Originally Posted by
Stu @ M Developments
Boost doesn't help power in diesels mate, it just allows input of fuel. The whole system works backwards to the petrol engines you know and love. The more boost you add, the less power they make, unless you balance it with fuel to richen it back up.
Power on a turbo diesel is simply a balance between temperature and smoke output in essence.
The more fuel we add, the hotter and smokier it gets. The boost is there to lean and cool it all back off again.
Bad mapping is rife in this cars era as the DPF hides the soot, so tuners not working with EGT and AFR are creating time bombs, lots of failed turbines, cracked heads, cracked pistons etc. in the good old days they just made them smoke a tad and you were there, but now you can't see it. Lol
ive seen the aftermath of an old 22 litre diesel that was running to rich black smoking all the time in the end it split a piston right through the middle just 5000 hrs after rebuild !
i rebuilt the motor and diesel pump in 2007 and its done over 9000 hrs to date still going strong and using minimul oil
my gtr runs 6 temp probes in the manifold runners and it was tuned to keep it safe at i think ryan said about 1000c or just under max.
to keep in that envelope on v power it runs 1.3 bar mid range 1.5 bar uptop anymore and its past the temps he wanted to see.
on e50 it can run 1.6 bar midrange and 1.75 bar uptop and temps stay below 1000c 950hp.
i never used to really worry about it but now i have the data if i ran 2 bar of boost on v power the afrs would no doubt be ok but the temps would be so far through the roof it would no doubt fail in the end
whats the actual limit on temps for a diesel stu in the manifold roughly ?