Category Archives: CTS-V

Performance cost in MPG

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My current 2005 Cadillac CTS has a 3.6L V6 and is EPA rated for 16 city and 25 highway MPG using their current measure.  For argument sake this yields a mixed-driving target of 19 MPG.

I drive 15,000 miles a year, more or less.  So with my 2005 Cadillac CTS I might expect to need 15,000 miles / 19 MPG = 790 gallons of fuel in the next year.  The 3.6L CTS uses regular unleaded fuel, so let’s say $2.50 / gallon for a total of $2.50 x 790 gallons = $1,975 in fuel costs.

Here are the replacement performance V-Series cars I am considering:  the 469 hp 2008 Cadillac STS-V, or the 400 hp 2007 Cadillac CTS-V.

2008 Cadillac STS-V:  EPA rated 13 city 19 highway, 15 MPG combined.  With my expected annual mileage of 15,000 miles per year that would mean 15,000 miles / 15 MPG = 1,000 gallons of fuel.  Noting that the STS-V however requires premium fuel, which might cost $3.00 / gallon, that makes a total of 1,000 gallons x $3.00 / gallon = $3,000 in fuel costs.   So the Cadillac STS-V would cost an extra $1K/year, or $85/month in gas compared to my 2005 Cadillac CTS.

2007 Cadillac CTS-V: EPA rated 14 city 22 highway, 16 MPG combined. It also requires premium fuel.  15,000 miles x 16 MPG = 937 Gallons.  937 Gallons x $3.00/gallon = $2,811 in fuel costs.  So that CTS-V would cost an extra $836/year in fuel, or $70/month compared to my 2005 Cadillac CTS.

I plan to keep the next Cadillac for 5 years.  Comparing the new cars, STS-V will cost $200/year more than the CTS-V, or $1,000 over the 5 years.

On the other end of the spectrum, the current 2010 Cadillac CTS 3.6L DI V6 engine is rated at 18 city 27 highway for combined 21 mpg.  The current 2010 Cadillac CTS 3.0L DI V6 engine is rated at 18 city 28 highway for combined 22 mpg.  Either engine can use regular unleaded.  So replacing my CTS with the new 2010 Cadillac CTS 3.6L would yield a projected fuel cost of 15,000 miles / 21 MPG x $2.50/gallon = $1,785/year.  Although the new 3.6L has more power at 304 hp than the 2005 non-DI 3.6L at 255 hp in my car, the DI engine also gets better MPG, and is boosted by the 6-speed automatic vs 5-speed automatic.

Replacing my CTS with a 6-speed DI 3.6L instead of a 2007 CTS-V or 2008 STS-V model would save $1,026-$1,215/year.   However, the CTS DI 3.6L has respectable performance of 0-60 in 6.5 sec, while the 08 STS-V or 07 CTS-V will both accelerate 0-60 in under 5 seconds, out-brake, out-corner, generally out-perform the CTS 3.6L.  What cost performance?  Besides the initial price of entry, about $100/month in my case.  Is that worth the thrill of the added performance potential?  Would you pay another $1200 a year to drive a Super car versus a ‘normal’ sport sedan?

Lightly used V-Series

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I am constantly car shopping, but here are my current thoughts on narrowing the search for my next Cadillac.

I am excited about the 2006/2007 CTS-V with 400 hp LS2 V8, or the 2007/2008 STS-V with the 469 hp LC3 Supercharged 4.4L V8.  The CTS-V’s tend to be somewhat less expensive due to the year model and original pricing.

Advantages of the 06/07 CTS-V:

  • Easier to modify for more power — throw in a cam and heads
  • Lighter vehicle – 3850 lbs for the Gen 1 CTS-V vs 4233 lbs for the STS-V
  • More visceral / sporty

Advantages of the 07/08 STS-V:

  • More features / Higher standard luxury
  • More room / backseat space
  • More power ‘out of the box’

Both cars are low production and high performance.  Both are ranging near $25-30K based on condition and mileage.

I will be shopping for a model with around 25K miles.  I drive 15K miles a year, so over 5 years I drive 75K miles.  If I purchase at 25K miles, then I can drive a vehicle 5 years and still just be at 100K miles, which is in my experience a bit before higher maintenance/repairs kick in.

Ideal at this point would be a low-mileage 2007 CTS-V with some performance mods already professionally done at a great price.  As the new CTS Coupe and CTS-V Coupe arrives this summer there may be a lot of V Sedans on the market — here’s hoping.

Gen1 CTS-V: Supercharger?

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In my previous article about performance mods for Cadillacs I mentioned the great gains possible in the LS2 with a Cam/head package, and I argued that if you intended to add a Supercharger you might do that up front instead of doing a cam/head modification.  One advantage of a supercharger add is that it leaves no question as to the drive-ability of the car, and maintains a smooth idle.

Let’s look at the current situation for supercharger modification options.  The Cadillac solution of course, as used on the 2009+ CTS-V with LSA supercharged V8 is a TVS1900 supercharger.

The Corvette LS9 engine uses the larger 6th generation TVS2300 supercharger, and some CTS-V owners have found that if they upgrade from the TVS1900 to the TVS2300 they gain significant horsepower.  Based on my reading, it appears that the TVS1900 is good on a 6.2L engine up to around 800 crank horsepower; you would want the TVS2300 if you are targeting above this number.

For the 6L LS2 engine in the 2006/2007 for most applications the TVS 1900 Seems a better fit than the TVS 2300.

The previous Magnuson supercharger kit for the 2004-2007 CTS-V used the 5th generation MP112 1.84L unit.  That setup for LS6 engines made 6 psi of boost, and added on average 130 whp according to Magnuson.

Interestingly, the STS-V and XLR-V 4.4L engines used a modified version of the MP122 unit.  It adds 10 cubic inches to the M112, so rounds up to a full 2L of displaced air.

The size indicates the amount of air displaced with each revolution of the blower.  So at the same RPM and gearing the MP112 will pump 1.84L of air, the TVS 1900 will pump 1.9L of air, and the TVS 2300 will pump 2.3L of air.  The new TVS units are also more efficient, will make more power at the same boost due to lower heat added to the air charge, and are quieter.  The simple amount of air pumped per revolution does not tell the whole story.

TVS means Twin Vortices Series.  The new TVS series superchargers are 4-lobe Eaton units with 160 degrees of twist along the rotor.  This simulates twin vortices of air rushing into the intake system.  The 5th generation units like the M112 or M122 used 3 lobes with 60 degrees of twist along each rotor.  All TVS superchargers have a 2.4 pressure ratio capability and a thermal efficiency that exceeds 70 percent, which enables more compact packaging and greater output.  The M112 1.84L unit was replaced effectively by the TVS1320 (1.3L) unit due to the greater efficiency of the new series.

The LSA engine in the 2009+ Cadillac CTS-V is basically a supercharged LS3.  So it differs from the LS2 engine in the 2006/2007 CTS-V not only by the fact that it is supercharged but also because it has different heads, among other differences.

So how would a TVS2300 do when added to a ‘stock’ LS2 engine?  Try 130+ RWHP added, which seems oddly similar to the Magnuson number for the MP112 on a CTS-V.  My impression is that the TVS models have more head-room and can provide more air at lower temperature, and be spun faster with less loss of efficiency.  It is not clear to me from the raw numbers in kit claims that one system has more output in a near-stock setup than the other.

A supercharged 2007 CTS-V that pulled 350whp (wheel hp) stock, with a supercharger it might then make 480 whp.  Not surprisingly approximately what you might expect of a 2009+ CTS-V at the wheels.

Superchargers costs start around $7,500 plus installation, but reach beyond $10K depending on the kit and options.

With a Supercharger, premium fuel will be required.