Hybrid How-To No 16: Building the LS/VTEC engine

What and Why
You might have the biggest, baddest Honda B-series block around, but without a top end up to the task of sucking in enough air, you'll inevitably be down on power. The cylinder head's main job is to get air in and out of the combustion chamber, and in doing so it plays a major role in generating horsepower. Not using a head that's capable of taking deep breaths is an invitation for respiratory restrictions, and non-VTEC cylinder heads are inherent of just that.

If you happen to be stuck with one of these low-flow, respiratorily challenged B-series engines, there's hope. By yanking off the wheezing, base Integra's non-VTEC top end and exchanging it for one of the many higher-flowing DOHC VTEC heads, any B-engine can breathe easier.

Although a complete VTEC engine of the 1.8-liter variety would seem to be the most logical choice to begin with, the truth is, these are more expensive and harder to find compared to the non-VTEC blocks, hence the whole premise for the LS/VTEC. Fortunately, for non-VTEC'ers, upgrading to VTEC status by means of an LS/VTEC conversion will run you a lot less cash than stepping up to say, a GS-R or a Type R swap.

VTEC
Any tuner will tell you the preferred foundation for any big-power Honda buildup is VTEC. With two separate camshaft profiles, which work with a variable rocker arm, VTEC is the ultimate compromise in the struggle of power vs. emissions. Honda's signature system employs a milder cam profile at lower rpm, resulting in decent low-speed torque, improved throttle response, cleaner emissions and a larger cam profile at higher engine speeds for increased power.

The Blocks
With a slew of B-series engine blocks available, it's easy to be confused. Breaking things down it's easier to separate the non-VTEC (also known as LS) from the VTEC. Older non-VTEC B-series blocks are fairly abundant and can be had for little dough. Stamped from the Honda plant as the B18A1, early LS engines may be sourced from the '90-'93 Integra RS, LS and GS. Late -model B18B1 engines are found under the hood of the '94-'01 Integra RS and LS. Any other B-series block you'll encounter is going to be VTEC.

VTEC and non-VTEC blocks are very similar, despite their power differences. Externally, all B-series blocks share the same casting and appear to be one in the same. Much like the outside, differences are also tricky to spot internally at first glance. Sharing the same 81mm bore and open-deck design, B-series blocks differ mostly in their rotating assemblies. It's not until you scope out the underside that you'll find the real differences in the block itself.

Once the oil pan is removed, B18Cs can be distinguished by the heavy-duty aluminum girdle that connects the main bearing caps. These engines, as well as select B16As, are also equipped with under-piston oil squirters. The squirters pick up oil from the main distribution galley in the block and spray it upwards for a piston-cooling/lubricating effect. In addition, select VTEC B-series engines are also equipped with an oil cooler sandwiched in-between the filter and the block. If your block isn't outfitted with any of this good stuff, then you've got yourself an LS bottom end.

Besides what you can see there are also a few differences you can't see. VTEC engines are a result of a meticulous assembly process. Both the crankshafts and the connecting rods are zero balanced, allowing for worry-free revs in excess of 8000 rpm. You can't say that about a non-VTEC Honda engine. VTEC rod bolts are also beefier, boasting 1mm-larger diameters as opposed to the LS's dinky 8mm bolts. Both of these issues prove to be the major weak links of the LS engine, yet can be remedied providing your willingness to open the bottom end.

The Heads
Aside from the plethora of VTEC top ends available overseas, many may also be sourced from a number of Hondas and Acuras in the states dating back to the '92-'93 Integra GS-R. Although all B-series top ends share the same head-bolt pattern (except the '88-'91 Prelude B-series, which is useless here), VTEC and non-VTEC heads bear little in common with one another. Even though both are 16-valve heads with pent-roof combustion chambers, that's about all the non-VTEC version has going for it.

One of the first things you'll notice when peeking underneath the LS valve cover is the standard, run-of-the-mill camshafts as opposed to the VTEC's trick, third-lobe bumpsticks. No third rocker arm here. Other notable differences on the VTEC version include larger intake and exhaust ports as well as larger diameter valves. Smaller combustion chambers of 42.7cc on the VTEC heads as opposed to the LS's 45cc also result in higher compression ratios. The B18C GS-R's chamber will net even higher ratios with a volume of only 41.6cc.

With the exception of the '94-'01 Integra GS-R's variable stage unit, all the intake manifolds found on any of these heads are interchangeable with one another. Plus, all of the intake manifolds have larger ports than the non-VTEC versions, which makes them perfect for high-rpm power.

Who and Where
We spied on veteran LS/VTEC technician Paul Coogeshall of Power Extreme Racing Development as he performed the operation on a '91 Civic. The experts at Hasport Performance had previously swapped in the B18A1, so VTEC was just a head transplant away.

Installing the VTEC head won't prove to be a whole lot different than installing any other B-series top end. Consulting a service manual, it'll tell you the first step is to remove the LS head, complete with the intake manifold, fuel rail and throttle body. To make things easier, also remove the upper portion of the exhaust manifold.

Block Modifications
Before bolting down the new head, a few modifications need to be made to the block. Normally, on a VTEC engine, oil is fed to the VTEC pressure switch by an orifice on the deck of the cylinder head matching up with a corresponding hole on the deck of the block. Since the LS has no such hole, and you want VTEC to work, you need to be creative.

Begin by removing the factory oil pressure sensor and set it aside. Since the hole is of the BSPT thread type, the male BSPT end of a BSPT- NPT pipe tee will need to be threaded into place, leaving the two 1/8-inch NPT female ends exposed. Teflon paste or Hondabond is your best bet for sealing this fitting into place. Spare the Teflon tape for your next home improvement project, as pieces can easily find themselves lodged in the oil line here.

Next, custom-tailor a 22-inch long piece of -4 steel braided hose for oil delivery. A -4 to 1/8-inch straight adaptor will thread into the orifice on the top of the tee. Be sure and clock the assembly in such a way so it doesn't interfere with the oil filter once the hose is connected. Finish things up by installing the factory oil pressure switch into the remaining hole of the tee.

All B-series VTEC ECUs will require you to use a knock sensor. Unless yours was reprogrammed to not look for one, one will have to be retrofitted into the block since there aren't any provisions for one on the LS. Some non-VTEC engines have a blank spot on the rear of the block where the threaded hole would normally be drilled on a VTEC model.

If you're lucky to have this blank spot on your block, use a 10.9mm bit and drill a hole deep enough to run a 12mmx1.25mm tap through it a few turns. For those not so lucky you'll have to either find another spot on the block where a hole can be drilled or have your ECU reprogrammed. Throwing a knock sensor malfunction code automatically disables VTEC. With our Civic, a Hondata-modified ECU was used, which did not require a knock sensor. The Hondata unit will also allow us to extract additional horsepower from the engine later on, thanks to its fine-tuning capabilities.

Head Modifications
It's time to direct attention toward the VTEC head, which, in our case, is an early-model JDM B16A unit supplied by Honda Auto Salvage. Before moving on, the VTEC oil supply port must be plugged on the deck surface. A 1/8-inch NPT pipe tap must be run through the hole until it bottoms out. Although traditionally you wouldn't want to run a tap so deep, it's necessary so the plug won't stick out past the surface of the deck.

Next, a 1/8-inch NPT internal pipe plug must be threaded into the hole with sealant. Lastly, a factory-installed pipe plug needs to be removed from the rear of the VTEC cylinder head, just above and to the distributor side of the number four intake port. Chase the metric threads into standard pitch with a 3/8-inch NPT pipe tap. Once the aluminum shavings are cleaned out, a -4 to 3/8-inch NPT adaptor may be threaded into place with sealant. The -4 oil line mentioned earlier runs from this fitting to the tee assembly on the rear of the block.

Final head mods include a little drilling. In order for the head to be positioned properly on the block, the head-locating dowel pins need to be moved from the exhaust side to the intake side. Our head was sent over to Trian Georgou of Hasport Performance, who made quick work of boring the existing head bolt holes out to 14mm with a drill press. These holes should also be drilled 10mm deep so half of the dowel can be inserted into the hole.

With the two dowels relocated, any '90-'01 Integra LS head gasket will fit perfectly. The head must be fastened down using VTEC head bolts from either the B16A or B18C engine. Final head installation procedures should be followed per a service manual.

Electrical and Wiring
Distributors found mated to any of the VTEC heads mentioned earlier will bolt up perfectly. The trick, though, is finding the one that's compatible with your ECU. Later-model OBD-I and OBD-II LS/VTEC conversions have a few options, as late-model USDM VTEC distributors are pretty easy to come across. Simply choose the proper B-series VTEC distributor that corresponds to your ECU's OBD orientation and you're good to go.

Unless your wiring harness has been altered, '92-'95 vehicles will use OBD-I ECUs while '96-and-newer cars will be using OBD-II. OBD-0 LS/VTEC'ers will run into a bit more trouble though. Since VTEC wasn't brought to the States until the introduction of OBD-I until recently, early-style OBD-0 VTEC distributors could only be sourced from an older overseas JDM head.

Instead of taking chances with a 15-year-old distributor, Tuner Toys of Chandler, Ariz., manufactures brand-new, OBD-0-compatible B16A distributors, just like the ones you'd find on an early-model JDM B16A. These will bolt right into position in stock form and function flawlessly with either of the older PR3 or PW0 ECUs. Finishing off all things spark related, any B-series DOHC VTEC spark plug wires can be used. The non-VTEC plug wires are a bit too long and should be tossed.

The wiring portion of the conversion ranges from easy to easier depending on which computer and cylinder head combination is put to work. Most B-series VTEC ECUs will require adding wires for three additional sensors. Running wires for the VTEC pressure switch, the VTEC solenoid and the knock sensor are all that's needed to finish things off.

When using certain JDM OBD-II ECUs, a VTEC pressure switch isn't mandatory and won't need to be wired into place. You can skip this step only if the corresponding OBD-II ECU and VTEC solenoid assembly is being used. When using the P72 GS-R ECU with the dual-stage intake manifold, the intake air bypass valve must also be wired in place.

Timing Belt
Although the LS timing belt will fit, upgrading to the more efficient VTEC water pump is a good idea and in doing so, a timing belt from the '94-'01 Integra GS-R is required. The VTEC water pump pulley has 22 teeth as opposed to the 19 found on the LS version, thus requiring the longer belt. The B16A timing belt will not work with either water pump due to the fact that those blocks are about 8mm shorter than the 1.8-liter versions.

Fuel System
The new fuel rail, fuel injectors and fuel pressure regulator can all be used, although it isn't necessary because there aren't any major differences in comparison to the LS parts. If you're switching injectors though, be sure they match the type of ECU you have. The older peak-and-hold injectors that come standard on OBD-0 heads should be used only with the older OBD-0 ECUs accompanied by an injector resistor box. Newer saturated injectors will only function with the later-model OBD-I and OBD-II computers.

Use an ohm meter to measure the resistance of any injectors you may be considering to find out if they're compatible. Peak-and-hold injectors will measure about 2-ohm resistance, while the saturated units will read around 12 ohm. Either way, all B-series injectors flow at 240cc per minute, so to avoid any confusion you may want to reuse your original LS injectors. The original fuel feed line and fuel return line both will reattach in stock form.

Exhaust
Although the original LS exhaust manifold may be retained, higher-flow units may be sourced from any number of B16As and B18Cs, not to mention the aftermarket.

Cooling
When using anything other than the B18C GS-R cylinder head, an upper radiator hose from the '94-'97 del Sol DOHC VTEC will provide a factory fit. In the case of the GS-R, the original LS upper hose will work just fine.

Emissions
Depending on which VTEC head is being installed, vacuum lines all reattach much in the same way they were removed. Provisions for the lines exiting the evaporative emissions canister as well as those from the purge control solenoid valve, the MAP sensor and the fuel pressure regulator, can all be found on any of the VTEC intake manifolds. In some cases, the brake booster vacuum line will need to be removed from the bracket on the firewall in order to reach the manifold. Twisting the brass fitting on the manifold in order to reach the hose is a bad idea, because they can twist loose and leak. You're better off stretching or extending the hose a bit.

A/C and Power Steering
The AC remains unaffected by the addition of the VTEC head as does the power steering, provided you have the proper brackets. Power steering brackets vary depending on the year of the vehicle, as well as which cylinder head is chosen. In all cases, OEM parts are used and it's just a matter of pairing up the proper upper bracket and power steering pump to find the perfect match.

Wrap-Up
Even though the LS/VTEC's dark side has been known to rear its ugly head as far as the bottom end is concerned, it also has its good side: more power. How about an additional 26 hp to the wheels? Not too bad considering a bone-stock cylinder head and OEM exhaust manifold are still being used. Trying to muster up an equal amount of brawn by means of the LS cylinder head would be nothing short of an uphill battle, not to mention far more expensive.

The parts list to do a VTEC swap is anything but short. However, aside from the cylinder head and ECU, everything is fairly inexpensive. Here's what you'll need: