We have been focusing on the 1.6SOHC Civic for our past few articles. Generally we look at how we might upgrade the performance of the car and specifically, we have focussed mostly at how one can go about modifying the engine for more power. An important common thread in our articles was in setting the proper benchmark or target for the final power level from the project. The natural benchmark is of course the Civic SiR with the B16A which represents a 1st-class NA work on an engine of similar capacity. As a result, when we first looked at the simple filter/AFR bolt-on, then the LPT and finally the complete "NA" bolt-on package, we have always compared the resulting power curve against that of the B16A. As can be seen, except for going the route of force-induction, there is really no cost-effective and practical method to extract B16A levels of max power from the 1.6SOHC.
But across all our articles on the 1.6SOHC, in reality, one question really stands out and begs to be answered. If we are so "hard-up" about trying to equal the SiR with 1.6SOHC Civic, why not simply dump the 1.6SOHC and drop in a B16A in the first place ? "If we want the power, just go and get the engine !" In a way though, this will be considered as deviating from the topic because we are now not talking about modifying the 1.6SOHC but replacing it! A 1.6SOHC Civic with its engine changed to a B16A will no longer be an 'SOHC-Civic' but rather a mixed-breed. Nevertheless to the adventurous owners of 1.6SOHC Civics, this method is an equally valid one in the road to more performance. So, our series on "modifying a 1.6SOHC Civic for higher performance" can only be truly completed by taking a look at swapping a B16A into a 1.6SOHC Civic.
As far as swapping the B16A into a 'lower' Civic, the owner of the EG generation is very lucky in the sense that engine mounts are compatible all the way from the D15B 1.5 SOHC-VTEC engine right up to the B16A, B18C, and even the B18C-R engine. It wasn't so in the previous EF generation though where the 1.5SOHC & 1.6SOHC had slightly different engine mount configurations than the 1st generation B16As. The subsequent 2G B16A used on the EK generation Civics also had a slight revision of engine mounts too though they could still be adapted to fit without relocation. Readers who are interested in the intricate details of swapping engines are recommended to check with good information sources. A highly recommended one for B16A swaps into Civics is the B16A Hybrid Page" maintained by my friend Eric Bauer.
The featured Civic in this article is actually the same as that in the previous article about "NA drop-in" modifications to the 1.6SOHC engine. The owner Alan is an ardent "weekend track warrior", frequenting the local race-tracks on the weekend "open-days". Having built up his skills via years of track-days, he has reached a level where he feels the car lacks enough power for his needs. The brief experimentation with modifying the stock 1.6SOHC engine via NA means have shown that gains are not of the magnitude that he desires. An EG6 Civic SiR has always been his target so when an unfortunate mishap damaged the engine beyond repair, it gave the perfect 'excuse' for him to change the engine to a B16A.
The engine swap project itself was outsourced to an experienced workshop and was completed in a record few days. Here in Malaysia, engine sources for swap jobs are most commonly a half-cut, a short-hand term for the entire front half of a car, in this case, an EG6 Civic SiR, that has been written off due to a serious accident in Japan. The resultant wreck, provided the engine bay is relatively intact, is then cut into half and the front half (hence the term half-cut) is imported into the country as 'junk metal'. A half-cut is by far the easiest and smartest source to get the engine for a swap project because almost all the other items necessary to ensure a clean complete job would be available in the engine bay itself; critical items like the ECU, the wiring harness, the dashboard/meters, indeed even the often forgotten items like the master brake pump ! Prior to starting the project, Alan checked around with his contacts and sources for half-cuts in good conditions. Quickly finding one, he checked it out with a friend - the half-cut passes with flying colours, it is in great condition ! An arrangement was made to send the half-cut to the workshop and the car was sent there immediately for the project.
Consequently, the swap work itself was extremely tidy, the untrained eye will hardly recognize that the engine did not come as stock in the car. But because the rest of the car was originally done up for the 1.6SOHC engine, finances dictated that he had to use his old exhaust which was considered slightly under-sized (2" pipings). Late, there was an opportunity for Alan to get a used HKS Super-Power-Flow which he quickly bought to better complement the new engine.
Fortunately, upgrading the rest of the car to be commensurate with the new power level of the B16A is a relatively straight-forward job. This is because the EG6 Civic SiR gives us the perfect reference point by which to decide which part of the car needs to be upgraded as well as how much the upgrade needs to be, at a minimum. Subsequently both the car's original rear drum and the front brake discs were replaced with the discs from the EG6 SiR. The master brake vacumn and brake cylinder were swapped from the 'half-cut'. This confidently upgrades the braking system to be commensurate with the new engine power. The rest of the car, springs, shocks, etc are left intact though the drivers seat was already changed to the stock JDM SiR semi-bucket items. The dashboard meters were changed using the B16A items that came with the half-cut. Finally the B16A's P30 ECU was transfered over together with the required wiring harness. The P30 ECU was additionally modded to accept an external chip (stock JDM P30 ECUs uses a CPU chip with a built-in ROM for the PGM-Fi) and the workshop supplied him with two aftermarket chips, one with VTEC point set at a lower 4800rpm while the other has the original 5500rpm VTEC point.
When an opportunity came for Alan to share a block of dyno time with some friends, he quickly took it to test the two aftermarket chips as well as to correctly set the fuel pressure regulator for the new engine.
Following our usual format, we now look at the results from the dyno session. The chip with the 4800rpm was tested first, with the dyno graph clearly showing a "hole" in the mid-range, from 4800rpm to around 5500rpm. The accuracy with which Honda chose the 5500rpm stock VTEC changeover is clear to see ! The second chip, with the stock 5800rpm VTEC change point was promptly installed. The power delivery is now smoothened out, the hole has been abolished and the profile of the resultant power graph now closely resembles the stock graph published by Honda.
The dyno chart from the session is published on the right. Instead of printing the power graph for both chips, a more interesting graph would be the one as supplied to me, printing the graphs for both the original 1.6SOHC with the full complement of bolt-on mods against that for the newly swapped in B16A engine. This graph clearly shows the relative advantage of the high revving B16A engine. While the 1.6SOHC ends its power delivery at 6800rpm, the new engine revs all the way up to 8000rpm and beyond. This allows it to dyno at close to 144ps at the wheels, vs only 110ps at the wheels for the 1.6SOHC. Since the engine is relatively stock (the stock headers were used but the smaller 2" pipings may serve to restrict exhaust flow efficiency slightly - this however being compensated for by the higher flow HKS Super-Power-Flow filter), 144ps at the wheels on a Dynojet as we have seen is smack on target !
Rather unexpected however was the mid-range result. The 1.6SOHC clearly exhibited superior mid-range power ! By extrapolating, it can be seen that the two engines, the 1.6SOHC and the B16A will probably deliver roughly the same power at the low-end, from approximately 2500rpm and below. 3000rpm and above however, the 1.6SOHC starts to deliver at least 5ps more at the wheels, the difference taking a jump to around 10ps from 4500rpm and peaking at almost 15ps at 5500rpm ! Nevertheless, once the B16A's wild cams comes on, this situation is quickly rectified. At around 6300rpm, which is peak power rpm point for the 1.6SOHC, the B16A has already equalled its power and while the 1.6SOHC's power starts to dip with the rev-cut at around 6900-700rpm, the B16A easily revs on with ever increasing power right up to 144ps at around 8000rpm, only stopping at almost 8300rpm !
Engine swaps have lately become a common choice for Honda enthusiasts looking for more power from the car. Although there are 'higher' choices for the engine, the best choice for a Civic owner looking to upgrade their power via an engine swap is probably still the B16A. This is because the EG6/EG9 Civic SiR has proven the combination of the EG-Civic chassis and the B16A to be a potent mix and which will perform very well. But nevertheless, an engine swap project actually still holds many pit-falls and disadvantages. Legal requirements, at least here in Malaysia, dictates that the car's registration with the RTD be suitably changed to reflect the new engine, serial number and such. This may well cause some problems later when attempting to sell the car. The other problem is that an engine swap project is not a pure engine swap only. Just like an LPT project, the rest of the car needs to be taken care of too and the casual enthusiast who does not dabble deeply into mechanical work will hardly know what and how much needs to be done. This is why a B16A swap project is near optimum because the Civic SiR will give us the perfect reference point to what else needs to be done to ensure the car becomes optimally balanced between power, handling, safety and all other aspects.
Despite having stated all this, the Honda enthusiast who is willing to accept the inherent disadvantages and other pitfalls of an engine swap project should consider swapping a B16A into a 1.6SOHC Civic (together with suitably upgrading the rest of the car) to be a perfectly valid alternative. So readers with a 1.6SOHC Civic who are researching their options for upgrading their car's performance should consider this as well if they want to have a complete evaluation.
WongKN
September 2001
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