... Up late perusing through ePER and spotted a couple of things that jump out at me when comparing the 85hp TA engine in the 500 to the 500L's 103hp unit (Yes, 103hp - it's marked as a 77Kw engine):

• There's a different turbo
• A different head casting
• A different camshaft (don't forget the exhaust valves are 'conventionally' actuated, so more than likely differing exhaust lift/duration)
• A different ECU (obviously)

What's the same on initial looking:

• Pistons
• Rods
• Bearings
• Crank
• Flywheel (DMF as the 500L is a bigger/heavier car)

So fundamentally, the engine is strong enough - I note that the pistons have the underneath of their crowns cooled by oil jets on both engines.

Interested to see why a different head, implies the porting has been changed (so thus, the 85hp is restricted?). Means a head port is plausible to release some extra horsies, amongst other things like a remap.

The turbo appears to have the recirc dump valve electrically driven, rather than by vacuum as on the 85hp engine. Saves pipework, the wastegate appears to be controlled by a conventional vac actuator - no doubt modulated like the 85hp engine. I wonder if the turbo has different 'tuning' (A/R) partly because the car the engine is in a bigger, heavier car.

Lots to look at more closely; I shall keep hunting through documentation and update when I can..

That's really great info bgunn.
I feel more comfortable getting the 100bhp Magneti Marelli module now.
Cheers,
Ian.

The Twins said:

That's really great info bgunn.
I feel more comfortable getting the 100bhp Magneti Marelli module now.
Cheers,
Ian.

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Why? Different turbo, different head, different exhaust cam..
.

Anyone know if this is going to be fitted into the 500, seen a few reports on Web that it might , hope so would interesting .

gaza2013 said:

Anyone know if this is going to be fitted into the 500, seen a few reports on Web that it might , hope so would interesting .

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You probably wouldn't find out until near launch if they were.
Fiat won't want to slow sales of current models with people waiting for the new one.

You can tell it was late - I said the flywheel is the same and then said it's a DMF, which the 500s one is clearly not.

306maxi said:

Why? Different turbo, different head, different exhaust cam..
.

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Because the crank, pistons etc are the same so engine is strong enough to take the extra power.

The Twins said:

Because the crank, pistons etc are the same so engine is strong enough to take the extra power.

Click to expand...

Yes, but will you actually get the power without the right turbo?

306maxi said:

Yes, but will you actually get the power without the right turbo?

Click to expand...

He's right, IF the turbo differs in A/R - the extra power almost certainly comes from extra boost pressure, and winding up the 85hp's turbo to higher boost could result in charge temperatures that are very high (which will cause detonation amongst other things).

I need (and want) to find out if said turbo on the 103hp one is different in the important ways (rather than just for packaging reasons).

bgunn said:

He's right, IF the turbo differs in A/R - the extra power almost certainly comes from extra boost pressure, and winding up the 85hp's turbo to higher boost could result in charge temperatures that are very high (which will cause detonation amongst other things).

I need (and want) to find out if said turbo on the 103hp one is different in the important ways (rather than just for packaging reasons).

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Why do turbos die when reaching a certain amount of revs so suddenly after reaching top power like in the ta? Is it to protect the engine? Sorry if i am not clear but after hitting max power on the 1.4 at 6000 you have over 1000 rpm before hitting the rev limiter while with the ta you have 500 before rev limiting.

Effectively (and this is my understanding of it, so quite probably wrong), but once the turbo is spooled up and spinning at it's maximum speed (driven by the exhaust side of the engine), it reaches a maximum amount of boost that it can deliver to back into the inlet. Once that point is reached, it's not got anything more to give, and there is no point letting the engine rev any higher.

On an N/A engine, the fuel and air ratio is not restricted by the turbo's maximum speeds and boost levels.

306maxi said:

Yes, but will you actually get the power without the right turbo?

Click to expand...

Yes 100 bhp.

bgunn said:

He's right, IF the turbo differs in A/R - the extra power almost certainly comes from extra boost pressure, and winding up the 85hp's turbo to higher boost could result in charge temperatures that are very high (which will cause detonation amongst other things).

I need (and want) to find out if said turbo on the 103hp one is different in the important ways (rather than just for packaging reasons).

Click to expand...

The module is made by Magneti Marelli who make the engine management system forcthe 500 TA so I'm guessing that they know what they are doing and that 100 bhp is ok.

As I said in another thread, exercise caution on this. MM will produce the engine management system and design the software, but it will be FPT that actually map it on their own dynos. So effectively, MM are the 'third party' in this; whilst they know how the engine management system works, they may not know the physical limits of the engine.

You would hope that as MM are a subsidiary of FIAT, there would be dialog between FPT and them so the tuning box doesn't cause problems, but I would be careful to look out for it being endorsed by FIAT (or even warranted).

Hmmm, I really do have my reservations....

Spotted this when finding more figures about the two engines:

Power
105 PS (77 kW; 104 hp) @ 5500 rpm

Torque
145 N·m (107 lb·ft) @ 2000 rpm

vs.

Power
85 PS (63 kW; 84 hp) @5500

Torque
145 N·m (107 lb·ft) @1900

Torque is the same, but at higher speed, which equals more power. Would be interesting to see a power curve to know what the torque value at 1900 rpm is as a comparison. Hopefully not too much lower, as this will change the feel of the engine quite markedly.

Ahmett, the TA doesn't run out of puff as the revs rise - it's the rev limiter built into the ECU that backs it off to protect it. I hit this a few times when I first got my TA as the engine doesn't sound like it's revving that hard (only 1 bang per rev.) then before you know it it has zinged up to around 6000rpm and the "soft" limiter starts working. Don't know why the rev limit is relatively low - ideas, anyone?

I'd be more interested in the torque curves after as for me more relevant to my everyday driving, curious why the same as to whether it's an imposed limit due to component headroom

wigit said:

I'd be more interested in the torque curves after as for me more relevant to my everyday driving, curious why the same as to whether it's an imposed limit due to component headroom

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Indeed, the 500L TA appears to have a six speed 'box, so you'd think that has a higher torque capability.

The shape of the torque curve (and thus the power curve - as they are completely linked) will determine how the engine 'feels' when driven. Trying to find an official graph, but can't currently.

Just had a play on the Fiat Configurator for a 500L - chose the TA engine, then looked at the "Technical Details" - these say the camshaft is driven by a toothed belt, which certainly isn't the case with the 85bhp version. I did it very quickly, so may have done something wrong, however the configurator is known for the odd mistake. What's the verdict?