The_Josh_Bear
Full Access Member
This is essentially what Justin at R&D Idi Performance has said for years. He always likes the turbo engines around 6*BTDC, saying that it drives the turbo a little harder to help it spool up faster. I'm pretty sure Wes at Classic Diesel Designs is of the same mindset.My guess is because retarding the timing moves the combustion heat back, putting more heat into the exhaust and less into the piston itself. This is why some say ‘EGTs are just a number’
Moving that heat into the exhaust will spool up the turbo better, more heat moving is more energy moving. And with more exhaust force, the turbo will in turn push more air into the engine, an ingredient for better power.
As far as getting more timing out of the IP, I find it best to loosen ALL nuts for injectors and IP. That makes a big difference, then you can get all the movement your setup will allow. Also use a crescent wrench on the square block at the front side of IP or some people even have a fancy wrench that fits around the body.Miked, I have the same problem on my 94 factory turbo, It was smoking, especially on start up. I put new injectors in, and a turbo cartridge, then it smoked more.
Then I got all the tools to check the timing. It was retarded about 4 degress at 2000rpm. (The static marks were lined up though). Now I have it to 4 degrees advanced but can't move it anymore, like you. It doesn't smoke at all anymore.
Did you ever try 8.5 degrees, and did it make a difference from 4 degrees advanced ?
Bear in mind that at some point, a worn out(or poorly rebuilt) IP can run out of adjustment space and still have retarded timing. Meaning there's a point where your inability to turn the pump isn't the factor.