Thread: 4BD1T Turbo Sizing and Performance Prediction.

Originally Posted by Vern

Was going to remove the Pyro and use that hole, will see if I can find some copper pipe the same size as the probe. Ahh the joy of cars
My neighbour is a diesel mechanic, may have to ask a favour and get him to look at it, he did say something about putting a pressure gauge on somewhere and going for a drive, better give him a call

Fridgies are a great source of copper tube in all sorts of sizes.
I drilled another hole opposite the pyro. Drive pressure varies with EGT (higher EGT = lower drive pressure) so it's good to be able to measure both.

I'm not drilling more holes, I just don't have time for this, if I can't sort it over the next week, it goes in the shed until February, just don't have time. All the other isuzu's I have muck ed around with have just added fuel and boost, this has me stumped..

Originally Posted by Vern

I'm not drilling more holes, I just don't have time for this, if I can't sort it over the next week, it goes in the shed until February, just don't have time. All the other isuzu's I have muck ed around with have just added fuel and boost, this has me stumped..

Honestly I'd say park it.
You'd be amazed what problems and solutions you'll think of in a week or two away from it.

Plan was to take it on a trip to Tassie in 4 weeks, its so close, but with trying to run a business and the xmas rush on, my brain is fried. I will be REALLY disappointed if I don't take it away. will keep trying, just don't want to be having to pull it apart to drill holes is all I'm saying.


I wonder if Justin cooper is working on 30/12/14? I will be in his neighbourhood

Ok. Went for a spin, hit the governor in 1,2,3 and ran out of road to hit it in 4, didn't even make 5th. Speeds were 16k, 32, 71, 110.
Took the actuator arm off, wasn't really that much difference, was noticeable but not hugely.

Originally Posted by Vern

Plan was to take it on a trip to Tassie in 4 weeks, its so close, but with trying to run a business and the xmas rush on, my brain is fried.

Me too.

Originally Posted by Vern

Ok. Went for a spin, hit the governor in 1,2,3 and ran out of road to hit it in 4, didn't even make 5th. Speeds were 16k, 32, 71, 110.
Took the actuator arm off, wasn't really that much difference, was noticeable but not hugely.

The mystery deepens. More gauges needed. There has to be a blockage or leakage somewhere!
For a while I ran my drive pressure gauge off the same hole as EGT. The probe was long enough to reach through a T adapter.

In the last few weeks a Canadian has just got his 4BD1T with this same turbo and big intercooler running in an 80 series cruiser. I've asked him for some boost and acceleration times to compare.

So this engine was in a different rangie and working fine with the VNT turbo. You swapped it across to the LSE, changed the turbo and that's about it?

No engine came from a series3, I had it running with vnt in the lse only, but never drove it far enough to see how well it went, only around the block, vnt had a bent shaft. Felt torqier.
Wondering if its not getting required boost, dodgy gauge or actuator???

...in steps the least technical person here.

How about wastegate stuck closed? Or some other wastegate flow issue. My theory being it explains high boost and fuel being OK at smaller engine loads, but big loads in high gears causes too much back pressure? Winding the fuel screw back in appears to fix it because you never have enough fuel to cause the problem.