How to Build Honda B20 VTEC

Everything You Need for a B20 VTEC Build [EXPLAINED]

Nothing quite screams like a Honda B-Series motor spinning at over 8,000 RPM, and you screaming “VTEC” as you bounce off the limiter repeatedly is the extra cherry on top that only a few might understand.

But if you’ve been in the Honda game long enough, you’d know that not all B-Series are built the same, and that includes the B20 and its stock not-so-VTEC head.

If you’ve got a spare B20 lying around, then this guide has all that you need to know to turn your typical daily Honda into a lively B20 VTEC weekend warrior that you may end up using every day anyway!

What do you need for a B20 VTEC build?

Building a B20 VTEC motor is pretty similar to a lot of other Honda “Frankenstein” or hybrid builds in the sense that it’s not just simply slapping on two different halves of two B-Series engines and calling it a day.

However, throughout the years, there have been many proven combinations of parts and procedures that you should follow if you want to build a reliable B20 VTEC.

Aside from the obvious B20 bottom end + any B-series VTEC head combo, we’ve laid out all the other components that you’ll need to give your B20 that satisfying VTEC “crossover” sound without sending a rod through the block! 

B20 Bottom End (Block)

B20 Bottom End (Block)

The main engine block or “bottom end” will be the main foundation for low-end torque for your B20 VTEC build, and common choices can include a B20B or a B20Z.

Both the B20B and B20Z (B20Z2) can be had from a USDM Honda CR-V made between 1999 and 2001, with one of the main differences between them being their compression ratio (9.7:1 vs 10.2:1).

VTEC Head From B-Series Engine

VTEC Head From B-Series Engine

The whole point of a B20 VTEC build is to pair up a non-VTEC B20 bottom end with a VTEC cylinder head, so you’ll need one straight out of another B-Series VTEC engine.

One popular route that people take is to pair their B20 block with a B18C head, something that’s originally found in a JDM Integra GSR or an Integra Type R.

Another alternative would be to go for a B16A head, which is equipped on many different Honda models from 1989 to 2000, such as the Civic Si EM1 (B16A2), Civic SiR, CRX SiR, del Sol, Integra XSi, and many more.

New Head Gasket (B20/LS)

If you’re adding a VTEC head to your B20, then you also need to swap out its old head gasket for a new one.

For a B20 VTEC build, you should preferably go for a multi-layer steel type (MLS) made for either a B20 or a 1990 to 2001 LS B18A or B18B. Take note that a B20 gasket would be for an 84mm bore while B18A/B18B gaskets are for an 81mm bore.

However, if you also plan on reboring your B20, then you should opt for an aftermarket head gasket that matches the bore that you want instead.

Supporting Internal Mods

Moving on to the inside of the engine, there are several other things that need swapping out so that you can run your B20 VTEC build reliably, making the entire thing an actual “build” rather than simply bolting on some parts.

For the piston rings, you can swap them out for either an OEM or a Hastings part designed for the B20B or B20Z. As for the valve seals, an OEM part will do just fine.

Then of course, we’ve got the classic go-to setup of ARP head studs and rod bolts to fasten your engine parts firmly in place, which works exceptionally well in performance applications.

To add to that, it’s very important that you choose head studs and rod bolts specifically made for a B-Series VTEC head, like the B18C (GSR or ITR), as those made for a non-VTEC head will not be in the correct size and length needed for the swap.

Let’s also not forget about the ACL bearings, which are highly recommended for their “trimetal” design compared to the OEM bearings’ bimetal design. You can go for a set made either for a B20 or an LS B18.

18-Inch Steel Braided Hose (4AN)

18-Inch Steel Braided Hose (4AN)

Another essential part for a B20 VTEC build is an 18-inch 4AN steel braided hose or line, which will be your main oil line for the engine.

Right-Sized Fittings

Other than the main 4AN steel braided hose, a B20 VTEC conversion will require several different fittings for the various lines and other components going into the block.

These fittings will be primarily used to supply oil to the head later on, so be sure to follow the right sizes for the fittings listed below.

P72 Timing Belt

A B20 VTEC build will benefit from replacing its used timing belt with a genuine P72 timing belt, and as its name suggests, you’ll originally find it on Honda engines stamped with “P72” like that of the GSR or Integra Type R (ITR).

The P72 timing belt, like other P72 components, is an OEM Honda part used in several different engines, though you should specifically go for those made for the B18C (GSR/ITR) and not the B17A1.

Fuel Pressure Regulator

To aid in maintaining the correct pressure of fuel flowing through your B20 VTEC build, you will also need a fuel pressure regulator.

On setups that will be running on just a stock ECU and stock fuel injectors, you should ideally go for an adjustable fuel pressure regulator that can bolt on directly to your stock fuel rail.

P72 Oil Pump

P72 Oil Pump

As with the timing belt, your B20 VTEC build will work best with a P72 oil pump, preferably a new OEM part.

For a P72 oil pump, you get a lot more freedom when it comes to which B-Series engine you can actually source it from. 

In general, any P72 oil pump made for 1996 onwards B16, B20, LS, GSR, or ITR engine will be compatible with this particular build.

22-Teeth (22T) Water Pump

22-Teeth (22T) Water Pump

The water pump is also another important component you shouldn’t overlook when turning your B20 into a VTEC-capable setup.

First things first, you need to make sure that the water pump you use has 22 teeth (22T) compared to the original 19-tooth water pump of a stock B20.

This is because all of the B-Series DOHC engines that originally came with a VTEC head already have a 22T water pump from the factory, so this is essentially one way of prepping your B20 block to accommodate a VTEC head.

Another thing is that you need to match your water pump with whatever timing belt you’re using, and if you’ve been paying attention above, this means you should ideally go for a P72 water pump as well.

Magnetic Oil Drain Plug

After a motor has been completely built, there may be metal shavings present in the oil that are leftovers from the build process, and we obviously don’t want that. This is where a magnetic oil drain plug will come in handy.

A magnetic oil drain plug is quite important when it comes to breaking in your motor for at least 100 miles, and it’ll help you ensure that metal shavings don’t coat and damage your internals.

NGK Spark Plugs

Replacing your B20’s old spark plugs is one of the cheaper and simpler ways of preparing it for a VTEC build.

In particular, NGK spark plugs will be your best bet when it comes to running a B20 VTEC build, and we can go even more specific than that depending on the compression that you’re running.

For instance, if you’re running with a compression ratio of 10.0:1 to 12.0:1, then it’s recommended that you go for a set of NGK V-Power BKR7E spark plugs.

However, if you’re running a compression ratio higher than 12.0:1, then you should look into some NGK V-Power R5671A-8 spark plugs instead.

Replacement Gaskets and Filters

Apart from the main head gasket, there are also several other gaskets and filters around your B20 VTEC build that are worth replacing as well.

These can include things such as the oil pan gasket, intake manifold gasket, valve cover gasket, various rubber gaskets, oil filter, and fuel filter.

Assembling a B20 VTEC Build

Prepare Tools and Lubricants

Before you start putting together parts for your B20 VTEC build, it would be ideal if you have a set of wrenches and sockets of different sizes as well as some lubricants (e.g. ARP moly lube, RTV) we’ll be listing here.

For the wrenches, it’s recommended to have a set of 10mm, 12mm, 14mm, 17mm, and 19mm box-end wrenches. You’ll also be needing an ft-lbs torque wrench, an in-lbs torque wrench, and an Allen wrench/key.

As for the sockets, you will primarily need a 1/2 drive, 3/8 drive, a 6-inch extension, the same-sized socket wrenches for them, and a spark plug socket.

Prepare the VTEC Head

To prepare your VTEC head of choice, you’ll have to locate an Allen plug on its intake side, and then unplug it. Just in case you’re having a hard time pulling it off, you can apply some heat on it using a torch.

The next step would be to tap the cylinder head by using the 1/8 NPT fitting we listed earlier. You can either use Teflon tape, Teflon paste, or a thread locker to install the fitting on the head.

Prepare the Block

Prepare the Block

In order to prepare your B20 block for the performance of a VTEC head, you’ll be swapping out some internal parts, especially if you’re looking to gain a bit more power than the usual bare minimum setup can provide.

Now unless you’re doing an LS/VTEC build, which isn’t the main focus of this guide, then your OEM B20 pistons will do just fine assuming they haven’t been run into the ground yet.

The piston rings and valve seals, on the other hand, would be better off swapped with a fresh OEM set from Honda, though you can also go for Hastings or any other trusted brand of piston rings.

You’ll also need to swap out the bearings for the same type, but we personally recommend using ACL bearings because of their “trimetal” design.

Last but not least, do not skimp on replacing your head studs and rod bolts, which is why it’s highly recommended to go for ARP head studs and rod bolts that are specifically designed for the B20 block and VTEC head pair-up.

This means that if you pair your B20 block with a B16A head, then you need to use ARP head studs specified for that particular setup. Otherwise, they’re not going to fit properly.

Install the Head Studs

Before putting in the head studs, they first need to be cleaned of any sort of debris. You can use a combination of a carb cleaner and some compressed air to do this, but just be sure to cover the cylinders so any residue doesn’t get blown in.

Apply the lubricant that’s included with the ARP studs to all of their sides. Using an Allen wrench, tighten them fully then go back for about a quarter of a turn.

Install Oil Pump and Oil Pan Gasket

Install Oil Pump and Oil Pan Gasket

Remove all of the 10mm nuts and bolts from the oil pan and oil pickup tube. Afterward, remove the oil pump itself by untightening its mounting bolts.

Again, you’ll have to clean the mating surfaces for the oil pump and block since any leak or residue may affect how they’re clamped together. You can use either an intake cleaner or a brake cleaner.

Before installing the new oil pump, you can optionally prime it by filling the inside of the pump gear with petroleum jelly, and then applying high-temperature RTV on the mating surfaces for the oil pump and block.

Make sure to torque the oil pump, pick-up tube, oil pan gasket, and oil pan to the proper specifications for their 10mm nuts and bolts.

Install Water Pump and Water Pipe

To prepare your new water pump for installation, first apply a small amount of RTV on the gasket groove before putting the gasket in.

Be sure to properly tighten your water pump to the correct torque specs. You should perform this as you would when tightening wheel lug nuts, which is by following a criss-cross pattern.

Moving on to the water pipe, it will come with two rubber seals that need to be slipped on both ends of it.

One end of the water pipe should be connected to the opposite side of the water pump, while the other end (passenger side) should be connected to the thermostat housing.

The thermostat housing would then have to be torqued up to the proper specifications using its two 10mm bolts.

Install Oil Pressure Switch and Knock Sensor

The next step would be to install your B20 block’s oil pressure switch and knock sensor (M12x1.25), which can both be simply tightened down fully without any specific torque spec to follow.

However, the knock sensor does need to be installed at the upper alternator bracket, which means you need to also tap the right hole of the bracket by drilling it with an 11mm drill bit.

After drilling, you should tap the hole of the same size as the knock sensor, which is 12mm x 1.25 inches, then screw in the knock sensor. This will prevent a check engine light (CEL) from appearing on your dash.

Install Breather Box and Alternator Bracket

Install Breather Box and Alternator Bracket

To prevent a buildup of higher pressure in the crankcase, your engine will need a breather box, which the B20 doesn’t have from the factory — meaning you’ll have to get an aftermarket one.

Running a breather box on your B20 VTEC build will also ensure that your engine doesn’t accumulate too much byproduct from the combustion process too quickly.

The breather box will come with a small rubber o-ring that you need to fit at the back of the B20 block. After fitting the o-ring, simply fully tighten the bolt at the bottom of the box.

Do the same thing when installing the alternator brackets, which can also be simply tightened until they don’t budge anymore.

Install Tensioner Pulley and Engine Mount Bracket

The tensioner pulley will bolt on directly as long as you make sure the spring is aligned properly. However, leave the pulley just partly tightened for now to prepare for the timing belt installation later on.

When it comes to installing the engine mount bracket, it uses 3 bolts that need to be tightened down fully so that it sits securely on the driver’s side.

However, if you’re swapping your B20 VTEC into a smaller chassis like a Civic EF or CRX, then it may be better if you leave it only partially tightened for now to give you more room when actually swapping it in the engine bay.

Other than that, your block is now completely assembled at this point, and you’re now ready to install the VTEC head!

Install the VTEC Head

Before installing your VTEC head, it’s very important to install the oil galley plug onto it first, as this plug also plays a big role in making sure oil is redirected and actually flows properly via the external lines, making it possible for VTEC to “kick in”.

To make the next several steps of this procedure go smoother, you’d want to set your engine to its TDC (top dead center), or in other words, the #1 and #4 pistons should be positioned at the top of their stroke.

In order to do this, you can use the crank pulley bolt to rotate the crank counterclockwise until the #1 and #4 pistons are positioned at TDC.

Install the VTEC Head

One helpful tip to help you tell if the engine is at TDC is to look for a mark on the crank gear and a small arrow on the oil pump, and then align these two together.

The next step is to install the head gasket made for your block and VTEC head combo by sliding them over the head studs installed on the block earlier. 

Now for the moment you’ve been waiting for, which is carefully sliding the VTEC head over the head studs until it aligns and rests firmly on the B20 block or bottom end. You need to make sure that the head sits flush with no gaps or misalignments.

After that, continue by putting some ARP moly lube on the washers and nuts that come with the ARP studs, and then sliding them on. You will then have to torque them to ARP’s recommended specification, which is about 65 ft-lbs.

To properly torque the studs down, you need to do it in increments of 25 ft-lbs. This means the first turn should be 25, then 50, and then 65. 

In addition, follow Honda’s recommended torque sequence/pattern for the studs.

Install VTEC Solenoid Housing and Coolant Temperature Sensors

The two coolant temperature sensors can be simply tightened down to their threads, while the VTEC solenoid needs to be tightened according to the specification for its 10mm bolts.

One sensor has a single pin and is responsible for the coolant temperature displayed on your gauge cluster, whereas the other sensor has two pins so that the ECU can read both engine coolant temperature and air-fuel ratio.

Install Coolant Housing

Once again, you’ll be using a small amount or a “bead” of RTV sealant to coat the mating surface of the coolant housing before bolting it onto the cylinder head using its 10mm bolts with the correct torque specs.

Install Camshaft, Cam Gears, and Cam Seal

Install Camshaft, Cam Gears, and Cam Seal

Whether you choose to go for GSR (B18C1), ITR (B18C5), or CTR (B16B) camshafts, you’ll be installing them the same way in any case. It’s also recommended to pair these camshafts with ITR dual valve springs for more support at higher RPMs.

Also, it’s important to mention that any camshaft of your choice would need to have a higher compression ratio than stock. It should be no lower than 11.5:1, but you should optimally aim to be between 12.0:1 and 12.5:1.

For the installation itself, you first need to install the rubber cam seals at the back of the cam gears, then install and properly tighten the cam gears onto the camshafts themselves. In order to align them properly, you should use the woodruff keys included.

The camshafts (cams) need to be well-lubricated by applying cam lube or assembly lube on all of the cam lobes and journals. 

When installing the cams, take note that the slotted end should go on the intake side for the distributor. Properly place the cams in the correct positions on the open head.

As for the remaining cam seal, it should be installed at the passenger-side exhaust camshaft.

Install Cam Caps and Cam Holder Plates

There are also some caps for the camshafts as well as holder plates that should be installed, but before you do, it’s essential to first clean the head of any dirt or debris, especially if it’s a used head.

You will find that the caps will already be marked from 1 to 5 (going from the timing belt to the distributor side), and even the head itself has “I” (Intake) and “E” (Exhaust) markings for your reference.

Install Intake Manifold, Fuel Injectors, and Fuel Rail

Install Intake Manifold, Fuel Injectors, and Fuel Rail

The installation of your intake manifold can vary slightly depending on its bolt pattern, as you’ll have to match it with that of your cylinder head. 

For instance, a GSR head can only be paired up with a GSR manifold, while ITR and B16 manifolds are interchangeable.

As an extra option, you can even swap out the stock intake manifold gasket with an aftermarket one like those from Password JDM, Hondata, or other similar brands.

To begin the installation, first align the intake manifold gasket with the cylinder head, place the intake manifold in position, and then tighten all of its 12mm nuts/bolts to the proper torque specs.

For the fuel injectors, any set of 240cc ones (or 310cc if you’re aiming for higher power levels) that are made for a B-Series or even a D-Series motor will be compatible with the build. 

Simply slide their rubber gaskets on each of them, and then tighten them onto the intake manifold.

The next step would be installing the fuel rail, which the OEM/stock Honda one will already suffice for this particular setup. Go ahead and tighten each of its 10mm nuts while being careful not to overtighten them.

Install Oil Line and Timing Belt

Install Oil Line and Timing Belt

Depending on the exact oil line kit that you bought, it will be best if you follow the exact installation instructions that are included with it. But in addition to that, every single fitting that you put on will have to be taped with Teflon.

Moving over to the timing belt, you’ll first double-check the engine block and pistons to see if they’re still at TDC (top dead center). 

Both the crankshaft and the camshafts need to be aligned with each other. There are timing marks on the cam gears that you can use as reference, but we still recommend viewing your kit’s instruction manual for this part.

Once you’ve got the alignment down, it’s time to install the timing belt by first sliding it onto the cam gears, water pump, and finally the tensioner.

Pull down on the tensioner to loosen it, as you need it to be in the fully loosened position before you tighten its 14mm bolt down. After tightening, put the rest of the belt onto both the tensioner and crank pulley.

With the timing belt now in place, loosen up the tensioner by carefully using either a screwdriver or the bent tip of a metal coat hanger to pull on the tensioner spring.

Now that the belt has tension, you can then tighten the tensioner pulley’s 14mm bolt to keep the belt tightened in place. 

You can refer to the instruction manual to see how much play on the belt is recommended, as you wouldn’t want it to be too tight or too loose.

Install Timing Cover, Alternator, and Alternator Belt

To continue, you can now install the lower timing belt cover as well as the alternator and alternator belt. 

Aside from tightening all of the cover’s 10mm bolts, you’ll also be using another woodruff key as you’re sliding over and tightening the crank pulley in place.

Position the alternator on its specific brackets, install the belt on it, push the alternator outwards using a pry bar or any suitable tool, and then fully tighten all of its bolts in place. 

Install Distributor

To correctly install the distributor, the inside markings or lines at the back of it will need to be aligned with each other before you tighten all of its 12mm bolts.

It’s especially important that your block is still at TDC at this point since it will allow the distributor to be timed correctly once installed.

Install Valve Cover and Gasket

Install Valve Cover and Gasket

As with several other components we already went over, the gasket for the valve cover also needs to be replaced before installing the cover itself.

Before putting on a new valve cover gasket, inspect the head for any oil or debris and wipe it clean. Once again, apply a small amount of high-temperature RTV at the flat pads underneath the gasket.

After that, install the included grommets and 10mm nuts, and then tighten everything down but not too tight. Ideally, you should aim for them to be just slightly tighter than “hand tight”.

Install Spark Plugs and Wires

For this last step in the assembly, you’re now going to be installing the spark plugs and wires that are appropriate for your specific B20 VTEC compression ratio (Refer to “NGK Spark Plugs” above).

Thinly applying anti-seize on the spark plug threads beforehand is recommended, but not a necessity. 

Using a spark plug socket, install and tighten each spark plug to its recommended torque specs to avoid overtightening or under-tightening them.

The spark plug wires will have to be installed according to the firing order of your engine/distributor, which is 1-3-4-2 for 4-cylinder Honda engines and many other inline-4s.

Install Spark Plugs and Wires

Cylinder #1 will be on the timing belt side and going sequentially toward #4. The other end of cylinder #1’s spark plug wire should be connected to the bottom left terminal (#1) of the distributor cap.

Using the 1-3-4-2 firing order as your reference, plug each of the remaining spark plug wires going clockwise around the distributor cap. This means after plugging in #1, skip #2 and then plug in #3 first.

As a tip, the length of each wire will help you indicate which cylinder connects to which point on the distributor cap.

B20 VTEC Build Estimated Costs