240 General: Mpg

[morsing]

Originally Posted by liamcafs

What about 240s in the states?? Are the engines setup differently maybe because isn't their normal gasoline 88 or 90 Octane??

There are two parts to it - the US uses a different anti-knock index called MON instead of the UK RON index. They're not directly convertable, but US 91 is roughly UK 95.

The other thing is US engines traditionally used much lower compression ratios. The 10.x ratio B230E in Europe is 9.x B230F in the US. That is less efficient but more knock resistant and requires lower octane protection.

[morsing]

Originally Posted by Antz

There is a few minor errors in your argument too though.

1. Redblocks do have knock sensors from 1990. These cars run on LH fuel injection and they do have knock sensors.
2. The guide you linked me to only covers up to 1989 which is for carb or mechanical fuel injection cars. After this date they switched to LH and the ECU would automatically adjust for the fuel mix.
3. The V40 uses a whiteblock. All cars from the 940 onward use the whiteblock variant which was introduced in 1993 (I think) in the 960. These do have knock sensors fitted as they are all electronically fuel injected. There is only the redblock or the whiteblock......and diesels....oh and the GDI variant of the S40/V40 but that's a Mitsubishi engine and is definitely recommended to run 98 otherwise it runs like utter crap and cokes itself up.

What I should have said in my original post is that if your car runs a carburettor or mechanical fuel injection then it is recommended to re-jet and adjust this for 95 or 98 octane fuel to avoid detonation and reap the benefits. In a electronic fuel injected car then it doesn't matter although turbo equipped cars will benefit from the high octane much more than your B200F with a camshaft made of a piece of straight pipe producing roughly 14bhp (gutless things).

But just slapping some V-Power in your 240 without doing anything is a complete waste of money because you wont get any benefit from it. The reality of it being a pre-89 and being run on high octane fuel all its life is pretty much zero and with it having survived 27 years so far, its safe to say that it'll have been adjusted by now and that running it on 95 won't make much difference now.

I really don't get why anyone would adjust to suit 95 octane. It's not even going to save you money as both power and fuel economy would drop 10-15%.

On half the engines, like mine, the fix is to have two head gaskets, which at a shop would cost you an initial outlay of £500-700, and again, you'd end up with a car with 110bhp and doing 25mpg... Why not just use 98 octane? Not to mention the higher risk of head gasket failure.

I know what I chose - 133bhp and 33mpg, thank-you. I'm starting to understand people reporting 240s doing 0-60 in 16s...

I'd actually be curious to find out have many 240s have been converted - maybe a poll would be interesting.