Which is the best juice...

[revilla]

*arrowup* As Roadsport06 says, you would however need more power to achieve the same RPM and therefore road speed going into wind or up hill.

[Mostro]

Yeah, all obvious really..

[john milner]

Half hour after making the Ferrari KA post I realised it was tosh. The KA engine in a Ferrari would not work well at all as the gearing would be way too high. It is for a similar reason that my first gear is too low as it is designed for a Sierra not a big go-kart.

The root of the thing that I did not understand was how two identical cars one of which is slightly tuned and producing more HP would move at the same speed for a given RPM in the same gear as the other. It was as though the additional HP were lost somewhere. I think I have got it now it is due to torque - put both them on a very steep upward slope at gradient that just about stalls the low HP car and the higher HP car will be drivable(albeit poorly).

As for seeing more revs to attain a speed with different fuels. It is what I saw but trying to accurately read a speedo & tacho at 70 and with wind resistance to factor in is a flawed test.

The MPG figure was bit easier to measure. With standard fuel my MPG drops on a motorway. With Super it gets marginally better on a motorway. In general my car doesn't like Super and loses it's oomph so it may have induced a Driving Miss Daisy style of cruising.

[MADMALC]

❗ 🤔

[Mostro]

Quoting MADMALC: 

❗ 🤔

 

 

😬

 

Edited by - Mostro on 31 May 2013 20:15:40

[Roadsport06]

I am never convinced by comparisons of different fuels. I think you are in danger of driving to get the mpg you'd expect. I have done comparisons with my wife's car. It is my job to fill up the cars so I can fill up with different fuels without her driving style changing.

[Mostro]

Quoting John Milner: 

producing more HP would move at the same speed for a given RPM in the same gear as the other

 

A-ha! "in the same gear" is not the same as "having the same gearing"..... Perhaps this is where the confusion is arising 🤔

[john milner]

For same gear I also meant same gearing. Two cars the same apart from one having a performance tweak. Each car with the same RPM will move at the same speed even though one is producing more power than the other. Sounds daft at first as more power generally means more speed but in this case it doesn't.

 

Anyway I never did answer the title question "Which is the best juice...".

For me it is snake oil free Asda RON 95. It's usually the cheapest and I get 1% off that with my Asda credit card. I have never had any problems with always buying the cheapest. The only time I have ever noticed a difference in fuels is when experimenting with Super and that was mostly for the worse.