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Old 2 Weeks Ago   #31
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Re: T-Jet 120hp 'Chip-tuning'

Yeah, I know, and I considered doing the turbo mod + NA cams when its time for the timing belt, but then there's the cost of doing that + getting it from almost France to Squadra to have it tuned...
Price/performance gets a bit ridiculous then and it still is a daily driven Doblo that will probably see nothing but all-season tyres and stock suspension parts for all its life (with me anyways), so I decided it's smarter to just release the choochoo the stock hardware can put out safely for many many years on LPG fuel and enjoy it as is.
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Old 2 Weeks Ago   #32
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Re: T-Jet 120hp 'Chip-tuning'

ok, guys! it's not consipracy... just an idea. if i do chip, i will never mention it here. no evidence of result, no harm..

Gearbox fragile on higher gears on low rpms? really? i am not afraid to put extra rpms on the engine, i know no harm will be done by that. but harm to gear box by adding torque on higher gears wiht low rpms?
what's the connection between gearsize/rpm/torgue? is theere less torgue on higher rpms then? there will be the same ammount of torque if i do full throttle on 3500rpm.
has someone has any theory on this? --> this sounds like conspiracy and no substantiation...
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Old 2 Weeks Ago   #33
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Re: T-Jet 120hp 'Chip-tuning'

The thing is, when you accelerate higher in the rpm range, you'll be massively breaking speed limits if you'd do that in 5th or 6th, you'd be in 3rd or 4th depending on the speed.
The M32 gearbox tends to fail because the bearings on the 5-6 side on the shaft that contains 1-2-5-6 are its weak spot. By throwing torque at it in 5th and 6th you're creating heat right where those weakest bearings are, so on top of all the reasons why it's better to keep the engine in a happy mid rpm range, that's why it's bad for the box as well.
Nothing conspiracy about that, you don't have to believe us, just Google the M32 gearbox.

Also don't forget wheel torque is a result of engine torque and gearing. My Doblo is extremely limited in 3rd and delivers full power in 4th, yet a 50-70 acceleration in 3rd is still faster than in 4th because of the gearing, and it's even faster in 2nd despite the turbo noticeably runs out of puff somewhere around 60 on top of that same limiter.
A diesel has strong internals and a lot of raw torque all the way down around 1500rpm, which it loses throughout the rev range so fast that it compensates the gearing advantage around the 3.5k rpm mark.
The T-Jet 120 engine only reaches that point at about 5k rpm but doesn't have the raw torque and heavy duty internals, so lugging it around 1800rpm is pretty much as bad (both performance and reliability) as racing a diesel at 4500rpm.
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Old 2 Weeks Ago   #34
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Re: T-Jet 120hp 'Chip-tuning'

Talking about the interior filter, it has a time related change interval, not a distance interval.
It should be changed once a year, no matter the driven distance.
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Old 2 Weeks Ago   #35
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Re: T-Jet 120hp 'Chip-tuning'

I will google the gearbox to see what exactly you mean. Thanks!

Peter, dont agree here. Time and distance are related together in parabola. If i do 30k in half a year it means my filter the same dirty as i did 30k in a year, because i spend about the same time after all. My average speed is ~45km/h all year around.
didnt you notice that flow through vent decreases significantly when filter is dirty?
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Old 2 Weeks Ago   #36
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Re: T-Jet 120hp 'Chip-tuning'

Quote Originally Posted by romanche View Post
didnt you notice that flow through vent decreases significantly when filter is dirty?
No, I don't, (still I drive about 30.000 km's a year, and change that filter once a year, and I use a special Bosch carbon filter...)
In fact, most interior filters are NEVER changed at all.
My father in law bought a new Toyota Corolla () back in 2004, and he thinks changing that interior filter is a waste of money, so it wasn't changed until last year, when it was completely black and filled with sooth etc.
He didn't notice any difference with the new filter, as he told me, so now he is even more convinced that it's just a marketing trick to get extra money from customers...
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Last edited by Peter Pick-Up; 2 Weeks Ago at 19:49.
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Old 2 Weeks Ago   #37
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Re: T-Jet 120hp 'Chip-tuning'

Quote Originally Posted by Candisa View Post
... even faster in 2nd despite the turbo noticeably runs out of puff somewhere around 60 on top of that same limiter....
I'm going to try to explain what you are feeling:
-as i've said before the ecu limits boost in the lower gears, by using the boost controller solenoid
-in 1st,2nd and a bit in 3rd the max boost is limited:
-1st ...0,1bar
-2nd...0,2bar
-3rd...0,5bar
-4th,5th,6th...0,8bar
The values are MAX values, approximately accurate(i had graphs of the boost in each gear...can't find them)
In each gear the boost graph raises to max, holds a bit, and then falls back down to the top of the rev range... you might think it's the turbo.. but it's actually the ECU => boost solenoid =>wastegate =>lower turbine pressure=>lower boost.
You can actually see this by using graphs on MES.

There are numerous reasons why it's programmed that way, but in short it comes down to reliability (gearbox and engine) and efficiency.

So the idea is that the tuner can still raise the pressure twords the end of the rev range.... but it requires careful motorization, while tuning, on a dyno.. checking temps, knock, oil pressure, AFR...etc

Again.. for reliability they set it up so you wouldn't want to rev it over 5.5k (where the boost/torque really falls down)... if it doesn't feel good, people will not rev it that high=> longer life =>less chances of repairs under warranty and generally people considering the engines more reliable.
The behavior in the higher revs can be drastically changed by only upgrading to the VL36 turbo... it feel so much better now. Basically the cam shafts don't matter that much on a turbo car....where they might feel better is in the lower revs, just before the turbo kicks in; and of course in the higher revs it could make more power with lower boost... so more efficient.
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Last edited by aurick86; 2 Weeks Ago at 20:11.
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Old 2 Weeks Ago   #38
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Re: T-Jet 120hp 'Chip-tuning'

Peter: I have to be brutally honest, I've changed the filter at 30k/1yr as part of the official maintenance, the one that's in it now will do a whole lot more than that! (Not 12yrs though, YUCK!)

aurick86: What I ment was that my Doblo clearly goes beyond the most efficient rev range at about 60km/h in 2nd as the turbo doesn't help along anymore, but that it's still pulling to 70 faster than it does in 3rd because of the gearing advantage.
I wouldn't be surprised that the ECU indeed cuts off boost at lower rpm than the turbo would run out of flow if the wastegate was disconnected, but according to what tuners get out of it at the top there really isn't that much left anyways.

There is no difference between 2nd and 3rd in my Doblo stock: immediate 0.2bar* boost rising to 0.4 at about 3.5-4.5k rpm and afterwards backing out again.
1st is now releaved of its torque limiter and reaches slightly higher values, 2nd and 3rd will be brought to the levels of 4th and up (immediate 0.7bar* boost up to 4.5k rpm) hopefully soon.
I don't rev much over 5k rpm anyways as at that point my LPG ECU switches back to petrol.

*According to my analog boost gauge.
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Old 1 Week Ago   #39
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Lightbulb Re: T-Jet 120hp 'Chip-tuning'

Quote Originally Posted by santa View Post
As far as I know, Fiat dropped the M32 for the Tipo and are using the C635 (with 6-speed) and C510 (with 5-speed).
Yes, you are correct. Also C635 goes with Automatic Dual Clutch (DDCT) transmission. It promises 350Nm of max torque. So, my mind issues with 'weak' gearbox are irrelevant. it's a tough one.

Also, according to this source, this 1,2,5&6th gear are on the lower shaft. Which makes Isabelle correct. Since, max possible torque is massively higher than t-jet engine can produce, i would say it's save to accelerate on the 6th gear. Other wise we are also not allowed to accelerate on the 1st and 2nd too

You may say that speed of the shaft on the higher gear is different which heats up bearing as well. how come we still can drive it 120km/h and above normally?

http://www.autolusso.co.uk/gearbox-C635.html


I tried to look for this gearbox problems and couldn't find any. Can't say that M32 box has the same strength...

However, if you have 1.6 multiair diesel 120hp, i would chip it very cautiously as it already has 300Nm of torgue, with chip it will go to the red zone....
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Old 1 Week Ago   #40
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Re: T-Jet 120hp 'Chip-tuning'

If you indeed have the C635 gearbox you don't need to worry about the issues with M32 indeed.
Accelerating in 1&2 is indeed on the same shaft as 5&6 in the M32, but the forces on the selected gears are away from the weak bearings and away from the final drive, spreading the heat and load better. Also the torque is limited in 1 and 2, and even if you remove that ECU limitation you're still not likely to use all the torque at low rpm in those gears.

Fact is the T-Jet isn't a diesel, nor a high revving NA petrol, it's in between and that's how it should be driven to keep it happy. Not only is the engine much happier to deliver power above 2500rpm, it is also spreading the force over more power strokes per time and the oil and water pump are pumping better as well.
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Old 1 Week Ago   #41
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Re: T-Jet 120hp 'Chip-tuning'

Quote Originally Posted by romanche View Post
It promises 350Nm of max torque. So, my mind issues with 'weak' gearbox are irrelevant. it's a tough one.
The M32 is supposed to handle 320 Nm... how is that going?
Those numbers are only for recommended max torque .. . after that the gearbox might have catastrophic failure (it bends the shafts or rips apart the gears).

Can it handle more torque .. probably.. i mean there are lot of diesel Alfas that do.. the Asta vxr... etc
The max torque isn't that much of a problem.. is the design of the gearbox.. it accumulates heat..oil brakes down, lubrication isn't as good after that.
Repeated several times it will lead to bearing failure.
One of the few ways that save the gearbox is installing a pump and an oil cooler...not really worth it for a daily car that doesn't see any track time.

Although the C635 gearbox might be better than the M32 but it isn't bulletproof. I've seen a lot of forum posts about that as well.
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