Ignite Base on crit dmg?

Hello, I know that ignite does not multiply by crit multi, but if you hit an ordinary hit of 100, will ignite deal 90 dmg and if you hit the same attack with crit multiple 400% crit hit 400 the ignite dmg wil by 360?

Ignite base damage will be 90 per second.

Ailments inflicted by crits inherently have +50% to Damage over Time Multiplier.

A little confused by your question but I think what you're asking is does the ignite scale higher because the hit is larger when it is a crit.

The answer would be no.

From the ignite wiki:

"Critical Strike Multiplier does not affect Ignite damage, unless player has Perfect Agony keystone.

The damage multiplier for ailments from critical strikes exists independently from the critical strike multiplier used for hits.

A character's base critical strike multiplier is 150%. This damage multiplier does not function as 50% more damage but as +50% to Damage over Time multiplier, which stacks additively with other sources of Damage over Time Multiplier for Ailments.[5]"

So as the above poster has said you do get an extra dmg multiplier when you crit, but it is always +50% to Damage over Time Multiplier regardless of your crit multi stats (unless using perfect agony).

To use your example, you are doing 100 base fire dmg and ignite with 400% crit multi.

Without crit - hit dmg (100) + ignite dmg (90/s for 4seconds)

With crit - hit dmg (400) + ignite dmg (135/s for 4second)