[Pepper'D]

good suggestion gibbon

[cevans]

Well, lets set a few things straight:

I'm a VW diesel owner and an extremly active member of TDIClub.com, I know a bit about diesels.

150bhp is a very large strech for a 1.4L diesel. Remember that horsepower is the most power made by the engine, power that is created through revolutions. A petrol/gas engine can pull 5000-6000 RPMs, and that makes a HUGE difference with HP numbers. A diesel cannot produce power over 4500 RPM, no diesels can because of the nature of diesel fuel in that it takes a much longer time to do a complete burn. Higher RPMs than 4500 doesn't allow combustion, no power is made.

Someone made a reference to "tork", well, its torque first of all :-). Torque can be understood as how much power is made every stroke, or how powerful a downward force can be. Torque can cause clutch slippage very easily, once your clutch slips, you need a new clutch (the clutch issue plauges North American VW diesels). Why wouldn't HP cause slippage? Its easy to compare a car to a bicycle to explain: going up a hill it is very difficult to maintain speed using the highest gear, you loose speed and will continue to loose speed untill you stop because your legs cannot produce enough TORQUE. You shift into a lower gear and your legs are putting out less torque and moving faster, but you are able to maintain speed because more power is put to the wheel. Even though you can make alot of power, it comes from revolutions, not power of individual strokes.

Diesels are great because they have such powerful strokes, strokes are longer and compression ratios are usually double to comparable petrol/gas counterparts. This hihgher compression ration allows compression ignition and a better, more powerful, and thus more efficient, combustion.

How can you get more torque and more power? Chips are the first things that come to mind because they do a few things, including advance timing, increase amount of fuel injected, and increase boost. All these things can create problems, however, if used incorrectly (to be fair, *most* chips are safe). For instance, more fuel is great, to a certain point. Sooner than one might expect, you become over-fueling the engine and increasing emissions and soot. You could combat that my adding more boost. More boost equals more pressure, obviously, and with such a high compression ratio, very small boost adjustments make HUGE differences in peak pressure, more pressure, more heat. Too much boost, pressure and heat and you'll find yourself with cracked piston heads. Lastly, increasing timing assists in being more economical, but it also has many problems, mainly higher temperatures inside the cylinders(giving way to the aforementioned cracked piston heads) and much higher EGTs(exaust gas temperatures), bad for both the environment and your engine! Those with highly tuned diesels usually (well, should) have guages monitoring all these things to prevent major problems.

How are high performance diesels created? Mostly using different injection systems, most of which are extermly high pressure systems that atomize the fuel extremely well as well as other factors. Remember, however, those diesels are CONSTANTLY monitored by trained technitions, and a cracked cylinder head isn't the end of the world for them. For us, those htings mean $$ and inconvience!

Diesel tuning is so much different than petrol/gas tuning because the environment inside the cylinder is so much different. Gas/petrol engines are often modified to reduce compression ratios in favor of higher RPM power and ability. This sacrifcies torque and makes an extremely unejoyable city driving experience.

Stright-pipes are an extremly easy and quick way to increase power slightly, plus it solves the muffler maintence problem. K&N performance filters don't do too much, the engine is already getting enough air into the cylinders, it doesn't need less restricted flow through the air filter. (some will also say that K&N style filters often allow much more crud to get into your engine, thats another discussiong however).

Getting more power out of a diesel isn't impossible, it just takes alot of understanding, a little creativity, and the ability to recognize how much is too much.

Hope this helps people!

cevans

[Ibb]

Nice bit of info there Cevan, I'm sure that will help many of the MOD owners here.

[Pepper'D]

thanks cevan
whats your opionion on dump vaves on a diesel turbo?

[cevans]

Quote: Originally Posted by blb999&MS b

thanks cevan
whats your opionion on dump vaves on a diesel turbo?

I'm assuming that by dump vane or valve you are referring to a wastegate. I'm in the US and I can't really get much information regarding the type of turbo used in the MOD, so I can't say for sure. Most modern diesels use a variable vane system to regulate boost pressure, not a wastegate system.

If you were reffering to a blow off valve, they just don't work in diesels. Gasoline engines use the blow-off valves is to relieve pressure if the throttle plate is abruptly closed, pressure that will lead to surges. Diesels don't have a throttle plate, so there is no built up pressure.

If someone can give me more information, I can be more helpful! :-)

cevans