Leaf blower starter specs/recommendations?

[The Lazy Destroyer]

Are there any rough spec requirements for using a leaf-blower style starter for a DIY turbojet? Mine has an inlet size about 50mm/2.0” for reference (propane fuel)
I’ll need to pick something up and see ones ranging from 250cfm to 500cfm. I was about to pick up a budget 250 cfm capable one but started to wonder if there are any “minimum” or “recommended” cfm requirements when using as a turbojet starter based on size. Tried searching but couldn’t find anything recommending certain sizes or cfm’s to avoid.
I assume the mph ratings they reference aren’t as helpful of the actual cfm ratings?
I also have a shop vac that can be set to a blower mode but don’t remember it really pushing a lot of air?

[racket]

For a 2" inducer , a large shop vac on blower mode works OK , we need both mass flow as well as pressure to force the air through all the restrictions within the engine .

Because of the need for PRESSURE , the newer leafblowers with axial "fans" aren't suitable , neither are blower/vac units as the rather large clearances required for the vac mode to prevent jamming of the fan means poor pressure output , the straight blower leafblower using a centrifugal impellor is the best way to go , those with the highest output air velocities should provide the best pressure as pressure and velocity are the "same" thing.

Ideally you want more CFM than the engine flow at idle , though its not critical as most of my engines that used a leafblower for starting, "sucked" the blower against the comp housing inlet requiring some effort to unstick it once the engine spooled up .

With a 2" inducer engine , idle airflow would be ~20 lbs/min or ~250CFM , hence the reason why a decent sized shop vac is adequate , leafblowers are needed for larger engines , but the need for output pressure is more important than actual CFM , I had to shim my leafblower "comp wheel" to minimise clearances to prevent bypassing of pressure so that I could start my engine , ideally we want lotsa CFM and lotsa pressure , not always easy to find .

Cheers
John