Thread: Bigger Injectors

Originally Posted by Bigmark

Has anyone tried larger injectors, heres a write up i found on the internet.
What size do we have here in Australia.


"If you have a vehicle with a 90hp TDI and 5-speed manual transmission, you have injectors with 0.184mm orifices. If you have a 90hp TDI with automatic transmission in North America, you have injectors with 0.158mm orifices and a higher-pressure injector pump so as to push the same amount of fuel through these smaller injectors (for emissions reasons, at a cost of increased stress on the components and increased engine noise). The European 110hp model has what are known as 0.205mm injectors, and the European "Multivan" 150hp 5-cylinder TDI has what are known as 0.216mm injectors. All of these injectors are dimensionally interchangeable, so it is possible to install injectors one or even two sizes larger in place of the original ones. This will increase fuel delivery without the engine ECU knowing a thing about it, and it will do it without pushing the limits of the injector pump, nor will it extend the duration of the injection period - and not extending the duration is better for smoke, power, exhaust temperature, and efficiency."

Ummm - the above is about the VW TDI engines...

TDI FAQ

I don't know what engine you are asking about - but I'll guess 300Tdi!

I'm not aware of any off the shelf size options for 300Tdi injectors.

The injectors are Bosch manufacture, but AFAIK they are unique to the 300Tdi. Not surprising because each of the nozzle holes have to be at a particular angle to spray to specific locations in the combustion chamber - so they are designed for the particular engine.

I made inquiries about having the nozzle holes on my Isuzu injectors opened up, but had no luck locally. I may end up sending them to the USA to be done, but I have other things to concentrate on for now.

There are 3 methods for enlarging the nozzles:
1. Extrude honing - good for small increases in hole size. For large increases, there is the likely hood of producing waves in the hole, but worse is a rounding the inner edge of the hole, which adversely affects atomisation.
2. EDM (spark erosion). Not as smooth as extrude honing.
3. EDM to increase hole size, followed by light extrude honing to smooth it up - gives best results, but obvious costs more and less choice of shops that do both.

Some places will increase the number of holes, but this is for much larger fuel increases, and there is the problem of getting the angle of the new holes correct for the engine.