road BS1 and the RALLY BS1 version - differences

[abcman3000]

ex ufficial car Tominz-Mamolo female european champions '71



no images of the engine....sorry that's what I'm trying to find out.

[Snoopy]

http://www.abarth-gmr.be/new/gallery.ph ... _01&idp=15

[wmausbach]

Stephan,
Do you have any info on cam spec/timing and valve sizes for the 1608 engines?
Wayne

[stefhahn]

sorry, no. All info I have is written above.

[abcman3000]

I thought the rally version was a 1756 cc but I've been wrong before. 155 hp at the flywheel? That's a heck of an engine! My 1608 is around 120.

Actually I believe it was 155 HP (DIN) , not SAE so the power at the flywheel was even higher !

I found out some new details. Not from books or literature but from people that actually own Official Fiat Rally cars from that period.
Off course I'm talking about the BS1 1608cc
(winner of the Acropolis rally 1972 and second in the International Championship for Manufacturers '72, second only to the well established Lancia Fulvia) , NOT the Abarth CSA.

=================================
Weber 44 IDF carbs
Reinforced Chassis
Bigger fuel tank with 2 Bendix electrical pumps
Cage roll bar
Limited slip diff Colotti and different bevel gear
Racing gearbox Colotti
Double brake pumps, eliminating the servo-braking and with the possibility to choose the brake ratio front/back
Racing seats and wheel Fusina
Battery in the trunk
Balanced engine parts
Strengthened suspensions
Special Abarth camshaft
Stamped lightened pistons (designed to increase compression) (by Abarth)
Special piston rods, lightened and polished (by Abarth)
Valves made from Nimonic (special material for high temperatures)
Special sump more distant from the ground and a shorter oil pump to go with the sump.
Fan to be mounted on the water pump and therefore eliminate the one on the radiator
Special radiator that had an adjacent part for cooling the engine oil
The hood was metallic
Hardtop
4 x Carrello extra lights
================================

for wmausbach :
cam spec/timing: Abarth camshaft produced in '72 for the 1608cc
diagram 50°68°64°43° ( 4,70 intake. and 4,55 exhaust)

4 Regions Rally 1972 (Paganelli-Russo) WIN !


Please add info if you know more details !

[wmausbach]

Wow 155 Din Hp at the rear wheels translates to 178Hp at the flywheel (assuming 15% loss). Or did you mean in comparsion to SAE rating which is more like 5% difference? In any case if you use the same Hp to CC ratio for the 1756 if gets about 170Hp. It jives with quoted Hp for the Abarth two valve. It only makes sense that the factory would use their experience with the 1608 to the bigger 1756cc motor.

The cam data is great and is the first time I've seen the competition specs for the 1608 or the later Abarth two valve. However can you get the lift too? The cam timing is not that radical and is really just a hot steet cam especally with only 10.5 Cr pistons. For example PBS quotes a similar cam timing with 10 54 mm lift. Their all out racing cam is close to 12mm which I think is the limit of the cam towers without trickery.

Your sources are the best. What we call down here in Texas " Strait from the horses mouth" .

Ciao
Wayne

[abcman3000]

Wow 155 Din Hp at the rear wheels translates to 178Hp at the flywheel (assuming 15% loss). Or did you mean in comparsion to SAE rating which is more like 5% difference? In any case if you use the same Hp to CC ratio for the 1756 if gets about 170Hp. It jives with quoted Hp for the Abarth two valve. It only makes sense that the factory would use their experience with the 1608 to the bigger 1756cc motor.

I meant 155 (DIN)...I suppose if you add the 5% you get the SAE power at the flywheel.
I know that the racing (rally prepared, gruop 4) Abarth car(1756, 8V) had a declared 170HP so it makes perfect sense.
The later versions with increased capacity 1839cc, Kugelfisher mechanical injection, and 16V cylinder head developed up to 210-215 HP (DIN)

The cam data is great and is the first time I've seen the competition specs for the 1608 or the later Abarth two valve. However can you get the lift too?

This should be the lift: 4,70 intake. and 4,55 exhaust

Your sources are the best. What we call down here in Texas " Strait from the horses mouth" .

[wmausbach]

Thanks for the clarification, what units of measure is the lift data? 4,70 ( with a comma) usually refers to metric measurement.

Could you mean 0.47 inches of lift? That converts to 11.9 mm which is close to the maximum lift that will fit in the camtowers. All the data on Fiats is usually in metric which was my confusion thinking you were quoting 4,7 cm dia of valves . Stock lift is 9.4 mm with the 130Hp, 2 liter Abarth Street version having 10.0 mm of lift.

Your other cam data is interesting combination as the lobe centers are less than stock. What this means to me is Fiat was after good torque in the midrange as this was more important than absolute Hp. This makes the 155 Hp even more impressive. Do you also have the torque data?

Ciao
Wayne in Houston

[abcman3000]

@wmausbach

Hy Wayne,
sorry for the extra-late reply

The lift I was referring to is NOT the maximum lift, but the lift at the Top Dead Centre (TDC), and it was in millimeters.

the new data I found in an Abarth leaflet reffering to the KIT made for the 1608cc (125BC)engine
4,20mm intake
3,10mm exhaust
(at the TDC)


what do you think of it ?

[wmausbach]

Yes, I see the sheet but it makes no sense. Cam data is always given at maxium lift due to the fact that cam timing can change. I do not know what to make of this, have you foumd in other page that goes with this. It appears that Abarth didn't want to disclose the data. Any way good information and I will add it to my data. I just wish I could make sense of it.
Ciao
Wayne

[wmausbach]

To add to my earlier post, given a reading at TDC is like going halfway up a mountain and getting a reading. You still do not know how high the top is. In fact you do not know the slope is either. All you can do is make vague guesses. Most competition cams have a large radius at the peak to provide more duration at the maxium lift . The stock cams have a more pointed peak (ie smaller radius). The owners manual of a later Abarth gave the data per normal practice with a maximum lift.
Ciao
Wayne