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发表于 2009-8-2 19:17
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这吸气声可能大过排气声，在街道上跑怕没几个人受得了。
赛纳 发表于 2009-8-2 19:11
There's several reasons why I use them. Above all, it's because with two sets of matching injectors, staged on duty (ie running on the inners only until they run out of capacity, then running both sets together), maps really well.
The main reason is that you can use smaller injectors. I'm often told by people (usually people selling ECUs or injectors), that big injectors on modern ECUs are fine, to most people's expectations, that's probably true, but I map alot of engines these days and I know from my experience, that if you want good consistent fuelling at moderate speeds, the smaller the injectors the better. If you're running two sets staged, the injectors only need to be half the size and that makes a huge difference to the resolution and precision you have when small amounts of fuel are required.
Example: If you have an engine needing 300cc/min injectors to give enough fuel delivery around peak power, they will usually end up needing to only open for about 2 Milliseconds around idle. Injectors and the ECU driver will struggle to operate precisely opening that long, and if the opening time varies by 0.1 Milliseconds (not unusual at small openings), the fuelling will vary by 5%. If you're using two sets of 150cc/min, only one set of which are in use at idle, then the opening time is nearly doubled at about 4ms, which is much more comfortable for the ECU to control the injector and 0.1 ms fluctuation will only vary the fuelling by 2.5%, which if you're trying to make the emissions work and get a nice idle, is much better.
Consider also the length of opening relative to the movement of air. Many race engines use carefully timed sequential injection, to get the fuel into the air movement at the best time, but using batch or semi sequential at lower engine speeds, the longer the injecting cycle, the better the mixing tends to be on the whole.
Injector position is also important. Having the injectors mounted very close to the inlet valve, is the most efficient position almost all the time. I've played with this alot and it's become apparent to me, that having the injectors further up the tract is only beneficial near peak power/rpm in almost all cases, as I say, the rest of the time, right down on the valve is better, the power differences are almost untraceable, but the difference in throttle response and ambient fumes is substantial.
If we normally use the set by the valve, but switch to both sets, with the others near the top of the tract, we get the best of both worlds, precisely when we need it. We also get injection at two points in the airstream, further improving mixing.
Good mixing means efficiency, better economy, better throttle response, better power, it's all good basically. |
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。。。研究哈~~
发表于 2009-8-2 19:11
不过这种东西能大量吸入更多空气，但是调效好像很麻烦的。而且油耗大的不是一般。我记得我原来曾经发过一张白色的夏利2000的改装车，它的4A-GE的节气门的支气管就是安装了自制的支气管，它那个比较简单。但是油耗却很大。