I know this has probably been covered in a thred I seen awhile back, but I cant find it anymore so I was just going to ask your opinions on building a gas mileage engine. First off I have several choises for blocks to use.. I have a complete D15b2 with 177,000 miles, I know of a D15z1 complete swap, and a D15b8. I also have a spare d16y8 head with no cam, so thats the only bad thing about useing that. I also have a SI MPFI intake manifold and a DPFI manifold from the D15b2. I am thinking the D15z1 is probably gonna be the best bet, but then again I was maybe thinking the D15b8. I also dont know what manifold to use with either engine I choose. would the b8 with DPFI even work or would it be to gutless? I would also be adding a ebay header or Si or ZC manifold with a 2.25" catback. I plan to rebuild wich ever I choose also, so maybe upping the compression would help too, but I want to stay on pump gas (preferably 87/89). I just want to know all of your opinions and the way you would do it to get best results.. also how many miles could I expect from a gas milage build? I am hoping for at least 50-55MPG but if I could get 60-65 I would be REALLY happy. also wich tranny? I have the choise of a DX or VX at the time being.. If you have any other idea's to help get more MPG please let me know! thanks!