B16A Engine Swap

January 1, 2004

This page contains information about the B16A engine swap that my Honda Civic had done many years ago transforming it (albeit mildly) into a Honda Civic Hybrid. The donor engine was obtained from Dodson’s Autospares, a local importer/wrecker of used parts from Japan. The B16A engine is from a 1994 EG6 Honda Civic SiR (determined from the timestamp on the head).

The body shell for my EF9 Honda Civic SiR is in great condition. There is no rust anywhere and just the usual small dents down the sides due to inconsiderate drivers at shopping centers. Unfortunately the same could not be said for the engine. The original first generation B16A engine in the Honda was showing signs of weariness. It was going through oil at a rate much faster than I would have liked. Sometimes I would forget to check the oil level every now and, when I did, I would be lucky to find any oil on the end of the dipstick. Far, far from ideal!

I am pretty sure most of the oil was getting past the valve stem seals. The tell-tale sign for this was a large plume of blue smoke when getting on the go-fast pedal after some lengthy engine braking (like coasting down a hill). This probably caused some of the oil to disappear but I really don’t know where the rest was going. VTEC engines are supposed to be a little thirsty on oil, but the amount of blue smoke heading out the exhaust pipe was definitely not a good sign. All of this from a car with only 90,000kms on the clock. Somehow I don’t think so… I get the feeling that someone wound the clock back a hefty amount before it either arrived in New Zealand or before going on sale in Japan.

Engine Choice

Given the choices, an engine swap seemed like a nice project for the Honda Civic SiR. I’ve always been keen to give anything a go and have pretty good mechanical know how so I started looking for a second generation JDM (Japanese Domestic Market) B16A out of a later model Honda Civic. Although the first and second generation engines are very similar, the second generation engine produces an extra 10HP due to a slightly higher compression ratio, better cam timings, and slightly higher cam lift. A more in depth comparision between the first and second generation engines can be found on the B16A Reference web-page.

I contemplated going to a DOHC VTEC B18C out of a Honda Integra (which has an extra 200cc of displacement) but I was somewhat keen to see what performance enhancements could be done to the stock B16A with some (hopefully) smart external modifications. The B16A is a fabulous engine and puts out very good performance figures stock standard. However, I was hopeful that even more could be made with some relatively straight forward modifications to make it inhale and exhale more easily.

Additional Modifications

Also, while I was going through the trouble of taking the engine out of the car, I figured I might as well do something about the peg leg differential at the same time. I couldn’t use an LSD gearbox from a second generation B16A, because they are all hydraulically operated, so I also placed an order for a rare LSD Y1 transmission (second hand of course). It took a while for the local importers to track down an LSD trannsmission in Japan, but I think that the wait was well worth it.

While the car was going to undergo such a large operation I also decided to do a bunch of other things that are much easier to do with an engine sitting on a stand in front of you, rather than cramped in the engine bay. These other things included:


Overall, the B16A engine swap went relatively smoothly. However, there were a few snags and this page contains some of those snags and photos of the process that converted my Honda Civic SiR into a Honda Civic hybrid.


Below are details and photos taken during the various stages of the B16A engine swap into the Honda Civic SiR.

  1. The new engine with the rocker cover off to inspect the cams and rocker arms for any signs of wear. Everything looked pretty good with only a few very small shiny patches on a couple of rocker arms and high lift cam lobes. We replaced the timing belt since the engine had been sitting for a while, and inspected the water pump for signs of wear. The water pump looked and felt fine, so we didn’t replace it. "Second generation B16A with rocker cover off"
  2. The engine with the intake manifold removed since we were going to replace the intake manifold gasket with a Hondata Heatshield gasket. Second generation B16A with intake manifold removed"
  3. The engine with the stock Honda exhaust manifold removed since we were going to replace it with some Custom 4-2-1 Headers. Second generation B16A with exhaust manifold removed
  4. The engine with the intake manifold gasket removed all ready for the new Hondata Heatshield gasket. Second generation B16A with intake manifold and gasket removed
  5. The second generation intake manifold cleaned up ready for installation. Note the differences between a first generation one and a second generation one: extruded aluminium fuel rail vs cast alumimium, 3 moulded raised bars on top of the plenum vs a PGMFI label. The first generation fuel injectors have to be retained since they are a different plug fitting and have a different impedence. Second generation B16A intake manifold
  6. The Hondata Heatshield gasket in place on the engine. It is about 5mm thick and made of a material that does not conduct heat. It prevents heat soak from the head to the intake manifold to keep the intake charge as cool (and hence dense) as possible. This means you can squeeze every last pony out of the engine and it is relatively cheap to do. Hondata heatshield on second generation B16A
  7. The throttle body with the cold idle valve location blanked off with a piece of aluminium and sealed using some liquid gasket sealant. Note the difference between the second generation throttle body and the first generation. The first generation engine has the cold idle valve attached to the intake manifold whereas the second generation engine has it attached directly to the bottom of the throttle body. Also, the second generation throttle body is 60mm at the butterfly compared to 58mm for the first generation. Second generation B16A throttle body with cold idle valve blanked off
  8. The hot water that used to flow through the throttle body to prevent icing on cold mornings has been re-routed so that it completely bypasses both the throttle body and idle control valve. The hot water used to flow from the main return line through the IACV (idle air control valve) to the cold idle valve, through the throttle body and then back to the head. Now the hot water flows directly from the main return line directly back to the head. This should also help to keep the intake as cool as possible. Since the climate in New Zealand is relatively mild, there shouldn’t be any problem doing this. And now that all of the other initial idle problems have been sorted out the car idles just like it used to. Second generation B16A hot water bypass
  9. Not a very good shot of the LSD. In LSD equipped gearboxes you can see directly through where the drive shafts get connected. Second generation B16A LSD gearbox
  10. Fabricating the new 4-2-1 headers on the engine. We sent the VTEC cam timings to Edgell Automotive to get the optimum dimensions for the exhaust manifold. The numbers returned were very interesting and very LARGE. The primaries are nearly 2](../images/19.jpg)
  11. The finished headers after receiving a ceramic coating. The two bungs for the oxygen sensors are located at the end of the collectors for the primaries. Fabricated 4-2-1 headers for the B16A
  12. The car with the old engine removed. That’s quite a big hole in there. At this stage I really started to wonder why I was doing this. Too late to turn back though… B16A removed from EF9 chassis
  13. The old engine with the rocker cover removed. Suprisingly, not too much wear on the cams or rocker arms. The intake manifold was caked with oil and crap, but then I guess you get that with an engine that is over 10 years old. After cracking apart the gearbox, one side of the clutch plate had completely worn down to the rivets. The pressure plate was knackered because of this. There was also evidense of hot spots on the flywheel. Just as well the new engine came with a clutch and pressure plate that still has plenty of miles on them.�Surprisingly I didn’t really notice any slippage problems with the clutch even in its shocking state. Rocker cover off the first generation B16A
  14. The new engine in where the old one used to be. What a mission getting the new engine in! We had to notch a bit out of the front cross member because the new exhaust manifold managed to clobber the front cross member even after being fabricated on the engine and having it built as close as physically possible to the oil pan. Thank goodness for plasma torches, a guilotine that cuts through 2.5mm plate with ease, a pressbrake to bend it to fit, a few whacks with a big ball pein hammer and some MIG welding… We also had some problems with the CV (constant velocity) joints. The left hand side fell out and took ages to get back in. What’s with those really annoying square bits on the bottom of the bearings? It makes it almost a three person job to put a CV joint back in. Second generation B16A in EF9 Honda Civic chassis
  15. The mass of wires and vaccuum hoses still to be connected up. There was only one electrial connector that needed to be altered (except of course for the re-use of the first generation B16A distributor). The fan switch for the second generation B16A is located next to the thermostat as opposed to being in the block. This required extending some wires and using the slightly smashed second generation temperature sensor. Honda New Zealand wanted an arm and a leg (nearly 14 of the price for what I paid for the engine) for a new one. Why can’t people be a bit more careful when ripping out engines from wrecked cars? Scheesh. We also had to swap the throttle pulley for the first generation one so we could get full throttle properly. EF9 Honda Civic engine bay with all the wires still to be connected
  16. A shot of the new headers in the car. Not much room to move in there. In fact I ended up removing the back cover for air conditioning fan because the headers rested against them. Now I have about 3-4mm clearance. Tight! Minimal clearance for the new B16A 4-2-1 headers
  17. The engine all back together and actually running. Surprisingly it fired up straight away once the fuel rail had been primed with fuel. Unbelieveable! Just some initial problems with the idle that turned out to be because the second generation IACV has a bigger hole where bypassed air escapes. And the oxygen sensors were put in the wrong way round. The new engine all connected up
  18. The 2.5” mandrel bend exhaust. This was made on the car by cutting and welding lots of mandrel bends together. Note that the exhaust does not go over the rear suspension but rather around the fuel tank. There just wasn’t enough room around the suspension for the 2.5” bends. Also no catalytic converter or temp sensor (because these were removed shortly after I got the car). I used the largest straight through resonator and muffler that I could find. No schwanky stainless steel muffler though because they cost about 5 times as much as a normal one. The complete 2.5" mandrel bend exhaust


Initially I had some problems with idle after the swap and some pretty bad hesitation problems when driving as well. I sent it to a local shop to have a look and they originally thought it was because there wasn’t enough back pressure with the huge exhaust. They put in a back pressure restrictor, but that didn’t help. Research on the Honda Hybrid Tech Forum made me realise that I might have put the Oxygen Sensors in the wrong way. I swapped them around and, voila, problem solved.


The car felt a lot better with the new engine than what it did. It pulled much better with the VTEC cams activated but there was a mammoth torque hole just after VTEC kicked in as shown in the original B16A Dyno Run. This was because of the backpressure restrictor, which was eventually removed. Other than that it went pretty well. It’s definitely louder than before when VTEC is engaged. It’s a totally different car when the big cams are being used.

Things To Retain

Below is a list of all the things you need to retain from the first generation B16A (or things that need to be modified to work with the second generation B16A).

The EF9 uses a cable clutch whereas second generation (and higher) B16A engines all use a cable clutch so you have to keep the original gearbox. See the imagesHonda Gearbox Ratios](GearboxRatioReference.htm) for more information on this and other gearboxes that might be suitable swaps.
The second generation B16A normally runs with an ODBII ECU. The distributor used with this ECU has more teeth in it, and I believe the plug is different as well so you have to use the distributor off the first generation B16A.
Fuel Injectors
The fuel injectors from the original B16A must be used. The second generation injectors won’t fit into the existing plugs, and have a higher impedence than the first generation ones. I am not sure whether the type of injector was altered (peak and hold vs saturation), but it is just easier to use the existing ones. The second generation fuel rail is a different shape than the first generation one but can be used. Unless you managed to also get the second generation plastic holder that bolts onto the fuel rail for the wiring conduit, you will have to zip-tie the conduit to the fuel rail (because the original plastic one doesn’t fit).
Oxygen Sensors
The EF9 ECU (PR3/PW0) requires two oxygen sensors. You need both of them because the ECU uses the reading from each O2 sensor fuel to determine the fueling for only 2 cylinders. Don’t try to run a single O2 sensor because it’ll just end in tears.
Exhaust Manifold
Becuase the EF9 ECU (PR3/PW0) requires two oxygen sensors, you need an exhaust manifold that will house both of them. Either use the existing first generation exhaust manifold or get a new 4-2-1 header with two bungs at the end of the primary collectors. Note that a 4-1 exhaust manifold is harder to get running right because of the requirement to have two O2 sensors. Newer ECUs from Honda use a single O2 sensor, which makes using a 4-1 header much easier.
Engine Mounts
The engine mounts for the EG6 Honda Civic are ever so slightly different to the EF9 Civic mounts. Not enough to really notice visually but enough that the second generation engine won’t fit quite right without using the original EF9 ones.
Crankshaft Pulley
I can’t clearly remember if this was changed or not, but we definitly took it off and re-used it for some reason…
Power Steering Pump
The second generation power steering pump has a different pully on it. Although we changed the pully over to the original one, it still wouldn’t mount correctly because the power steering fluid line that bolts onto the top of the pump has a slightly different bolt pattern/arrangement.
Radiator Fan Switch
The location of the radiator fan switch in the second generation B16A is in the thermostat housing instead of in the back of the block. You need to extend the 2 wires that normally connect into the block so they can reach the new location. I am not sure if the plug is different because mine was smashed, but I would presume so.
Idle Air Control Valve (IACV)
The second generation IACV has a larger hole through which the bypassed air flows. This adversely affected the idle on the car because I couldn’t get it to idle low enough (pesumably because too much air was getting through). With the original IACV the idle was fine.
Throttle Pulley
The throttle pulley on the second generation B16A is a different shape to the first generation pulley. Without using the original pulley we couldn’t get full throttle because it wouldn’t turn the butterfly far enough.
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