Durham mate, Motech Mike done it, 184 to 215.
Like Enda has said, it is possible to see more power at times than expected. Take for instance a 320d 150bhp model, we have seen them getting to 210-215bhp with just a decat and map. We normally see the 184bhp 330D's getting anywhere between 220 and 230bhp with out any problems. It takes a hell of a lot to damage an engine and we have tried! There are so many safety limiters in place, that even if you ask too much from something on a map the safety limiter will not give what is asked for. But at the end of the day it's not all about numbers, and some people go over board on figures. What really matters is how the car drives after a remap.
Yep, BHP on a diesel is a bit funny.
The ECUs work by calculating how much torque is needed, and it'll do what it is told to keep on making that torque for as long as possible.
For a large proportion of it, you can infact imagine the engine is being limited back to make it drivable.
Towards the top end, where BHP starts coming in (BHP is a function of how much torque is produced at a particular speed, so F1 cars have big BHPs even though they make less torque than a lot of cars, purely because they do it at such a high speed)
If the engine can hold on and keep making the requested torque, it'll give better BHP.
It might even be the rolling roads themselves that help, as the car has an easier time on a dyno than on the road.
The tyres usually have is harder, but a good example is the time it takes for a run through the revs.
You'll see on a dyno a car in a low gear (to avoid a large difference to due air resistance) will be able to fly through the revs quicker than it can on the road.
In some cases, old dynos go can go crazy with a torque monster, and if a dyno doesn't have enough braking for the engine to work against, is can fly through the rev range before the turbo gets a chance to do its thing.
Normally aspirated petrol cars are a world apart. Tuning with one of them is going for the absolute maximum, but on a diesel (or even most turbos) you have to use a bit of common sense and stick to safe levels.
A hell of a lot of the big power Jap cars only do their power runs for a few nervous seconds before the boost level is turned way down for street driving.
Similar to nitrous, it's no good having an engine with a 600bhp print out if it is only used at lower powers.
The M50 and M52 petrol engines have shown themselves to be capable of very high powers, so imagine what a stronger diesel engine could do.
I might need to check the numbers, but I think you'll see most of the 3.0 diesels use about 1.25 bar of boost, some of the newer higher power versions run at about 1.4, and the 335d is at about 1.7 bar.
The boost doesn't give the power, it just allows more power to be made cleanly, but with a fancy turbo, bigger injectors, maybe an uprated diesel pump and intercooler you'd be able to get over 300bhp from a 330d.
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