Fixing a boost meter

JohnCKL · Post by **JohnCKL** » 10 Apr 2004, 07:58

Hi, has anyone fixed a boost meter running from the engine bay of a Xantia 1.9TD to the cabin? I have an old 30psi pressure meter but need to run a 1cm diameter reinforced clear tube from the engine bay through the firewall to cabin. Where would be the best place in the firewall to thread the tube through? Thanks.

BonceChops · Post by **BonceChops** » 10 Apr 2004, 12:42

Why use such a large pipe?
My temp gauge runs through the gap between drivers door and pillar using 4mm OD nylon pneumatic pipe and works perfectly.
It's been there for months [:D]
Neil

Dave Burns · Post by **Dave Burns** » 10 Apr 2004, 14:41

Before going to the trouble of fitting it, try it with just the pipe going into the cabin through the open passenger side window to the gauge.
A dedicated boost gauge has built in hysteresis to counter the rapidly fluctuating air pressure in the manifold, especialy at lower levels, this type of gauge also needs to be able to cope with vacuum and read negative boost to prevent damage to it, the needle on your gauge will very likely vibrate rapidly as each pressure pulse is recieved, the gauge wont last long in that state.
You will have to use either very small bore tube or experiment with different levels of restriction in the tube you plan to use if the gauge is to last, providing it can resist the small amount of vacuum its likely to encounter.
Dave

vanny · Post by **vanny** » 10 Apr 2004, 14:54

Diesels dont get vacuum the way petrols do so they never go wildly negative (making half the guage completely useless!) You'll need a guage that goes to at least 2 bar to make it any use on a TD engine. 1cm diameter is way to big unless its got a really small ID. On the BX i had my pipe run through the same hole as the speedo cable (and before you say it, i put in a new hole so the speedo cable fed into the right instead of the left. Probably not massively usefull, but its not hard to put a tiny lil hole in and a grommet. It will probably fluctuate quite a bit on idle, but as the turbo speeds it the guage will become steady and accurate (dependant on the quality of the guage). The way round the low speed vibration is to put in a tiny canister type fuel filter (the sort fitted to the likes of ride on lawn mowers) or at least thats what im told!

oilyspanner · Post by **oilyspanner** » 10 Apr 2004, 15:59

My boost pipe only measures 4mm diameter, I poked a drill through the bulkhead, through the soundproofing and fed the pipe through, finishing off with a blob of silicone sealer around the hole forming a neat grommet and seal in one, next I ran all of the pipes and wires up to behind the dash mounted tweeter (BX) and fed em through the grille, no visible holes. BX with water temp and turbo boost, I wish it was as easy to get at the wastegate......
Stewart

JohnCKL · Post by **JohnCKL** » 10 Apr 2004, 18:09

Hi all, thanks for your advice and tips. I should have gotten a smaller adaptor and a smaller hose. I thought the hose should be the same size as the one connecting the intercooler air hose to fuel pump. The pressure meter belongs to my dad's era. lol. It has no negative reading as it is the analog needle type. I could just test it through the window first as I don't know if it is still accurate. Thanks again.