Offroad-Express

hey all, where is the best place to plumb a gauge in??
there is a few hoses around the inlet manifold not sure which one it is thanks

best place is between pressure sensor and the little filter which is positioned on the inlet manifold around #1 cyc as the filter will stop the gauge flickering with pressure fluctuations.

cool. i found that and had it on went for a test drive all sweet as. getting 12psi tops, sounds about right thanks for the quick reply mate

first of all: please excuse my ignorance... but plumbing the gauge in where is will not be affected by pressure fluctuations seems to defy the logic of installing one in the first place...
i'm used to turbo petrol jappas so maybe this isn't relevant, but i have always wanted to see the pressure fluctuations... knowing your boost level doesn't make much difference if you can't see spiking (sudden rises in pressure) becasue 99% of the time your boost should sit at the predetermined (by the wastegate actuator) pressure, but it is the 1% of times that it doesn't that kills your engine (wastegate/actuator sticking, dodgy boost tap letting air out at uneven flows etc).

Surely this is the sort of thing you want your boost gauge to actually read?

please correct me or call me an idiot if it's appropriate;-) (and explain why?)

on a petrol yes you do want to see them and you will still see fluctuations it just dampens the reading, on this engine(1kz-te) you get the needle jumping around by 2-3psi at a rate you can't see, also it is not such a issue on a diesel as air-fuel ratio does not need to be as precise as it does with a petrol. which is why most diesels don't run a throttle body to control the air flow, with a diesel if you run rich you just blow smoke and if you run lean you simply don't make as much power, ie you can run the same amount of fuel at 18psi as you do 12psi boost with no damage you just make the same amount of power. but if you did that with a petrol you would no longer have an engine. hope this helps explain it .

Cheers for that mate, much appreciated!

Yep, it did help too, i'm still struggling to figure out why the needle would be jumping around in the first place... especially with no throttle body the pressure between the turbo and intake would be fairly consistent the whole way through (bar a bit of pressure loss due to the pipe's resistance etc)... and if it's a mechanical gauge, and it's "jumping" around, does that mean your actual boost level is jumping around too? or is the mounting point of the boost line near a venturi/vortex inducing bend/protrusion?

hmmmm sorry about all the questions mate i'm just trying to get my head around it so i can try and understand a bit better;-)

no probs. from what i can work out it is the pulsating effect of the intake valves opening as it does not have a intake plenum like most turbo charged engines. Toyota was obviously not worried about it as they installed the little filter to give a smooth reading for the map sensor as to why this is i'm not sure but i have noticed on the intercooled pardo 1kz motor there looks to be a small plenum on the intake and they move the map sensor to read from the intercooler rather than the manifold and taken the filter away.