Inlet mani plumbing...

F

F4kus

Member +
Yo, Just a very quick question for anyone that can be bothered to have a quick look in there engine bay... I just dropped a new lump in my starlet and got everything connected up but cant figure out what is meant to connect to this on the inlet Manifold ( Pretty much next to dip stick) Is it some sort of vac line>?

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F

F4kus

Member +
Cheers buddy, would the hose for this have been attached to those muliple vac lines near cam belt cover/boost solenoid? Do I need to connect anything up to it or block it off? Im a bit confused....
 
Texx

Texx

Super Moderator
The fuel pressure regulator should be connected directly to that port using a single short length of vacuum hose with nothing in between.
 
F

F4kus

Member +
Sorry for all the questions, which is fuel pressure reg? I cant figure out where that hose would have gone when i took the engine out?? Maybe its just late and im being stupid... Cheers for both your help =)
 
dark_knight

dark_knight

Member +
Texx said:
The fuel pressure regulator should be connected directly to that port using a single short length of vacuum hose with nothing in between.
Click to expand...

i've seen lots of chaps taking their boost readings off this line. is there any relative danger to this..? besides a sluggish response on the part of the FPR when manifold pressure changes..?
 
S

STARLET N/A

Member +
most boost controller instructions will tell you to take the a vac line from there so that probably one of the reasons why
 
dark_knight

dark_knight

Member +
my boost gauge feeds off the MAPS line and i chose this because electronically speaking, this is what the ecu uses for its' calculations so it would be the closest reading possible to the actual manifold pressure state.. :)
 
A

AdamB

Member +
It will depend what you class as "boost pressure"
You can take a vac feed from the turbo nipple for example, that will be the closest possible source to get the "boost pressure" the turbocharger itself is producing.

However when taking readings from the intake manifold this will give you a source as to that pressure in the manifold which in a force inducted engine should be above atmospheric, but don't forget by the time the air coming from the turbo outlet gets to the intake manifold it would have lost pressure and velocity due to flow restrictions.

Theoretically the pressure in the intake manifold should be that of Gauge pressure + Barometric pressure, which is known as Absolute pressure. For example your turbocharger may be producing 1 bar of gauge pressure, and the pressure outside is say 1001 millibars or 1.001 bar Barometric pressure. Therefore your Absolute pressure is 2.001 bar. Hence the reason why turbo compressor flow maps work on pressure ratio's.

Just my input :)
 
wildchild

wildchild

Member +
dark_knight said:
my boost gauge feeds off the MAPS line and i chose this because electronically speaking, this is what the ecu uses for its' calculations so it would be the closest reading possible to the actual manifold pressure state.. :)
Click to expand...

i tried this and my car kept stalling and missing. now its connected to one of the vacuum lines right above the TB.
i also realised that there is a significant pressure/vacuum difference in the inlet manifold before and after the butterfly valve in the TB.
When the valve is closed as in idle then theres a vacuum in the intake manifold after the TB and on the otherside (that is at the beginning of the TB inlet) theres a pressure from the turbocharger spinning and forcing air. There is a difference in readings on these two sides at different times and levels of boosting. i guess it never occurred to most here?
 
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