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Intake System mods

20K views 49 replies 15 participants last post by  JetFuelOnly 
#1 ·
Hello everyone,

I am a new owner of a 2014 v-sport (previous 2012 CTS-V 6at, 2013 CTS-V 6MT coupe) and I feel the car is leaps and bounds better than the previous model. On Friday I made a few baseline passes in the car and my best pass was a 13.2 at 107 with a 2.2 60 foot (traction issues), I was able to cut a 2.0 on a different pass it was not as fast as I was experimenting with shifting the car with the paddles (not as fast like I thought it). The car actually got faster the more it was driven so I think it has to do with a heat exchanger system issue, I do not hear the pump at idle so it may only be running in boost (should be able to be turned on with ignition in a tune and run consistently). On drag radials/slicks this car should have no problem cutting a 1.6/1.7 with loaded turbos and should run a 12.5 on the stock tune.

Over the weekend I started examine the intake system and learned that this intake is VERY restrictive from the factory (quite possibly the most restrictive system I have ever seen on any vehicle). The passenger side being the worst side, as the track of the intake is very long, and the inlet to the turbo resonator is much smaller than the drivers side. The air box has a very small inlet on the bottom side. there is also a intake duct on the drivers side of the center front grill, but it looks to have a very small outlet on the backside.

I made a few modifications to the intake system and the car is already performing much better, I wish I wish I made a baseline dyno, but I will go off the trap speed for gains. The first modification was to the bottom lid of the air box, I used a dremel with a cutting wheel and cut the entire bottom side of the airbox off, but left the plastic on the engine side, down to the frame rail to prevent heat soat. I also trimmed all of the ribs out of the airbox bottom to help with turbulent airflow concerns with the stock mafs. All mounting points are left intact and it seals just like the factory, just with MUCH more airflow. The second modification I made was to the turbo resonators themselves (pre turbo) I took a carving tool, cutting wheel and other dremel bits and carefully removed the white silencers inside the resonators themselves. This is a major pain to do, but well worth it as the car sounds great now and the turbos spool faster. When these are manufactured from the factory, the resonator is 2 pieces of plastic fused together. I did not want to brake this factory seal and introduce the chance of unmetered air into the system. Take your time and it is possible to removed them, a few pieces at a time is the way to go!

Next weekend I plan to take off the outlet tubes and examine them as well, there seems to be a resonator in these as well, and I will be checking for airflow restrictions.

I also was trying to get rid of the wastegate rattle. I placed a small shim between the actuator rod and turbo actuator arm on the drivers side and it still rattles on cold start and acceleration/decel around 1500-2500 rpms. I will look into some other ways to get rid of this rattle and i have a few ideas on how to do so.


A few more observations:

*turbos have VERY SMALL cold sides and the inlets are flattened to fit behind the belt run accessories
*Heat exchanger upgrade in the center grill will be very easy as there is a hose that runs directly between the stock heat exchangers
*stock heat exchanger pump looks to be of good side
*stock muffler looks terrible, but exhaust systems looks great (car will benefit greatly from a rear suitcase muffler delete with straight though bullet mufflers added)
*downpipes look to be an easy swap
*all vacuum sources are plastic hoses and click type connectors (very nice)

I will check back with more findings!

-Steve
 
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#2 ·
Steve,

Thanks for diving under the engine cover to explore these mods.

I think you are spot on about increasing flow to the turbos being of benefit.
I've not looked at the CTS Vsport intake, but my experience is turbos respond well to a freer flowing intake.

Next time you work on your car, could you take a few pictures?

Again, thanks for sharing your experiments and an in-depth post.

cheers,
brad in houston
 
#3 ·
It was my plan to take pictures of the parts as they were modified, altough the weather didnt want to cooperate and I had to get the car back together. Next time when I take it apart I will show what was modified. I have a few pictures of the parts before they were modified as well.
 
#10 ·
I was curious about the OP's work in the system so I dug in yesterday morning and frankly don't see any low hanging fruit with the exception of the air box, but honestly what the heck do I know. Understandably (because 95% of buyers want quiet) OEM's design the intake system to among other things quell objectionable noise so seemed to be some noise cancelling elements more than flow restrictions. Everything I saw looked to be very carefully engineered and formed so going in with a Dremel and hacking away parts is beyond my comfort/knowledge (at least on the air flow engineering side). It would also appear a true CAI on this car would be a little more complicated than a NA car, but I would buy one that improved performance and added some intake noise (but did not throw CE codes!!) and if my last CAI turbo experience is any indication (Mazdaspeed 3) both will come in spades. Curious to see what D3 comes up with.
 
#12 ·
I dug into the intake system yesterday on our car. And below are some pictures that I took. I also don't see any restrictions in the stock system. The hole in the bottom of the air filter is plenty large enough. And the white resonators simply quiet down the intake system. By removing them, you're going to have a large empty chamber that then feeds the turbo, which won't be good for air flow. The stock system has the same diameter through it, with the white resonator only removing sound. Also, the drivers side was free from oil, but the passenger-side had noticeable oil in it. Trifecta also stated that the stock intake system flows plenty of air even for a tuned motor.
 

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#24 ·
I dont know, but im pretty sure these restrict airflow. and opening up the airbox isnt going to hurt anything.... View attachment 275529 View attachment 275537
Hack & mod away my friend, but if Trifecta says this car is not intake restricted even with a tune, I'm going to believe them since they have incentive to tell us otherwise and develop an intake, but they aren't. No one can explain what the white plastic pieces are so for you to think they are restricting air flow is nothing more than wishful thinking. They look to me like some sort of velocity device that cuts turbo lag, at least that would be my guess.
 
#31 ·
Any forced induction car will see benefit from better intake flow, removing the silencers and resonator will benefit the car. the main set back at this time is that we have to make due with the factory paper filter. Everything from the turbos up will be high temp 3 inch smooth silcone tubing connecting to the factory airbox. getting rid of the rubber elbows with the ripples and the resonator pipe, everything will be smooth and straight through. How much will it gain? who knows and i really dont care. Its a side project im doing for fun.
 
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