Does anybody know how I can install Flames that come out of the manifold or exhaust pipes on Startup on the a2a simulations P51 D civilian Mustang?

You seem to be a glutton for punishment!   The first thing to do is look in your aircraft.cfg under

[Effects] for anything that says engine start.  My example is for the l-1049.

[effects]
wake = fx_wake
water = fx_spray
dirt = fx_tchdrt
concrete = fx_sparks
touchdown = fx_tchdwn, 1
//contrail = fx_1649a_contrail
//startup = fx_1649a_engstrt
startup = fx_1049_engstrt<---------------- (this effect gives this aircraft what you want)
windshield_rain_effect_available = 1

There are many civilian and military freeware aircraft that have this.  You will have to do your own search for it. There are effects that are for engine start only and some for the entire flight.

Worst case scenario would be to add the flame effect to your smoke section that you had so  much fun with!

Are you looking for something like I show in my screenshot?  If so, it will take a lot of work editing the

aircraft.cfg either the [SMOKESYSTEM] or [Lights] to add the effect for all exhaust ports.  I only

did the rear set of exhaust pipes.  This particular effect also needs to be edited to get both engine

emitters closer together.

 

2 hours ago, charliearon said:

Are you looking for something like I show in my screenshot?  If so, it will take a lot of work editing the

aircraft.cfg either the [SMOKESYSTEM] or [Lights] to add the effect for all exhaust ports.  I only

did the rear set of exhaust pipes.  This particular effect also needs to be edited to get both engine

emitters closer together.

 

I want it only on Startup

Then, like I said in the first post, look in your FSX/Effects folder for an enginestartup effects file like this one:

 

[effects]
wake = fx_wake
water = fx_spray
dirt = fx_tchdrt
concrete = fx_sparks
touchdown = fx_tchdwn, 1
startup = fx_1049_engstrt<---------------(This is the engine startup effect)
windshield_rain_effect_available = 1

9 hours ago, charliearon said:

Then, like I said in the first post, look in your FSX/Effects folder for an enginestartup effects file like this one:

 

[effects]
wake = fx_wake
water = fx_spray
dirt = fx_tchdrt
concrete = fx_sparks
touchdown = fx_tchdwn, 1
startup = fx_1049_engstrt<---------------(This is the engine startup effect)
windshield_rain_effect_available = 1

Where can I go to download a really good engine start-up flame effect?

Look through the AVSIM, Flightsim, Libraries.  Google can be your best friend.

4 hours ago, charliearon said:

Look through the AVSIM, Flightsim, Libraries.  Google can be your best friend.

 so would I have to find something that is made for another aircraft and then put it on my aircraft?  what do you recommend?

1 hour ago, airrace said:

 so would I have to find something that is made for another aircraft and then put it on my aircraft?  what do you recommend?

You will be in for a tough going on this!  My recommendation would be to search for a similar aircraft as well as a P-51 Mustang.  Hawker Hurricane, Spitfire, P-40 Kittyhawk,and anything that uses a Merlin engine. I have searched through my aircraft assortment and using Google search and came up with many that use a Jenny_engine_start.  This is nothing more than a brief puff of startup smoke from the under carriage.  Keep in mind that you don't have to install any of these aircraft.  You just need to look in the aircraft.cfg under [effects] to see if the developer included and engine start effect.  Then copy the effect and texture for that effect into your FSX/Effects folder and copy the effects wording into your P-51 aircraft.cfg under [effects].  I wish you good luck on your quest!