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Stock Cadillac STS exhaust flow: 308 CFM

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Found this interesting info graphic from a Corsa performance ad on a Lingenfelter site:

Corsa vs Stock Exhaust for Corsa 14157

 

The graphic shown is for the 14157 system versus the stock 2005 Cadillac STS system. This is particularly interesting for the STS-V since this is the same Corsa system that D3 sells for the STS-V.

The text notes: * Flow bench-tested 42.3 gain in exhaust flow vs. stock muffler.

This I read to mean that the graph is for flow through a single Corsa muffler versus a single stock muffler.  So in other words, the dual Corsa mufflers probably flow around 437 x 2 =874 CFM and the stock mufflers flow around 308 x 2 = 616 CFM.  Recall our target is 2.2 CFM/HP for 0 backpressure, so with a modified STS-V making 500 hp plus S/C load we would need 560 hp of exhaust or 560 x 2.2 = 1232 CFM.

I am guessing that the STS-V stock exhaust flow is similar to the STS stock exhaust flow.

We can see from the numbers then that the stock exhaust flow is insufficient, and that the Corsa’s are an improvement, but there is still some margin for further improvement.

 

Cadillac August 2011 CTS Sales up 39%

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Good news — Cadillac sales overall were flat August 2011 compared to August 2010.   Why is that good news?  With the DTS discontinued, flat sales means that CTS and SRX sales have stepped up to hold the line until the XTS, ATS, and ELR arrive.

CTS sales blossomed at 5.8K for the month, a 39% month vs month, or 34% increase when the number of sales days are factored in.  SRX sales continued to show strength at 4.6K for the month.


 August
(Calendar Year-to-Date)

January – August

2011 2010 % Chg Volume %Chg per S/D
2011 2010 %Chg Volume
Selling Days (S/D) 26 25





CTS 5,783 4,155 39.2 33.8
37,237 28,756 29.5
DTS 719 1,896 -62.1 -63.5
10,172 12,117 -16.1
Escalade 1,105 1,076 2.7 -1.3
8,964 9,842 -8.9
Escalade ESV 655 724 -9.5 -13.0
5,057 4,874 3.8
Escalade EXT 174 188 -7.4 -11.0
1,241 1,196 3.8
SRX 4,627 4,325 7.0 2.9
34,960 32,703 6.9
STS 145 324 -55.2 -57.0
2,806 2,728 2.9
XLR 0 1 ***.* ***.*
12 177 -93.2
Cadillac Total 13,208 12,689 4.1 0.1
100,449 92,393 8.7

Summary

Cadillac sales are up 9% from last year for the same period.  Cadillac CTS sales are a highlight.

Press Release summary: Cadillac:  Combined sales of the Cadillac CTS sedan, coupe and wagon increased 39 percent compared with August 2010.  Cadillac reduced its fleet sales by 51 percent.

 

Next Cadillac update? Intercooler FMHE or Exhaust

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I am split on my next Cadillac update.  The choices are to replace the mufflers with performance, high flow mufflers, or to begin to experiment with intercooler cooling system improvements.

For the exhaust I am settled on replacing the stock, low-noise mufflers with Magnaflow 14326 mufflers.  The exhaust system itself is stainless steel, and appears to already be bent properly.  The cost should be around $100 ea x2 for the hardware, plus installation.  I suspect it will free up 10-15 whp.

The intercooler system uses Laminova tubes with a small heat exchanger in front of the car.  I plan to add a 2nd front mounted heat exchanger in serial with the stock heat exchanger.    The original LC3 testing was done assuming harsh heat conditions with high intercooler coolant temps.  Later when required to SAE certify, the engineers also needed to reduce the temperature  for the intercooler coolant; the engine famously went from 440hp with the original assumptions to 469 hp with the cooler assumptions.  So I suspect that anything we can do to reduce the temperature of the intercooler coolant is worthwhile in terms of more hp.

Technically, reducing the intercooler air temp does not add more oxygen to the air, since at that point the mass of air coming into the system out of the supercharger is fixed.  However, what cooler air across the intercooler does do is allow the LC3 engine to run more timing, which it will do automatically, and achieve more power.  Reducing the temperature of the intercooler coolant is one way to achieve cooler intercooler exhaust (IAT2).

Another thumbrule I have read is that Laminova heat exchangers operate best if the area of the heat exchanger is equal to the area of the coolers.    I had to think about that a bit to understand what was meant.    For the Cadillac the area of the Laminova coolers would be 96 square inches.  The area of the stock heat exhanger would be 21×14=294 square inches, which would appear to meet the thumbrule.

It is inviting to do something really revolutionary like put an intercooler reservoir in the spare tire compartment and run hoses the length of the Cadillac, but probably better to stay conservative for a daily driver.

I am happy with my Ambient / IAT / IAT2 measurement capability.  I would like to have a direct measure of intercooler coolant temp before the next changes, but I am unsure how best to achieve and log that.