Thanks for your reply and the link:

From this link:
http://www.turbofast.com.au/racefuel.html
called my attention
POWER FUEL ADDITIVES/METHANOL ADDITIVES
Propylene Oxide.
From the tables of the end , I copy the following:
Propylene Oxide not known 9.6 : 1 14,000 220 Used as an ignition accelerator additive particularly with nitromethane (up to 20 percent by volume with pure nitromethane) where noticeable increases in power are possible. Easier starting and smoother running are other benefits when blended with most other fuels (up to 5 percent)

From another link that I am enclosing

www.nuigalway.ie/chem/CNF6080.pdf
(Ignition of alkyl nitrate/oxigen/argon mixtures in shock wawes and comparison with alkanes and amines)

“Nitrates an peroxides have been known since the early 1900s to promote the ignition quality of diesel fuel. They act by decomposing to form chain-initiating-radiacals, and there is also evidence to suggest that the head released during the decomposition of the additive in the pre-ignition phase contributes further to decreasing the ignition –delay-time.”...

Decreasing in the ignition delay time is the effect that produce an ignition accelerator
Then, nitrates and peroxides are ignition accelerators.

Summarizing:
If propylene oxide used as ignition accelerator additive produce easier starting and smoother running, why nitrates and peroxides (another ignition accelerators) could not produce the same effect?


On the other hand, I can not denied the logic of your reasoning.
I agree that the nitrates do not produce more power. ( we do not detect increasing in RPM) and I do not have in mind the mechanism to justify our feeling (improve starting and running).