Camaro nameplate, first of all, and be premium in every respect while delivering an outstanding performance/value equation vis-a-vis the competition. This is the car that GM must get right if the Camaro is going to be a success in the market."

Expectedly, we're not as doubting as Mr. Kranz, but we agree with one of his implications which is shared (but, stated more emphatically) by Mr. Jensen and Mr. DeLorenzo. Just in case you still aren't heads-up on the sitch, here's our spin: Chevrolet needs to back-up the promises made by the fifth-generation Camaro concepts with solid product and the key part of that is going to be not the high-performance, V-8 powered SS--but the base-level, V-6, Sports Coupe.

So what does the 2010 Sport Coupe need to be? Well...Rick Jensen's mandates "...fun to drive and easy to live with..." are good for starters. Peter DeLorenzo's point that its execution must, "...be premium in every respect while delivering an outstanding performance/value equation vis-a-vis the competition." drives the point home. Not only that, the car must have quality surpassing that of any Camaro of the past. It's interior must be comfortable, practical and refined but not overladen with stupid technology for the sake of technology. As for performance: the new V-6 needs to be more powerful and capable of at least equal or better fuel economy.

The Holden Commodore uses GM's 3.6L Global V6 engine. It's available in three flavors, 235-hp, 240-hp and 260-hp. Image: GM Holden Ltd.

An '10 Sports Coupe will likely have GM's 3.6-liter "Global" V-6 Engine under the hood. GM will be remiss if they don't use what the Australians at Holden who developed the engine, call the "190" version, which is the high-output variant with 260-hp at 6500 RPM. Since Camaro's 1967 debut, a six-cylinder engine ('67-'79, I-6; '80-'02, V6) has been either standard or, for four years in the early-’80s when General Motors made the awful mistake of an inline-four for a base engine, a midlevel option. For the Camaro's first ten years , V8s outsold sixes by a considerable margin, but in 1977, with our country in the throes of an agonizing gasoline shortage, V6s sold on par with V8s. From then on, until production temporarily ceased after model year 2002 (MY02), six-cylinder market penetration averaged 50.4% and, for MY93-02, V6es sold 62.4%. Bottom line, there’s a ton of sixes out there, especially in fourth generation Camaros.

One reason V6es sold well towards the end of the 4th Gen era was the 200-hp, 3.8-liter engine introduced in halfway through 1995. Called “3800 Series 2”, it’s the unblown version of the supercharged motor used up to MY05 in the Impala and Monte Carlo SSes. By mid-'90s standards, for buyers looking for a sporty coupe but for whom performance was a consideration but not the most important one, this offered a more affordable alternative to the V8-powered Z28s and SSes.

Back in late-'05 and early-'06, when gas prices went bonkers, visitors to our parent company, Tom Henry Racing (THR) were asking about V6es. Aftermarket companies tell us demand for V6 performance products has grown indicating interest in hot-rodding those cars. There are even web sites devoted to V6 Camaros at www.forum.camarov6.com and http://www.3800pro.com/forum/.

Here's our project car. It'll take us about year but it will end-up as the Tom Henry RS and will use a few general ideas we hope to see in the '10 base Camaro. Image: CHpg staff.

We decided to jump on the bandwagon, acquire a 2001 Camaro V6, 5-speed and try some mods. We're calling the car a "Tom Henry RS", in honor of the famed V8-powered Tom Henry SS "tuner" Camaros of  '01 and '02. Since we're starting this project in the dead of winter '06 / '07, we've farmed the job out to THR's, West Coast development "laboratory" near Los Angeles.

Our goal is more exciting street performance, not building a drag race car. In addition this project is a little bit of "what-if". We want to modify the engine to about the 250-hp level to simulate the performance of which a 2010 base Camaro should be capable. Additionally, to get an idea of how we'd like a 2010 Camaro V6 sports model to handle, we're going to modify the suspension of this 4th Gen V6 and see what happens.

Our engine mods will pass a state exhaust emissions test and won't degrade low-end torque. Our suspension enhancements will improve handling but will still have the car riding reasonably nice enough for commuting over the rough surfaces of freeway/expressway systems in cities with the worst roads in the country, such as Philadelphia, Detroit and Los Angeles.

Before we start working, let's talk about service data because information is power–power over your Camaro if you work on it yourself. Unless you’re an experienced Camaro technician, you need a factory service manual (FSM) from Helm, Inc., publisher of GM all service data. Our 2001 Chevrolet Camaro Service Manual was indispensable in preparing this series.

What about parts? Most of the GM and aftermarket parts we're going to use during the next 12-months or so can be sourced from Tom Henry Racing, the performance parts sales division of Tom Henry Chevrolet. In the case of the few parts which can't be purchased from THR, we'll tell you where to get them.

The staff of Tom Henry Racing's parts operations, headed by Parts Manager, Stan Lorence, stands ready to assist any Camaro Homepage visitor in finding Camaro parts. Additionally, the people at Tom Henry Racing's Service Department, headed by Manager, Cory Holland, can install many of the modifications discussed in this series.

First Mods

After wheels and tires, perhaps the most popular aftermarket modification performed by Camaro fans is the addition of an aftermarket exhaust system. Flowmaster’s American Thunder system for ‘98-’02 Camaros with 3800 V6es (PN 17358) has larger, 2.5-in. aluminized pipe, an 80-series muffler and stainless steel tips, all typical Flowmaster features. It's unique part is a resonator, cleverly-packaged beneath the passenger-side rear seat. Flowmaster R&D chief, Kevin McClelland, says that certain frequencies of V6 noise are difficult to attenuate and this resonator facilitates that. One Saturday, we got the car up on jack stands and installed the American Thunder system using hand tools. We demanded increased performance, improved sound and better appearance. Flowmaster’s cat-back got us all three.

The full power curve shows that gains begin around 4000 rpm and go all the way to the rev limiter, which in this test was 5700 rpm. The second graph, a close-up of the peak power sections of the curve shows an 11.1-hp SAE increase at the rear wheels. Clearly the stock exhaust on these cars is quite restrictive. Images: CHpg staff.

At Tom Henry Racing we put lubricants from the Red Line Synthetic Oil Corporation in a lot of customers' modified, street high-performance Chevrolets. From the Cobalt SS Supercharged to the Impala SS and from the Camaro to the Corvette Z06, just about any hot rod Chevy can benefit from Red Line's premium synthetic products.

Dyno runs, quarter mile testing and aggresive street driving made colder spark plugs desirable, so we installed Denso IT-20 Iridium Power plugs which are sold by THR. The IT-20 is one heat range colder and its iridium tip is more durable but has less resistance than the stock platinum, AC Delco plugs that were in the engine when we started. The Densos' small, 0.4-mm center electrode and tapered ground electrode give the spark maximum exposure to the incoming, air-fuel charge. We should add that even General Motors must see merit in the Denso spark plug design because after about 2004, some Chevrolets have Densos from the factory.

The GW rear arms each have a rubber bushing and a spherical bearing. Rubber goes in the body pickup point and the bearing bolts to the axle. Image: CHpg staff. Here are most of the pieces we used in the rear. The Bilsteins have heavy-duty valving which improve the handling of any 4th-gen Camaro. Image: CHpg staff. Once the control arms are in place, set the isolator atop the spring, then raise the spring, such that its top goes into the spring seat, then push it onto the rear axle.  Image: CHpg staff. Between the much stiffer lower control arms and the aggressively-valved Bilstein shocks, the rear suspension is going to deflect less and better damped. Access the shocks’ top nuts through the interior. On the bulkhead behind the rear seat are two carpeted access flaps. Fold them back, pull out the sponge insulators and there are the nuts. Once the shocks’ lower bolts are tight, you can take the rear end off the jacks. Image: CHpg staff.

We bolted-on Quiet Ride tubular steel, rear control arms (PN TBC14) which fit ‘82-’02 Camaros and offer an increase in rigidity over the stamped-steel stockers. GW arms use a Moog, rubber bushing in the body end and a spherical bearing on the axle end. These arms can be installed in an hour.

Next, we ordered Eibach Springs and Bilstein high-pressure, gas shocks. The rear Eibachs are a stiffer, progressive rate design, dual-rated at 75 and 135 pounds-per-inch. They lower the car about 1.5-in. and are part of the “Pro Kit” (PN 3870.240) for V6 Camaros. The Bilsteins' (PN B46-1914) stiffer damping is an excellent match for our spring rates and ride height. We added a 19-mm, Z28 rear stabilizer bar. We used the production Camaro mounts and end links but installed Global West polyurethane link bushings (PN 19-428).

Side-by-side are the stock and Global West trackbars. The GW upgrade offers an increase in rigidity and is of value to any modified Camaro, be it an autocrosser or a drag racer. Image: CHpg staff. One neat feature of the Global West Trackbar is that it's adjustable so the chassis can be centered on the rear suspension no matter what the ride height. You loosen the nuts then turn the hex section as necessary to center the chassis. Image: CHpg staff. The rear stabilizer and Global West Trackbar are in place, so the rear is done, except for centering.  Image: CHpg staff.

We finished the rear with a Global West, Quiet Ride Trackbar (PN PHC3), an improvement over the flimsy, rubber-bushed stocker. Made of tubular steel with a poly bushing in one end and a bearing in the other, it’s a stiffer lateral link so suspension deflection during cornering is reduced. It’s adjustable for length, so the body can be centered, regardless of ride height. All these rear suspension parts came from Tom Henry Racing.

When reinstalling control arms with rubber bushings, have the arms at ride height while tightening the bolts. Bushings don't rotate, they twist. Tighten the bolts with the suspension hanging and, when it returns to ride height; the bushings are constantly twisted. When the suspension nears full compression, they’ll really be twisted, which can damage the bushings. Also, with the rear bushing in the front lower arm of a 4th-gen car, if you tighten the bolt with the suspension hanging, the bushing may turn off-axis in the crossmember. If that happens, setting alignment is difficult, the misaligned bushing can cause increased harshness and the cross member and bushing may be damaged.

We disassembled the front strut assemblies, scrapped the stock springs and shocks then installed the stock spring seats, 377 lb/in. front springs out of the Eibach Pro Kit and the stock upper spring mounts onto two Bilstein shocks (PN B46-1913).

The Tom Henry service department uses a high-dollar, J-tool jig in a hydraulic press to assemble 4th-gen front struts, equipment out-of-reach of most DIYs. You can use ordinary strut compressors if you orient the shock’s lower mounting bar and the upper strut mount in specific positions while tightening the shock absorber nut.

Your “jig” is your garage or shop floor. Each strut mount has two threaded studs and a rubber pin near its front edge. Once the struts are assembled with the springs compressed, the springs’ upper ends seated in the strut mounts and the shock absorber nuts loose, lay the struts with the front edge of each mount flat on the floor. Rotate the left shock so the end of its lower mounting bar is flat on the floor and (looking at the strut top) inclined down to the right (pointed outside the vehicle). Rotate the right shock so the end of its mounting bar is flat on the floor with (looking at the strut top) the crossbar inclined downwards to the left (pointed outside the vehicle). Now, tighten the shock nut and remove the spring compressors and you’re ready to stick your struts back on the car.

Just One More Thing

The stock rocker ratio is 1.6:1. Higher ratio rocker arms offer more valve lift and duration for a given lobe lift. The stock cam for an unblown 3800 has .256-in. lobe lift. With that cam, valve lift with stock rockers is .410" but with the SLP 1.8s, it's .460". Generally, more valve lift means more air into the engine and more power out.

Another difference between the SLP 1.8s and the stock rockers is 0.5-oz. less weight per rocker. In theory, a lighter rocker taking mass out of the valvetrain should improve the engine's ability to "RPM", however, right now, the engine in the Tom Henry RS peaks at 5000 rpm and we've still got the stock rev. limiter in the ECM calibration so even if the SLPs do offer an advantage at high rpm, at this point; we can't use it.

With the SLP rockers installed, we went back to the chassis dyno at Westech. In a series of six passes on their Superflow 840, three with stock rockers and three with the SLP 1.8s, the results were mixed. At 4900-5000 rpm we saw just a hair less than a 6-hp average increase, but below 3400 rpm, we saw as much as a 3.5-hp loss. This increase up high but a loss down low is typical of adding both lift and duration. Nevertheless, from 3700-up, there's a consistent increase so, in the real world, on the street or the drag strip, you might see a slight decrease in e.t.

This particular 1.8 rocker is not available direct from SLP but is sold by LM Performance. The manufacturer of these rockers was Yella Terra, an Australian company which makes performance products for 3800 Series II V6es (down-under, they call it the "Ecotec 3800") and private-labeled them for SLP.

Once LMPerformance sells out of the SLP 1.8s, V6 Camaro DIYs will be able to get Yella Terra's new, "second-design" 3.8 rocker which is available in both 1.8:1 and 1.7:1 ratios. Later in this project we'll acquire a set of the Yella Terra 1.8s and test them but, for now, the SLPs work quite well.

We'll be back in about two months with the second installment of the Tom Henry RS built-up in which we'll really roll-up our sleeves and turn some wrenches. We'll start with cylinder head modifications.

Click here to read Tom Henry RS Project Part 2

Sources:
All the GM parts and most of the aftermarket parts discussed in this article are available from Tom Henry Racing at www.tomhenryracing.com. The products not available from THR are listed below: