engine mods

[Hypermiler1995]

Don't know if this counts as an engine mod, but i switched from 5w30 conventional oil to 0w20 synthetic in my 05 prius and done a test run (same route, diff. days, cruise on 54mph)
it showed an improvement of 4%!

[BikerModder]

I mean that's a mod. Or an improvement. A turbo is a thing that would develop a reputation over time, as far as reliability goes. And if you say your prius gets 4% improvement I could believe it. I just did the same thing with my Smart Fortwo and was able to buy it in the gallon size and for a special price under $20 dollars. I want to go by the manual on the 12 month yearly oil change but I choose a different filter brillo for the intake The intervals are important to some.

[squirrl22]

I modded the fuel injection on my 1986 1.6 IDI VW diesel - pretty easy to do - just advanced the timing, modified the Fuel injection governor so that it no longer limits the fuel over 3000 RPM, installed new, more precise Bosio fuel injectors- Also wrapped electrical heating element around injection lines- preheats fuel to abt 180F -hot fuel atomizes better, runs better esp when engine is warming up. Also inflated the tires to max sidewall PSI, dropped the suspension by 1 1/2 inches w some GTI springs and Bilstein shocks to improve handling and reduce air resistance over 55mph. Bumped my MPG from 44 to 60. (at a steady60MPH), bumped my top speed from 82 to 107MPH, improved my acceleration-still not quick, but at least I can keep up with traffic now.

[oil pan 4]

Since the fuel injectors are screwed into the cylinder head once the engine is warmed up the fuel will be getting injected at the same temperature the cylinder head is at.

[squirrl22]

true to a point- in the winter, it can take 10+ miles for my IDI diesel engine to fully heat up if the temp is somewhere above 30F. If below 30F, it takes many more miles.
In the summer, it will still take 5+ miles to fully heat up. Hence, the advantage of pre-heating the fuel- which takes less than 1 minute.
5 miles, or 10+ miles- I would rather get maximum MPG starting in the first mile.