Technical Header Unit for Uno.

[sharan23]

hi,

i want to know what performance exhaust i can use for my Uno 45 999cc FIRE. ive been reading about REMUS exhausts. what must i keep in mind before i fit one of these free flow exhausts andhow harmful is it for the car, does it improve performance significantly?

my car is 12 years old, will fixing one of these header do more harm to the engine than good.

Also, can i try using synthetic oil for my car. i currently use Shell Helix mineral oil. ive read a lot about the benefits of syntheitc oils. but will my 12 year old engine be able to handle it. please suggest a brand of oil and the grade to be used.

Sharan

 

[alexGS]

Hello Sharan,

Any sort of exhaust that is more freely-flowing will not do any harm to the engine. However if the exhaust is far too large in diameter, then you will get no additional performance and there may even be a performance decrease. In particular, the way that the two pipes leave the manifold (as standard) and then combine (below/behind the engine) is carefully-calculated to increase the efficiency at certain RPM (the pulses from cylinders 2 & 3 aid the pulses from cylinders 1 & 2). A performance header system (we call this 'extractors') should be designed in a similar way.

The standard system on the 999cc FIRE Unos that I've seen also has only one muffler/silencer, which combined with the dual downpipes makes, in my mind, quite an efficient system considering that the engine only has 45bhp.

I believe that the upgraded exhaust systems are more useful for turbocharged engines where the free-er flowing exhaust helps to maximise output of the turbocharger. That is why (I think) my Uno Turbo happens to have a fairly large pipe diameter (2.5") all the way through - it was this way when I bought the car - the downside is a thundering, booming noise inside the car when the engine is under load. There wouldn't be much point in having this noise if there is no performance benefit.

What I'm saying is that I think it might be a waste of money to fit an over-large exhaust system to a 999cc FIRE - make sure you talk to several specialists to find out exactly what size they recommend - perhaps one or two sizes larger than standard, but I doubt that 2.5" is necessary or desirable. And definitely, if you're going to increase the pipe size, do it right the way through - no point having a huge tailpipe if the rest of the system is standard...

Personally I feel that modifying the exhaust should be done at the same time as other changes to the FIRE engine's camshaft (valve timing - the camshaft is very restrictive as standard and the engine peak power is under 6000RPM - racecar engines have peak power nearer 8000RPM) and carburettor/fuel injection system (again, the standard single carburettor or single-point injection is very small). If you do only one of the three, I think you're unlikely to see much benefit. But I could be wrong.

As for engine oil, the original grade is 15W40. I believe that a semi-synthetic oil of 10W40 is sensible, such as Castrol Magnatec (I'm sure there will be a Shell Helix oil that's semi-synthetic 10W40 as well). That gives you some advantages of synthetic oil (e.g. better cold-start protection, theoretically better efficiency as the oil is a little bit thinner and easier to pump around the engine) without the expense of fully-synthetic oil.

How clean is the inside of the engine? (you can tell from looking in the oil filler with a flashlight to see whether the valvegear is blackened). If it is very clean and you want to keep it that way, then you should either change the oil fairly frequently (if used on short trips, every 8000km is a good idea) or you may want to use fully-synthetic oil as you said. I believe the reason that fully-synthetic oil has become popular is because manufacturers use it to extend the servicing interval of new cars (the oil lasts longer between changes).

If it is not very clean, then I think it is a bit of a waste to use a really-expensive oil, as it will become dirty quite quickly and I think you would be better off to use a cheaper oil and change it more often.

Meanwhile my pick of fully-synthetic oil is the Castrol range because they have higher weights (thicker viscosity) than Mobil 1 or some of the others. There was a Castrol oil called 'Formula RS' which is superseded by 'Edge' and available in 10W60 - good if the engine is often really hot.

Otherwise the thinnest I reckon you should go is 5W30. The FIRE engine was not designed for (i.e. does not require) 0W30 oil, so I don't think you should use it (or any grade starting with '0W') - that means the oil can become very thin under certain conditions and this may endanger certain parts of the engine such as the camshaft and valvegear.

Other opinions may vary, so let's see what everyone else here says

Cheers,
-Alex

 

[sharan23]

hi alex,

That is a very clear explanation thank you. i do agree that free flow exhaust systems probably work better on turbo engines. but if the purpose of the free flow is to push the exhaust gases out quicker, then i dont see why there wont be a power increase. the quicker gases get out, the quicker the combustion process and thus more power output. or more responsive the engine becomes.

i think i will consider moving to semi syhtetic oil. i currently use 20W50 shell helix oil. but if i want to movet o fully synthetic or semi synthetic, do you believe its too late considering the car has clocked 70,000 Kms already on mineral oil. how to i do the change from regular oil to semi / fully synthetic oil. must i drain out all the oil when the engine is really hot??

one last question, i am curretnly running 155 / 70 R13 (pressed steel wheels), i am unable to find alloys for the 98 PCD in India. i am looking around for 14" 98 PCD alloys. any recommended brands, also what make and size of tyres do u recommend for 14: alloys. i currently can gt goodyear, michelins, bridgestone, yokohama & federal easily here.

i cannot get anything more than 14: alloys as the roads here in india are bad and it will hamper my ride quality, not something i wanna do.

 

[Chas Uno]

i do agree that free flow exhaust systems probably work better on turbo engines. but if the purpose of the free flow is to push the exhaust gases out quicker, then i dont see why there wont be a power increase. the quicker gases get out, the quicker the combustion process and thus more power output. or more responsive the engine becomes.

You must remember that if you 'tune' an engine you should do it from all angles - i.e. all the way from the induction to the exhaust. Just using modified parts in one area will have little effect (or may even be detrimental) if the rest of the engine/ induction/ exhaust isn't tuned to suit.

For instance, a free flow exhaust system will only be effective if the induction and engine are able to flow more air/ fuel. The Uno 45 999cc engine is designed for torque and economy rather than outright power, and as such it's camshaft timing is restrictive and it's valves slightly small plus it's not tuned for high revs. It is also not designed to flow higher amounts of air/ fuel as standard, thus fitting a free flow manifold/ exhaust will do little other than upset the back pressure and disturb the exhaust scavenging effect.

To get the most out of your engine you need to ensure it can get enough air IN to the engine as well as OUT. Probably the single most restrictive intake part on the 999cc 45 FIRE is the camshaft. Fit a camshaft from a Punto 75 and you'll get longer valve opening duration as well as lift, which will enable you to flow more air/ fuel. Along with a free flow exhaust/ manifold and intake system you'll be able benefit from the improved engine breathing.

But then you have to make sure that the carburettor/ SPi system is able to flow enough fuel to cope with the increase in air volume. If it can't then you run the risk of having a weak mixture, which can lead to all sorts of problems not least melted pistons!

Thus when tuning an engine you need to consider it as whole rather than modifiying one area alone. This is why it's often much easier to find a bigger capacity version of your engine and swap them over along with its induction/ fuel system. It seems like hassle but in the long run it often works out cheaper and easier than trying to extract power from the engine you already have. So get looking for a 1242 Fiat engine!

 

[sharan23]

what your saying actually makes a lot of sense, i do agree that we need to consider revamping the entire system and not just one particular aspect of it.

the only reason i decided to consider the output (exhaust) of my engine is due to the unavailability of most other components. the 1242 engine was launched in india in it MPFi form. but sourcing an engine alone can be quite a hassle.

i guess i need to drop the idea to make any changes and target retaining it in its current form with good maintenance schedules.

but i would honestly like to consider shifting to fully synthetic despite the costs as it has longer standing benefits. the problem is that the specified oilo grade for my engine is 15W40, but only recently i have learnt that my garage has been using 20W50 for my engine. in their explanation due to the harsher driving conditions in india, the 20W50 grade is best suited. i lack the technical expertise to argue that. but i do want to shift to the 10W40 grade of fully synthetic. due you agree?

 

[alexGS]

in their explanation due to the harsher driving conditions in india, the 20W50 grade is best suited. i lack the technical expertise to argue that. but i do want to shift to the 10W40 grade of fully synthetic. due you agree?

I agree with their viewpoint, 20W50 is OK for hot weather, and I suggest that perhaps 10W40 semi-synthetic will be your best choice (and, it's cheaper than fully-synthetic). There's no special procedure to make the change of oil type - just drain the old, replace the filter, and fill up with the new. If the old is very dirty, you might consider draining it (not removing the oil filter) and then putting in about 2L of cheap oil, run the engine for a minute or two, then drain it again, replace the filter, and fill up with the semi-synthetic.

-Alex