Building the Tom Henry RS

Part 5, Page 3

Road Test

With the Eibach/Global West spring combo, QA1 Shocks, upgraded Track Bar and SFCs in place, it was time to road test and we started with some miles on city streets and urban/suburban freeways. First thing we noticed? The shock settings of 4-clicks, compression, 6-clicks, rebound proved a good compromise between control and comfort for around town driving.

Road test fun! After our suspension upgrade we ran the car over California's famed Angeles Forest Highway. The car's lateral grip is substantial. Its behavior at the limit is predictable and easy to control. Could we lower the car a little more and increase roll stiffness a bit? Perhaps, but this car is street-driven every day on California's crumbling, urban and suburban roads. We think a little more suspension travel is a good thing for that usage. Image: Gary Peterson.

Next, we headed for some twisty, back-country roads to really beat on this car. We didn't drive very far before confirming that at the rear, the constant-rate springs and double-adjustable shocks provided more consistent suspension action and excellent damping. Because the upgraded track bar was now height-adjustable, we could adjust it a little lower than stock, providing even better bite off corners or in drag-strip-style, standing starts.

Expectedly, the Tom Henry RS is just a blast to drive really hard. The car has a hell of a lot of lateral grip. Plenty of roll stiffness, our front alignment settings and the 265/40ZR17 Goodyear F1 Supercars (set at 30-psi cold) on 17x9.5-in. Fikse Profil 5S wheels we installed for Part Four make this car stick. The QA1s, set at front, 6C7R and, rear, 5C7R, gave us outstanding wheel control in aggressive driving, but might be a bit harsh for daily-driver use. For race track use on smoother surfaces, you'd probably want even more damping and that's available from the QA1s by simply turning their adjuster knobs.

The THRS is generally neutral steering, but with little bit of drop-throttle oversteer which can be used to control yaw angle. Off the turns, as you roll on the throttle, the car now really hooks. There's little doubt, the Global West TrackLink and Track Bar systems enable the 4G F-car rear suspension get the power down in a way that the stock suspension could never achieve. That's probably why many road racers and autocrossers who run fourth gens, use Global West Suspension parts.

We also gave our rebuilt brakes and Baer pads a good workout. The new parts performed well. Image: CHpg Staff.

Executive summary: our revised Tom Henry RS suspension and brakes are freakin' awesome.

We Be Programmers

In Part 3 of the Tom Henry RS, we had aftermarket calibration engineer, Ron Zimmer at Z-Industries reprogram our Camaro's PCM and Ron’s son, Drew, worked with us in Part 4. We have greatly appreciated the Zimmers' help with the THRS, both this Internet version and the shorter print version of this series which ran in Camaro Performers but, for this fifth part of the series, because we’re up for the challenge of learning something new; we're moving our engine controls calibration activities in-house. From Summit Racing Equipment, we ordered a copy of HPTuners “VCM Suite”, which includes “VCM Editor,” a software application for creating aftermarket calibrations for 1997 or later GM vehicles. We picked "HPT" because the guys at Z-Industries often used it when working on our car and it’s the leading software app for tuning. This software runs on any PC using Windows XP or Windows 7 so I loaded it onto my trusty Acer 5670 laptop.

With the deadlines we have at the Camaro Homepage, our learning curve for VCM Suite was pretty steep. There are a several avenues by which one can learn to calibrate. Find an experienced professional tuner who give you an “internship"–great idea but a rare opportunity. Search the Internet and hang out on the numerous forums devoted to tuning–good idea in theory, but in practice it’s difficult to determine if what you’re reading was posted by one of the many “faux experts” who inhabit forums or by one of occasional, true Internet tuning authorities who dispenses free information. You can guess your way through using “trial-and-error” methods–probably a bad idea. You can read some of the books on tuning late model cars or, you can take classes on tuning. I decided on a mix of the last two.

First, I studied Greg Banish’s books, Designing and Tuning High-Performance Fuel Injection Systems and Engine Management: Advanced Tuning along with Dyno Testing and Tuning by Harold Bettes and Bill Hancock, all three published by CarTech Books. Then, I went to school–I ordered a home-study class offered by the “Tuning School” of Odessa, Florida in its “Tuning the Right Way” series: A Beginner’s Guide to Tuning GM Vehicles with HP Tuners Software.

I found the Tuning School's curriculum indispensable in our situation: needing to learn tuning basics in a short amount of time. The class covers proven methods for tuning a 1997 or later GM vehicle’s PCM with HP Tuners. While the most of the material is oriented towards students working with the Gen 3 or 4 V8s in late-‘90s or later cars and light trucks, most of key techniques you'll learn in the Beginner's class also apply to writing calibrations for the 3800 Series 2 V6 in ’98-’02 Camaros.

Newbie tuner at work. In our first attempts at calibration work, we had the Tuning School's textbook perched on the steering wheel and the Acer on the passenger seat. Image: CHpg Staff.

A week's worth of nighttime reading had me through the Tuning School’s beginner’s text book. After that, I was out in the shop, sitting in the car with my laptop on the passenger seat and the book rested on the steering wheel, going over some of the procedures in the text and learning VCM Scanner and, finally, how to download the ECM's existing calibration to my laptop. A week later, after some more study and several hours working with VCM Editor, I was ready to reflash the ECM in the THRS with my first calibration. There's no way we could have gone from HPT newbies to writing calibrations in two weeks without the Tuning School’s home study courses. No doubt, we still have more to learn, but we were on the right track.

At first, we lacked a wideband oxygen sensor–a requirement for any cal work involving power enrichment (PE). While we shopped for one of those, we started using what we learned from the Tuning School to improve our 3800's part-throttledrivability by getting its part-throttle, long-term fuel trim values closer to zero.

When an engine control system operates in closed loop, it's always “trimming” the fuel delivery commanded by the look-up tables in the calibration by the amount necessary to have the air:fuel ratio (AFR) as close to “stoichiometric” combustion as possible. A stoichiometric AFR results in the least exhaust emissions and good fuel economy. With "straight" gasoline, depending on its blend, stoichiometric combustion occurs when the AFR is somewhere between 14.5 and 14.7:1. If it's the oxygenated gasoline required in many parts of the country, it can have up to 10% ethanol blended with the gas but usually the ethanol component is 6-8%. We tested a sample of the Valero Premium gas we usually put in the Tom Henry RS and it was about 7% ethanol. We've read posts on various Internet forums by folks who've tested their fuel and 7% is common. Mix 7% ethanol (stoichiometric at 9:1) with gasoline (stoichiometric at 14.64) and you get a 14.25:1 stoichiometric air: fuel ratio.

In the calibration we were using, the value for stoichiometric AFR was 14.57:1 and had never been changed. That number is the stiochiometric AFR for a special type of gasoline, known as "indolene clear," which car companies use when developing engine controls calibrations or doing fuel economy testing. Since the Tom Henry RS always runs on oxygenated gas, we reset the base air:fuel ratio for the system to 14.25:1.

Why did we do this? Well–the engine controls use the "stoich AFR" value in their calibration as the "standard" to which to trim fuel delivery. If the value set in the calibration is not the same as the actual stoichiometric air:fuel ratio of the gasoline being used, some of the ECM's fuel trimming ability will always go trimming for the difference between the stoich value in the cal and the actual stoichiometric AFR of the gasoline. That can be half-a-point in air:fuel, or more, that the ECM will always correct before it can trim fuel delivery for any other reason.

If the AFR is exactly stoichiometric, the long-term fuel trim (LTFT) values are zero. If the AFR is more lean than that, the LTFTs will be positive, ie: the system adds fuel to the base fuel schedule. If the AFR is rich, LTFT numbers will be negative, ie: the system subtracts fuel.

Our V6 is modified to the point that its part throttle fuel needs were quite a bit different than stock. Consequently, the system was trimming the stock calibration’s fuel delivery schedule quite a bit to maintain stoichiometric AFR. As the ECM moves between cells of the cal’s “main VE" table, if long term fuel trim (LTFT) has to move more than 5-7 counts from one cell to the next,  it may have to skew the fuel trim quite a bit. That is: if most cells require -3 to +3 LTFT, that spread is more advantageous than if some cells require -8 and other, adjacent cells need +10. The more often the system has to move through a wide range of less-then-ideal trim values to get to the proper figure, the more drivability and response can be compromised.

The Tuning School's book, MAF and VE Tuning taught us how to use VCM Editor and VCM Scanner to evaluate the existing part throttle calibration then alter that to produce a new part throttle cal which decreased the range through which long-term fuel trim skewed as the ECM moved from cell to cell of the calibration's main VE table. The result was improved drivability. Since we were working with AFRs at or near stoichiometric, where a narrow-band sensor has highest resolution, we were able to use data from the engine's stock O2 sensors.

The Tuning School's book, MAF and VE Tuning taught us how to use VCM Editor and VCM Scanner to evaluate the existing part throttle calibration then alter that to produce a new part throttle cal which decreased the range through which long-term fuel trim skewed as the ECM moved from cell to cell of the calibration's main VE table. The result was improved drivability.

This screen shot shows the main, high-octane spark table after we changed the spark timing at idle to improve idle smoothness. Image: CHpg Staff.

Another drivability issue we learned how to use HPTuners to solve was idle stability and throttle response. A couple of years ago, when the initial calibration work was done for Part 3, a problem we could not fix was idle speed surge. 

We knew from data taken using our Bosch Mastertech scan tester and, of late, HPTuners VCM Scanner, that idle spark timing was fluctuating between 3° and 6° BTDC. We believe this variation was a function of our camshaft profile. This variation in idle spark timing caused idle speed to surge. Plus, the retarded spark was making the engine lazy just off idle.

When we looked at the main spark tables with VCM Editor, in the idle cells, the timing was a lot more than what we were seeing when we took road test data with the Mastertech or VCM Scanner. We suspected there were other look-up tables which modify the base timing table at idle but access to them is not supported by VCM Editor. An email exchange with HPTuners Tech Support confirmed that. They, also, told us that a future version of the app will include support for those tables.

While there are some ways to access those idle spark tables if you have your calibration in a binary (.bin) file rather than in the HPTuners format and you acquire some additional tuning software which can manipulate .bin files, it was easier for us stick with HPT and “fool” the ECM into advancing the spark at idle by adding 10° to the main spark tables in the cells where the engine is idling. Doing that did not eliminate the hunting but it reduced it significantly and vastly improved throttle response just off idle. The engine's throttle response went from "reasonable" to downright snappy.

Back on the Dyno

At this point, with a wideband not yet in our hands, we wanted to do some WOT calibrating. We had a chassis dyno session scheduled at Westech to test our recent exhaust upgrades, so we decided to use the wide-band O2S which is part of Westech's Superflow Autodyn dynamometer installation.

At Westech, dynamometer technician, Ernie Mena, using the Superflow Autodyn's control module, sets-up for a chassis dyno run. Image: CHpg Staff.

First thing we did was add enough Rockett Brand 100-oct. unleaded racing gasoline to bring the octane of the fuel in the tank up to about 95.5. Whenever we're going to do any testing where we change the fuel or spark spark calibrations, we start with about 95-oct, to keep the engine out of detonation. Once we have the fuel and spark to where we think we like it, we'll validate with 91-oct and see how much, if any, knock retard results. Next, we ran three passes to validate the larger S-pipe and new cat. Finally, we worked on the engine's WOT performance because, previously, we had trouble with air:fuel ratio (AFR) being too rich.

With HPT's VCM Editor, looking at the "Power Enrich vs. ECT" table, we could see the existing cal was commanding as low as 11.2:1 AFR during PE. While that's quite rich for gasoline–rich even when 7% ethanol is blended in the gas–it's common with stock calibrations. We changed that to 12.15:1, a better choice for max power on 7% ethanol, then had Westech’s Ernie Mena run another pass. The rich condition was improved, but still not right. The problem seemed time-related, ie: AFR was ok for several seconds into a dyno run, then it would still go rich and became inconsistent at high RPM.

We discovered part of the problem was the "Power Enrich Fuel Adder RPM vs. Time" table. Once the system is in power enrichment for a certain length of time, this table adds additional fuel for cat overtemp protection or as a detonation hedge. We decided to disable this function below 20-seconds (about the length of a fourth-gear chassis dyno run) then reduce its effects by 50% during longer periods of WOT operation. With that cal written to the ECM, we had Ernie Mena make three more runs on Westech’s AutoDyn. The AFR at WOT was now in the 12.1-12.4 range which was better, but still not consistent enough.

 

In spite of the AFR weirdness in PE, in that final chassis dyno session for Part 5, we made our best SAE-corrected, rear-wheel, peak power and torque numbers yet: 228.3-hp@5660-rpm and 221.0 lbs/ft@4630-rpm. Using a .82 correction factor, that works out to about 278-hp and 270 lbs/ft SAE at the flywheel. The dyno data, also, explains why the Tom Henry RS is such fun to drive. The torque curve is flat as the proverbial pancake–between 200 and 225 lbs/ft rear wheel torque from 1800-5900 rpm.

Dyno results from the best run of the bunch. We're not sure what caused the little dip just past peak power but, in Part Six, of the THRS series will try to find out. Image: CHpg Staff.

On the dyno, using “VCM Scanner”, we learned that at WOT and high rpm, the PCM was commanding very high injector duty cycles. Running the injectors for sustained periods at high duty cycle is not recommended.

When we looked into installing new injectors with higher flow capacity, John Park at RC Engineering, the leading supplier of high-performance electronic fuel injectors in the aftermarket, told us if the sustained duty cycle is 85-100%, the engine may have inconsistent air-fuel ratio because the injectors are difficult to control consistently when they are near full-open. RC Engineering and other experienced tuners suggest "larger" injectors when the sustained duty cycle is greater than 85%. In Part Six of the THRS series, we'll address that issue. We’ll, also, have more on using HPTuners to further tweak our ECM calibration. We'll work on that dip in the torque curve just past peak power.

Did our cal changes effect emissions? Nope. Right after the dyno test, the car passed the California Enhanced Smog Check. This time, for hydrocarbons (HC), carbon monoxide (CO) and carbon dioxide (CO2), the car was actually cleaner than it was three months before, when we ran it through the Smog Check prior to registration renewal. Oxides of Nitrogen (NOx) increased slightly, but were still under the limit. Image: CHpg Staff.

The final engine-related activity for this part of the THRS series was to take the car to Mike Garibay's Quality Auto Service in Pomona, California for an exhaust emissions test. Garibay rolled the car onto his special chassis dyno used for the California Enhanced Smog Check procedure. Once again, the Tom Henry RS passed the Smog Check easily–continuing proof that the right mod package and the right tuning can provide a significant performance increase combined with low exhaust emissions.

One interesting lesson we learned during the time leading up to our emissions test at Quality Auto Service. We had code P0128 set because of the slow warm-up discussed in the section on cooling system mods. We cleared codes with our Bosch Mastertech but, when that happens, all the second generation on-board diagnostics (OBD2) “readiness flags” are wiped out, too. Those flags set in the ECM once it determines various tests of emissions controls, such as EGR function and catalyst  efficiency, which are required by OBD2,  are ready to run. 

State emissions tests which have the test technician connecting his equipment to the car’s diagnostic link connector (DLC) will usually fail the car, regardless of its tailpipe emissions, if readiness flags are not set. Many scan testers, including our Bosch Mastertech and the Actron AutoScanner discussed earlier, can display readiness flags so if you cleared codes shortly before going for a smog check, look at the flags with a scanner before you test to verify they are set.

After codes are cleared, the flags eventually reset during normal driving but it can days hours, days, even weeks for them to do so. You can force the flags to set in a shorter time if you drive the car according to a specific “drive cycle” listed in the Factory Service Manual. Typically, this takes less than an hour. 

We did that–several times, in fact–but found some tests remained incomplete. After thinking about this for a while and re-reading the information about DTC P0128 in the FSM, we decided to take out our 180° thermostat and replace it with the stock 192° unit.

And Voila! One drive cycle and all the flags set. Some of those readiness tests, specifically the EGR function and the catalyst monitoring tests, won’t complete unless the engine coolant temperature (ECT) is higher than 180°F. After the flags were set, we reinstalled the 180° thermostat, took the car for the smog check and passed easily.

Braless No More

This project car is ten years old and will be on the road for a number of years. Because of that, we decided to put paint protection film (PPF) on our Camaro's front end–something we probably should have done much sooner.

 Known to the car hobby as a “clear bra”, polyurethane PPF, was developed by the 3M Company for aerospace applications. In 1990, the Department of Defense made “3M Scotchcal” famous when, during Gulf War I, it discovered the film significantly reduced dust and sand erosion of helicopter rotor blades during take-offs and landings in the desert.

In the early '00s, 3M introduced Scotchcal to the automotive aftermarket but rebranded it as “Scotchgard”, a name more familiar to consumers. This adhesive-backed, polyurethane PPF is 0.8-mil thick and is applied to parts of the car’s exterior which are susceptible to abrasion and pitting from sand, dirt and small stones.

Clear bras usually can’t be installed by DIYs because of the difficulty in working the product. A proper installation takes training, experience and special equipment. 3M has a nationwide network of factory-trained installers. After some research, we found the best clear bra installer near the THRS base of operations, was Transhine Auto Detailing in Whittier, California.

Transhine's owner, Bill DeBever, has been in the auto detailing business since 1981 and has been installing clear bras on cars and trucks since the early ‘00s. He told us that Scotchgard and 3M’s other PPF, Ventureshield, along with competitors from Avery, XPEL Technology and others, have similar price points. DeBever says Scotchgard is the most durable, however, it is, also, the most difficult to install. DeBever recommended Scotchcal for cars like ours which see high annual mileage.

When we arrived at Transhine, Bill gave our Camaro the once-over then announced that, because a clear bra must be installed over a clean surface and that our car's paint was in reasonably good condition, but its finish was covered with contaminants and water spots; it would be best to do Transhine's full “Exterior Polish and Wax Detail”. We couldn't argue with the $165.00 price. It was a heck of a deal considering how much work the THRS's exterior needed.

Transhine's Bill DeBever at work, clay barring the THRS. A secret of detailing is to clay bar the exterior while it's still wet after rinsing.  Image: CHpg Staff.

 

Once the car has been clay barred, then it's rinsed a second time and dried. Image: CHpg Staff.

During the Exterior Detail, the entire body was clay-barred during the water rinse stage of the car wash process. Water spots were removed with a special chemical which Transhine applies, lets stand for a short period then wipes off. After that, the car was re-rinsed, dried and moved to Transhine's PPF installation bay to have the clear bra installed. We were surprised how much “whiter” the car looked after being clay-barred and having the water spotting removed.

The clear bra installation begins with downloading a pattern from a pattern vendors and loading that into a PC. The computer controls an automated cutter which cuts the pattern into the film. Image: CHpg Staff.

The sections of Scotchgard are cut from long rolls of film by a computer-controlled machine. The pattern is in software running on a PC and Transhine has patterns for most cars and light trucks. A water-soluble lubricant is sprayed on the front end bodywork and then the film is laid in place. Once the film is positioned, the lube and any air bubbles which develop are squeegeed away with special rubber blades designed for applying PPF. The tough part of a clear bra installation comes when installing the film on body work having compound curves or other complex shapes. A special "steamer" is used to soften the film when its applied to parts of the body having sharp corners.

Once the clear bra was in place, the car was moved to Transhine's exterior detailing area where wax was applied and buffed by Ryan Kreiss. Image: CHpg Staff.

Installing ScotchGard PPF requires training, skill and, in some situations, special tools, such as a steamer. First the film is wetted with a solution which allows repositioning of the film once it's applied. DeBever places it on the panel, positions it, squeegees away bubbles and pushes the edges in place. On a surface with tight or compound curves, the steamer is used to warm the film and make it more pliable. Image: CHpg Staff.

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