i have replaced some hose with 8mm. But only the ones that were 8mm. My vacuum hose is 3mm but looking at going 5 or even 4mm
 
The ID of the hose will not make a blind bit of difference to anything.

Its more the physical size of the actaul connector that will determine the ID of the hose. I.e you wont get a 3mm hose on a n75 barb.

If anything, +3mm ID is more likely to cause leaks.
 
In the same way the piston size in a brake caliper is irrelevant......:blink:

I didn't see anyone mention brake calipers or pistons?? In the context of the post then the vac line ID is irrelavent. Changing from a 3mm id pipe to 4mm pipe isn't going to make any difference at all.
 
so a 5mm id will pull harder than a 3mm id. Because if it does then thats what i want. Or am i bein stupid?
 
Yeah 5mm cause's less friction so should pull harder on your dv. Although how bigger difference it'll be cause of the pressures invovled i dont know.
 
Most people on here don't even have heat shields over there turbos/exhaust manis. If you wanna reduce under bonnet temps there the place to start looking.
 
why did heatshielding come into this anyway matt?

Mind you i have been looking at that heatwrap for when i get new down pipe fitted. Do it all at once.
Reduce temp a little. But i purpose if u wanted to keep any thing hot or cold you could heatwrap it. Would probably end up lookin a mess though.
 
just thought it may have been something to stop the lines going a bit soft and spungy when they grt real hot :shrug:
 
i wouldn't wrap the down pipe. But while it was off i would do manifold. And heat wrappin something would keep the heat in! Thats right aint it?