Over the holidays, I took delivery of my 1991 Vanagon Carat powered by a Bostig-installed Honda K24z, and wanted to share my impressions with you. Jim Akiba at Bostig did the install, and this engine is the first Bostig-installed K24z-swap using the Honda factory drive-by-wire ECU setup.

The install is compact, clean, and clever. The engine cradle is a great design, leaving lots of room in the engine bay, and everything looks neat and organized. At the time of the install, we also did an overhaul of the coolant system, including stainless coolant pipes and a separate auto-transmission cooler. What that means in practical terms is that so many of the things I’ve worried about failing for years are all brand new, or Honda-reliable. It’s a pretty amazing feeling.

I drove the newly-installed K24z back from Boston to Saint Louis, Missouri. That was a 1200 mile, 20-hour first-drive, and it handled it like a champ. Driving the Vanagon with a K24z makes accelerating onto the highway just like driving a modern car. No more worries about getting up to speed and plenty of oomph to get up the long steep hills without a strain. Despite a few hiccups, it was an amazingly solid performer for the whole trip, even though I put it through a torture test of weather and terrain. I managed to get caught in a storm that dropped 10 inches of snow on my location on the first night, cutting the day’s driving short. I had 30-40mph winds through the mountains and hills of New York, thick fog along the Pennsylvania Turnpike, and then insanely strong winds (50mph headwinds with stronger gusts) on the leg from Ohio to Indianapolis.



When the weather cleared up and the terrain leveled out, the engine was very relaxed cruising along at just under 75mph. However I wasn’t able to see how it performed for long at higher speeds. The main hiccup we ran into was a false-triggering of the sudden unintended acceleration (SUA) system. The ECU was receiving a false signal that the brake was being intermittently applied (despite the brakes not actually being hooked to the sensors). At higher RPMs and engine loads, this made the engine computer think I was using the brake and the accelerator at the same time, which triggers the SUA system, cutting acceleration. Jim is applying a fix this week, but on the trip home I just kept it under 75mph and that tended to avoid the false triggers (other than going up long hills where I dropped it to 65-70mph). Other issues were minor. One involved a coolant clamp that came loose (easily tightened), and the other was a resonant noise when ‘flooring’ it, which Jim is tracking down. And the time I panicked because I mistook the low-coolant light for the oil pressure light? No, I don’t think I will count that at all. :-)

My goal in doing this swap was to have a reliable Vanagon, and Bostig’s implementation of the Honda K24z power plant I think will guarantee that. What I didn’t realize is that it would be so much more fun to drive. Since I’ve had it home, I’ve been able to take it on a bunch of little trips around town. It’s no exaggeration to say it drives like a modern car. My wife keeps saying, "Well the old Vanagon couldn't do THAT!" She likes the get-up and go, especially in contrast to the sluggish old behavior when accelerating from rest.

Tom Ronan

91 Vanagon Carat with a Bostig K24z