Cadillac Conversations

In a water to air heat exchanger cooling system as used on the Cadillac STS-V and CTS-V, ambient air coming into the front of the Cadillac is used to cool the intercooler coolant.  The coolant is then pumped through the actual intercooler to cool the air charge entering the manifold.  Intuitively we expect changes in ambient air to change the equilibrium point of the intercooler cooling system.  This is because the colder the ambient air over the heat exchanger, the better the heat exchanger works and so the lower the expected intercooler temps will be.  Today’s test explores to what degree ambient temp changes impact IAT2s.

The test today and the prior data shown are both for the current intercooler setup:  Updated intercooler hoses, retest hot S3TC heat exchanger

OEM Heat Exchanger + S3TC additional heat exchanger and hoses.  Fluid capacity ~4.6 quarts.

I experimented with the Mityvac system and repulled a vacuum on the intercooler coolant, pulling coolant along with the vacuum, and refilled it.  But the hardware is unchanged.  The test is a 20 minute loop at highway speeds, with one or more acceleration runs along the way to demonstrate intercooler heat up and cool down times.  These show as spikes on the graph.

The graph shows IAT2 temps, which is the incoming air temperature after the supercharger, on a prior test day that averaged 69F ambient temp, and today with 84F ambient temp, or 15F higher.  There are 4 lines on this graph.  The dark blue is IAT2 today, and the light blue is IAT1, or air coming into the engine intake, today.  Dark red is IAT2 on the cooler day, and salmon (pink) is IAT1 on the cooler day.

What the comparison appears to show is that when ambient temps are 15.3F warmer (avg 84.8F vs 69.5F), air coming into the engine (IAT1) is 15F warmer (avg 94.2F vs 79.2F), and air out of the intercooler is 11.2F warmer (avg 124.7F vs 113.5F).  Knowing that ambient temps flow into the intake as IAT1 and on through the supercharger to become IAT2, we might have predicted that a 15F ambient delta would resolve to a 11.2F IAT2 delta.  However, that’s why we test, to find out what happens.  In general an increase of 1F ambient leads to 1F IAT2 leads to 0.8F IAT2.

I also note that IAT1 averages 10F above ambient, and IAT2 tends to be 30-32F above IAT1

Same trend for this dataset of about 3 sec after acceleration starts to IAT2 begins to rise.

Posted in Cadillac Performance Mods, Intercooler, Site Info / News | No Comments »

DETROIT – The summer road trip season is near, meaning millions of drivers are planning getaways – with lots of stuff. The Cadillac SRX crossover’s unique Cargo Management System is designed as an ideal companion for long weekends and driving vacations.

“We put a lot of thought into what kinds of items Cadillac customers would want to bring into the SRX and where they’d want to put them,” said Elizabeth Pilibosian, SRX chief engineer. “The philosophy was not just to maximize total space but to have a place for everything and everything in its place. That makes a huge difference on longer trips.”

The rear compartment Cargo Management System uses a segment-exclusive U-Rail track system with an adjustable cargo fence that segments the area to contain items of various sizes and restrict their movement when the vehicle is in motion. The fence is sturdy, but also easy to move around the U-shaped track to adjust to a variety of positions to suit a range of items and packing arrangements.

The cargo fence can be removed, retracted and conveniently secured beneath the load floor when not in use. An optional cargo net, organizer or area divider may be used in place of the tubular fence. Four steel loops positioned in each corner of the compartment provide convenient connection points for nets or bungee cords that a driver might bring into the vehicle.

The rear compartment’s load floor has a latch that reveals a waterproof bin, measuring 26 by 12 inches by eight inches deep. This easy-to-clean bin is ideal for storing damp or dirty items from a beach trip, or it can be used as a cooler, or to house smaller items under the floor and out of view. A smaller secondary bin holds the vehicle’s tire inflator kit that can be used as a pump for bike tires and beach toys depending on valve compatibility.

Flanking the main bin are two smaller discreetly covered compartments designed to be ideal for stowing small tools, such as a tire pressure gauge. Regular use maintains proper tire pressure, which can help maximize fuel economy.

A two-position cargo shade can be used to conceal the rear compartment when the hatch is closed.

In SRX’s passenger area are several additional storage areas. Each door has upper and lower bins, as does the glove compartment, which can cool fruit and beverages when the air conditioning is on. The center console offers an upper level for small items like an MP3 player or mobile phone, and a lower level for larger items.

The cup holders between the front seats are dual-level as well, with a retractable floor that lets the user go from a small coffee to a “grande” at the flip of a switch The false floor also creates a secret compartment that can hide a wallet or wristwatch.

In front of the cup holders is the SRX’s smallest bin, designed expressly to house mobile phones and sometimes known as the “phone throne.”

Open SRX’s rear programmable liftgate and more than 29 cubic feet of storage space behind the second row seating awaits, more than enough room for four rolling suitcases, sports equipment and sundries. With the 60/40 split rear seats folded flat, the cargo area grows to more than 61 cubic feet to accommodate items like a bike or baby stroller.

“We know that SRX customers are active people who value enriching experiences,” Pilibosian said. “They expect their journey to be just as enjoyable as their destination, and the SRX is tailored to meet their needs and exceed their expectations.”

Cadillac has been a leading luxury auto brand since 1902. In recent years, Cadillac has engineered a historic renaissance led by artful engineering and advanced technology. More information on Cadillac can be found at media.cadillac.com.

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Pressure loss in a water/air intercooler cooling system as used on the Cadillac STS-V or CTS-V is relative to the losses in the hoses, losses in the elevation around the circuit, and losses in the intercooler or heat exchanger.  Generally pressure losses are measured in psi or feet of head.  The overall pressure that the system of hoses, intercooler, and heat exchanger present to the centrifugal intercooler pump used along with the flow characteristics of the pump determine the flow in gallons per minute through the system.

In my current STS-V intercooler setup I have the OEM heat changer, two extra hoses, and an added S3TC front mounted heat exchanger.  I don’t know what the OEM coolant flow rate is.  Although the Bosch pump is rated at 8 gpm that is against no resistance so we know the OEM flow is something less than 8 GPM.

Here is the Bosch pump flow diagram from an earlier article on the same topic:

Bosch Intercooler Pump Flow vs Pressure

Now,  I know it reads in liters/hour and hPA but we can use it to get to gallons per minute and PSI.

1 liter per hour = 0.00440286754 US gallons per minute. 1 bar = 14.5037738 pounds per square inch.

So the table reads:

and we see that the Bosch OEM pump is rated at 8 gpm against no pressure, and falls to 0 gpm against 7 PSI of pressure.

It occurs to me that knowing the pump stats, we could measure GPM and derive pressure head for the system as installed.

Here is the performance curve for a popular alternate, the ’29 gpm’ Cyclone pump:

Jabco Cyclone intercooler pump

Which gives this updated table:

So if for example my system has a flow with the Bosch pump of 4 gpm (my guess), then the system at 4 gpm has a pressure head of 5 psi. The cyclone pump against the same pressure of 5 psi would do around 12-15 gpm.

Hedland flow meter

A good next experiment would be to measure the gallon per minute flow of the current setup as accurately as possible.   I think a flow meter like this one if rigged in a test loop would give me a clear measure of gpm flow in the system, albeit with some added resistance due to the test setup itself.   The meter measures measure 1 gpm up to 16 gpm across 0-250 F which should make it robust enough for my purpose. However, unless I am missing something the added resistance of the flow meter is 4 psi at 4 gpm, rising to 9 psid at 16 gpm.  Therefore the meter itself would overpower the system pressure range I want to test.

My guess is I will have to test the direct way — add some hoses to/from buckets and see how much the pump can pump in how many minutes.

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With a number of very important vehicle introductions in upcoming months (and a rapid pace of change to follow after) this seems a good time to get more organized in sales and service leadership.  Today Mark Reuss made some line-up changes that look promising to add more depth to the leadership team and keep the right focus on Cadillac Sales and Service going forward.  Chase Hawkins had been serving as the Northeast Region Director for Cadillac, and is now promoted to VP Cadillac Sales and Service.  Lots to do with the ATS and XTS on the way and big opportunities for Cadillac in line leadership.

Chase has been in the automotive industry since 1990, with GM since 1996, and a GM Executive since 2007.  He has lived around the world on various assignments for GM, including South Africa, Switzerland, Mexico, and the UAE.

DETROIT – In preparation for numerous product launches in the coming months, General Motors North America President Mark Reuss today announced the following changes for U.S. sales executives:

• Alan Batey, 49, is appointed to the newly created position of GM vice president, U.S. Sales and Service.  He will report to Reuss.
• Don Johnson, 55, currently U.S. vice president, Sales Operations is named U.S. vice president, Chevrolet Sales and Service, replacing Batey.
• Kurt McNeil, 48, replaces Johnson as U.S. vice president, Sales Operations.  He had been U.S. vice president, Cadillac Sales and Service, since 2010.
• Chase Hawkins, 43, regional director, Cadillac Sales and Service Northeast Region is promoted to the position of U.S. vice president, Cadillac Sales and Service replacing McNeil.
• Ed Peper, 50, currently general manager, Fleet and Commercial Operations, is named U.S. vice president, Fleet and Commercial Sales.

Johnson, McNeil, Hawkins and Peper will all report to Batey, as will Brian Sweeney, who remains U.S. vice president, Buick and GMC Sales and Service.  The moves are effective   June 1.

Chase Hawkins U.S. vice president, Cadillac Sales and Service

“GM is playing offense with an aggressive rollout of new cars, trucks and crossovers,” Reuss said.  “Strengthening our U.S. sales team will help take full advantage of these growth opportunities and continue delivering solid improvements in customer satisfaction, dealer profitability and resale value.”

By the end of 2012, GM will have all-new or freshened cars and crossovers in segments that represent 60 percent of the U.S. light vehicle market, and all four of GM’s brands in the United States are poised for growth.  By the end of 2013, 70 percent of GM’s North American portfolio will be new or freshened vehicles compared with 2011.

Chevrolet will have transformed its passenger car, crossover and truck line up with new vehicles like the Sonic, Spark and Impala.  Buick, with the Verano and Encore, and Cadillac with the XTS and ATS, are entering segments where they don’t compete today.  And GMC will have one of the newest vehicle portfolios in the industry.

Batey began his career with General Motors in 1979 as a mechanical engineering apprentice for Vauxhall in the United Kingdom.  He has held senior management positions in the U.K., Korea, Germany, The Netherlands, Switzerland, Australia and the United Arab Emirates.  Prior to joining Chevrolet in 2010, Batey served as Chairman and Managing Director, GM Holden Ltd. Operations in Australia and New Zealand.

“As aggressively as we’re investing in new products, our dealers are likewise investing heavily in remodeled and new facilities,” said Batey.  “We’re confident that this combination will make our customers’ dealership experience the best in the industry.”

 

Dearborn Classics is an international mail order company that specializes in the manufacture and supply of quality parts and accessories for the Ford Ranchero, Ford Falcon, Ford Fairlane, Ford Galaxie, Ford Torino and Select Mercury models.

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I am thinking more about this graph of IAT2 over time as the Cadillac STS-V accelerates:

Let’s consider the stock, OEM Bosch intercooler pump.  This pump is rated for 8 gallons per minute (gpm) against no resistance, and likely does 5 gpm in the STS-V system.  It is overall a very good pump, and very efficient.

Now, a gpm is 1/60=0.083 gallons per second (gps).  So 5 gpm would be 0.42 gps.  The STS-V can accelerate 0-60 in under 5 seconds.  So on an average 0-60 run, the intercooler pump moves 5 sec x 0.42 gps = 2 gallons of fluid through the intercooler.

Now, keep in mind that the OEM system had 2.6 quarts of fluid, and my new HX added 2 quarts, so now my system has 4.6 quarts or just 1.15 gallons. A small part of the capacity is likely counted in the side fill loop, so we’ll say 1 gallon.

So on an average 0-60 run, the pump can move 2 gallons of fluid through the intercooler, and the system has 1 gallons in the main loop, so the coolant sees the inside of the intercooler twice in that 5 seconds.  Put another way, my current 4 quart capacity system has a circuit time of ~3 seconds — every ~3 seconds the system circulates the entire coolant capacity.

For the intercooler testing I was focused on just getting an acceleration spike and not best time.  But if we look at this graph of speed vs time vs IAT2,

What it appears to show is that the IAT2 temps are near constant for the first 3.27 seconds (looking at the exact figures in the data table), and rise dramatically after that.  Now it is dangerous to read too much into a single sample, but this seems to validate our figures that at 3.27 seconds the intercooler coolant starts a 2nd loop through the system.

From this I conclude that a system with a 2 gallon capacity of coolant would have fresh, cool fluid in the intercooler for the first 6 seconds.  Now 0-60 mph is not the end all and be all of performance.  To keep uncirculated coolant in the intercooler for a dyno run one might need 10 seconds of fluid or 3 gallons — as a thumbrule think 1 gal per 3 seconds.

Also, if you speed up the pump, you’ll need more system capacity to offset the faster circuit time.

What do you think?  Am I missing the boat?  Do you agree?  Hit the comments please!

Posted in Cadillac Performance Mods, Intercooler, Site Info / News, STS-V | 3 Comments »

This morning I took the front clip off my STS-V once again to replace the intercooler heat exchanger hoses with Spectre braided stainless sheathed hoses and then retest.

I did a first shake-down test run, then let the car sit and heat soak, then did another 20 min test capture.

The chart shows intake air temperature 2 (IAT2) after the supercharger over time during a 20 min test drive. The spikes on the chart are acceleration runs.
Today’s weather is overcast, with 72F air temperatures, similar to the historical data file for the OEM capture. What this suggests is that the S3TC heat exchanger in series with the OEM heat exchanger acts to lower IAT2s around 10F.  The end of the test was curtailed due to a traffic stackup; I stopped scanning and capturing data to save time on conversion.

Because today’s temps are similar to the historical air temps, I compared today’s run to the historical data without modification.

Overall the new S3TC Heat Exchanger results continue to be good.  The Spectre hoses are on and do appear to have better success at avoiding kinks or crimps than the rubber heater hoses did.

Here is a zoom-in on the acceleration run today, showing the trend for IAT2 vs RPM and Speed.

In this graph we see initially there is actually a decrease in IAT2, as the throttle opens, all the flow goes through Supercharger as opposed to the bypass, and the intercooler is at max cooling. As the supercharger continues to dump heat into the system, the manifold heats up more than the intercooler cooling system can sustain.

Posted in Cadillac Performance Mods, Intercooler, Site Info / News, STS-V | 1 Comment »

The first question for the upcoming 2013 Cadillac ATS is:  do you want the 272hp 2L Turbo 4 — starting at $35,795 — or the 321 hp 3.6L DI V6 starting at $42,090?

The all-new Cadillac ATS navigates through the turns and straightaways at Atlanta Motorsports Park during performance testing Tuesday, May 8, 2012 in Dawsonville, Georgia. The Cadillac ATS is engineered to be the lightest compact luxury sports sedan, reducing weight through the use of advanced materials - but not at the expense of performance. (Photo by Sam Sharpe for Cadillac)

Right behind that choice however — and the 2L Turbo is likely to be the price / performance silver lining  — will you want the 2L Turbo Performance Package (1SJ), or Premium Package (1SL)?

In Cadillac parlance, the Performance Package generally includes the key performance options in an easy selection.  The Premium package however often adds features — at a price — that are desirable even for hard core performance enthusiasts.  There is also a ‘Luxury’ model available (1SG) that combines more luxury oriented features that non-performance Buyers may prefer.

The 2L Turbo Performance package looks like this:

and the Premium package adds the full color heads-up display (!), steering wheel paddle controls for the auto trans, FE3 performance suspension, limited slip differential, and Magnetic Ride Control:

The Premium package also has navigation standard, while the Performance package has Nav as an option.

Suspensions — generally Cadillac grades suspensions from FE1 to FE3 or FE4 as the capabilities move from standard to highest performance.  The Magnetic Ride suspension on the Premium model is the most desirable setup.

The grill and parking assist items on the Performance Package list but not on the Premium Package list are a bit of a red herring, since they are standard on the Premium Package and part of the Luxury Package:

The other BIG feature standard on the Premium and optional for the Performance will be the Cadillac User Experience (CUE) system.  The 2L Sport model can be optioned up to include the HUD as well.

Both the Sport and the Premium package get the seating package standard, which adds power memory seats and rearview backup camera:

Summary:

How will you option out your Cadillac ATS?  Will you keep it clean and disciplined and stick to the Performance model, or will you write a check for the Cadillac ATS 2L Turbo Premium?

Posted in ATS / Alpha, Cadillac Models, Site Info / News | 2 Comments »

One of the great things about OEM heater systems is that they have hoses exactly bent and shaped the way needed, so that the hose is perfectly formed for the job.  Good advice for aftermarket installations like my intercooler cooling mods is to measure out exactly what type of hose you need, then go look at the big books of existing OEM hoses at an auto parts store and find the one snowflake that is similar to your needs.

Another option is the Spectre stainless steel sheathed heater hose, 39798, which is designed to allow a variety of hose turns without kinking or crimping.

Spectre hoses in their packaging

The hoses I need are 3/4″ inner diameter. These Spectre hoses are rubber hoses with a stainless steel braided sheath around the rubber.  For Spectre 39798 the hoses are 4 ft (48 inches) long.
Here is a shot out of the packaging:

Vanity shot of the hose out of the packaging

The sheathing helps prevent hose crimping. After playing with one of the hoses in various bends I would say it is helpful in resisting but does not eliminate crimping. So I will still need to ensure that the hose routing helps as much as possible to avoid crimping the hoses.

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Cadillac has a clear target in mind for the upcoming Cadillac ATS: to handle and perform better than a BMW 3-series. In order to achieve that goal they are designing a new platform from the ground-up, selecting appropriate materials, and the right power trains. If they are successful, the Cadillac ATS will be the new benchmark for luxury performance.

Engineers look over the all-new Cadillac ATS before performance tests at Atlanta Motorsports Park Tuesday, May 8, 2012 in Dawsonville, Georgia. The Cadillac ATS is engineered to be the lightest compact luxury sports sedan, reducing weight through the use of advanced materials - but not at the expense of performance. (Photo by Sam Sharpe for Cadillac)

DETROIT – When engineers set out to make the all-new 2013 Cadillac ATS as light as possible they used advanced materials to minimize weight throughout the compact luxury sports sedan but never compromised performance capability.

Lightweight parts such as an aluminum hood and magnesium engine mounts help ATS achieve a curb weight less than 3,400 pounds, and highway fuel economy well over 30 mpg. Keeping weight down also enabled balanced distribution of vehicle weight that helps delivers a world-class driving experience.

“We designed and engineered ATS’s vehicle architecture to deliver quick, nimble and fun-to-drive dynamics,” said David Masch, ATS chief engineer. “We distributed mass to key areas, much like an athlete builds muscle where he needs it most. This enabled ATS to achieve the performance characteristics that luxury sport sedan buyers demand.”

One seemingly heavy way the ATS engineering team achieved its performance goals was using cast iron in the rear differential instead of aluminum, a learning taken from the performance-tuned CTS-V.

The differential provides torque and rotation to the wheels, and ATS’s cast iron design helped distribute weight equally between the front and rear wheels to provide agile handling while reducing noise and vibration. Cadillac benchmarked it against world-class competition to deliver a driving experience that is as well-tuned for sound as for ride and handling.

Unlike a differential made from aluminum, which expands and contracts twice as much in response to temperature change, a cast iron differential is stronger and retains its shape better under temperature extremes, which allows the ring and pinion gears to operate more quietly. As a result, a cast iron differential also requires less energy to operate, contributing to higher fuel efficiency. To the consumer, this means more miles between fill-ups.

The ATS team also achieved significant weight reduction in the rear suspension by using specially engineered straight steel links with lightening holes instead of using aluminum.

“The team focused on grams, not pounds, every day of the ATS’s development,” Masch said. “Even the smallest of changes could contribute to the overall mass goal.”

ATS’s wheels also benefited from 50-50 mass distribution between the front and rear. While heavier cars need larger wheels, tires and brakes to account for heavier mass, ATS’s relative light weight enabled the use of optimized high-strength aluminum wheel forgings and Brembo brakes that deliver stopping distance of approximately 129 feet decelerating from 60-0 mph, which is expected to be best in the segment.

Inside the ATS, the vehicle team took advantage of a new process that places sound-absorbing material between two layers of laminated steel. By doing so, Cadillac refined a part and process it pioneered on CTS.

These sound-buffering materials help reduce noise coming into the cabin from the powertrain and fine-tune the sound to a sporty growl that communicates powertrain response and road characteristics to the driver.

ATS also uses an acoustically laminated windshield and side windows that are lighter than standard tempered glass and provide better wind and powertrain noise reduction for a quieter interior. Acoustically laminated glass also offers almost double the amount of ultraviolet ray protection.

“Smart material selection and styling modifications that reduce complexity are key enablers in our quest to reduce vehicle mass,” said Bob Boniface, Cadillac exterior design director, who spoke Thursday during a panel discussion on lightweighting at the Automotive Press Association.

“As consumer demand for more features, space and comfort continues to increase, so too has our proficiency in designing vehicles that offer aerodynamic performance and efficiency equivalent to lower vehicle weight,” he said.

The ATS, which starts at $33,990, goes on sale this summer.

Posted in ATS / Alpha, New Technology, Site Info / News | No Comments »

Got the AVS tank I ordered in the post today.  Very interesting.  Previous mention:  Cadillac STS-V inline flow-through intercooler tank

AVS tank in the box

I ordered this as a possible inline tank addition to my Cadillac STS-V intercooler coolant loop. Additional coolant would act as a buffer to temperature changes (both up and down). The stock system has 2.6 quarts. My system has the S3TC heat exchanger added, which holds 2 quarts, so it is running 4.6 quarts. The new tank would add 4 quarts, for 8.6 quarts total.

The tank has a drain at the bottom, 1/2″ NPT fittings that handily I have 1/2″ NPT to 3/4 inch hose barbs from my 45321 experiment to fit, and a 1/4″ NPT fitting for a gauge which I will either stick a stopper in or a temp gauge.

1/2" NPT to hose barb attachment added

I will have to decide whether to add the tank during in this weekend’s big install adjustments session, or wait and test with the new Spectre hoses in place first so I have a clean baseline, then redo the circuit with the tank in place. Notionally with the angle brackets on the bottom, this tank would just sit directly on top of the S3TC.  Choices are good.

Update:

This temperature gauge, with 1/2″ NPT fitting, 2″ probe length, and 0-220F temperature scale could work and hopefully be visible through the grill on close examination.  Hmm.

Tags: AVS Tank, Cadillac STS-V, Intercooler cooling
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