chveron 油的分別? 

最近去chveron 加油發覺油pump 上面寫著 10% (ethanol) or someting like that word 所以我想問 87 89 91 94他們到底除了這個分別以外還有什麽呢？ 請高人指教.![s:201][s:201][s:198][s:199]

94  没有酒精添加 其他的有 up to 10%

辛烷值不一样，具体可以 google 或者百度知道一下

哦，对不起，是“除了那个10%以外”。 基本上不同的辛烷值会影响你的ignition timing，不同车型timing设置不一样，用他recommend的那种会给你最好的性能（基本上差不多），不过用87的也不会伤车。 我车上的owners manual 有写，recommended 91 will provide best performance for the engine but any unleaded gasoline no lower than 87 won't damage or cause any premature problems.  

一般都是说+87或以上，我2辆车都是。

94 没有酒精添加？

[quote]引用第5楼willbebest于2011-01-11 17:37发表的  : 94 没有酒精添加？ [url=/club/job.php?action=topost&tid=273406&pid=6266629][img]p_w_picpath/back.gif[/img][/url] [/quote] 没乙醇

听说有ethanol 对turbo不好

The study of ethanol's impact on engines found the 10 per cent blend caused no substantial changes, except slight swelling and blistering on the carburettor and an increase in carbon deposits on pistons. But when the fuel contained 20 per cent ethanol, substantial problems were encountered. The outboard engine stalled on occasions, exhaust gas temperature increased by a significant margin and in some cases there was extensive corrosion of engine parts.

理论上是没有多大区别，但是实际应用中区别还是比较大的。 通常来说，好点的车都加高标号。有钱都加94号。为啥？就好像你喝酒一样，给你兑点水，可能味道还是差不多。可是下去的酒精量就不同了。同样的道理，加了点酒精的汽油，都能燃烧，但是产生的物质，爆炸时的热点，燃烧值，产生物肯定会有不一样。

感觉进排气都改过的车子，加高的声音好听

那些数值叫做anti-knock index（AKI），由于本人中文不好，不知道中文叫啥，所以暂时叫做”反爆缸数“吧。 这个数值越高代表汽油越难在压缩的情况下点燃，适合压缩比高的引擎。说白了，贵的车是必须要喝高数值的汽油。 由于乙醇的”反爆缸数“的数值达到129左右（学过，但是太specific的东西，想不起来了），所以它现在被加入到汽油里面作为iso-octane的代替品。现在的加油站其实都是只有2-3个storage tank，其中一个一定是乙醇。你选哪一种油就实际上是从这些storage tank里面的油混起来达到那个”反爆缸数“的数值就过关了。 除非像chevron的94那样说没有乙醇，不然其他的很大机会是乙醇加其他反爆缸数低一点的汽油。毕竟这种乙醇不是我们喝的酒精，是石油的byproduct。（好像是用ethylene, 然后用hydrolysis提炼出来的。我不是读这个的，有待这方面的高手回答）。 上面有人说太多ethanol对引擎有伤害，我也觉得肯定定有这个可能性。但是理论上ethanol自带氧的分子，对达到理想的14.7：1AFR(汽油-空气比率）也应该有帮助。（我不是读chem/mech engineering的，但是这是我用以前学过的东西interpret出来的。） 一句话总结：现在石油短缺，所以在汽油里面加乙醇已经是合法化了。[s:205]

有点off topic.. 可是不知道为什么.. N54引擎加chevron的油.. fuel pump坏很快... 加其他家的油就没事...

I am a loyal chrevon customer, have their points card and everything, and I usually only get 94. but here's my question, with Chervon with 87,89,91 they share the same pump, and it says may contain upto 10% ethanol.  and 94 says contai no ethanol. yet, Shell's 91 says contain no ethanol......isn't that a bit odd? anyone care to explain why that is? so does that mean chervon's 94 is equivalent  to Shall's 91?

each gas station has their own method of cost control, which is what i've said in my earlier post about the gasoline that you get is a mixture of fuels of higher AKI and lower AKI to obtain that specific value of AKI that you paid for. In any case, chevron's 94 octane will NOT be equal to 91 octane in Shell regardless of the presence of ethanol because of the difference in AKI values. That said, however, does not deem Shell to have lower grade of gasoline; it's just simply what the customers opt for. And that's precisely why there's those so-called "trick-fuel" or something like that in the US with AKI values of 98 to 102-ish that they sell. I think that's about the highest you can get without using other substances like lead as a fuel stabilizer. **That's the reason why they say the fuel is unleaded.** Just some technical stuff for your reference.[s:200]

分别就在对车的好坏。。。但是每辆车对油的要求不同。

[quote]引用第14楼gwh0803于2011-01-26 13:24发表的 回 13楼(bunnyface) 的帖子 : each gas station has their own method of cost control, which is what i've said in my earlier post about the gasoline that you get is a mixture of fuels of higher AKI and lower AKI to obtain that specific value of AKI that you paid for. In any case, chevron's 94 octane will NOT be equal to 91 octane in Shell regardless of the presence of ethanol because of the difference in AKI values. That said, however, does not deem Shell to have lower grade of gasoline; it's just simply what the customers opt for. And that's precisely why there's those so-called "trick-fuel" or something like that in the US with AKI values of 98 to 102-ish that they sell. I think that's about the highest you can get without using other substances like lead as a fuel stabilizer. **That's the reason why they say the fuel is unleaded.** ....... [url=/club/job.php?action=topost&tid=273406&pid=6359648][img]p_w_picpath/back.gif[/img][/url] [/quote] that's pretty clear actually. Thank you ![s:277]

no problem; nothing special. just another one of those technical things in a prospect engineer's head. i think my analysis in 11楼 is too technical...[s:205] it's more like something extracted from a textbook. plus, i cant explain well in chinese and that might have confused lz...= =

不知道是不是心里作用，用他们家的94号跑一箱油能开的路程比他家的91号远不少。