How soft is too soft for turbo hose?

[JamesH]

Hi All

I have not noticed any decrease in power or anything but the other day after seeing those sexy silicon hoses in a related thread I gave my 90 deg hose a squeeze. It is oil soaked and quite easy to pinch, much easier than the rubber cooling hoses. Is tyhat normal? It does not show any signs of collapsing in on itself but could it be doing so under load?

(Thanks Rick130 for reminding me of this in your reply to the other thread)

[pawl]

They won't collapse as there is positive pressure in them. How soft is too soft, I don't know, but I installed silcone hoses after thinking mine were too soft and made no difference. But at least I have removed the possibility of failure of the soft hose.

[5teve]

pressurised on the turbo side, vacuum on the engine side isnt it?

Thanks

Steve

[Scouse]

Positive pressure or not, they do suck in when they get very soft.

[pawl]

pressurised on the turbo side, vacuum on the engine side isnt it?

Thanks

Steve

Pressurised from turbo to engine, vacuum from airbox to turbo

[feraldisco]

Positive pressure or not, they do suck in when they get very soft.

How can something suck in with positive pressure (i.e. being fed from the turbo)??? :confused:

[Yorkshire_Jon]

The biggest problem isnt necessarily the hoses squashing together, but the standard hoses can delaminate, looking fine on the outside and restricting air flow on the inside.

Take them off and have a look inside them, best you can. They dont normally cause problems.

There arent really any performance gains to be had by changing, but the silicons do look better!!

Weve run silicons for testing purposes but, unless I have to replace a pipe, I'd leave the stock items in place.

[rick130]

The biggest problem isnt necessarily the hoses squashing together, but the standard hoses can delaminate, looking fine on the outside and restricting air flow on the inside.

Take them off and have a look inside them, best you can. They dont normally cause problems.

There arent really any performance gains to be had by changing, but the silicons do look better!!

Weve run silicons for testing purposes but, unless I have to replace a pipe, I'd leave the stock items in place.

Ditto what Jon said, except I didn't want mine to delaminate in service, (it was pretty sopping wet) so swapped it out. A 90* 2" silicone hose is pretty cheap. There is no performance gain.

[Blknight.aus]

http://www.aulro.com/afvb/technical-chatter/49850-td5-recent-turbo-lag.html

theres a good link on it... post 10 (yes its one of mine)

details the main methods of failure for the hoses and how it happens but the real short version is..

at idle the turbo aint doing squidly, when you hit the go pedal hard the turbo lags behind the engines demand for air and a manifold low pressure condition exists, once this happens the engine cant draw enough air, therefore cant burn the fuel so the turbo doesnt spin up and your hose stays shut till you back off and slowly apply the loud pedal OR an alternative situation (like a coast down hill) means the engine needs less air.

as for how soft is too soft... take the cap off of your cooling system while its cold, squeeze the top hose (assuming its new if it aint go ask someone whose got a new car if you can do this) thats about the same level of stiffness that a turbo hose should have..

[Scouse]

How can something suck in with positive pressure (i.e. being fed from the turbo)??? :confused:Just going by experience.
A soft hose is also a sign that it's delaminating too.

[feraldisco]

Just going by experience.
A soft hose is also a sign that it's delaminating too.

mine are positively flaccid...the intercooler hoses that is...:blush: but with absolutely no signs of delamination (i.e. they look in good nick inside and out)... Nonetheless, Dave's post above has convinced me to go silicon...

[llandro]

Mine is (was) a bit like that.... so... with a dash of lateral thinking I made up a coil of stainless mig wire and inserted it inside.
Bit fiddly, but the fact the hose was liberally well oiled made the insertion easier, now no chance of collapsing.
Turned the ends out so they stick in the hose, but no chance of moving anyway.
Bloke should patent it,eh!
Owning a Landy means you always need creative thought foremost!
llandro

[Blknight.aus]

Mine is (was) a bit like that.... so... with a dash of lateral thinking I made up a coil of stainless mig wire and inserted it inside.
Bit fiddly, but the fact the hose was liberally well oiled made the insertion easier, now no chance of collapsing.
Turned the ends out so they stick in the hose, but no chance of moving anyway.
Bloke should patent it,eh!
Owning a Landy means you always need creative thought foremost!
llandro

thats very intuative thinking and while I like the approch (going to rain on your parade here sorry :( ) whats going to happen is that where the hose pulls in and rubs on the wire or the wire vibrates from the air flow it will chafe through the rubber causing premature delamination......

[awabbit6]

I recently changed the two short hoses between the turbo and intercooler on my Disco. What prompted me to do this was watching them swell significantly when giving the engine a rev (no load). It was like watching a balloon!
They were quite soft so I pulled them both off and they had started to delaminate where the clamps were fitted. I got intouch with a mate of mine who builds high performance turbo charged Jap engines (Subaru mostly) and had a chat to him. He was able to supply me with a couple of silicon hoses. No hose swelling anymore ... no noticable performance increase either, but I really didn't expect any.
So to answer the original question - so soft they swell as the turbo spins up is too soft!

[RoverOne]

My originals now 11 years old wouldn't hurt to change them before something does go wrong, silicon it is.