>> 上面说的很清楚

Oh, you haven't seen my reply to your duplicate post downstairs yet... So I guess you don't realize that "上面说的" is wrong:

First of all, I've never said the following in my previous posts, as you allege:

Speculartor的前面的帖子承认这样的假设:
两个引擎：引擎 1和2
引擎1最大马力 p1@r1
引擎2最大马力 p2@r2
p1>p2, r1>r2.并且各自的扭矩曲线都是平坦的（locally flat).

(1) I said the POWER curve is locally flat and made no assumption on the TORQUE curve whatsoever.
(2) From the below, you probably misunderstood what "locally flat" means. Locally flat means precisely that if p(r) is the power curve, then its derivative, p'(r1) = 0. It makes no inference about what happens away from r1 at all.

Now look at what you say further down:

引擎1 300hp@6000 rpm
引擎2 200hp@3000 rpm
我们都知道，马力等于扭矩乘以转速后除以一个常数 p=t*rpm/5250 (where p in hp, t in ft.lb)。按前提条件推算，
引擎1 的扭矩一直都是262.5lb.ft左右。引擎2的扭拒都是350lb.ft. 也就是说引擎1在4000rpm以后的功率输出p1 > 200hp.

How do you "按前提条件推算，引擎1 的扭矩一直都是262.5lb.ft左右"??

If 引擎1 的扭矩 starts at 10 lb.ft @ 1000 rpm and ramps up to 262.5 lb.ft @ 6000 rpm, it satisfies your 前提条件 of "引擎1 300hp@6000 rpm", no?

If 引擎2的扭拒 starts at 1,000 lb.ft @ 1000 rpm and ramps down to 350 lb.ft @ 4000 rpm, it satisfies your 前提条件 of "引擎2 200hp@3000 rpm", no?

Therefore the 4th line that you wrote above is wrong, making the rest of the calculation invalid.