Whee! Vroom!! Etc!!! :-D

[denny]

Yeah, the car is nice.

It's a bitch to start :-\ but once you get it going, it very definitely goes :)

Now it just needs a decent stereo (and possibly some new spark plugs), and all will be well with the world.

Had an amusing moment in a petrol station on the way home when I couldn't get it to start again... a bloke, obviously a mechanic of some kind, wandered over in oily overalls and said he knew what the problem was, he could sort it if I lifted the bonnet. I asked what it was, and he said the points were out.

I told him the car has no points. Then I told him it has no pistons either. That was when he looked really confused, poor bloke :)

Anyway, I'm seriously overdue for bed, haven't managed one early night this week, and the weekend isn't looking to be full of them either! More details on my car-buying excursion tomorrow. Just don't talk to me about petrol station opening hours in the sticks.

Comments

[azekeil.livejournal.com]

Any ideas why it's such a bitch to start?

But Yay, W00t, etc :)

[cryx]

yay!! new car! it's yours! yaaaay!

[dennyd.livejournal.com]

Well, possibly I've been sold a lemon, this often happens to me. Let's hope not eh? :)

Hopefully it just needs new plugs or some other kind of minor servicing. Filling it with super unleaded might help too, presumably that's more inclined to go 'bang' than normal unleaded is.

I wish I hadn't filled the whole tank last night now, but I didn't think about it at the time - I was just so bloody pleased to find a petrol station that was open. And it was kind of funny to realise just how empty it was by how much I managed to fit in there.

[kissycat1000.livejournal.com]

Super unleaded has a higher octane level and was made for cars that are older and have been converted to unleaded, but still need the 'bang' that leaded gives. AFAIK it's not advisable to put it into a car that was never converted, since a greater tendancy to 'bang' may well cause pre-ignition problems etc, especially if there is already a high compression ratio.

This is a genuine question; have you seen any advice anywhere that advocates using it in high performance unleaded cars? If yes, I'd be very interested to read about it (having not come across it myself). If no, do bear in mind that things like having spark plugs with fatter sparks will be more beneficial because the ignition will still definitely happen at the correct time.

[stuartl.livejournal.com]

Argh. This requires a very long answer and I'm supposed to be going to work.

Clothes would help too...

[stuartl.livejournal.com]

Right, I have some clothes. I'm not wearing them but hey, who needs clothes to answer unleaded related questions...?

The higher octane level means two things:

• It burns harder


• It burns more quickly

Because the "bang" is bigger in high octane fuel it's possible to use this power and get more out of the same engine than you do with a lower octane fuel. There are, of course, catches. The bigger, hotter bang puts much more stress on the engine and can cause premature wear and tear if the engine wasn't designed for it. In extreme cases it can cause major failure of component parts, particularly the pistons, con rods, small/big ends or crank and its bearings. These cases are fairly extreme but they do exist.

The biggest problem with using high octane fuel is not the impact (!) of the bigger bang but the fact that it burns more quickly. The spark plugs in an engine are ignited fractions of a second before the bang is needed because it takes time for the spark to generate the explosion and hence the propulsion. In practice this means that the spark plugs are actually ignited slightly before the piston hits top dead centre of its stroke and now the problems become quite obvious with a faster burning fuel. With a high octane fuel in a car designed for the lower octane the explosion will happen before the piston hits top dead centre. This means that the explosion actually slows the engine down until the piston hits TDC. Then the explosion accelerates the engine again. This results in a VERY inefficient engine.

The situation is complicated much further by modern electronically controlled engines. Such engines are capable of automatically advancing and retarding the ignition timing to accommodate for the particular fuel characteristics they observe through their network of sensors. Adjusting the ignition timing isn't enough to make an engine efficient on different fuels but it can alleviate the more serious problems associated with changing fuels. The computer doing the processing is restricted by its programming and some ECUs are much smarter than others. Some ECUs only learn the characteristics of the fuel in the first 1000 miles since a reset. Others can revoke previous education and learn from scratch on the fly, others take time to adjust to the different fuels. As far as I'm aware there is no way of finding out how your ECU manages the ignition timing and how long it takes to relearn. Car geeks often post about this topic but it's fairly clear that none of them actually know the answer and are speculating.

As if that wasn't complicated enough faulty, worn or badly designed sensors can feed the ECU crap and cause it to make bad decisions about fuel mixture, ignition timing and injector duration.

So what's the answer? The answer is VERY simple. RTFM. Every car in the UK will be tested with UK fuels and will have a specific recommendation in the manual for which fuel is most efficient. Cars designed for 95 RON will be less efficient on 97/98 RON and are likely to lose significant performance as a result. The car may also suffer internal mechanical damage. Cars designed for 97 RON can often take 95 RON but will lose some performance. There is little risk of damage but you may as well pay the extra 4p per litre to run the car on the fuel it was designed for.

Cars designed to run on leaded are a problem area. The mechanic doing the conversion will have set the engine up for a particular fuel (hopefully) and will have adjusted the ignition timing appropriately. Unless the mechanic has told you which fuel he's set it up for you're much better off running the car on 95 RON until you can confirm that the engine ignition timing is set up for 97/98 RON. And even then I wouldn't bother. Super unleaded fuels still aren't everywhere (there's only two stations in Newbury selling it) and once in a while you'll have to run your car on 95 RON. Why bother setting it up for 97 RON when the engine is so old technology that it's likely to have suffered major wear and tear and isn't likely to be able to deal with the bigger bang?

[dennyd.livejournal.com]

Hooray for naked automobile lecturers :-P

[dennyd.livejournal.com]

Opinion seems rather divided on the RX7 forums on which fuel is better to use...

[dennyd.livejournal.com]

Sparkier spark plugs sounds like a good idea. There's some very definite advice on which plugs to run on the owners club forum, so I'll make sure I've definitely got those ones.

[kissycat1000.livejournal.com]

Ah, so basically, when you use this fuel on a car that's supposed to run on normal unleaded, you get pre-ignition problems (with the 'bang' forcing the piston down before TDC, thus causing engine damage and power loss) which are more likely in a high-compression engine where the act of squishing the air/fuel may cause it to ignite before the spark?

/me points up at previous comment :P

[kissycat1000.livejournal.com]

Do bear in mind that if you're doing that then you should also get some decent HT leads to get most out of them. Bear in mind that, as Stuart points out, ignition will happen slightly sooner with decent sparks (as well as being more powerful, but not in an engine destroying type of way) and you may need to retard the timing very slightly to make the most of this. I'm assuming that the flywheel is fully adjustable already (and can be changed to any position at all rather than just any notch) but if not a lightened alloy one will give you that advantage.

I think I've reached almost the limit of my knowledge about this particular subject now, so I'll shut up and bow to superior brains...

[taoist-goth.livejournal.com]

Yay can we race now? :D

Oh and blimey your insurance was more than mine! :O

[stuartl.livejournal.com]

Nyer :P

[dennyd.livejournal.com]

Hehe. No ta :)

That would be thanks to my collection of points and accidents, I presume.

[taoist-goth.livejournal.com]

Speeding points don't affect insurance, so I'm guessing you must have bugger all no claims bonus, unless your points are wreckless driving ones or sommat. All the same, a grand to insure and eight grand car is monstrous!

[dennyd.livejournal.com]

Six points for IN10 - driving without insurance - plus a large (motorcycle) accident claim with as-yet unresolved liability.

I have full no claims bonus, which is the only reason I could afford to do this at all :)

I'm told that once the accident is resolved non-fault and the points are cleared (Dec 2006) then I should be looking at about half the current rate.

[taoist-goth.livejournal.com]

It's just as well points disappear after 5 years! I'd be on 9 speeding points instead of 3 otherwise, and driving on eggshells, heh.

[d-floorlandmine.livejournal.com]

When does your car date from? MineBringer is a '92, and set up for unleaded (possibly partly due to Japanese ancestry, although it's a UK-spec vehicle, not an import). It's set up for 95 RON, but yours might have been timed for something more sporty and punchy. Oh, and the fact that you've got that freak engine might change some of the rules, too ...

[dennyd.livejournal.com]

1995. Like I mentioned above, opinion seems divided on what fuel to use... I've found one place saying they're set up for US fuel (88 RON), but I don't know if that would apply to a UK model like mine, or just to imports.

*shrug* It seems I'd be as well to leave it on normal unleaded for now, at least until I get an expert opinion. The spark plugs sound like a good starting point for trying to get it firing up more easily, and the advice from owners is more consistent and confident there.

[d-floorlandmine.livejournal.com]

I'd guess one that's been running for several years in the UK would be set up for UK fuel, so 95 RON is probably a good catch-all. Were they originally 4-star burners, or has it always been unleaded? (I can't recall when the change came, and my previous two were both 4* cars - although neither were in any way sporty.)

Always a good call to go with the general opinion of the owner's club! I presume the battery's fully charged, too?

[dennyd.livejournal.com]

The battery is in very good condition. Fortunately, considering how much I've had to crank it last night and this morning.

[d-floorlandmine.livejournal.com]

[rueful grin] I take it that's not a "known problem" with rotaries, then? Still, nice car!

[dennyd.livejournal.com]

They're easily flooded, I know that much. Dunno about more general starting problems... I'll check the plugs are the recommended type and work from there.

I intended to get it checked over and/or serviced quite soon after getting it anyway, so hopefully that will tidy up any little glitches.

[d-floorlandmine.livejournal.com]

Good call. I had to do that, but then mine had no clutch and a coolant leak when I got it. Then again, it was a former minusbatmobile ...

I know this is old...

[kingginger.livejournal.com]

...but Japan has much higher RON than we have...

I would imagine Optimax + Octane booster would make your engine run sweeter still (albeit the cost per mile goes up even more!)

BTW... Cos I'm a car nut... Mind if I add you to my friends list??

Re: I know this is old...

[dennyd.livejournal.com]

Add away.

My car isn't a Jap import - it's one of the 124 RX7's sold in the UK (and tuned appropriately).