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Discussion Starter #1
Hi - Enjoying the Picanto, but road noise on rough surfaces with the low profile tyres seem bit high.
I tried checking with various phone apps, but they measure db decibels and not the normal db(A) decibels as "A" weighting is closest to human hearing and is the industry norm.
So bought a small meter and run some tests today to establish a base.
I will then try various sound deadening mats etc and see what results. if any I get in future-
Readings below- up to 77 db(A) sounds comfortable, but above that noise is irritating. AirCon and fan was running as it is hot here in Australia at present.

Outside test 1
Engine idling43db(A)
Engine idling + fan on No146.2db(A)
Engine idling + fan on No1 +AC on51.9db(A)
Outside test 2
Engine idling43db(A)
Engine idling + fan on No149db(A)
Engine idling + fan on No1 +AC on53.8db(A)
100 KPH - Vent fan on No1 + A/C on
On smooth road surface73.4db(A)
On moderate rough surface77db(A)
On very rough surface82-84db(A)
80 KPH - Vent fan on No1 + A/C on
On smooth road surface68-69.5db(A)
On moderate rough surface?db(A)
On very rough surface82db(A)
 

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Yes, I live in Victoria where coarse chip roads are everywhere. It was a big culture shock coming from NSW with their very smooth surfaces. I ended up buying Brigestone Serenity Plus tyres and they made a noticeable difference, though there is no way this car is going to be as quiet as a $50,000 car no matter what you do. Mind you, it isn't that difficult to add extra insulation but I have not felt compelled to go that far.
 

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2020 Sportage GT-Line CRDi
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What you are doing is interesting, but without comparison to a similar, vehicle in similar conditions it's difficult to know if it's worth the effort. It will be interesting to follow this thread.
 

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Discussion Starter #4
Western Australia seems to have increasing number of coarse chip road surfaces. Unfortunately the Serenity tyres are not available in the lower profile size the GT uses.
My above figures would be difficult to compare with other cars, but my thoughts are that they will serve me as a base measurement for a few deadening steps.
I plan to do simple stuff first, such as -

Under bonnet insulation and fill any body gaps that might direct sound towards cabin (top of fender area)
Some Dynamat behind the plastic wheel arch covers. Might try some under body bitumen spray also in wheel well.
Boot floor insulation. Hatches are often more noisy than sedans.

After that perhaps Dynamat inside the doors etc leaving harder stuff like under the carpets to last
 

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Seen a few posts on the issue. Seems Kia is not exactly well known for lots of sound deadening materials.
 

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I think every review I've seen in respect the 2017+ Picanto's (which is a lot of u-tube time) say it's a noisy car at speed or on rough surfaces, especially with the 15 and 16 inch wheels. One reviewer, I think he was Australian or NZ, even recommended turning up the radio during motorway driving which baffled me completely. Other advice was to change to 14" wheels. However the reviewers also say that the Picanto is designed and sold as a small city car (which are noisy by the nature of being a small car) and is no noisier than any other small city car reviewed. The advice on practically all of the reviews was that the Picanto is great for urban and local rural driving, but if you want to achieve stress free motorway driving you need a bigger and quieter car. Personally I just remember how bloody noisy my first car was (1966 850 mini traveller) and then turn my hearing aids off and my journey seems much more peaceful :cool: :D
 
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Hatches are often more noisy than sedans.
Yes, I am annoyed there is no such thing as a Picanto sedan. Would have got it in a heartbeat over the hatch. My rear hatch just now seems to have developed the same problem as reported in the Stinger forums (an intermittent rattle over course surfaces that just doesn't seem to respond to all the usual fixes and adjustments).

Infact when I get a second car in a couple of years although another Picanto would do the trick I am half tossing up getting something like a Cerato simply so I have a sedan option (and SUV tailgates just have the same problems as the massive and heavy hatch rear doors in my experience).
 

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Discussion Starter #8
Under bonnet Dynamat and insulation foam added. See images. I stuck the Dynamat to the 3 panels as this is mid bonnet and should reduce panel resonance. Then covered with 8mm acoustic cotton and butyl foam.
Have only done static test measurements with car idling but there is a small improvement in readings.
Engine note at low RPM sounds same, but think I detect a slight improvement at higher RPM when driving. Will post results on various road noise reading in next few days. I also covered most holes and slots in bonnet reinforcement structure with foam or felt.
Outside test 3 Dynamat+ foam bonnet
Engine idling42.5-43db(A)
Engine idling + fan on No146.2db(A)
Engine idling + fan on No1 +AC on48.6-50.6db(A)
Outside test 4 Dynamat+ foam bonnet
Engine idling42.9-43db(A)
Engine idling + fan on No146.5db(A)
Engine idling + fan on No1 +AC on48.1-51.4db(A)

Conclusion about 0.5db(A) reduction at idle with with fan and A/C off and somewhere between 0.5 -2.5 dB(A) reduction with A/C on with fan at No1. It various a fair bit, depending on how A/C is loading engine to cool. Dynamat on.jpg Foam over Dynamat.jpg
 

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Discussion Starter #9
Went for a run on same route as base measurement test. I also did a other temporary tweak. I have a spare boot floor carpet that I place on top of existing floor carpet as a deadening idea. As I had spare acoustic foam (but have not installed it), thought I would simply make a temporary "sandwich" with a layer of foam between the two boot carpets.
Results were encouraging - here is before deadening vs with bonnet insulation and temporary boot mod.
100 KPH - Vent fan on No1 + A/C on - No Insulation100 KPH - Vent fan on No1 + A/C on - Bonnet and boot sandwich
On smooth road surface73.4db(A)On smooth road surface71.2-73db(A)
On moderate rough surface77db(A)On moderate rough surface77-78db(A)
On very rough surface82-84db(A)On very rough surface80.4-82db(A)


For some reason on moderate road surface 77 dB(A) went up to 77-78, but on smooth surface 73.4 went down to 71.2- 73 ( most time the lower figure) and on coarse surface 82- 84 went down to 80.4 to 82 db)A).
Whilst only about 2 db(A) improvement, it did actually sound a lot less less irritating.
So, I am happy with the start of my experiments. More to follow, once more deadening materials arrive in post in next few weeks.
 

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I think it might not be how many dB you are reducing, but more about which sound frequencies you are eliminating. It may be the higher and lower frequencies are more perceivable and annoying. The insulation is probably reducing those annoying frequencies. It's just a thought.:unsure:
 

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I think it might not be how many dB you are reducing, but more about which sound frequencies you are eliminating. It may be the higher and lower frequencies are more perceivable and annoying. The insulation is probably reducing those annoying frequencies. It's just a thought.:unsure:
Ha, I was just about to post the same!

On my previous car I used to switch between a summer tyre set and a winter tyre set. The tyres were rated identical for noise (external pass I know, so not directly relatable) and the winter tyres were notably more tolerable on noisy bits of road. While the summers produced a sort of white-noise hiss, the winters had a lower brrrrr type sound.
 
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I must admit road/tyre noise is the main thing I dislike about the Picanto. On a coarse motorway surface it is noisy, throw in rain spray noise & it's time to turn the radio off. Our "2" is on 14" wheels with Nexens so I do wonder if different tyres will make a difference.
I think the main fault stems from lack of soundproofing in the wheelarch area. A layer of additional felt (or whatever) under the carpet might make a big difference & cut down noise.
 

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I must admit road/tyre noise is the main thing I dislike about the Picanto. On a coarse motorway surface it is noisy, throw in rain spray noise & it's time to turn the radio off. Our "2" is on 14" wheels with Nexens so I do wonder if different tyres will make a difference.
I think the main fault stems from lack of soundproofing in the wheelarch area. A layer of additional felt (or whatever) under the carpet might make a big difference & cut down noise.
Well mine came with the Nexens originally (14 inch wheels and 175/65 size rubber) so I could directly compare them to the Kuhmos (on my mother's 2017 JA Picanto) and the replacement Bridgestone Serenity I have put on mine now. Kuhmos are the worst of the lot in terms of noise and steering / handling but the Nexens are actually a pretty good all-rounder. The Bridgestone, however, are a very noticeable improvement from both without any compromise whatsoever in ride or handling. This is in direct contrast to the main "quietness" competitor which is the Michelin Primacy 3 ST. I had those on my previous Corolla when its original plain boring Dunlops wore out and the steering and handling just turned to mush (it's handling and steering were not up to Picanto standards to begin with but the Michelins made it far worse again). They were horrible. But quiet....

That said, here in Australia we cannot get the Michelins in the 175/65 /14 size anyway - it is really only the Bridgestones. I will happily buy them again when I next need tyres and possibly even when I buy my next new Kia given the difference over the Korean-branded tyres they come with and how much difference they make on our horrible coarse chip roads (which are actually so bad I have had screws fall out of car interiors...not Kia cars mind you).
 

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Discussion Starter #14
Good result

I did another tweak and this seems to be simple and best noise overall noise reduction so far.

I stuck 8 mm self adhesive acoustic foam insulation (butyl and cotton) to the underside of the boor floor liner. Aussie cars do not have the two level boot floor, just the rigid mat. Here are results of test and image

100 KPH - Vent fan on No1 + A/C on - Bonnet and boot mat acoustic with foam attached
On smooth road surface70.4-72db(A)
On moderate rough surface75-76db(A)
On very rough surface80.1-81db(A)

boot foam.jpg

Short version is a general 1-2 decibel reduction on previous tests, and on our roughest stone chip road even just by ear the noise has gone down from "angry" to just irritating.
On a new section of smooth tar at 100KPH I even had readings in the 69.3 to 70.1 db(A) range. Well worth a try!
 

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I'm having trouble visualising exactly what you did here. Are you talking about the rigid lift out floor that fits directly on top of the spare and fits into a couple of tabs at the rear? And what exact product did you use please? I might try this myself as I feel that most of the noise does actually come from around here (one reason I wish Kia had made a Picanto sedan).
 

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Discussion Starter #16
I'm having trouble visualising exactly what you did here. Are you talking about the rigid lift out floor that fits directly on top of the spare and fits into a couple of tabs at the rear? And what exact product did you use please? I might try this myself as I feel that most of the noise does actually come from around here (one reason I wish Kia had made a Picanto sedan).
Yes it is the thin rigid floor with rear tabs. The insulation is fitted to the underside, and even on the two no rigid mat sections (near wheel arches). I bought the foam off Ebay

Be sure you get the Butyl/Cotton material. Whilst it looks light gray on my photo ,it is almost black. It has a "gooey " feel to it unlike most foams.
There is heaps of plain grey sticky back foam insulation also on Ebay, but think the plain foam will not be as absorbent.

Another trick I might try is one I read on a Honda Jazz forum, and that is remove the trim access panel at top of rear shocks, and stuff the gap between inner trim and metal wheel arch with Polyester wadding.This could stop more sound ingress?
 

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Discussion Starter #17
Went for 100 km drive on country roads yesterday, and just by ear, I can confirm the insulation of boot mat has made a significant difference to road noise intrusion.
Car much more pleasant overall, and radio sounds so much clearer, with no need to adjust volume level.
 

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Yes it is the thin rigid floor with rear tabs. The insulation is fitted to the underside, and even on the two no rigid mat sections (near wheel arches). I bought the foam off Ebay
Thanks. That is a pretty reasonable price. I will certainly try it when I get the inclination and time on my hands. This could be as close as we can get to what a Picanto sedan might have been like had it existed.

By the way, I have found on my car that after a few years the rear hatch "loosens" up a bit and the catch on the rear door/hatch frame needs to be adjusted as far forward (as in towards the back seats) as possible and then the screw out rubberised stoppers on the hatch itself adjusted outward (to around 25 - 26 mm - exact same distance as the Stinger!). Further to that, Kia (like other makers) just have a clear and slippery adhesive "disc" stuck onto top of the rear bumper where those stoppers come into contact with it. I replaced those stock clear discs with self adhesive clear discs (19mm) from Bunnings so that the surface was no longer "slippery" and I did not have to adjust the stoppers out quite as far (since the Bunnings discs are thicker than the ones the car came with. Doing these things also quietened down the back of the car for me and has done so for a good couple of months (so seems permanent).

 
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