YoshiFab 16 Valve Conversions
Why do it?
Greater power potential. People will argue that an 8v can do everything a 16v head can. Sure it can get close but it's not going to be cheap or easy. You will be running an aggressive cam, larger valves, and good port work. The 16v head flows what a heavily worked 8v does and still has a ton of headroom if you want to take it even further.
Why can't I just bolt an entire B234 engine into my car?
Beyond the 16v head, the b234 also has a much different oiling and balance shaft system than the traditional red block. The external balance shafts and oil pumps make the motor have a different form factor. In a 700, you should be able to swap in the 16v motor mounts and brake booster. A 200 would be much more involved requiring custom motor mounts. Even if you are willing to do the work, in the end you are stuck with an odd motor. The external balance shafts and oil pump open up more opportunity for leaks. The added complexity of the timing belt setup leaves a lot of opportunity for failures. The stock 16v pistons have much thinner ring lands meaning if you are looking to build a turbo charged motor, they will be much less forgiving than a turbo piston. The higher compression is less than ideal for a pump gas driven turbo 16v car.
This answer will be broken down into sections:
1. Head/short block
2. Timing belt
3. Valve reliefs
4. Intake manifold
5. Exhaust manifold
7. Instillation and Maintenance
1. Head/ short block
Obviously to do a 16v conversion you need a 16v head. Please read our guide to inspecting 16v heads to make sure you get something serviceable. The head will come off of a 89-90 760GLE 16v. If you are getting your head from a junk yard, you are going to want to pull the following from the donor car.
1.Head, upper and lower sections
2.Cams and cam gears
3.Crank sprocket (if you are using a b21/23 style crank, you will not be able to use this.)
4.Intake manifold/fuel rail (unless you are going with a aftermarket manifold that does not require a core)
5.An extra 16v cam gear if you can find one.
6.Exhaust manifold if you are planning a NA build.
7.Brake master cylinder/booster if you are using an unmodified stock intake manifold on a 700/900.
You are obviously going to need a b23/230 short block to bolt the head to. The better condition the short block is in, the better running motor you are going to end up with. Piston walls with scored or with worn x hatching and large ridges at the tops of the cylinders should be reconsidered. In our experience, turbo motors wear out a lot quicker than NA motors. B21/b23s seem to wear better than b230s. All the red block motors have their good and bad aspects, but that's a discussion for another time.
The best solution is a built long rod motor with forged internals. That's going to be the most forgiving and the more consistent route but its also significantly more expensive. We offer our long rods HERE and forged piston sets HERE. We do not consider a built motor a necessity until the 350whp mark on a 13mm b230ft. If your goals are below that and you have access to a good condition used short block then work with that. If you are ballin on a budget then at a minimum you will need to upgrade the connecting rods to our forged H beam rods found HERE in order to safely go beyond 350whp.
2. Timing Belt
There are many solutions to the timing belt. Many people experiment with different belts, tensioners, and gears from various cars. Our kit uses common components and allows the use of the stock cam gears. Many of the DIY setups necessitate using adjustable cam gears to get the proper cam timing.
Our kit includes the timing belt, tensioner, idler, and the mounting plate/hardware. You will need to acquire a 3rd 16v cam gear to drive the aux shaft. We often have used gears in stock HERE. If you are using a b230 style motor you will need a b234 crank gear. The stock b234 crank gear has a flaw however. They key that locates it on the crank tends to break and cause the valves to hit the pistons. We stock a billet steel crank gears that prevents this from happening. You can find them on our website HERE. B23 style motors will need a special crank gear. Please contact us for availability.
3. Valve reliefs
You are going to need have the pistons clearanced for the 16v head. There are several ways to do this. If you are converting a car and do not want to pull the motor, we rent a jig that allows you to notch the pistons with the motor assembled in the car. You can rent the jig HERE Another option is to have a machine shop notch your pistons. This is usually more expensive than renting the jig and requires disassembling the motor. If you are building a motor, all of our piston sets come with the required valve reliefs cut in them.
4. Intake manifold
You will hear all kinds of talk about the stock b234 manifold. The internet says its bad because of uneven distribution the the cylinders. 2&3 see more airflow than 1&4. With that said it's a nice flowing manifold and simply destroys the b230 style manifold in the flow department. In a 700/900, the manifold can be used without issue. You will want to swap to the slim 16v brake booster to get the necessary clearance. A 200 series is a bit more space restricted. Some people have made the slim booster fit in a 200 and used the stock b234 manifold. Another option is to take the manifold to a local welding/fab shop and have them shorten the runners a couple inches. Shortning the runners however is a sacrfice. Volvo got the runner length right, by shortening them you are moving the power band higher than the rest of the head is setup for.
While the b234 manifold is fine, its nothing spectacular. The plenum is very small and that's a restriction on topend power. There are a few large plenum manifolds on the market. Ours is a modified b234 manifold. We cut the stock plenum off and weld on our custom plenum. It's setup to use a 960 throttle body which is also an advantage. We have also started selling this manifold in kit form for our DIY customers. You can find it HERE.
In other parts of the world (Not
B230 manifolds At one point we offered an adapter to use the b230 manifold on a b230 head. People still ask if we sell these adapters. We no longer offer them for a reason; they are just too much of a restriction for not much gain. The throttle body is still tight in a 240 and the manifold itself is very restrictive. You add in the adapter plate and the restriction starts to get excessive. A few have had success with porting the manifold and head but that's a bit extreme to get a sub standard manifold on you nice 16v head.
5. Exhaust manifold.
For a NA setup, the stock b234 exhaust manifold is a nice piece.
For a turbo setup things get a bit more complicated. The cheapest and easiest solution is to adapt the 8v exhaust manifold. This is done with our 16 to 8 exhaust manifold adapter kit. The port shapes are different so this is a restriction however our shop car put down 398whp using this setup. Its less than ideal but for the effort/money/reliability of a cast manifold its impossible to beat.
The nicest solution is to get a tube manifold. There are a few sources, contact us for the who is currently producing them.
The ignition you use is going to depends on a few factors. If you are building a 700/900, you can use your stock distributor on the back of the head just like the stock b234. In a 200, you cannot use the rear mount distributor. You will need to plug the hole in the back of the head with a factory Volvo plug. The block mount distributor does fit with the head on however the stock cap does not. We offer a crab cap that clears the head. Because of the location of the head you will not be able to remove the stock distributor with the head bolted on. If for some reason you need to be able to remove your distributor, we offer a short distributor that can be removed with the head on. We also offer a billet cam angle sensor adapter that clears the 16v head and should be used with your favorite stand alone
The 16v builds we do at the shop are all megasquirt controlled and use a coil on plug setup. Denso 12977-3881 motorcycle coils fit the plug wells perfectly and are a good reliable coil for these motors. You can find the coils used on ebay for very reasonable pricing. We offer an ignition module that works well with them HERE and we also offer the connectors HERE.
We have had a few customers have success with lh2.4, you are obviously going to need an injector upgrade and a host of other mods that go along with making more power on LH. This article is about a 16v conversion and the LH conversation is its own separate deal. We choose to run a stand alone EMS on the cars we build here but either can get you down the road.
7. Instillation and maintenance
Valve springs: At a minimum you MUST replace the valve springs. If you do not, you will have valve float issues. Many people skip this and spend a lot of time fixing misc. fueling and ignition items which never solves the symptoms. The easy cheap solution is Ford 4.6 valve spring. We stock them HERE.
If your setup requires high revs (class spec race motors, dedicated drag cars) we can supply a solid lifter and cams to suit. This is a expensive proposition and would require some conversation to get you what you need. Please contact us.
Sealing the head:
When assembling your head, its very important to take some precautions. The tricky issue is sealing between the two halves of the head. Do NOT use RTV to do this, it WILL leak and could potentially block oil to the cams and lifters. Volvo uses a proprietary anaerobic sealer which works very well if you can get your hands on it for a reasonable cost. We use the Volvo stuff at the shop, but Loctite 518 works well when we don't have the Volvo pink stuff.
We highly suggest purchasing a Earling b234 head gasket set. The gaskets are of the highest quality and the kit includes everything you are going to need. Replace the valve stem seals while you are replacing the valve springs.
Stock replacement b234 bolts work fine for most. If you think you migh have the head off in the future, know that you play hard, and or dont want to worry about sourcing new bolts if the head ever has to come off we stock an ARP bolt set for these heads HERE. Torque specs can be found HERE