So you want to swap out that puny 91 cubic inch weed whacker engine of yours and replace it with a fire-breathing DOHC? That’s cool. But which engine should you go for? The 5th and 6th generation civic owners are lucky in the fact that its bigger brothers were designed very similar to the civic in many ways. This allows the ability to transplant various other engines from other H-cars without too much fuss. Integra, Prelude, other civics, even the sport Ute CRV engines can be considered. In addition you can do more than just swap out the whole engine, you could take a Vtec cylinder head and put it on your existing engine or swap out the whole engine and THEN swap the head on that. The possibilities are many. To help you wade through this mess, First I’ll talk about the different engine choices, and then I’ll talk about head swapping choices and its benefits. I’ll get into the pros and cons of each to help YOU decide which choice is wise for you according to your courage, budget and power needs.First off I need to mention a few things. When looking for your possible swap candidate, have a plan and research EVERYTHING. Find out as much info from as many sources as you can find. Now when putting $$$ aside for the swap, put aside as much as the components costs (Engine, transmission, etc), add shipping if necessary, then add at least $1000 for small extra parts you might need and/or broken parts on the engine (PCV valves, distributor core, AC bracket, axles, shift linkage, new polyurethane mounts, etc), and finally calculate how much you’ll need to replace all the high wear components: Timing belt, plugs, oil pump, clutch, etc. Believe me, it’ll cost ALOT less to replace them now than if they break after you’ve installed the engine. You should buy the helms manual for the engine you plan to get to get a complete run down of all the technical stuff. AND before I forget, remember that your stock cooling system will most likely need to be upgraded in one way or the other to cool the new bigger engine. And plan on the safe side to be without the car for at least 2 weeks. It shouldn’t take more than a weekend of work but something ALWAYS goes wrong. As we Hispanics say: “Dress yourself in patience” and expect the worst and you’ll be fine.As for exactly what you need to complete the entire swap, unfortunately it changes slightly with each engine considered, which is why it’s extremely important to research exactly what you need, but here’s the general list:
Two things that are very important that I need to discuss before we get into each engine are the Rod to Stroke ratio and OBD.
The Rod to Stroke ratio:
OBD stands for On Board Diagnostics. Most every modern car has a version of OBD and it’s basically an engine monitoring system. It consists of many different sensors in strategic locations that monitor various aspects of the engine’s performance. Some examples of the sensors are O2 sensors that monitor the air to fuel mixture, the throttle position sensor that senses how open the throttle plate is at any given moment, and intake temperature sensor that monitors the temperature of the intake air. All of these sensors are monitored by the ECU, the car’s brain monitors the OBD system and changes variables according to pre-programmed specifications. There are currently 3 versions of OBD and each version gets progressively more complex and stricter on the amount flexibility it will allow before taking action to prevent what it sees as a potentially engine damaging situation. OBD1 started with the 5th generation civic 1992-1995. OBD2 continued with the 6th generation 1996-2000 and the latest version is OBD3 and can be found on the 7th gen. civic 2001-???.
NOW, Let’s get to the engines starting with the smallest and cheapest candidates:
D16Z6, D16Y8, D15B7:
B16A1, B16A2, B16A3:
They all lack a sufficient amount of torque due to their small displacement but their small mass and a bad ass R/S ratio of 1.74 allows them to rev to astronomical proportions. They also all have a HUGE aftermarket support. The only thing I don’t like about this particular swap is that this seems to be only one people think of. Whenever they want to swap engines, they all go for the B16. Don’t get me wrong, it’s a great engine but there are other engines out there to consider. I’ve even known people to be disappointed because they expected more. That’s what this article if for
There are really two choices for dealing the B20 as far as power goes. You could leave it as is and simply swap the head for B16 model. The cylinder head on the B20B model (particularly the tall intake manifold) doesn’t clear the hoodline of the civic, which is ok since the B16 head swap will add Vtec abilities and increased power. OR you could go about what is called a CR-VTEC conversion. This is what I consider to be the ultimate engine build-up for civics’. You can check out www.crvtec.com for details. The first thing you need to know about B-series engine (B18, B16, B20) is that they all have, for the most part, interchangeable engine parts. So the CRVTEC buildup basically consists of taking the best parts of all the engines and making an unprecedented Frankenstein of motor that has a perfect Rod to Stroke ratio of near 1.75 which allows for great naturally aspirated performance (A HUGE redline) or the ability to turbocharge the engine to very large proportions without worrying about engine stability. It is unfortunately rather expensive but this setup will take you anywhere you want to go. The simple B20/B16 swap costs as follows: $1000-$1500 for the B20 short block, +/- $600 for the B16 head, +/- $300 for the B16 ECU + tranny and other small parts. The price for the CR/VTEC could be calculated on the aforementioned site.
Unless you’re simply happy with the stock B20 swap, the only reasons it should be considered are CRVTEC conversions or Forced Induction. The aftermarket support isn’t as plentiful for the B20 as it is for the other engine mentioned so any engine upgrades usually come from other B series or upgraded aftermarket parts for other B series. Which is more less slowly building a CRVTEC engine. But I still highly recommend this engine for the best bang for the buck power adder.
H22A1, H23A1, H22A4:
From talks with several veteran H22 swappers I can give you the overall driving opinion. To make the swap work, first off the springs and shocks in the front need to be stiffened to appropriately handle the extra weight. The overall suspension tuning should concentrate on trying to create heavy oversteer to offset the natural understeer problem the extra weight will create. There is another way to offset the understeer problem but most ppl don’t want to go through with it. It involves placing a few hundred pounds of weight in the trunk to even out the weight distribution. But most ppl want to go the other way by stripping everything out of the interior, effectively making it worse. The cooling system will amazingly enough be fine for about 75% of the time. However, on hot days or with spirited driving, the engine can start to overheat itself. For the financially strapped, an extra wide Integra radiator can be swapped in for about $100 that will provide all the extra cooling you need. You can learn about it here: http://www.hybrid.honda-perf.org/tech/jsrad/jsrad.html. If you have the extra money, you could swap in an all aluminum thick ass racing radiator with a smaller and more efficient fan and for extra insurance, a low temperature thermostat (160 degree rather than 180) could be replaced. Considering you no longer have air-conditioning the extra space that was once used by the AC condenser could be put to good use and it could be used for an external oil cooler. With this setup you could go uphill mountain racing without fear overheating. The braking system for the most part could work but if you really want to trust your life to stock system, be my guest. If you’d like to upgrade it, the cheap way is to replace the rotors for better heat dissipation (You could either get stock sized cross-drilled or slotted rotors, or you could opt for a bigger rotor kit that uses a relocated bracket so you can use the stock calipers) better brake pads and rear brake disk swap if not already equipped (Instructions HERE). If you have some money, you could get a 4-piston caliper upgrade with extra large rotors with great pads. Just the thing to stop you at 150 mph. If you do opt for the bigger rotor upgrade, remember that the stock wheels will no longer fit over the larger brakes. Some systems suggest 16” or larger.
Let me remind you that this is all extra $$$. The basic swap still includes about $1000 worth of junkyard parts just to make it work, which includes axles, linkages, ECU, HASport mounts, etc. PLUS the cost of the engine itself. This is definitely not the cheap swap.
Ok, So far we’ve covered the D16Z6, D16Y8, D15B7, B16A1, B16A2, B16A3, B16B, B17A, B18B1, B18C1, B18C5, H22A1 H23A1, H22A4 and the F20B. Talk about choices!!! But we’re only half way through. Now we go to the second part of the swapping experience, which is cylinder head swapping. Sometimes called a Frankenstein, engine hybrid, mini-me or LS/VTEC swaps. Head swapping usually includes getting a Non-Vtec block (B18B, D15B) and taking the entire cylinder head assembly from a Vtec enabled block (B18C1, D16Z6) and swapping it onto the Non-Vtec block. Effectively giving the non-Vtec block Vtec capabilities just like his older brothers. Hence the name LS/VTEC. LS for Non-Vtec and Vtec for…Vtec . It isn’t easy though. The Vtec assemblies use oil to activate the system so oil lines will need to be tapped, the block and head need small preparations to flawlessly mate the two and the ECU from the Vtec enabled block will also be needed. So the grocery list includes the ENTIRE cylinder head set and everything attached to it, The intake manifold, throttle body, throttle cable, distributor, Vtec solenoid, EVERYTHING. You will also need the ECU, Vtec oil pump and various other lines and fittings and someone who’s done this before. Here’s a great site that gets to the nitty gritty of the procedure: http://www.geocities.com/thelsvtec/
Now this opens up a whole new world of possibilities. But first you need to know the rules before continuing. These are:
There are of course downsides to mating two engine parts that were not designed to be together and expecting to work together. One of the main problems is that Vtec enabled blocks were designed to rev allot higher than their non-Vtec counterparts. Of the things Honda designed into the Vtec blocks to help them survive high rpm use are oil squirters. Oil squirters serve dual functions both as piston coolers and piston lubricators. Both of which are very important when revving to 9000 rpm. The lack of which could result in damage from prolonged high-rpm usage. Another aspect is that non-Vtec blocks usually have worse R/S ratios making the situation that much worse. The stock oil pump will also need to be replaced as it might not have enough pressure to satisfy both the block lubricating needs and the oil-activated Vtec assemblies. Valve clearance is another issue that needs to be addressed before you not only mate the head and block but also play with cam timing. The valve relief’s in the stock pistons are usually deep enough to accommodate the new longer travel of the Vtec valves but if they aren’t, they need to professionally widened or aftermarket pistons need to be used. And when using camshaft gears to tune cam shaft timing, each setting both 2 and 4 degrees advance and retard need to be tested for valve clearance as well. Failure to do so may cause the valve to crash into the piston when it arrives at TDC (Top Dead Center) which could bend it or chip it which may cause even more damage. Either way the head needs to pulled and repaired.
Head Swapping Pros:
One of the points of swapping in a Vtec head is they usually flow allot better than their non Vtec counter parts. And this can even be improved further with a port and polish. So with that in mind, the best flowing DOHC heads can be rated in this order:
The B16B head is by far the best head but it’s rather expensive and rare. It’s basically a B16A head with a factory P&P and lighter valvetrain assemblies among other things. This goes as well for the Integra Type R head. It’s basically a GSR head with a factory port and polish, slighter better and lighter cams, valves, springs, etc. The best compromise for price and availability is the B16 head and the last one the list would be the GSR head. Of course it needs to be said that simply swapping the head onto your engine won’t give you all the HP from the engine the head came from. Like swapping an GSR head onto an LS block won’t automatically give you 170hp. There were more changes to the engines than just the head like displacement, compression and air flow tracts. But it’s still better than your stock head.
In reality, the majority of your engines power capabilities come from head design. This goes especially for naturally aspirated engines. With each one of these head swaps, you could completely redo all the components in the head to make the HP jump even greater. The exact changes of course depend on if you want to stay naturally aspirated or decide to take the plunge into forced induction. The details of both will be covered on another article. Also between the generations, small changes were made in an effort to produce more power and better mileage. Example, the SOHC head changed from the 5th generation to the 6th gen. In particular the quench area, the area where the compressed air and fuel collect when the piston reaches TDC, was changed to a more squared area. Rather than the circular area on the 5th gens, this new square quench area forces more of the A/F mixture closer to the spark plug which results in a cleaner and more powerful burn. These subtleties can greatly affect the overall power production of your new engine design.
So now, what are your greatest bang for the buck options? Let’s break them down by what engine you have:
D15’s: Say you have a Dx or Cx engine, then you could go ahead and swap out the head for a D16Z6 head. You could probably get the whole swap for $300. The 6th geners with Cx’s or Dx’s can swap for a D16Y8 and build that for greater NA or FI power.
B16: Swapping the head on this engine isn’t really necessary since the head is already a top-notch design. What could be done is a head redesign (P&P, Cams, valves) or you could swap it for a B18C5 head, which is better, but not by much. This swap would be more for the WOW affect. Although a turbocharger or supercharger can both easily be installed on this engine and its air flow characteristics let it achieve more than 200 wheel hp.
B18B’s: The GSR or B16 head swap would be ideal in these situations. Can also be turbocharged by using the kit designed for the head you swap in. But as mentioned before, the R/S ratio would still be a limiting factor in maximum power output.
B20B, B20Z: Now HERE’S where the real deal is. Since the giraffe intake on the B20B doesn’t clear the hood, the head has to be swapped anyways, so you could use any of the choices above as well for the B20Z. My personal favorite, you swap in a B20 with lots of usable torque, then you swap in a modded B16 head and make a few ECU changes, like rev limiter and now you have lots of torque with Vtec high end and an 8000 redline. Or the low compression rate allows for decent turbocharging and you can achieve great heights with the B16 head flow.
H23A1: Generally the swap here is an H23 block with an H22 head swap. It makes for great Vtec high end and the larger displacement block makes for the biggest torque of all the engines listed here.