B16A Engine Swap

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!

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 comparison between the first and second generation engines can be found on the B16A Reference web-page.

Engine Choice

The second generation B16A engine was chosen because it is a direct bolt in replacement for the first generation engine. The only real differences are:

• Second generation intake manifold (extruded aluminium fuel rail vs cast aluminium)
• Second generation throttle body (60mm vs 58mm butterfly)
• Second generation distributor (different plug fitting)
• Second generation idle air control valve (IACV) (bigger bypass hole)
• Second generation cold idle valve (attached to throttle body vs intake manifold)
• Installation of a Hondata Heatshield

Additional Modifications

The second generation B16A engine swap was done at the same time as some other modifications:

• Custom fabricated 4-2-1 headers (see Custom Headers)
• Custom 2.5" mandrel bend exhaust
• Custom 72mm cold air intake
• Hondata Heatshield gasket

Installation

The installation was done over a couple of weekends. The hardest part was getting the new engine back into the engine bay because the new headers were much larger than the stock ones and required us to take a notch out of the front cross member.

Steps

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.
2. The engine with the intake manifold removed since we were going to replace the intake manifold gasket with a Hondata Heatshield gasket.
3. The engine with the stock Honda exhaust manifold removed since we were going to replace it with some Custom 4-2-1 Headers.
4. The engine with the intake manifold gasket removed all ready for the new Hondata Heatshield gasket.
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 aluminium, 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 impedance.
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.
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.
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.
9. Not a very good shot of the LSD. In LSD equipped gearboxes you can see directly through where the drive shafts get connected.
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.
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…
13. The old engine with the rocker cover removed. Surprisingly, 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 evidence 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.
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 guillotine 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.
15. The mass of wires and vacuum hoses still to be connected up. There was only one electrical 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 1/4 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.
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!
17. The engine all back together and actually running. Surprisingly it fired up straight away once the fuel rail had been primed with fuel. Unbelievable! 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.

Problems

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 realize that I might have put the Oxygen Sensors in the wrong way. I swapped them around and, voila, problem solved.

Results

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

• First generation B16A distributor (different plug fitting)
• First generation B16A fuel injectors (different plug fitting and impedance)
• First generation B16A throttle pulley (for full throttle)