General A question about JTD 16v Multijet tuning - or diesels in general...

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General A question about JTD 16v Multijet tuning - or diesels in general...

PureTNT

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I had an opportunity to test two diesel modules from the same company for a period of time. While the acceleration with those modules installed is stunning, the top speed doesn´t seem to have gone up at all. Now, since I´m deciding on what to actually buy, I feel the need to pose a few questions.

1.) Does the limited top speed increase have anything to do with the power after certain revs? The top speed is reached at approximately 4000 rpm and the car just won´t go faster unless there´s an incline (redlines at 4500 rpm). That goes for both the standard and the module versions. Both top out at 220 km/h on the speedo.

2.) Would performing a remap instead of a normal module help increase power? Meaning, if boost was added, would power carry on over 4000 rpm?

Thanks in advance for any suggestions or answers.
 
I think the modules only adjust the preassure (if at all :confused: ) and length of the injection, thus the max. power will still come at 4.000 rpm.

With a remap you should be able to adjust when the max. power should be (perhaps push it to 4.500 rpm) and adjust the boost.

When I had my Punto JTD tuned via a module, the power and tourque curves were the same as standard only higher (instead of 80bhp at 3.000 rpm it had 105 bhp at 3.000 rpm).

I would choose a remap instead of a module, because the remap will be made for specifically for your car and not to all multijets.

So in short:
1: Yes, the limited top speed increase is because the max. power is still at 4.000 rpm.

2: I think it could push where the max power is delivered (pushed to 4.500 rpm as opposed to the standard 4.000 rpm).

Perhaps Alfanige can answer this better?
 
what your trying to do, is shift the power band which envolves more than just a chip/remap. keeping the revs to a max of 4000 rmp is in keepping with the way fiat designed the engine because the boost pressure peaks betwwn 2750 and 3750 so that is where the most acelaration is so there would be no benafit from reving it to 4500 as the boost pressure tails off at 4000rpm so all your going to benafit from reving it to 4500 is a few extra mph.
depending on how high the boost/fueling is turned up you may find it holds its peak boost aliitle longer but you will see what i mean when you get it done and have the power graphs in front of you!!
 
mat-nos said:
what your trying to do, is shift the power band which envolves more than just a chip/remap. keeping the revs to a max of 4000 rmp is in keepping with the way fiat designed the engine because the boost pressure peaks betwwn 2750 and 3750 so that is where the most acelaration is so there would be no benafit from reving it to 4500 as the boost pressure tails off at 4000rpm so all your going to benafit from reving it to 4500 is a few extra mph.
depending on how high the boost/fueling is turned up you may find it holds its peak boost aliitle longer but you will see what i mean when you get it done and have the power graphs in front of you!!

Well, I think you guys both understand what I´m saying. The acceleration is excellent, but the top speed is lacking for its HP. So if a remap would allow the powerband to expand further up into the rev range (say 4250 rpm), the car would gain an extra 10 mph. With my car, that´s 230 km/h, which would be in line with over 180 BHP.
 
yeh i see what your saying but i personaly see it as piontless as how often do you go well above 120 mph in england?? where as if you are next to somone reving the 1.8 petrol focus at the lights it would give me great pleasure in leaving them in a puff of black smoke!! :)
if i was german then maybe i would see it differently!!
 
mat-nos said:
yeh i see what your saying but i personaly see it as piontless as how often do you go well above 120 mph in england?? where as if you are next to somone reving the 1.8 petrol focus at the lights it would give me great pleasure in leaving them in a puff of black smoke!! :)
if i was german then maybe i would see it differently!!

I live close to Germany and I drive a LHD vehicle :) . I actually go above 120 almost every single day. I would however like the car to do let´s say 145-150 mph (with its horsepower, about 180-190 it´s possible). Add some stiffer coil-overs and better brake pads and you have a pretty solid performer. As for the 1.8 Focus, already smoked him with my old 1.8 Stilo, no fun in that :D
 
i got 138 out of my old jtd (down hill) and the revs were just sitting on 4500 rpm!!
so yeh 150 should be possible with around 180 bhp but make sure its mapped with the boost coming in later than normal so that it sould hold its peak boost over 4000rpm.maybe a bit laggy around 1500-2000 rpm.

my mate runs a nice little website called deiselinside.com get yourself on there and introduce your self there are some mad powerfull cars on there like a 300bhp 206 deisel that does 11 sec quater miles.......awsome!! also lots of advice about tuing deisels etc

must be nice to be able to rag it to work at 120 without the risk of being banned and fined lol :)
 
mat-nos said:
i got 138 out of my old jtd (down hill) and the revs were just sitting on 4500 rpm!!
so yeh 150 should be possible with around 180 bhp but make sure its mapped with the boost coming in later than normal so that it sould hold its peak boost over 4000rpm.maybe a bit laggy around 1500-2000 rpm.

my mate runs a nice little website called deiselinside.com get yourself on there and introduce your self there are some mad powerfull cars on there like a 300bhp 206 deisel that does 11 sec quater miles.......awsome!! also lots of advice about tuing deisels etc

must be nice to be able to rag it to work at 120 without the risk of being banned and fined lol :)

He he. 300 HP? I gotta log in there :D . As for the driving to work part, we have Provida 2000 vehicles plus Multanovas and Gatsos, but a good pair of eyes and my Valentine One take care of those.
 
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