Boost coming on too early?

[Downhillnz]

Hi all,

I have just fixed my external gates leaking issue. I have gone from target boost at just over 2k to just on 1.5k. My target boost is 15psi

It makes it feel lazier to drive in the mid range. Or more flat.

Anyone else have this issue. Do I just wind some more boost at it?

4jb1 with a vf8 hybrid.

[isuzurob]

more fuel as the turbo is moving alot more air than a standard turbo, also adjust the boost compensator on the top of the injector pump

[Downhillnz]

That had been done when I first put the turbo on. Maybe I have been used to it just coming in later with more punch? Or so it feels?

[Powertruck31T]

If you only have the standard 10.5 housing on it with the larger vf8 compressor and you have played around with the fuelling and it still feels flat I would say your drive pressure is getting high. The 10.5 housing chokes up real fast when you start introducing more fuel. Try track down a 12R housing like hens teeth to find now days though

[Powertruck31T]

Try backing the boost off to say 9-10psi and see if it feels any better. This will lower the drive pressure in the manifold and allow it to breathe better. Only other way is to put a fitting into your manifold and actually measure what drive pressure you have this will tell you straight away. Most jap turbo diesels will run a 2:1 ratio between exhaust and intake in standard form

[Downhillnz]

I have a 15R in the garage off a 3.1
How bad is the lag going to be if i swap them out?

[geeves]

My old 4jb1 was pretty flat from 1800 up to about 4 once it had a 2.5 exhaust snorkle open filter and a tickle from the diesel shop. It was all on at 1800 and didnt change much to just below red line. I miss that motor