Technical Knock Sensor?

[arseofbox]

Hi.

May sound a silly question, but Im looking into fitting a 16v head on the Cinq (1242). Eventual plans involve turbocharging with an element of boost control.

This boost control will need a knock sensor, so to simplify my choices of head, does anyone know if any of the MPi 1242cc 16v Bravo/a's had knock sensors on the Engine Management side of things?

Cheers!!

 

[paw]

just over ride the sensor and u will have no problems cause u dont need it

 

[paw]

just stick a push button or a flick switch on ur dash to operate the turbo

 

[dave]

i was told my punto had a knock sensor

 

[jug]

i've seen knock sensors on the block, head and inlet manifold depending on car, the most common place is next to the crankshaft pulley on the block, and i think that is where they are on bravo's too.

as for the turbo idea, its only good for the novelty value and maybe the dump valve, but if you want to go faster then this is the wrong route to go down. there are millions of reasons why this is a bad idea;

1. performance: sticking a turbo on a engine will not neccessarily make you go faster, and on a 1.2 engine you should be prepared for a loss of performance. BHP doesn't equal speed, and the gains in power will be offset by a loss in torque. you may see a small increase in acceleration and top speed but that will be mostly due to the higher rpm you can achieve which brings me to my next point.

2. reliability: a turbo will force your engine to rev higher than it is designed to. this isn't good, especially on a small fragile engine like the 1.2 cinq bottom end, you can expect to bend conrods or even snap them, even if you're lucky and the engine happens to be well balanced (which it isn't) then the increase in pressure will create heat and cause premature wear of the engine or may cause it to overheat because the coolant capacity and water pump are not up to the job on a cinq, and neither is the oil circulation. either way the expected life of the engine will be hundreds of miles rather than thousands.

3. cost: the cost to find parts, get them fitted, set the thing up so it works properly and then pay insurance (which will be very bad), and petrol (which it will waste badly), its madness. the cost cant justify the mod, it will be cheaper to buy a faster car.

4. better alternatives: if you want to get your cinq flying and you want a one off job they you should consider full engine and gearbox replacement from another car. a good example is the 1.2 bravo. taking the full engine and gearbox from a donor bravo will give you a complete, matched and reliable setup. the bravo 1.2 engine is better quality, and proven to be more reliable. just the basic engine/gearbox swap will give you a big increase in performance mostly from the bravo gearing in your lighter car. you can then do a bit of basic headwork such as port/polish and highlift cams, coupled with a programmable ecu, airfilter and full exhaust, this lot set up correctly would kill a 1.2 turbo cinq, will use less petrol, will be far more reliable and will cost less to do.


i've seen a 1.1 fiesta that was turbo'd (at 90bhp), yes it was funny, and people did admire all the work, but it still got beat by a 1.1 saxo and died in a matter of weeks when a conrod snapped. the cost to build was over 2k, i still laugh whenever i see the lad who did it, he stuck a 1.3 fiesta engine in and he says the 1.3 is faster as standard than his 1.1turbo ever was. speaks for itself.

i'm not trying to offend anyone here, i just really hate to see good money wasted. the old modders rule applies here, get the best engine and gearbox setup you possibly can and then do basic headwork, its the fastest, cheapest and most reliable way to do it. if it was me and i wanted to be crazy i'd get a punto GT turbo engine, but thats another story...

 

[arc]

just over ride the sensor and u will have no problems cause u dont need it

yes..you do.. they're helpful when trying to get the boost right - and avoid pinking!

just stick a push button or a flick switch on ur dash to operate the turbo

eh?

i was told my punto had a knock sensor

It does, on the back of the block i think


Jug.. you're points seem very flawed.. i'll try and address them, and please don't take anything i'm writing as 'having a go'

1. performance: sticking a turbo on a engine will not neccessarily make you go faster, and on a 1.2 engine you should be prepared for a loss of performance. BHP doesn't equal speed, and the gains in power will be offset by a loss in torque. you may see a small increase in acceleration and top speed but that will be mostly due to the higher rpm you can achieve which brings me to my next point.

The only loss of performence is going to be outside the turbo range, as the compression ratio will be reduced. BHP does equal top speed. Torque equals accelearation. BHP is a product of revs and torque, so if an engine has more BHP at a certain RPM than it did before the turbo then it must have an increase in torque.
A turbo'd engine will generally have a much higher torque figure than an N/A engine tuned to the same BHP.

2. reliability: a turbo will force your engine to rev higher than it is designed to. this isn't good, especially on a small fragile engine like the 1.2 cinq bottom end, you can expect to bend conrods or even snap them, even if you're lucky and the engine happens to be well balanced (which it isn't) then the increase in pressure will create heat and cause premature wear of the engine or may cause it to overheat because the coolant capacity and water pump are not up to the job on a cinq, and neither is the oil circulation. either way the expected life of the engine will be hundreds of miles rather than thousands

a turbo will not force the engine to rev higher than it is meant to.. i'm not sure where you got that from. A 999cc FIRE engine from a Panda has been tested with stock internals and saw around 150bhp before any damage occured. Obviously not safe for a daily driver, but gives an indication as to what can be achieved. Tom's Cinq (like mine) has a Punto75 bottom end in there. It is stronger than the Cinquecento (which FYI the biggest engine offered in the cinq was 1108cc) Punto55/60 and Panda bottom ends. Admittedly it is not as strong as the blocks used on the 16v engines as they have a brace on the con rods iirc.
The cooling system on a Cinquecento isn't that bad. My tuned 1242 N/A runs an alloy rad, low temp thermostat and a punto GT fan switch and that'll sit at 90c doing in excess of 115mph. Anyone who turbo's an engine knows to fit an oil cooler to aide in cooling the oil which is heated by the turbo.
The oil circulation isn't a problem on these engines either. Remeber all FIRE blocks are VERY similar to each other. If you take a look in the Cinq/sei section you will find many turbo charged Cinqs, that have been going for tens of thousands of miles, not a few hundred!

3. cost: the cost to find parts, get them fitted, set the thing up so it works properly and then pay insurance (which will be very bad), and petrol (which it will waste badly), its madness. the cost cant justify the mod, it will be cheaper to buy a faster car.

I'll work backwards through this one.. Yes, it might be cheaper to buy a faster car - but that isnt the point. No-one expects a Cinquecento sat behind them on the motorway flashing them move out of the fast lane because you are holding them up! It won't badly waste petrol if setup properly. Insurance will be pricey, but i know of turbo drivers who pay similar to what it costs me to insure my N/A. Setting up will be a faff, but once its right - it'll be reet. Fitting the parts, well, i know Tom will be doing the work himself. And finding the parts isnt too tricky either.

4. better alternatives: if you want to get your cinq flying and you want a one off job they you should consider full engine and gearbox replacement from another car. a good example is the 1.2 bravo. taking the full engine and gearbox from a donor bravo will give you a complete, matched and reliable setup. the bravo 1.2 engine is better quality, and proven to be more reliable. just the basic engine/gearbox swap will give you a big increase in performance mostly from the bravo gearing in your lighter car. you can then do a bit of basic headwork such as port/polish and highlift cams, coupled with a programmable ecu, airfilter and full exhaust, this lot set up correctly would kill a 1.2 turbo cinq, will use less petrol, will be far more reliable and will cost less to do.

The Bravo engine is not better quality than a Cinq engine. They're both mass produced engines, produced side by side at the factory. Can you please backup the statement that it is proven to be more reliabe. The 1242 Bravo engine.. i'm guessing its around 80bhp just like the 1242 16v Punto engine. 16v Punto engine conversions have been done before so a Bravo engine is possible but it is quite a lot of work. You end up with problems with engine mounts, gear selection problems, clutch problems (the cinq has a cable clutch vs the bravo hydraulic clutch).

My 1242 engine has headwork done. It is ported (not polished, you dont want a shiny inlet tract), it has multi angle valve seats cut, skimmed to raise the CR, higher lift cam, 40mm tb, port matched inlet manifold, BMC CDA inudction kit, remap and a lighten flywheel - and with all that work, it can be beaten by a turbo charged 1108cc Cinq.

There is no way it would be cheaper to build what you have suggested. A programmable ECU is not cheap. And once its done, the turbo'd engine will have more torque. We have a 1242 16v Seicento on here, has had a lot of work done to it. It runs throttle bodies etc, but still didnt have an awful lot of torque.

i've seen a 1.1 fiesta that was turbo'd (at 90bhp), yes it was funny, and people did admire all the work, but it still got beat by a 1.1 saxo and died in a matter of weeks when a conrod snapped. the cost to build was over 2k, i still laugh whenever i see the lad who did it, he stuck a 1.3 fiesta engine in and he says the 1.3 is faster as standard than his 1.1turbo ever was. speaks for itself.

They are old..naff, engines. None of that is really relevant.

i'm not trying to offend anyone here, i just really hate to see good money wasted. the old modders rule applies here, get the best engine and gearbox setup you possibly can and then do basic headwork, its the fastest, cheapest and most reliable way to do it. if it was me and i wanted to be crazy i'd get a punto GT turbo engine, but thats another story...

Appricate that your not trying to offend anyone here - but i think you need to take a look into what has already been done to Centos and what these engines are capbable of. There is only so far N/A tuning can go, and there is a point where pound for foot pound it makes sense to turbo it.
You'd have fun fitting the PuntoGT engine in there, its a tad too tall. But the Uno turbo engine fits in there. It's a lot of work to do - but again, it has been done before.

 

[jug]

due to bad reading skills i assumed the original post was suggesting a cinq sx bottom end with a cinq sporting head and a turbo stuck on top, nothing else. i dont know why i thought a standard cinq would be 1.2 but i guess its because i was half asleep.

i thought a sx bottom end, sporting head and random turbo would be a bad idea because the standard cinq bottom end isn't going to have very strong components, especially conrods, and as such i also assumed the cooling and oil circulation would be insufficient on the standard cinq lump due to low oil and water capacity, weak pumps, small radiator, low oil and water flow rates, narrow oilways etc etc. it wouldn't last very long at all.

i accept that the 1242 punto bottom end will be much more capable of taking a turbo, this is the same reason i suggested the bravo engine, same idea but different donors and practically the same engine really. i didnt realise he was already using a punto block. now that i do realise this i accept this mod is possible and could be reliable. judging from other peoples efforts i found online is seems fairly easy to do as well, and yes it doesn't cost the earth if you can do it yourself.

if i knew he had a punto engine i wouldnt have thought this was such a crazy idea in the first place, but admit a standard cinq bottom end with a cinq sporting head and some turbo would be a bad idea, even if you did get it working it wouldnt last long.

so yes i was wrong, yes the idea will work, yes it will probably last for many mile, yes it wont cost the earth to do... but,

the reason i think torque will suffer is because torque is the mean effective pressure in the cylinders. that means torque = (average pressure on the expansion strokes) - (total of the average pressures on the induction, compression and exhaust strokes) look it up if you dont believe me.

a turbo works by using exhaust gasses to turn the turbine, which in turn creates greater intake pressure. this pressure will increase the average pressure of induction strokes, which reduces torque.

think about it, average expansion stroke pressure is unchanged, but the induction stroke pressure increases, that has to reduce torque. a turbo is basically a supercharger that is powered by the exhaust, all it does is create greater pressure for the intake so it is easier for the car to take air/fuel mix into the cylinders. its forced induction, nothing else.

aside from all the mechanics and physics i know torque suffers because i've seen printouts from a scooby that had its turbo upgraded, it had more power and less torque with a T3 turbo than it did with the standard one, although power was up quite a bit and the increase in power is far greater than the loss of torque. the garage explained that this is normal and turbo's do sacrifice torque for power. thats ok on a car with high torque to start off with but on small engines torque is critical, every lb/ft of it. as you say torque does equal acceleration.

""The only loss of performence is going to be outside the turbo range, as the compression ratio will be reduced""
explain how the compression ratio can change? compression ratio is the ratio of the total volume enclosed in a cylinder when the piston is located at BDC compared to the volume enclosed when the piston is at TDC. if you arent changing the piston size or piston stroke then the compression ratio cant change. thats impossible.

as for BHP meaning better top end speed, well i cant understand where that came from either. BHP is related to torque in as much as power is torque in relation to time, for example torque could be 100lb/ft, that expresses the actual turning force produced by the engine, power can be expressed as lb/ft/min if you times the power by 33000 (its true check conversions on answers.com), that means power expresses the rate at which the turning force can be delivered by the engine, it is an expression of the efficiency of the engine not its actual power. the turbo increases efficiency becuase the engine can take air in more easily and hence it becomes more efficient, i.e. it requires (or wastes) less energy during operation. this is where the power gains come from.

basically a more powerful engine uses its torque more efficiently, but it is limited by the torque, the torque is the only true rating of an engine's ability to pull, if the engine can use its torque more efficiently how does this mean it will have greater top speed?

 

[custard]

a few points from your post.im running a '96 cinq 1.1 turbo which was coverted from new and is currently on 92k with the original engine so as for lasting very long............
compression ratio's change as(except in low boost conversions)you need to lower the standard compression ratio to allow for the boost pressure from the turbo either via dished/shaved pistons or spacers.shaved pistons in my case.
you are using one example where the turbo obviously wasnt suted to the set up off that car. the turbo adds wads off torque.check out the turbo FAQ sticky in the cinq section for figures.

also from another angle a bigger capacity engine adds more weight which can upset the handleing of small cars such as the cinq.a turbo add on isnt an ideal siuation but gives a healthy bang for its buck

 

[HP]

a turbo works by using exhaust gasses to turn the turbine, which in turn creates greater intake pressure. this pressure will increase the average pressure of induction strokes, which reduces torque.

On the intake stroke the piston is travelling down, so if you put air under pressure in there you're helping force the piston down and reducing pumping losses.

think about it, average expansion stroke pressure is unchanged, but the induction stroke pressure increases, that has to reduce torque. a turbo is basically a supercharger that is powered by the exhaust, all it does is create greater pressure for the intake so it is easier for the car to take air/fuel mix into the cylinders. its forced induction, nothing else.

What it does is put air under pressure in the cylinders. Air under pressure will contain more oxygen, so you can add more fuel and while maintaining stoichiometric burning you will increase power output.

aside from all the mechanics and physics i know torque suffers because i've seen printouts from a scooby that had its turbo upgraded, it had more power and less torque with a T3 turbo than it did with the standard one, although power was up quite a bit and the increase in power is far greater than the loss of torque. the garage explained that this is normal and turbo's do sacrifice torque for power. thats ok on a car with high torque to start off with but on small engines torque is critical, every lb/ft of it. as you say torque does equal acceleration.

Ah, that's most probably true if starting with a turbo car and upgrading from there. When starting with a normally aspirated and adding a turbo, if the fuelling and ignition are sorted you can't really lose out.

""The only loss of performence is going to be outside the turbo range, as the compression ratio will be reduced""
explain how the compression ratio can change? compression ratio is the ratio of the total volume enclosed in a cylinder when the piston is located at BDC compared to the volume enclosed when the piston is at TDC. if you arent changing the piston size or piston stroke then the compression ratio cant change. thats impossible.

If you're running more than a handful pf psi boost, then you need to reduce the compression ration to stave off detonation. Performance off boost will be poorer with a lower compression ratio. If you don't change the cam or cam timing on a FIRE/Superfire then the useable rev range won't really change. Mine still runs out of puff at 6000 revs.

as for BHP meaning better top end speed, well i cant understand where that came from either. BHP is related to torque in as much as power is torque in relation to time, for example torque could be 100lb/ft, that expresses the actual turning force produced by the engine, power can be expressed as lb/ft/min if you times the power by 33000 (its true check conversions on answers.com), that means power expresses the rate at which the turning force can be delivered by the engine, it is an expression of the efficiency of the engine not its actual power. the turbo increases efficiency becuase the engine can take air in more easily and hence it becomes more efficient, i.e. it requires (or wastes) less energy during operation. this is where the power gains come from.

basically a more powerful engine uses its torque more efficiently, but it is limited by the torque, the torque is the only true rating of an engine's ability to pull, if the engine can use its torque more efficiently how does this mean it will have greater top speed?

I've got a 1242 engined Cinq running 5 psi boost, and it'll do the quarter mile in 16 seconds - 3.5 - 4 seconds faster than a factory standard car. It's running the standard 9.6:1 compression ratio, and will tickle the rev limiter in 5th, on 14" wheels.

 

[HP]

Hi.

May sound a silly question, but Im looking into fitting a 16v head on the Cinq (1242). Eventual plans involve turbocharging with an element of boost control.

This boost control will need a knock sensor, so to simplify my choices of head, does anyone know if any of the MPi 1242cc 16v Bravo/a's had knock sensors on the Engine Management side of things?

Cheers!!

Back on topic, Tom - the MPI Seicentos use a knock sensor, might be easier to rob a loom from one of them.

 

[arc]

no worries about the mix regarding bottom ends. The 899cc engine is not actually a FIRE engine, so there would be no way you'd get a 16v (or even a sporting) head onto it!

regarding compression ratio, i mentioned the lack in performence because i assumed that Tom will be modifiying the pistons to allow him to run higher boost - this would reduce the CR, causing a drop in performence.

the reason i think torque will suffer is because torque is the mean effective pressure in the cylinders. that means torque = (average pressure on the expansion strokes) - (total of the average pressures on the induction, compression and exhaust strokes) look it up if you dont believe me.

i know, but as Pete has said - if you are forcing more air and fuel in on the intake stroke you are going to get a higher resulting pressure from the expansion stroke.

as for BHP meaning better top end speed, well i cant understand where that came from either.

I didn't really explain what i meant there properly. BHP is a product of torque, revs, and the magic number 5252. A low torque figure, but high BHP figure suggests torque at higher RPM therfore a higher top end - because the engine still has decent torque at higher RPM.

 

[jug]

""On the intake stroke the piston is travelling down, so if you put air under pressure in there you're helping force the piston down and reducing pumping losses.""
if you actually believe that a few psi can help to push a piston then you're crazy. the piston is forced down by the pressure created in another cylinder, the cylinder that is firing, the explosion of fuel/air mix creates pressure which forces that piston down, it is connected to the crankshaft via a conrod, which is then conected to the other piston via another conrod, which pulls down the piston. a few psi extra in the intake manifold will not force the piston down, it is pulled down by its conrod, nothing else. the piston pulls air in, it isnt forced in by the turbo, the turbo just makes it easier for the piston to pull the air in (the efficiency increase or power gain)


""What it does is put air under pressure in the cylinders. Air under pressure will contain more oxygen, so you can add more fuel and while maintaining stoichiometric burning you will increase power output.""
it adds pressure in the intake manifold which allows the air to enter the cylinder more easily, which is more efficient so you get extra power. it should increase the density of the air entering the cylinder which will allow more fueling, and i think this is where the torque gains will come from. i was wrong about the torque increases

""Ah, that's most probably true if starting with a turbo car and upgrading from there. When starting with a normally aspirated and adding a turbo, if the fuelling and ignition are sorted you can't really lose out.""
i agree with this, i wasn't considering the effects of more dense air and greater fueling, and it is especially true if you modify the piston.


so yes i agree the torque will increase if you convert a N/A car to turbo

 

[HP]

""On the intake stroke the piston is travelling down, so if you put air under pressure in there you're helping force the piston down and reducing pumping losses.""
if you actually believe that a few psi can help to push a piston then you're crazy. the piston is forced down by the pressure created in another cylinder, the cylinder that is firing, the explosion of fuel/air mix creates pressure which forces that piston down, it is connected to the crankshaft via a conrod, which is then conected to the other piston via another conrod, which pulls down the piston. a few psi extra in the intake manifold will not force the piston down, it is pulled down by its conrod, nothing else. the piston pulls air in, it isnt forced in by the turbo, the turbo just makes it easier for the piston to pull the air in (the efficiency increase or power gain)

You've lost me with

but the induction stroke pressure increases, that has to reduce torque

then....

 

[arseofbox]

Hmm....well thanks for that . Interesting ideas forwarded.

I see what youre saying re: MEP, jug, but I also agree with Pete on the turbo helping force gas in, and equally pull it out.

I was talking to Howard at AllItalia earlier today about it, and he recommended using a Mk1 (pre OBD MPi systems) 16v 1242 head and block. Sounds alright to me, as the pistons are pre-dished as the SuperFIRE would be interference design without them, I'll just use a decomp. plate to sort the static CR out (to ~8.0:1)...then run that somehow on an SPI (although it will underfuel) for a bit till I have the ECU figured...