Welcome to IsuzuPiazza.com :: Uniting Isuzu/ Holden Piazza Enthusiasts since 2002

hi just asking what piazzas run stock
any in fo on this would be good all so does any one know at what pressher the bost reless valve on intake opens

Hey mate, please search forum first b4 asking questions wich already have been answerd.. Also I believe this information is available on the main website.

7 PSI if you must know..

Chris wrote:Hey mate, please search forum first b4 asking questions wich already have been answerd.. Also I believe this information is available on the main website.

7 PSI if you must know..

thanks heaps and i did have a good look but there was know clear answers out there. Also does any one know what psi the emergency over boost realese valve opens on intake <not the one on turbo>

About 10psi I think but don't quote me mine might just be sad

overboost valve opens at about 10 or 11 psi from experience

gonna bin mine shortly

the silly pssst pssst pssst all the time is starting to get rather annoying!!!

cool thanks guys ive herd that a 1in brass water cap fits just right.
i cant wate to get mine going in ute so i can have a bit of fun
tring to find some one around my area thats got a piazza so i can go for a spin with them to see what they go like.

pop on over and madmike will take you for a gallop in his, that'll keep your attention!

I think I tested mine to open at about 9psi, I stuck an extra spring in to stop it opening but then I got given a plug since, but no I couldn't just leave it at that I had to go make a fancy billet alloy adjustable valve..

The thread is more like 1.25 inch if it's an imperial thread

The thread for the overboost valve is 1" BSP and they open standard at around 10psi. However and here is the sneaky bit. Once they open they can continue to bleed off until the pressure drops back to about 7psi. Don't think its meant to be like that but age and gunk probably prevent a fast close.

thanks everyone thats cool i going to piss mine off after i get the aftermarket ecu but any info on piazza is good info as i dont know much lol thanks

1" bsp actual diameter is 32-34mm? What a silly way to do that...

1" bsp actual diameter is 32-34mm? What a silly way to do that...

The reason for using a pipe thread is sound, it is self sealing without gaskets and as it is a BSPT and not BSPP it releases easily for removal which is always a good idea when screwing into alloy.

I now feel compelled to show i did learn something during my apprentice years.

Tubes (usually thin wall) are measured on the outside diameter, pipes however are measure as a nominal bore size. In other words 1" bore pipe can be larger or smaller than 1" depending on wall thickness as the outside diameter can't change to comply with manufactured fittings like tees, sockets, flanges etc. When Mr Screwit Ltd decided it would be a good idea to join pipes and fittings with threading as opposed to welding he had to invent a thread that was fine pitch for effective pressure sealing. The thread of course isn't 1" at all it is a thread that is cut on the outside of a 1" pipe. Universally it has become a " 1" PIPE - thread " and not a 1" THREAD - pipe" This applies to all sizes and is universal throughout the world, even in European and Asian countries. EXCEPT the USA where they speak funny and invented their own thread, the criteria for sizing is still the same but they use NPT which is a coarser version of BSP and the twain don't mix.

All of this applies to all sizes of pipe from 1/2" up to 6". It is unusual to find threaded pipe larger than 6" To further confuse the issue they derived two versions of BSP, parallel and taper forms. Tapers for standard fittings and parallel for running threads such as used on screwed tube and tank fittings sealed with backing nuts and sealing washers where a taper would be a pain the scrotum.

By the way there is no such thing as metric pipe, sure all the pipes and fittings are now being sold in metric designations such as 15nb, 25nb, 32nb, 40nb etc. etc, but it is a soft conversion as no physical change has taken place.

Here endeth the lesson...not that anyone is still awake