Tuning Fuel efficient cinq project

[chrisb7777]

Hi everyone

Had a search on the forum and can't find much on anyone modifying for fuel efficiency!

Just spent £600 on my cinq for MOT but i know it's as good as showroom (mechanically) now.

My 2 routes for this would be:

- Modify the 899cc to squeeze as much MPG as i can (Currently 45-47mpg)

- Engine swap to a fairly new engine (turbo?)

Any mod i want to do has to improve MPG, if it adds power too then thats a bonus! I don't want to end up losing power however!

Let me know what you think

Thanks

Chris

 

[David C]

What size tyres are you running?

 

[chrisb7777]

155/65/13

 

[David C]

Mine is on the tiny 145/70R13.

Probably not enough difference in drag & rolling resistance to get their cost back in MPG, unless you were looking for another set anyway.

I get nowhere near your MPG though, but being in London doesn't help and any time I see a clear road my first thought isn't "lets see how good I can get my MPG" ...

It is amazing how good your MPG can be in any car when the tank is close to empty though.....

 

[chrisb7777]

I used to have that size but much prefer the added grip and quietness of the wider tyre!

I do a mixture of motorway and city driving. Around 320-330 miles to a tank!

I do love the handling of an empty tank

Coming up to 100k miles now too

Chris

 

[John P]

Probably the biggest change you can make is free - it's how you use your feet....

Firstly you need to keep the engine at a relatively constant speed. Conventionally this is between 2000 and 2500 rpm on a petrol engine.

Motorway cruising means no faster than 60mph. I know. But drag increases exponentially with speed, and 60 tends to be where the sweet spot before drag really builds up.

Avoid pressing the brake. Anticipate the need to slow down and coast up to a halt. In gear as this uses less fuel.

For comparison my cinq sporting was good for about 45mpg with a broken thermostat in cold weather, on a 15 mile commute on dual carriageway with about 1 or 2 miles of town on either end. I expect to be better than 50mpg when everything works as it should. More if I follow the rules I just wrote...

 

[yiorgos]

Unfortunately the short gearing means that motorway cruising at a safe & legal speed (i.e not too low!!!) is never going to be as economic as it should on a cinque.

If you are serious about economy, I would say LPG and/or a modern engine transplant (with collateral power benefits for the later )

Everything else will be marginal

 

[Huwbishop]

I don't know why you're getting such rubbish consumption. My current cinq was not brilliant in 899 format, but she was a bit tired and wheezy.

But even in 1242 8v form I'm getting 50mpg on a run.

My previous 899 was much better, nippy and tight engine. Running about I used to get 60mpg, and on a trip to croft for the bsb she averaged 72mpg.

As for coasting in neutral or in gear, if you're in gear you will pull up quicker due to engine braking. If you're in neutral you will Coast further.

Although coasting in neutral is illegal I believe.


My blue/silver cinq had 145 13s, I used to run them at 40psi.

Make sure you're brakes aren't binding etc.

 

[David C]

My blue/silver cinq had 145 13s, I used to run them at 40psi.

40PSI...

That is monstrously high.

It is higher than the 18" on the front of my V6 TT run at...!!

 

[Huwbishop]

Yep, 40psi.

It's within the range of tyres recommended pressure. I did the same with the 175 13s on the wheels I sold to the black box, those tyres are 4 or 5 years old and still legal.

It does make them bumpier, but there is always a compromise.

72mpg I must have done something right.