hmmm interesting that you guys dont use diesel to calibrate the pumps. learn something new everyday!
one thing is for sure though... Giles is rebuilding my mTDI pump for me. the guys over in Europe building mech pumps have nothing on Giles. i'd buy stock in his company if i could :lol:
Thanks for the kind words, Jtanguay.
Main reason for not using diesel for calibration is that the ASTM specs for fuels don't closely regulate the composition or physical characteristics of the fuel. That is to say that they are functional guidelines, not chemical recipes. The difference is an important one - diesel fuel or gasoline must behave in certain ways, but their actual makeup is not stipulated at all by the specs that govern them. That makes it much easier for refiners to make diesel / gasoline, because they can "fudge" the numbers a bit depending on the makeup of any given barrel of crude. (OK, I'm sure that's more than enough info on petrochemical manufacture for everyone's liking but me :lol: ) Anyway, the spec that governs calibration fluid (VISCOR diesel stuff is only one example) is a specific composition guideline as well as a functional guideline. Basically, the upshot is that diesel or gasoline can vary wildly in terms of composition - all you know for certain is that it is within the necessary operational parameters for your engine to run... not necessarily to run well, or ideally, but to run nominally. With calibration fluid, you know from day to day, week to week, and month to month EXACTLY what the stuff is made of, and EXACTLY how it will function. So any test reading done with that stuff consistent and externally as well as internally valid. That's also why testing is expensive - you need to drain a pump, mount it up, etc. - you can't just throw it on the bench, because contamination of calibration fluid with diesel fuel destroys the carefully enforced spec, potentially throwing your test readings out in future.
As far as the European pump builders and others - some of those guys do really take pride in their work - I'm not knocking their integrity or anything. But my experience with a number of such pumps (experience which is limited, so take from it what you will) includes strange and undesirable things like mixing and matching components (One head goes with one rotor - there is no such thing as a "good" head and "bad" rotor or vice versa... tolerances are so close that you CANNOT mix and match.) And heavy use of inexpensive non-OEM components which are always "pretty close" but not necessarily close enough to work for very long.
Then again, there are other guys who do a perfectly passable job for a perfectly passable price. Their customers may not be excited fans, but they can be perfectly satisfied too - it all depends on what you want and what you expect. When good enough is good enough, you may not need to deal with Performance Diesel Injection. If you'll only settle for the best... Giles would love to do whatever crazy modifications you've got in mind.
