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#71
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"Friedrich Ostertag" wrote:
I always find it intriguing, that almost everything we develop today as supposedly latest techology has been there half a century ago. The only really new thing in engines today is electronic control. regards, Friedrich Exactly...and it's one of the reasons that, although I consider myself quite knowledgeable engine wise, when I open the hood of an ailing engine I quickly close it and get on the fone for a towtruck...there's just so much complication in all the electronic sensors, computers etc to squeeze every ounce of efficiency out of a litre of fuel that I find it daunting. My wife's Corolla just finished it's lease and I bought it and leased another Toyota for her. A 'Matrix'. They have an intriguing feature called VVTi (Variable Valve Timing). Neat system!...hope it's rugged!, looks expensive if it comes adrift in flight... Cheers -- -Gord. |
#72
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On Fri, 23 Apr 2004 21:58:30 +0200, "Friedrich Ostertag"
wrote: Hi Gord, Well, just a comment about domestic automobiles, I didn't mean to indicate that I operate them below the manufacturers specified octane ratings, after all, I believe that the manufacturer knows his engine best and I'd never try to second guess him, but I have all kinds of friends and relatives who use hi octane fuel in their cars even though low octane is recommended. (complete waste I feel) Ah, you're absolutely right there! Sorry for the misunderstanding. There is no point in using higher octane than what the engine was designed for. Even knock control will not advance ignition beyond the calibrated map for the designated fuel. However a lot of people over here fell for a marketing trick of Shell Oil: Instead of the 98 octane highest grade fuel sold in Germany and most euroean countries they offered a 100 octane (by the way, this is ROZ, not ROZ+MOZ/2 as in the US) fuel called "V-power" with supposedly all kinds of mysterious additives at 10 ct / Liter premium over other oil company's 98 octane. Lots of car magazines and also the ADAC (your AA) tested it in various models and found no difference whatsoever in power and consumption. Yet Shell sells 10% of it's turnout in V-Power while the other's only sell 5% 98. Talk about snake oil... Definitely agree with you there ... The Puma that I have has a reaction to the higher octane 98 RON Optimax fuel that Shell sell over here. It's not a good reaction, like increased power or economy, it's a bad one. The bad reaction takes the shape of the engine management struggling for the first couple of miles to get used to the differing octane rating. Symptoms included poor running including reluctance to idle. I suspect that the anti-knock control was self adjusting itself for the increased octane rating. It also takes a little while to get used to 95 RON unleaded when that goes back in. Anyway, no measurable economy improvement (I nerdishly track my mpg) and no perceptible power improvement. Although other people reckon they see power improvements with other cars. Pete Lilleyman (please get rid of ".getrid" to reply direct) (don't get rid of the dontspam though ;-) |
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On Sat, 24 Apr 2004 17:29:50 GMT, "Gord Beaman" )
wrote: "Friedrich Ostertag" wrote: I always find it intriguing, that almost everything we develop today as supposedly latest techology has been there half a century ago. The only really new thing in engines today is electronic control. regards, Friedrich Exactly...and it's one of the reasons that, although I consider myself quite knowledgeable engine wise, when I open the hood of an ailing engine I quickly close it and get on the fone for a towtruck...there's just so much complication in all the electronic sensors, computers etc to squeeze every ounce of efficiency out of a litre of fuel that I find it daunting. I like to think I know a pretty decent amount about engines, enough to do my own maintenance when I was too poor to go to garages. But when I got the Puma, I didn't even bother opening the bonnet. I knew I wouldn't recognize much of what was under there and that the key things would be hidden from view. All I needed to convince me that the running gear was in excellent shape was a flying trip down the local dual carriageway :-) (Happily 3 years later nothing serious has gone wrong) My wife's Corolla just finished it's lease and I bought it and leased another Toyota for her. A 'Matrix'. They have an intriguing feature called VVTi (Variable Valve Timing). Neat system!...hope it's rugged!... This is on the Puma too, as Variable Cam Timing. I think it's fairly failsafe. Taking a mechanical engineer (which I'm not - I'm an elec) view, I'd say they do it by retarding/advancing the valve timing according to revs and load. So if the system fails or degrades, the valve timing wouldn't adjust but the cams would still go round and the valves would go up or down. Not heard of rampant engine trouble in the variable timing cars so they must have got it licked. It seems to work on the Puma ... I moved from Rover 2.0 16 valve to Ford 1.7 16 valve and the Ford unit has just about equal power but it's far more flexible across the rev range. The Rover unit was fairly quiet until about 3250 rpm where it would take off. The Ford unit has usable power down at about 1800/2000 rpm. Pete Lilleyman (please get rid of ".getrid" to reply direct) (don't get rid of the dontspam though ;-) |
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