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Old 03-03-2017   #1
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Question JTD difference between Alfa and Fiat, help needed

Hello here,
I did not find any information concerning my question.
If you have a look to the 1.9 JTD spec (105hp for ex.), you can see a diffrence of max torque:
200 N.m For a Fiat Bravo, 255 N.m for an Alfa 146.
I was thinking the engine was the same, gearbox and clutch to, so?
So, am i wrong, or it is just a marketting difference?

Thanks!
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Old 03-03-2017   #2
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Re: JTD difference between Alfa and Fiat, help needed

Quote Originally Posted by Cuda View Post
Hello here,
I did not find any information concerning my question.
If you have a look to the 1.9 JTD spec (105hp for ex.), you can see a diffrence of max torque:
200 N.m For a Fiat Bravo, 255 N.m for an Alfa 146.
I was thinking the engine was the same, gearbox and clutch to, so?
So, am i wrong, or it is just a marketting difference?

Thanks!
Hi,
Different engine tune. Probably just in the ECU, possibly different camshafts. You could look on ePer for the cam part numbers to check.
You also need to get hold of the power and torque versus engine speed graphs. These tell you much more than just the one (presumably peak) figure.
The Fiat could be fairly flat at 200Nm across a wide rev range for easy driving and the Alfa could be peaky for more sporty response. Gear ration will be different too but that does not affect the torque the engine is capable of.


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Old 03-03-2017   #3
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Re: JTD difference between Alfa and Fiat, help needed

For me it is probably a ECU prog difference.
In my case, i have a 110 hp, but 200 N.m, really poor....
My previou car (Xantia 2.1 Td) was 260N.m for 110 Hp and it was quite good...
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Old 23-06-2017   #4
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Re: JTD difference between Alfa and Fiat, help needed

Up!
No more information to understand the difference?
Are gearbox the same?
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Old 12-07-2017   #5
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Quote Originally Posted by Cuda View Post
Up!
No more information to understand the difference?
Are gearbox the same?
As suggested..
Use ePER..OR other parts fische comparison sites
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Old 12-07-2017   #6
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Re: JTD difference between Alfa and Fiat, help needed

It is not really possible because gearbox Ref are changing with the final ratio, if i want to know, i have to detail the internal shaft...
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Old 12-07-2017   #7
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Re: JTD difference between Alfa and Fiat, help needed

Quote Originally Posted by Cuda View Post
It is not really possible because gearbox Ref are changing with the final ratio, if i want to know, i have to detail the internal shaft...
For camshaft, ePer will give you the part numbers for comparison (some are the same). They are under "main engine components" - "distribution"

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Old 13-07-2017   #8
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Re: JTD difference between Alfa and Fiat, help needed

Thank you, but i prefer to see difference "after the flywheel"
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Old 13-07-2017   #9
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Re: JTD difference between Alfa and Fiat, help needed

Quote Originally Posted by Cuda View Post
Thank you, but i prefer to see difference "after the flywheel"
The torque figures you quoted are at the flywheel. This is done for consistency. The gearbox ratios are in the vehicle specifications (owners handbook) so you can calculate the torque at the wheels, but these do not affect the engine torque and power (apart from losses). Gearbox ratios (and peak speed / flatness of power & torque) are more to do with drivability. but can lead to distorted 0-100kph & top speed at expense of high range acceleration and drivability. Some performance Fords were known for this, but it's mostly gone with 5 and 6 speed gearboxes.
You need to look at everything, but the torque differences you discuss in your first post are measured at the flywheel and can only be affected by the engine design and state of tune, the transmission has no effect on these figures.


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Old 13-07-2017   #10
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Re: JTD difference between Alfa and Fiat, help needed

I know all that...
BUT...

I think the difference of torque between Fiat and Alfa is due to a derated soft in the ECU (very easy to do).

But i want to know the reason:
- Politic? => Fiat are popular cars and Alfa sports car (so they have to be more performing)
- Technical => The gearbox is more weak on the Fiat (I was thinking it was stadard between the two manufacturers except the differential ratio)

In the first case i can remap the car @ 260 N.m (keeping my 110 HP) without any problem, in the second case, the gearbox will die...

( I worked for car manufacturers, and I know that sometimes, ECU setups are different but the engine excactly the same... Political reasons...)
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Old 13-07-2017   #11
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Re: JTD difference between Alfa and Fiat, help needed

Quote Originally Posted by Cuda View Post
I know all that...
BUT...

I think the difference of torque between Fiat and Alfa is due to a derated soft in the ECU (very easy to do).

But i want to know the reason:
- Politic? => Fiat are popular cars and Alfa sports car (so they have to be more performing)
- Technical => The gearbox is more weak on the Fiat (I was thinking it was stadard between the two manufacturers except the differential ratio)

In the first case i can remap the car @ 260 N.m (keeping my 110 HP) without any problem, in the second case, the gearbox will die...

( I worked for car manufacturers, and I know that sometimes, ECU setups are different but the engine excactly the same... Political reasons...)
Only the people who made the decision know the answer to that.
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Old 10-08-2017   #12
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Re: JTD difference between Alfa and Fiat, help needed

Bit of info on engine calibrations, reasons, and effects. Hopefully sheds some light for someone.

I worked in Fords diesel cal dept for a while and was surprised the 1.6 diesel Ford/Peugeot-Citroen base engine (block/heads/cams/manifolds etc.) were the same, but during the same time period (years) they had to use two suppliers for the fuel injection equipment as a whole (PCM/HPFP/injectors), turbos were also same spec but again provided by two different suppliers. The reason was a contract to use supplier A, but to make the price more competitive - brought in supplier B to break the monopoly. Anyway, based on that kind of part variability possible it would not be beyond the reason the higher output JTD's may have different injectors/HPFP outlet diameter, as well as calibration.

Also - as someone already mentioned; to make the cal's for lower power output engines, the peak power cal is made first then the torque curve is offset downward to clip off torque across the whole range. The low output cal is handed out the base model vehicle and they sell the high output cal at extra cost or as in this case, offer it only with the big shiny leather trimmed super version of the car.

Note; the dual mass flywheels/clutch sometimes needed beefing up to handle the extra torque and 'sporty' driving style - another part number to check.

FYI aftermarket cal's tend to alter these areas of cal drivability;
*removal of the smoke limitation maps (a limit for how rich the air:fuel ratio can go)
*removal of gearbox instantaneous torque limitation (limits the rate of torque generated so your gbox doesn't grenade the cases)
*pedal map - rather than doing what you ask of it, the pedal request is filtered to death and what actually happens is a slowed down version of the driver request for the above reasons and others such as fuel economy (accelerate a heavy car a little slower uses a fair bit less fuel). Mapping the pedal to give exactly what your foot asks of it and makes it feel mega responsive.
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