2.5L Swap Anyone?

I started out with a V-8 swap using a novak adapter between the T-18 and the bellhousing. I think it is going to be to much power for the stock drive train. I know the old Iron Duke inline 4 cyl had the same chevy bolt pattern as a inline 6 cyl (194-292)and the SBC, but will a newer 2.5 L 4cyl TBI from a 90's S-10 with the smaller bellhousing work with that adapter? I know I am going backwards, but the TBI 2.5L should out perform the stock flathead.

 

thought about this swap myself, thinking finding the bellhousing is gonna be the show stoper mehh 4.3 would be easy though, same bolt patteren as the sbc

 

You're better off referring to these engines by their cid rather than by their liter displacement.

There is a 153 cid (2.5L) engine, which is basically 2/3rd of the Chevy 230 inline 6 of the 194/230/250 family. This engine is also available in a 181 cid (3.0L) version that only appeared in industrial and marine applications. This engine is the same as the Chevy inline 6s, using the SBC bells. Everybody loves these engines.

There is a 151 cid (2.5L) engine that appeared in CJs, Pontiacs (Fieros) S-10s, and other GM vehicles. This is the engine termed "the Iron Duke." This also has the SBC bell pattern - indeed, the bells from the Jeep 151 is sought after as a factory adapter from the SR4/T4/T5 transmission to the SBC (not a good swap IMO). These engines are durable and cheap, but have a mixed reputation.

There is also an AMC 150 cid (2.5L) that came in CJs and XJs. This engine shares a lot of design elements with the 4.0L inline 6s. Everybody likes this engine. It has the GM 60 degree V6 pattern, and can be adapted to GM applications using a bell from an S-10 - see here http://www.jeeptech.com/convtrans/sm420yj/ - you should be able to make this work with a T-18 too, likely without your SBC-T18 adapter.

If it were mine, I'd go with either the 153 or the 150, depending on what I could find at a reasonable price. The best option is the 181 IMO, but it would cost more and be harder to source than the 153 or 150.