Quote:
Originally Posted by Gilly1964
Am I missing something obvious here but I would have thought that most of the difference in power output could be explained by the fact that the 30D (35D in the US) has one turbo, the 40D has two and the M50d has three?
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The use of multiple turbos is to eliminate turbo lag. My 550i had two turbos - one for each side of the V8. They were very small turbo's but I had full torque at 1700 rpm compared to my Porsche that only had full torque at 5100 rpm. That's why I say these are very complex machines.
To answer your question, on a diesel, you need to force air in the combustion chamber (diesels do not provide vacuum like gassers, therefore no butterfly valve) and you need injectors to dump fuel. The 3 key components are: cam timing (when to open/close the valves), fuel timing (when to inject fuel during the compression cycle - 20, 25, 30, etc degrees before top dead center??) and boost (how much). The number of turbo's dictate the characteristics of the power and not the total HP. For example, I can install one large turbo that produces more HP than 3 of the turbos on the 50d. But, those three turbo's are engineered to provide torque and HP right off idle because there is no turbo lag (engine characteristic). Therefore, off the line, the 50d kills my theoretical motor with a bigger turbo and bigger HP because it takes 3,000 rpm to get the turbo spooled up to provide the needed HP and torque.
But that's what I am getting at with this tune. There are physical differences in the motors which suggests to me the 35d is not detuned. It sounds like it is perfectly tuned with all it's accessories and parts. So, how is the tune getting
30% more power out of an optimized engine?
I bought the Dinan tune for my 550i about four months ago. I took it home for the weekend and drove it around normally to check drivability. The tune advertised +100 hp and +125 lb ft torque - that's huge. Then, I nailed the accelerator to the floor and omg. In fact, I could feel the car twist under me. It wasn't acceleration, it was violence. I called Dinan and spoke to the tech and he said, yep, that's what it's supposed to do. And I asked, how long does the engine, tranny and rear-end last with all this additional power. He said he didn't know, but it would be fun until something failed.
I removed the tune the next day.