General 1.1 sx

[cioccixxx]

well im back again had a lil break, anyway to the point. ive been reading the posts and the majourity of punto's are the 1.2 8 valve, and since i got a 1.1 beast this dosnt prove v usefull....so kum on who has the 1108 and wots there speeds n stuff...as im still a leaner i aint bin able 2 push mine

 

[JonnyBoy]

My 55SX maxed out at 103mph as standard and now does 107 with a K&N induction kit fitted

------/F/I/A/T/------

Fart In A Tin
<font color="orange">1994 Punto 55SX, metallic red, small, Italian and beautiful! </font id="orange">

 

[dave]

ohh don't do 107 to often it will go bang

----------------------------------------------------------------------------------
Please do not Email or PM me asking for support. Post on the forums instead. Your reply may help someone else. Thank you

 

[pritch]

55sx. 105mph but I don't recommend you doing that after you pass. You will die. I reckon driving a 55 at 90+ requires more car control than driving a 4x4 sports car at 155. If you get a big side wind in particular it ain't pretty.

Spirito di Punto | M-reg 55SX, black, 5dr. Clear repeaters. Remote locking fitted, no light confirmation yet though - need relay fitted

 

[FiatPunto1.1sx]

yeah, i did 110 in mine along the A47, with a m8 in the car, now i rarely take it past 80, n generally i stick to the speed limits coz

A: i got caught doin 60 in a 30, got let off so im not riskin the lucky 2nd chance i was given

B: the punto 55sx revs so high it just cains ur mpg while goin even at 70 constant, as mine revs pretty close to 4k revs doin that speed

 

[JonnyBoy]

Yep, 107 is NOT a comfortable speed for a 1.1 Punto - I went that fast for all of 30 seconds just to see how quick the car was, then back to 70 to let the engine relax a bit!

------/F/I/A/T/------

Fart In A Tin
<font color="orange">1994 Punto 55SX, metallic red, small, Italian and beautiful! </font id="orange">

 

[pritch]

[?]

My Punto is economical at 70. Granted it's at its most economical at just below 60 but from my rough calculations I've had around 50 to the gallon on long m-way journeys at 70. Drop to 60 though and you'll get 55mpg if your engine's in good nick.

Spirito di Punto | M-reg 55SX, black, 5dr. Clear repeaters. Remote locking fitted, no light confirmation yet though - need relay fitted

 

[Lampredi]

Drop to 50mph, and it'll get even better. 40mph - better still. I reckon most economical speed is probably about 30-35 (continuous 1500rpm) in 5th gear - your doing less work wrenching air out of the way and frictional losses are less than they would be at higher engine speeds...

Thoughts?

Here come da judge...

 

[cioccixxx]

well yeah thats true :| but who does 30-35 anywhere nowerdayz?

 

[pritch]

No, I don't agree with that, from my expereince any way. I'm sure it's most economical at 50-60 in 5th. Low revs in 5th seems to use more fuel than driving 'properly' I've found, and the engine seems to get warmer too. I tried driving like that for a while but gave up due to this and the lack of low-end power. Obviously if you are very gentle with the throttle at these low-rpms you can get great economy but everyone will overtake you when it goes from a 30 to 50 limit due to impatience! It's a tiring way to drive as well.

Spirito di Punto | M-reg 55SX, black, 5dr. Clear repeaters. Remote locking fitted, no light confirmation yet though - need relay fitted

 

[JonnyBoy]

Pritch is right on this one. Never do less than 40 in 5th on a small engine; it places a lot of strain on the engine bearings as it takes a lot of torque to pull 40 in 5th. You'll find that doing the same speed in 4th requires a smaller throttle opening and uses less pterol, as well as doing far less damage to your engine.
Accelaration is best done in a lower gear, with higher revs and a part-open throttle, than in too high a gear, foot to the floor and the engine struggling to shift the car. Theoretically an engine is most efficient around it's peak torque - I think this comes at about 3500rpm for a 1.1 Punto, making 55mph-ish the most economical cruising speed.

------/F/I/A/T/------

Fart In A Tin
<font color="orange">1994 Punto 55SX, metallic red, small, Italian and beautiful! </font id="orange">

 

[Lampredi]

Nah...it takes more torque to maintain 60mph in 5th gear than it does to maintain 30. When maintaining a given speed your throttle opening is constant - the faster you go the more work you do wrenching air aside (it's a viscous fluid) - therefore you require more torque (force) to maintain a higher speed. Which is why the car drinks more juice for a given distance at higher speeds.

Why would you need a smaller throttle opening to maintain a given speed in a lower gear. This doesn't make sense to me? In a lower gear the engine has to run faster to maintain that speed, assuming motion is constant (no acceleration), you need a smaller throttle opening for any given speed in a higher gear.

Not sure if that's true about engines being most efficient at there torque peak - what theory would suggest that would be the case? Thermal Efficiency of IC engines is dependant largely on two factors - heat loss and frictional (=heat & noise) loss. Assuming heat loss is largely constant (assuming constant ambient temperature) then most of the losses within the engine and transmission are down to mechanical friction. Once you have full oil pressure (about 1500 revs on most engines that are working OK), then bearing surfaces are not in contact and the coefficient of friction will be largely* constant througout the remainder of the engines operating speed range - as such the higher the engine speed, the greater work done against friction... and my original hypothesis - about 1500rpm (full oil pressure) at a constant speed will have the vehicle running at it's most economical state.

PS - We agree on one thing at least, accelaration is best done in a lower gear!

* - Ignoring the fact that the oil is also a viscous fluid and as such the faster the engine runs, the more work it will do moving oil about the lub system.



Here come da judge...