Exhaust Whistle

[jonathon555]

Just got a 172 mk1

its done 35k & the engine feels really tight, On the very top end of the rev band the exhaust makes a whistling noise.

This feels like it is restricting the engine can anyone help ?

Will a decat make it free reving & how much power does it add ?

 

[BenR]

the early MK1 cats are not that restrictive and decats will gain a bit, nothing drastic.

as for the whistle......describe in more detail, where from, can u hear it outside/inside the car, you sure its not teh intake?

 

[jonathon555]

The whistle sounds like it is coming from the exhuast, but it may be from the engine bay.

the car revs cleanly but for the last 1000 rpm you get a low whistling noise.

I drove a mk1 172 a day earlier before driving this one and it revved more freely on the last 2000 rpm with no whistling noise. But it was slow unitil the last 2000 rpm.

I have only heard a whistling noise like this once before & that was on a 1988 pug 309 gti.

Do these 172s run best on super unleaded or 95, what is the easiest way to make it free revving & gain mods.

Is there anywher why i can find results of tuning ?



Cheers Jonathon

 

[BenR]

check the inlet pipes under the airbox.

 

[jonathon555]

What effect will the inlet pipes under the air box have on the performance & noise?

 

[BenR]

if they are loose/jammed/squashed (made of a fibre) then it will hinder you and possibly make a noise....

if it was teh exhaust it would blow and make a farty noise rather than a whistle.

unless you are moving fast and have teh window ajar or something silly like that.

 

[RenaultFreak]

I think that the valve lift change at higher revs (+5k) makes the engine sound like that...

 

[BenR]

what valve lift change?

 

[SHORTY]

mines makes a rattle at the last revs , a bit like a exhaust heat shield thats a bit lose nothing major it still pulls like a b*****d but still come to think of it
it does sound a bit like a whistle noise
mine has 37k