What other motor(newer) will bolt straight in to my 91 si with the b21a1.....The car has 358k miles on it and i think its getting close to the end for it....Im going to run the car till it does die i just want a back up ready

 

That is the only motor I know of that is a direct swap. People have done H22 swaps before, but it's not cheap and takes dedication. There's tons of info about it though. I would just get another B21 though. It's like $300 vs. $3,000 dollars at very least considering a h22 will need custom axles, mounts, wiring, firewall clearance, exhaust work, etc.

 

I dont want to put another highmileage motor in the car..........I have an H22 in my eg..H22's are 1800 complete......Wonder if the f20 will bolt in

 

F20B? That would be the Exact same process as swapping a H22. Same block, different bore/stroke. Nicer head though, but that's off subject.

 

Sry i meant the B20.......You know since i have a the biggest b series already.LOL........