Is there a chart or can someone tell me the biggest engine you can swap in a 2008 2.3L? More curious than I am wanting to do this.

legally a 4.0 v6, illegally whatever you want if you've got the wallet for it. Most common on rangers is 5.0 v8 from an explorer, but seeing you have a newer ranger, the electronics won't match up well so you would have to do some serious electrical fab

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2000 Ford Ranger XLT 2WD ~ Work-In-Progress: 5.0 V8, M5R2 5 Speed, 4" Suspension Lift, 3" Body Lift, 33" BFG's, Bilstein 5100's, Comp Cams XE258HR-12, 24# Injectors, Torque Monster Headers, Flowmaster 70 Series,
1987 Ford F-150 Lariat 302 ~ Decommissioned
2006 Honda Civic LX 1.6 ~ Totaled
2011 Acura TSX K24 Base ~ Daily Driver, Supercharged 10PSI, 310whp 241lb/ft

What would I have to buy extra to make it compatible also? Tranny, driveshaft, radiator?

search.
many many write ups on v8 swap