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2018 XT5 Black on Black
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Discussion Starter #1
I normally don't start one, but I was wondering what everyone thought of the comment from Motor Trend, October issue. In the MT Confidental section, there is a bit about the 3.6DI.

It states that GM insiders know they have a minor NVH problem with the new 3.6-liter direct-injection V-6 fitted to the new Cadillac CTS and the revised STS. And, frustratingly,they know it's a problem that can't be fixed; it's a design fault, admits one senior engineer. Wonder if they'll get a rebate from the folks who actually designed the engine for GM--British engineering company Ricardo.

Interesting little commentary, no? :thumbdown:
 

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Sedan de Ville, CTS
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Whoops! Well, at least GM has never produced/sold engines with problems in the past. (Where do I start??)
 

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Cadillac
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I haven't seen a single post from an 2008 CTS owner saying that NVH is a problem. I don't buy it. A comment like that from MT doesn't worry me a bit.
 

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2017 ATS Performance Premium Luxury Crystal White AWD 3.6DI
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186 Posts
Hope this doesn't sound dumb, but what is NVH?

Steve
 

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2008 CTS AWD FE2 DI 304hp
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12 reviews from various magazine.. Motor trend finally found something..to bitch about...

Its standard fare for the biased press. Otherwise I thought the review was excellent..

Remember they get paid to find both the attributes and faults..with every vehicle.

They had to look very hard and the Direct injection comment a small point in the article.
 

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2011 SRX & 2010 Corvette Grand Sport Convertible
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GM did a lot of design work to reduce engine NVH. Here's an interesting exerpt from WardsAuto.com on August 30. I think they did an excellent job.

Direct injection, a process utilized by most diesel engines, results in more noise than traditional gasoline mills, particularly at startup, which has kept GM from bringing it to market sooner.
Specifically, pulses from the injectors run at about 1,750 psi (121 bar), far above traditional injectors. To help quiet the harsh ticking, GM engineers modified the engine structure. For example, they isolated the fuel rail, which prevents the transmission of injector noise into the engine.
The patented approach ranks as an industry first. GM also has switched to a structural oil pan cast from aluminum, rather than one that is stamped.
“It bolts directly to the transmission, stiffens the powertrain itself and helps isolate sound,” John Zinser, vehicle line director, Cadillac CTS, says during a media backgrounder here.
GM added acoustic treatments atop the engine and installed a front dash panel made of laminated steel between the driver and the engine compartment.
Additional acoustics have been added to the wheel wells. A 360-degree seal mitigates noise at hood-level, while a belly pan muffles unwanted sound that normally would bounce off the pavement at the vehicle’s underside.
 

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2017 XT5 and 2014 Corvette
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I haven't seen a single post from an 2008 CTS owner saying that NVH is a problem. I don't buy it. A comment like that from MT doesn't worry me a bit.
I have about 500 miles on my 3.6DI and this is a non-issue.

:cheers:
 

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2017 ATS Performance Premium Luxury Crystal White AWD 3.6DI
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I have about 200 miles on mine and the only noise is a very faint ticking heard when standing outside the car in the front. It is not perceptible inside the car. There is no vibration and no harshness.

Steve
 

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Cadillac Maniac
Cadillac Escalade
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Even the new Lexus GS350 is getting this annoying tick from their direct injection engine.. I'd love to see a side-by-side comparison of this noise on both the GS350 and CTS..
 

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So basically they are right in a certain sense. Some slight additional noise is a design flaw in the DI 3.6, in the same way that excessive gas consumption in a design flaw of a 400 big block.

But the designers made the decision that since the perfect engine hasn't been invented yet they would make the trade off to get additional HP and better gas mileage in exchange for a little bit of extra noise if you were to stick your head in the engine compartment at high RPM...
 

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2008 CTS DI
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I have 300 Miles on mine and this is not an issue thus far, if it becomes an issue rest assured i will let it be known to this forum and the dealer. I have owned many GM vehicles in the past, if it is a lemon they will replace it, however at this point i do not see that being a problem wiht the triple sealed doors and double sealed engine compartment there is no noise inside and it is so smooth you can barely tell it is on.
 

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I had read about the same engine issue in another review. I can't remember which one it was. The reviewers thought it would only be an issue for the most extreme car enthusiasts.

It's nothing an aftermarket intake and exhaust won't cure...

Tony
 

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This ticking is inherent in all Direct Injection gasoline engines. Cadillac choose to tackle this with numerous sound reduction methods including the previous stated ones along with; the 360 degree weather seal on the hood, the engine cover was designed to absorb sound, the thickness of the glass along with others. Also this weeks Autoweek makes referance to the NVH from this engine. I've heard it, doesn't bother me (it's not as bad as the MB Bluetech E class Diesel - a good friend has one uses it to go to his office in Portland from his home in Orange, CA, but his daily driver is a C6). I'm still pricing local dealers for the best 'deal', getting a Thunder Gray / Coca - Cashmere SIDI loaded.

Tim
 

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2008 Cadillac CTS
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I'm still pricing local dealers for the best 'deal', getting a Thunder Gray / Coca - Cashmere SIDI loaded.

Tim
What exactly does SIDI stand for? I know DI is Direct Injection, but I thought SI on an engine name meant Sequential Injection. I thought it was one or the other, not both.
 
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