Thread: Query on setting up turbo on NA 4BD1

Originally Posted by rar110

I fitted a GT2560 (GT28R ?) to mine on a genuine Isuzu top mount T2 manifold. It spools up fast, engine doesn't smoke, so I don't think it is over fueling. As with Ben my compressor had to be rotated requiring some modification to the actuator arm. I had mine fitted by a Brisbane turbo specialist with a long and good reputation. The result was excellent but cost a lot more than Ben's. Two things the installer insisted on was an over boost safety valve and new injectors. I went 3" mandrell pipe with a lukey muffler.

besides the obvious ,a overboost safety valve, ????????
i no see no hear nothing of,
please explain?

Originally Posted by dylan gover

besides the obvious ,a overboost safety valve, ????????
i no see no hear nothing of,
please explain?

It is just a valve on either the inlet manifold or the pipe between the compressor outlet and the manifold. It is set so that if the wastegate sticks closed (etc), causing the turbo to overboost, then the valve will pop open and vent the excess pressure.

There are a few pics floating around of genuine 4BD1T setups which show them.

Originally Posted by isuzurover

It is just a valve on either the inlet manifold or the pipe between the compressor outlet and the manifold. It is set so that if the wastegate sticks closed (etc), causing the turbo to overboost, then the valve will pop open and vent the excess pressure.

There are a few pics floating around of genuine 4BD1T setups which show them.

A blow off valve...acheewww achewwww

Originally Posted by rovercare

A blow off valve...acheewww achewwww

fully sik bro!

Originally Posted by rovercare

A blow off valve...acheewww achewwww

I am sure there are some people with BOVs on diesels... You would have to install a throttle butterfly to get it to actuate though

I know someone with an automatic rotary who installed a BOV

Originally Posted by isuzurover

I am sure there are some people with BOVs on diesels... You would have to install a throttle butterfly to get it to actuate though

I know someone with an automatic rotary who installed a BOV

SD33 comes with a throttle butterfly, well the turbo equivelant does

Originally Posted by rovercare

SD33 comes with a throttle butterfly, well the turbo equivelant does

So do the Toyota B, L and KZ series.
But that's not all, you get free head cracks too.

Some diesels use a pneumatic governor, the butterfly pressure difference is what sets the fuelling. One advantage is reduced NOx emission due to less excess air. One big disadvantage is the pumping loss that goes with that.

While our Rangie isn't on the road yet we got a turbo kit from Turbo Glide in Wollongong, they are very helpful, we did the install it ourselves, a friend who is a pro welder brazed the oil feed to the designated nut and added the connector to the removable panel on the left side of the Isuzu.

The turbo itself is based on the Garrett T25, if I heard John correctly Garrett added an internal wastegate which the standard T25 is missing, he said it is made for the army 6wd Landies.

I asked a diesel mechanic we know about adjusting the injector pump to match the turbo, he told me to get the motor going and adjust fuel flow till we get the standard boost pressure, I'll try it his way first.

John also told me to get my EGT probe and meter from Wadeair at Spring Hill near Orange, from memory I had to ask for the meter from China and a 8M X1 probe, I rang up and ordered the parts they were in our PO box the next morning. Talk about great service.


Glenn