The B234F's were all LH 2.4 injection with EZ-K ignition. Why on earth would you want to put a 16-valve into your car? As nice as these engines are they weren't one of Volvo's better efforts in terms of reliability and ease of maintenance. If you love your car that much and want more power it would be easier and make more sense to transplant a turbo. If you expect your engine to fade out of existence from high mileage then other aspects of the power train and suspension won't be far behind. If you want to stay with an RWD for the long haul then I would look at replacing your car with a good used low mileage 94-95 940 with a well maintained B230FT or better yet step up to a well maintained 95-98 960/S90/V90. There aren't a lot out there so start shopping early. I know that's only moving up a year or two, but there were refinements. If performance is not an issue, but gas mileage and lower maintenance are important, then look for a 94-95 940 with the base B230FD engine. IMHO, as far as RWD's are concerned, that's the best combination of features and reliability Volvo ever made for shade tree mechanics. If you've got a good B234F sitting around with nothing to do, sell it to someone with a head damaged B234F.
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Dave -own 940's, prev 740/240/140/120's & quasi-expert only on a good day