[Labiarat]

Does anyone know what a healthy TD4 turbo boost pressure would be? Ive done the searches but no luck

 

[hd3]

i've seen mine up to 28 psi ..
that was uphill in 4th gear .. @ about 3.6k rpm .. go-pedal on floor ..

only know that by glancing at a 'scangaugeII' for a split second
as i was more concerned with watching the road at the time ..

don't know if it would go any higher .. i've not tried to find out ..

regular driving .. normaly runs between 15 to 21 psi .. depending on engine loading ..

~~~~~~~~~~~~

a.f.a.i.k. my td4 be in good health

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i think .. but not 100% sure .. that 30 psi or so ( aprox. ) be about a top-boost average for most stock diesels ..

 

[Labiarat]

hmm sounds like mine is under boosting then as I am only getting 15-16psi im using dash command

 

[Labiarat]

Thanks for the reply HD3, anyone else with any figs for comparison?

 

[matacaibo]

Mine peaks at 215 Kpa absolute when accelerating hard, thats 2.15 bar absolute, about 30 psia, because its absolute pressure you are only getting about 15 - 16 psi of boost press.

 

[matacaibo]

hmm sounds like mine is under boosting then as I am only getting 15-16psi im using dash command

Might be measuring in psig, if it is add 14.7 psi to convert to psia

 

[hd3]

I am only getting 15-16psi im using dash command

does 'dash-command' read the MAP sensor for that ??

( i should have clarified .. my 'scangauge' reading was from the map sensor ..
( i.e. manifold-absolute-pressure ..
( not sure from where else one would get the boost info from the standard sensors on the td4

 

[hd3]

Might be measuring in psig, if it is add 14.7 psi to convert to psia

cheers .. just now learnt somethin' new

had never heard of 'psia' and 'psig' .. 'till now ..

a quick Google search clarified that one ..

 

[matacaibo]

cheers .. just now learnt somethin' new

had never heard of 'psia' and 'psig' .. 'till now ..

a quick Google search clarified that one ..

Yeah, if your reading goes below 14.7 psia its actually pulling a vacuum, think I might have some graphs somewhere, if I can find them I will post them

 

[matacaibo]

Heres a graph I recorded using Palmer PCMSCAN software & a Mobydick OBDII scanner, unfortunately the MAP pressure is in "Hg (inches of mercury), but Atmospheric pressure is normally about 29 - 30 "Hg. with the throttle open 100% boost pressure was about 65 "Hg or about 30 psia which equates to about 16 psi of boost

 

[hd3]

if your reading goes below 14.7 psia its actually pulling a vacuum

or one is situated fairly higher than sea-level .. engine at idle .. ??
saw mine at 13.9 once ( @ idle ) .. was wondering what was going on 'till i realised were i was ..
( hopefully that was the explanation .. 'n not something worse

 

[matacaibo]

or one is situated fairly higher than sea-level .. engine at idle .. ??
saw mine at 13.9 once ( @ idle ) .. was wondering what was going on 'till i realised were i was ..
( hopefully that was the explanation .. 'n not something worse

Where were you, half way up an Alp

 

[Labiarat]

Wow thankyou for the info, I will go back and have a look to confirm but... as the dashcommand has two readings one of which is the MAP which tops about 220kpa and another giving boost pressure. Whats confusing is the haynes manual stating the turbo max boost is 1.75 bar which is 25psi give or take

 

[hd3]

Where were you, half way up an Alp

no alps here .. just some big hills ..

i think it were 'see attached pic'
were about a week or two after the last major snowfall ..
i went up there to see if the road was open
( ignoring 'road closed' signs )
road had been bulldozed closed with snow .. i went around the first barrier
but next one would have needed a shovel ..
then i saw the height of snow above the road sides 'n figured it had been closed
due to the possibility of that snow bank collapsing onto the road and burying a vehicle
so .. i turned around .. sat 'n drank coffee whilst enjoying the view ( clear sunny day )

"A" on the pic is at 582 metres

figures .. as at about 500 metres .. 13.9 psi ( 95 kPa ) makes sense ..
https://en.wikipedia.org/wiki/File:Atmospheric_Pressure_vs._Altitude.png

( sub to .. https://en.wikipedia.org/wiki/Atmospheric_pressure )

trivial height info by county ..
List of English counties by highest point - Wikipedia, the free encyclopedia

What's confusing is the haynes manual stating the turbo max boost is 1.75 bar which is 25psi give or take

my Haynes has neglected to include that info :-(
i've a tuning box that adds about 33bhp to the stock 112bhp
so i guess that might account for more boost that standard at higher rpm ..
( i don't know what psi would be an 'over-boost' occurence ..
( in which case the ecu puts the engine into 'limp mode' for self preservation

 

[matacaibo]

Its generally accepted that Boost pressure is the additional pressure above atmospheric pressure or psig, MAP (manifold absolute pressure) is the pressure above absolute vacuum. So the figure from Haynes is wrong for either !!!, doesn't surprise me, the Haynes manual for the Freelander 1 facelift has several errors.
My first Freelander was a manual TD4 facelift without any form of tuning & my current one is an automatic TD4 facelift with a Roveron Synergy II with the wick turned right up !!, boost pressures are practically identical when compared to RPM, I haven't got my head around that yet !!