I think of the tuning box as the pure diesel tuning,in the sense that it fool the car into injecting more fuel than the original ecu
map specifies for any given condition.
If we take the view that the boxes really the same, how effective one will be seems to depend on how much tolerance is built into your engine type.
I have only had direct experience of a "box" on a 90 bhp diesel,but Ive read others experience of what is probably a very similar box on the 110bhp version of the same engine.
What I get with my "box"is approximately (I think)a 115bhp type engine at hi and medium revs and something that can actually improve fuel economy if its kept on the torque curve (around 1750-2250)
If I drive it hard ..like revving to the dizzy heights of 4000+ in the gears the mpg will be worse than normal..
The impression I get from people with a box on 110bhp versions of the same engine is that they get ,maybe a 120 bhp engine at hi revs and close to a 125/130 bhp and medium revs
The torque kick is big..no doubt..higher performance wont go up much unless your fuel system is understressed as standard.
The above engines have a different turbo
but are pretty much the same otherwise..
The easiest to understand diesel tuning quote ive read is :
"Add more fuel till it smokes, then add more turbo
pressure,then add more fuel "..and so on.
Tuning boxes just fool the ecu
into adding more fuel at any given time/load requirement.The original map is set to add the minimum amount of fuel for the same situation.
Ehats with the economy claims on tuning boxes then?.
I think its a case of holding a low rev /hi torque state even more rigourously than than the manufacturers allow for.
With a box you get a good acceleration "kick" compared to without, but the "torque curve" seems narrower.
The common box cant affect that directly..how could it,its just a variablle resistor in the fuel pressure sensor feedback.
with a box all you get is more fuel pressure,up to the sensors limits.
There are 3 sensor tuning boxes around for alfa multijet engines..I dont know how good they are but to get it set right you would think remaps would need to be involved too.
It seems like ,if your engine has a reasonable fuel pressure safety margin.you can get ok results.
Mine is 1650bar max normal operating pressure..just like the 110bhp version but cos its in a lower state of tune it might not go to 1650bar as often.
The sensor for both engines goes to error at approx 1800 bar.
The remap,if its a good one, you would think should provide the fuel and the extra turbo
pressure,at least if its a vvt turbo
and its max pressure isnt contrilled mainly by a physical wastegate.
A good remap should provide more than you would get from a tuning box as the tuning box is really dependant on a best case scenario in terms of fuel pressure headroom.
There are remaps which use tuning boxes!..shows the importance of fuel pressure probably.
Cost.. well there you come to a big q...My box £35 second hand.A remap..£300 for a good one?..200,I dont know.
After 18 months on the box..I have I think at least a 20% better overall result.
A remap alone might be better .
For example I cant go over lvl 7 on my box to be 100% sure of no errors perhaps with a remap I could get to use up tothe level 9 max(0-9) all the time.
Doesnt really matter,I wont be getting a remap till guarantee is gone anyway.
It be too difficult to change back for service.