Community Project - Micah's Aftermarket Exhaust Test

[TB Rich]

@Micah

Went to test this am. Two things immediately crossed my mind.

Are we all using same app ? (My tickover is noticeably less than yours).

And even more so - we are alll on different gearing. So 70mph in one car is different RPM to someone else.

So shouldn't we be rev not speed tested to make it scientific ?

The fact everyone will be using different phones is a huge issue too, at the very least just using results from a manufacture like Apple would probably help in consistency. Either that or try and convince people to spend £15 on a mini dB reader, which are stll +/- 1.5dB, which goes to show that the variance between all these mobile makes/models will be massive - and 3dB as we know is a doubling in sound volume.

Revs too good idea, as mines 4100rpm at 70mph!

 

[Micah]

Well this is turning into a bloody minefield

 

[Johnny 99]

Maybe it's an excuse for a meet sometime. Everyone takes turn driving down the same stretch of road measuring decibel level with the same piece of equipment.

 

[sevenfourate]

The fact everyone will be using different phones is a huge issue too, at the very least just using results from a manufacture like Apple would probably help in consistency. Either that or try and convince people to spend £15 on a mini dB reader, which are stll +/- 1.5dB, which goes to show that the variance between all these mobile makes/models will be massive - and 3dB as we know is a doubling in sound volume.

Revs too good idea, as mines 4100rpm at 70mph!

Absolutely.

I also thought about tyres (Road noise differences might hugely effect the results) and even on a relatively sane level - the seats people have and if / how they absorb sound more than another type......

However those and many other factors aren't easily and quickly changed. The app were using and making sure we are all at the same revs should be controllable.....

4100rpm at 70 Rich. Wow ! Knew you were using lower ratios: but - a full 1000rpm below me on bog standard gearing for example ! Night and day different.

What's your redline at now for reference ?

 

[jasonlovesfrench]

Maybe everyone could cut and paste this as a template?

System Standard with K-Tec decat pipe
Iphone SE
Phone location - passenger Recaro
Idle (warm) 80.0d
70mph 86.3d 3.500 revs
Acceleration from 70mph 89.0d
Radio OFF
Fan OFF
Windows UP
Seats/Parcel Shelf FITTED

 

[Chris]

How did I miss the pure lol's topic yesterday!!!

 

[TB Rich]

Absolutely.

I also thought about tyres (Road noise differences might hugely effect the results) and even on a relatively sane level - the seats people have and if / how they absorb sound more than another type......

However those and many other factors aren't easily and quickly changed. The app were using and making sure we are all at the same revs should be controllable.....

4100rpm at 70 Rich. Wow ! Knew you were using lower ratios: but - a full 1000rpm below me on bog standard gearing for example ! Night and day different.

What's your redline at now for reference ?

ah my bad, it's 4000rpm @ 71mph, remembered the '1' wrong. It's obviously quite compromised now for motorway but overall works a treat. If you drive a 200 box (or later 197) around in 5th, that is basically my 6th! - there is only 0.2mph difference at 1000rpm and 2.1mph at 7700rpm. However it still works well on the road because I elected to use the longer 197 1-3 ratios which has pretty much kept them the same as the 200 short 1-3



Redline is 7700rpm, no point going that high though as the cams don't warrant it. Of course when some bigger ones land it'll be useful and may go up to 7800rpm - but you need to keep a relative safety margin on hydraulic tappets. Got a daily now though, so could always put solid tappets in and rev it out to 8500rpm!!

Back on topic though, I'll look out for the app and next time I take the car out will have a nosey at the numbers.

 

[jasonlovesfrench]

ah my bad, it's 4000rpm @ 71mph, remembered the '1' wrong. It's obviously quite compromised now for motorway but overall works a treat. If you drive a 200 box (or later 197) around in 5th, that is basically my 6th! - there is only 0.2mph difference at 1000rpm and 2.1mph at 7700rpm. However it still works well on the road because I elected to use the longer 197 1-3 ratios which has pretty much kept them the same as the 200 short 1-3



Redline is 7700rpm, no point going that high though as the cams don't warrant it. Of course when some bigger ones land it'll be useful and may go up to 7800rpm - but you need to keep a relative safety margin on hydraulic tappets. Got a daily now though, so could always put solid tappets in and rev it out to 8500rpm!!

Back on topic though, I'll look out for the app and next time I take the car out will have a nosey at the numbers.

How is my 197 doing 3.5k revs at 70mph then?

 

[Big Ben]

197's got shorter final gears compared to 200 box Jason. Think Rich has a custom built box...

 

[TB Rich]

yeah I've paired a different final drive to early 197 ratios (which has the longer 1-3 and shorter 5/6) vs my original 200.

Based on 215/45/17 tyres...
-Early 197 @ 70mph ~3600rpm
-Later 197 / 200 @ 70mph ~3350rpm

 

[Jimmy]

System Scorpion resonated cat-back (R27)
Iphone 5C
Phone location - passenger Recaro
Idle (from cold start) 80.2db. Peak (start-up) 92.7
70mph Not done yet - no opportunities
Acceleration from 70mph As above
Radio OFF
Fan OFF
Windows UP
Seats/Parcel Shelf FITTED

That's all I really had chance for today, will try for a warm idle tomorrow.

 

[Micah]

Seems to be getting worse now. 70mph on a level stretch of road averaging at 93db, that's like 4 more than the first time I tested. Had the seats down last night to fit in all the pressies from my parents and maxed the free app out at 99.9db under moderate acceleration.
Something doesn't seem right [emoji20]

 

[Jimmy]

It seems like you're really not enjoying this new exhaust Micah is it just the app reading that's convincing you things are getting worse, or can you 'hear' it getting louder, if that makes sense...?

If it helps at all, I have had something that's been bugging me... I like having the windows down when I'm driving to better hear the nice new noise. However, when I do that I can hear a slight vibration/rattle sound on acceleration... I know that you're a worrier like me, so the point I want to make, is that these worries can spoil the enjoyment of our cars. They aren't perfect and if we try and chase every little fault to try and make it perfect, it can be a never-ending game.

That's not to say that you should ignore anything serious, however I think we can all be guilty of overthinking things and causing ourselves problems that we really shouldn't.

 

[Big Ben]

Seems to be getting worse now. 70mph on a level stretch of road averaging at 93db, that's like 4 more than the first time I tested. Had the seats down last night to fit in all the pressies from my parents and maxed the free app out at 99.9db under moderate acceleration.
Something doesn't seem right [emoji20]

Might be time to get it up on a ramp and see if everything is connected/sealed as it should be. You could tick that box and then decide wether to keep it or not.

 

[Micah]

@Jimmy Definitely notice it without. Both me and the gf thought it was louder (she really hates it) which made me use the app a few times since last night. I'm really disappointed to be honest, I can't think what could be wrong. My mate fitted it and he is a very skilled technician who works on supercars for a living, and an exhaust centre also checked it over.
I will likely put the standard system back on and sell it, just doesn't seem to be right for this particular car. No amount of padding under the boot carpet is helping either. Totally miffed!


Sent from my iPad using Tapatalk

 

[Jimmy]

Such a shame @Micah I can understand how frustrated you must be! Do you think you might get used to it over a bit more time?? Do you use a lot of motorways then? I haven't used them apart from the trip to Peterborough the other weekend, so I suppose I've not experienced it much at 70mph...

I do think it's a very loud exhaust for a resonated system, but I'm enjoying it - I like the extra noise and it's really not too bad around town. So it does very much depend on how we each use our cars as to how much we like it or not. It won't help that your girlfriend has no time for it either...

I know that @Pav 's is very loud (non-res) and he did suffer with it on the trip to Czech...

 

[sevenfourate]

I'll get some readings next time i'm out......

My trial on the app i had; wasnt giving readings like your though TBH.

Scorpion worth a bell ? Do they publish db readings on their website site in ref to this system (Be amazed if they didn't).

 

[Micah]

Hi guys. As I was working from home today and getting more and more stressed about what's going on with the exhaust and thinking the car is just a pile of sh*t, I decided to take a break and remove the rear diffuser - what fun! It was so easy.
I then gave everything a damn good shake and checked clearances - the system was solid as a rock, perfect clearance from everything and the hangers were in very good condition. Started the beast up and it's definitely the 'so called' silencers that are the loud part. Covered up both pipes and no leaks (was a bit shocked when I uncovered them!). With my head dizzy from fumes I refitted the diffuser and went for a drive up the road and back. First impressions... quieter! Still some drone from 30 to 20 in fourth that goes through your head, and the app was always in the 90's, but didn't correspond to what my head was going through. Most strange. There's been a few piles of ash-like substance on my drive, and was also in the diffuser, but not sure what it is.
We shall see what happens tonight when I drive on the motorway.

ADDITIONAL COMMENT AND VIDEO AT THE END OF THIS POST!

Clearance


N/S Hanger


O/S Hanger


Ash??


Ice?!


On an exhaust related note (lol, great pun) I thought I'd check the flexi's at the manifold as I'm still paranoid about those. Video here, let me know your thoughts...

 

[Sean197]

Are you sure it's exhaust noise and not resonance? Maybe try different hangers which don't hold it so solidly?

 

[Micah]

Are you sure it's exhaust noise and not resinance? Maybe try different hangers which don't hold it so solidly?

It's definitely resonance in the cabin, and something @Jimmy also suggested. These are OEM hangers though, wouldn't anything uprated be firmer?
Time for Jimmy to get under his diffuser and have a look