Overboost v Wastgate

[jackmech2]

Do the 4jb1's with a overboost valve have a wastgate aswell?
These two devises seem to do the same thing to me.... does the overboost act like a dump valve?
I think the wastgate controls how fast the tubo spins (thus the amount of air that enters the engine), does a turbo with overboost valve spin as fast as it can untill the max pressure is reached?
I'm only curious so don't put too much priority to this question.

[pig75]

Yes they have a wastgate and over boost valve
The over boost valve is just a safety valve in case something goes wrong with the wastgate

[98Rodeo]

the turbo will push about 17psi beofre the overboost kicks in too,
if you want to test if this works (not saying its a great idea) disconnect the wastgate actuator line and see how much boost you get

[ftomas]

The overboost is a simple valve with just a spring... and when open sends the excess air to the breather hose and the turbo sucks air from the airbox and breather hose... correct?
If that spring loses strength with time maybe it opens soon?

And the wastegate not only protects the engine from excessive air pressure, but essentially from excessive rotation on the turbo... correct?

The fact is the 4JB1TC that was applied to the Vauxhall (opel) fonteras doesn't have the overboost valve (i think my frontera is the only one i see with that valve!!)

Can we blank the overboost valve??

Regular frontera 2.8, with turbo and front IC

[jackmech2]

the turbo will push about 17psi beofre the overboost kicks in too,
if you want to test if this works (not saying its a great idea) disconnect the wastgate actuator line and see how much boost you get

My rodeo is an Australian import, so doesn't have the overboost valve, thats why i was wondering about it?

[pig75]

Can we blank the overboost valve??

Other people have and have had no trouble

[wbski007]

My motor is a 2001 2.5 and as far as I know it never had a overboost on it, just a waste gate, I tightned up my spring so now I'm getting 14 lbs of boost, was only getting 10 lbs before, it made a big differance, then I had to give it more fuel, now its like a little rocket compared to the dud it was before.

[4x4fun]

The item pointed out in the picture isnt an overboost protection, its part of the cold startup system, its job is to choke the engine so it gets air, You dont have an overboost valve its normally where that plate is pictured on the inlet manifold

[pig75]

I think the picture was used just to show the blank manifold

[DAYLIGHT24]

Does any one have any idea on how to up the boost on my 3.1 wizard easily?i hear of this idea of packing the spring with two washr on the 2.8,but have no idea where to find it on my wagon.

My motor is a 2001 2.5 and as far as I know it never had a overboost on it, just a waste gate, I tightned up my spring so now I'm getting 14 lbs of boost, was only getting 10 lbs before, it made a big differance, then I had to give it more fuel, now its like a little rocket compared to the dud it was before.

[Captcol]

I saw $30 boost controllers on ebay from a link on here, with a boost gauge as well you could tell exactly what is going on.

[lewis]

Try trademe, I bought a second hand Go Fast Bits inline boost tap for $20 and a boost gauge for $15, yet to fit though Should be easy in the wastegate hose