Bottom Line Up Front (BLUF):
Successfully installed a 15B-FT in my Canadian spec 1986 BJ70. It was more challenging than I anticipated which delayed initial roll-out and road trials (~May2025).
Current results are very satisfactory;
Let me share my apology in advance. I am not a good writer and it will show.
The Start
While attending the CMCC2023, a combustion pre-cup in my 3B broke apart and dropped into the cylinder. This resulted in the loose portions of the pre-cup being hammered into the head causing damage. Once the head was pulled, it was clear that the pre-cups had been improperly staked and were moving. The one that broke loose had actually worn through the head gasket and into the block. This left me needing to replacement 3B block and head to support rebuilding the engine or replace with a new engine.
Over the years, I have developed a great appreciation and preference for the Toyota engines in my Cruisers. My mechanical knowledge/skills/experience base is very limited, so I needed to find a solution path that was within my abilities. It was also obvious to note that my potential for budget approval was limited. My bride’s first preference was to sell off the BJ70 as a derelict carcass and cut our losses, but she was open to cutting me some slack and room to try. Further because of my novice abilities, a high potential for failure was present, so I decided that any path that I selected would be reversible (i.e., I could unbolt/remove what I have done and gone back to stock configuration).
From these perspectives, an LS/R2.8 or other conversion were off the table for me. I would need to select an engine that supported me doing the work within my limited skill/ability set.
So what were my options?
Starting from my reversible back-to-stock groundrule, this effectively eliminated the non-B family of Toyota engines because these engines would require modifying the frame to accommodate mounting these engines. This seemed wrong relative to the advantages offered in converting to a H family engine, but I felt my reasons were valid for me (my limitations / my objectives).
My steps through the B engine family was short since there are (were) very few in the US with any potential to obtain,
Successfully installed a 15B-FT in my Canadian spec 1986 BJ70. It was more challenging than I anticipated which delayed initial roll-out and road trials (~May2025).
Current results are very satisfactory;
- Ample power (readily accelerates to highway speed and easily cruises at +70mph),
- Good economy* (data points: +21mpg at +70mph, ~24mpg at 55mph)
- Easy operation [such as, readily starts cold or hot / normal driving does not need to be tailored for boost or EGT limits]
Let me share my apology in advance. I am not a good writer and it will show.
The Start
While attending the CMCC2023, a combustion pre-cup in my 3B broke apart and dropped into the cylinder. This resulted in the loose portions of the pre-cup being hammered into the head causing damage. Once the head was pulled, it was clear that the pre-cups had been improperly staked and were moving. The one that broke loose had actually worn through the head gasket and into the block. This left me needing to replacement 3B block and head to support rebuilding the engine or replace with a new engine.
Over the years, I have developed a great appreciation and preference for the Toyota engines in my Cruisers. My mechanical knowledge/skills/experience base is very limited, so I needed to find a solution path that was within my abilities. It was also obvious to note that my potential for budget approval was limited. My bride’s first preference was to sell off the BJ70 as a derelict carcass and cut our losses, but she was open to cutting me some slack and room to try. Further because of my novice abilities, a high potential for failure was present, so I decided that any path that I selected would be reversible (i.e., I could unbolt/remove what I have done and gone back to stock configuration).
From these perspectives, an LS/R2.8 or other conversion were off the table for me. I would need to select an engine that supported me doing the work within my limited skill/ability set.
So what were my options?
Starting from my reversible back-to-stock groundrule, this effectively eliminated the non-B family of Toyota engines because these engines would require modifying the frame to accommodate mounting these engines. This seemed wrong relative to the advantages offered in converting to a H family engine, but I felt my reasons were valid for me (my limitations / my objectives).
My steps through the B engine family was short since there are (were) very few in the US with any potential to obtain,
- Stay with a 3B. A full rebuild of a 3B was not cheap and I needed to locate the very rare (a 3b block and head, or a complete 3B engine as core). Since I had just paid to have my 3B overhauled twice, I was well acquainted with the costs/challenges/risks involved. This would have to be my fallback path.
- Switch to a 13B-T. This appeared to be a good choice for form/fit/function plus improved performance over a 3B. But the 13B-T path quickly developed into sourcing the very rare (not available in my searches). I was successful in locating a complete 13B-T engine, which prompted optimism. It was reasonably local; it had been fully overhauled and placed in climate controlled storage for a project that never materialized. The owner understood the rarity and would consider selling for a price in the $20s (thousands before any jokes fly). The fact that this 13B-T had been overhauled before being placed in storage without even being fired up concerned me greatly. [I had just had my 3B overhauled twice for poor machine shop workmanship/skill causing failures. First, a poorly overhauled turbo led to metal fragments from the turbo being spread through the entire engine via the oil. Second, incompetent staking of the pre-combustion cups had led to a catastrophic failure as described earlier] Due to the combination of cost and risk of an unproven overhaul, I stepped away from the only 13B-T that I found. Again this shaped up as a fallback path.
- Switch to a 15B-FT. With my failed searches for rare 3B and 13B-Ts, I continued my search across the B engine family. By chance a 15B-FT engine happened to surface. As a late increment in the B-engine family, the 15B-FT engine shared numerous form/fit/function characteristics with the 3B. So it was projected that the 15B-FT could utilize 3B components to enable bolting up to the BJ70 as if it were a 3B. As good fortune would have it, Alberto (@AlbertoSD) and Roma (@roma042987) had researched converting 3B equipped Cruisers to 15B equipped and imported several 15B-FT engines. They had already identified the parts required for converting a 15B for installation as a 3B replacement, plus proven that the parts were available. Roma had only imported engines for his needs, but Alberto had imported more engines than what he needed and had sold the extras. Since all were sold, it appeared that I was too late, but Fate smiled at me for once. The intended project for one of engines sold by Alberto had evaporated and the engine had just become available for resale. I contacted new owner of the engine to discuss a possible sale. With the cost of a used 15B-FT engine plus the cost of the identified conversion parts, it was clear that converting to the 15B-FT engine appeared to be less than half the cost to overhaul a 3B. This appeared to be my best option. These lower costs provided margin to deal with unknowns that were likely to occur. Plus possibly the biggest benefit … the engine and conversion parts were available. This appeared to be my best path.
