Back again. Isuzu 4bd1 turbo in my loading shovel. Just find the engine a bit short of horsepower. I thought it should be just a but quicker to rev up to max etc. There is a non genuine exhaust set up as possibly this isn't the first day engine in this early 90s machine so more than lightly something was put together to donthe job. The pipe work coming off the turbo is all only 48mm (outer diameter) steel before going to the silencer exhaust. Should it really be 3 inch ? Could I have too much back pressure ?
It “looks like” a factory job.?? Have u checked boost pressure.? There’s usually a plug on the intake manifold that can be removed and a standard fitting installed to hook up a length of hose and a 0-30 psi gauge, so u can put it in the cab and monitored while driving under a load.. Check it as it’s set up now.. record the readings.. THEN, unbolt the exhaust flange and rerun the same route.. compare the readings.
Maybe fixing the exhaust leak you have will correct your issue.