Fuel Economy/boot Spoiler

[Guest c5vtr]

Afternoon

 

If you haven't seen my previous threads i recently took ownership of a vtr, economy initially was 32 mpg. I had a major 100k service done (also on a thread), the 'brain' noted one of the injectors out of tolerance and the mechanic recommended using Millars additive on short fills to try to clean it up and bring the injectotor back within tolerances. It seems to have been working, my wife has had the car on lots of stop start driving and we've seen the mpg rise to over 35. A long run yesterday to Dublin and back (220 miles) has seen that rise to over 36.

 

So a couple of questions

 

1. The boot soiler is factory fitted, regardless of whether i could actually take it off, would i improve overall economy or potentially lose any downforce/drag it may or may not be generating?

 

2. i noted with interest the previous threads on tyre pressures and inflating to -10% of maximum, anyone continue the experiment and what did u find?

 

any and all thoughts welcome as ever

[Randombloke]

1. The boot soiler is factory fitted, regardless of whether i could actually take it off, would i improve overall economy or potentially lose any downforce/drag it may or may not be generating?

 

I'd leave it.

 

2. i noted with interest the previous threads on tyre pressures and inflating to -10% of maximum, anyone continue the experiment and what did u find?

 

I've had a small period of poor economy. Didn't check pressures as I had done it not long before. Checked them and all 4 were low by about 0.4 bar. Pumped up and economy much better.

 

If you have Dunlop SP 2000s I would suggest a minimum of 2.5 bar all round and more like 2.5 front, 2.8 rear even with no load.

[Ronin]

The boot spoiler will cause drag, that's what they are designed to do. However I would agree with RB and leave it on, It will not make any difference to the mpg unless your speed is above 85mph constantly.

Spoilers on all modern cars are for aesthetic purposes and offer no downforce advantages what so ever. The only cars that it does help with are the likes of subaru imprezza turbo's and Evo's and even then it only has a slight stability effect above 100mph.

 

Fact: Remember this story? It was in the papers and on the news...

 

Humberside police once had a couple of escort cosworth's in the 90's complete with the picnic table sized whale tails!. They removed the spoilers and found the car was actually faster but a little bit more twitchy at speeds above 100+. They went one further and replaced the front spoiler with a standard escort bumper in order to get over speed humps quickly and again the car was a little faster but actually balanced the twichy handling. They never reported any increase in fuel economy though.

Unfortunately a pursuit driver totalled one into a farmers field during a chase and the insurance wouldn't pay out because the police workshop had "modified" the vehicle! Needless to say the spoilers were replaced on the other cossie much to the dismay of the other pursuit drivers.

 

Humberside Constabulary tried to sue Ford UK for damage to the crashed vehicle, Their arguement was that they had proved ford had made an inherently unstable car with all the spoiler addititions! It never made it to court but Humberside got a brand new cossie powered escort in a rs2000 spec bodykit free from Ford.

 

Now that was comedy you just can't buy B) :lol: :lol:

[Guest c5vtr]

The boot spoiler will cause drag, that's what they are designed to do. However I would agree with RB and leave it on, It will not make any difference to the mpg unless your speed is above 85mph constantly.

Spoilers on all modern cars are for aesthetic purposes and offer no downforce advantages what so ever. The only cars that it does help with are the likes of subaru imprezza turbo's and Evo's and even then it only has a slight stability effect above 100mph.

 

Fact: Remember this story? It was in the papers and on the news...

 

Humberside police once had a couple of escort cosworth's in the 90's complete with the picnic table sized whale tails!. They removed the spoilers and found the car was actually faster but a little bit more twitchy at speeds above 100+. They went one further and replaced the front spoiler with a standard escort bumper in order to get over speed humps quickly and again the car was a little faster but actually balanced the twichy handling. They never reported any increase in fuel economy though.

Unfortunately a pursuit driver totalled one into a farmers field during a chase and the insurance wouldn't pay out because the police workshop had "modified" the vehicle! Needless to say the spoilers were replaced on the other cossie much to the dismay of the other pursuit drivers.

 

Humberside Constabulary tried to sue Ford UK for damage to the crashed vehicle, Their arguement was that they had proved ford had made an inherently unstable car with all the spoiler addititions! It never made it to court but Humberside got a brand new cossie powered escort in a rs2000 spec bodykit free from Ford.

 

Now that was comedy you just can't buy B) :lol: :lol:

 

I guessed the spoiler was doing little, i'm just happier to know it isn't doing anything worse! i think we'd be all over an actual Citroen high performance saloon!

 

The previous owner has really crappy 50 quid cheap tyres on, but i know i don't have them inflated to anywhere near the pressures you are describing so i guess thats where i'll go next.

 

Cheers

[Ronin]

As far as tyre pressures go. I check mine every week without fail and use the same pump in the same fuel station. I once was actually sad enough to try 3 different filling station pumps in my immediate area and found they were all registering different psi's, one as much as 7 psi less! Another was 5 psi more!

I bought a cheap tyre pressure checker from halfords and now use the filling station with the closest reading after they had the machine calibrated once I showed them the difference. The halfords TPC was only -1 psi out after calibration on the pump.

 

Never take air pumps at face value. If in doubt, ask when it was calibrated. Remember it's your money they are wasting in fuel economy and tyre wear if it's wrong and then some filling stations have the cheek to charge you 20p for the priveleage. :rolleyes:

[Randombloke]

2. i noted with interest the previous threads on tyre pressures and inflating to -10% of maximum, anyone continue the experiment and what did u find?

 

It worked. Try it yourself but with extreme care, noting remarks about accurate air pumps. Details in that thread.