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Hello! I finally got my dream car, a 2009 Z06! I have imported it to Norway from Oklahoma. But I need to have it approved by the very strict "DMV" over here, and therefore I need to reduce the valvetrain noise as much as possible. Any ideas?
Some info about the setup: I have just bought original exhaust manifolds with cats and a 2012 X-pipe (the one with extra cats). I have also bought the OEM intake manifold (was Fast LSXR 102). I have a Halltech air filter, which the government says is OK, but I'm still afraid this dampens less noise than the OEM filter? I do not have coil covers. Do they help on noise? I don't have the Halltech Heatshield either.
Any ideas?
Last edited by alkvalseth; Oct 30, 2018 at 09:33 AM.
Ha, that makes more sense. What testing do they do for import? Do they do noise (dB) tests and do you know how it is set up? Usually noise is measured from behind the car which the valve train noise wouldn't really affect. I can't imagine the slight sewing machine valve noise would be an issue unless you have to prove everything is 100% stock? I have run an ls3 with and without the covers and manifold insulation and it is slightly louder but nothing you would notice from behind the car.
Valve train noise.
Not sure of the exact issue as lifter / fuel injectors are not so noisy.
Could be the intake manifold "roar" or header "pinging".
Not knowing the testing in Norway, I think you are on the right steps to replace the intake and headers with stock components..
The plastic beauty covers (over the coils and valve cover6s) could muffle some noise but not by a lot IMO.
In that regard, perhaps lining those covers with Dyno Mat or like product could help, yet watch the heat rating, don't want that
material to catch fire.
Ha, that makes more sense. What testing do they do for import? Do they do noise (dB) tests and do you know how it is set up? Usually noise is measured from behind the car which the valve train noise wouldn't really affect. I can't imagine the slight sewing machine valve noise would be an issue unless you have to prove everything is 100% stock? I have run an ls3 with and without the covers and manifold insulation and it is slightly louder but nothing you would notice from behind the car.
They don't measure noise, at least they didn't last time (Maybe it was so much louder last time that they didn't even bother), but they do listen for anything being not stock. There is a quite big cam on the car, and the idle is up to 1050-1100rpm so it smooths the lobe out somewhat, but you also notice a quite apparent sewing machine valve noise as you describe it. For it to be approved it has to be 100% stock with the exception of air filter and rear muffler (if it's close to stock).
Originally Posted by Kenny94945
Valve train noise.
Not sure of the exact issue as lifter / fuel injectors are not so noisy.
Could be the intake manifold "roar" or header "pinging".
Not knowing the testing in Norway, I think you are on the right steps to replace the intake and headers with stock components..
The plastic beauty covers (over the coils and valve cover6s) could muffle some noise but not by a lot IMO.
In that regard, perhaps lining those covers with Dyno Mat or like product could help, yet watch the heat rating, don't want that
material to catch fire.
Good luck.
Actually the valve train makes a quite significant sound, I am 99% sure the sound is a mechanical sound from the valvetrain. I like the idea of lining the covers with sound dampening!
If the car was tuned for the headers properly they oxygen sensor tables would have been modified to help the idle with the cam and different sensor location. Now that you've swapped back to stock manifolds it may be worth getting to tune tweaked to see if the idle could be smoothed out anymore and the rpm lowered. Most guys that tune for cams want the chop so they don't spend much time working on idle but an experienced tuner can smooth out a pretty big cam if you want.
I'd leave the FAST intake on there...those come with CARB EO#'s here, which means they're 50 state legal. What isn't 50 state legal is that air intake from Halltech...so I would tend to think, that if your Halltech passes local inspections, so could that FAST 102 intake. Removing the headers will cut down on some sound for sure.
I like the idea of putting 'covers' back on the engine with some added 'insulating' materials, just for inspection of course...
engine 'lope' and idle behavior can also be tuned quite a bit, more timing more fuel usually smooths things out. Just don't leave it there.
As previous posts have mentioned: Pushrod length and oil weight; Temp resistant sound deadening over the valve covers and under the plastic engine covers would probably make a huge difference as the valve-train is somewhat noisy. Factory Intake/Headers.
I'm unsure what standard of sound level you have to reduce the engine noise to, but I cant imagine many other vehicles on the road there are that much quieter. As Unreal mentioned, checking pushrod length may help. I'd imagine high temperature sound deadening secured over the most of the valvetrain/top of the engine and also under the plastic engine covers would make a significant difference in the typewriter style noise these engines make.
An intake shroud may also help reduce some of the noise coming through the intake port.
Goodluck!
Last edited by ImBoosted; Nov 7, 2018 at 02:42 PM.
Reduced valvetrain noise
I don't have access to a tuner now, but I will definitely get a fuel rail cover!
