The First ‘Port’ of Call – Lohen’s R53 Performance Head

18 March 2020

There are countless ways to modify an R53 MINI to get more power and the majority of these modifications all come down to the same common factors: getting more air and fuel into the cylinders, combusting it efficiently and exhausting it as quickly and as smoothly as possible. Once the initial more common upgrades such as a Supercharger Pulley, Crank Pulley, Intercooler, Manifold and Camshaft have been made to your R53 and the power gains from these modifications have been reached, then a ported head would be one of the next steps you could take, if you want to increase performance further.

The aim of any head is to get as much air and fuel mixed as effectively as possible into the combustion chamber, and while every automotive engine is different, generally speaking, most standard non-performance cars will benefit from a little head porting. On the standard R53 MINI head, the inlet ports do an ok job but the exhaust ports are particularly poor and will be one of the main restrictions in achieving the maximum amount of horsepower. Cylinder head porting or adding one of our Big Valve Heads to your R53 MINI can be a worthwhile modification that can bring more of those all-important horses to your MINIs stable. This blog will be your ‘port’ of call for maximising the amount of horses your Generation 1 MINI produces.

What is Cylinder Head Porting?

Cylinder head porting refers to the process where the intake and exhaust ports of an internal combustion engine are modified to improve the quantity of airflow. This extra room (made by CNC machining) helps draw extra air into and out of the cylinders, mixing it with more fuel, which means more power. If you can increase the airflow through the head and into the combustion chamber, then your MINIs got the potential to make more power since more air in usually equates to more power out. It is the areas of the cylinder head that pass the most amount of air that benefit from a little porting and since the area at or near the valve seats passes the most air for the longest time, optimizing the airflow at this point is especially important.

There are several areas of a MINIs cylinder head that can be machined:

Exhaust Ports– Shaving material from the top of each exhaust port is done, as this is where the highest velocity of air is found in the existing cylinder.
Inlet Ports– Material can be shaved from this area to relieve the port of unwanted metal that may have been leftover from casting, a certain amount of surface roughness might be kept in order to encourage any fuel that is deposited on the side of the port to evaporate.
Valve Seat– Porting this area will make sure that the valves create an exact seal with the valve seat when closed, thus improving the volumetric efficiency of the engine.

Cylinder head porting should be done by a professional, as overdoing the head porting can be costly. If a head is over ported there is no way back, the over ported cylinder head will be binned and a replacement will need to be purchased. CNC machining is used to port most cylinder heads now; the beauty of this approach is accuracy, reliability and speed. CNC machined ported heads can be manufactured a lot quicker than those that are still hand ported.

How does a ported head help to make more power?

The slightest expansion of certain areas within the cylinder head will change the way in which your R53 W11 engine creates power. Torque is often sacrificed in the lower rev ranges due to the decrease in fluid velocity, but power gains are more likely to be seen in the higher rev ranges (from around 3000 rpm) as a larger volumetric flow rate of air and fuel makes its way into the cylinders. This is shown in the dyno graph (figure 1), included below. Removing the surface imperfections of the intake tract will reduce the amount of air turbulence within the intake ports. This allows air to enter your MINIs cylinder at faster speeds and this increase in speed not only allows the engine to breathe better, but it also helps the fuel to mix with the intake air better once it’s inside the cylinders. At the end of the day, the more air that is drawn into the engine, the more fuel can be mixed with it, which results in more power being produced.

The Lohen Performance Head

Our W11 R53 Performance Heads are CNC machined to ensure maximum accuracy and consistency on every port. The exhaust ports are enlarged to allow more air flow out and while the intake ports already do this quite well any imperfections left from casting are neatened off for maximum performance. The valve seats/port throat joints are accurately machined to give a consistent smooth shape that aids air flow and high spots within the combustion chamber are removed as this reduces the chance of ‘glowing’ and helps to prevent detonation under a high state of tune.

Our performance head also comes with enlarged Supertech valves. Enlarging the size of both the Inconel and Exhaust valves increases airflow and volumetric efficiency which will result in more power. Addressing the exhaust side offers the most benefits; the standard valves (23.3mm) are replaced with enlarged Supertech valves (25.5mm) with a single groove, this 2 mm enlargement allows the exhaust gases to release faster. New valve seats are cut and the ports are matched – these modifications made to the head offer an increase of approximately 14% with a standard camshaft – when compared to a ported head alone. The inlet side is also enlarged by 1.8mm using Supertech single groove nitridecoated inlet valves.

Lohen Performance Head

The Lohen Performance Head (with enlarged valves) has the following increases in flow compared to the standard head:

Testing and Development

As a MINI fan, Jack one of the technicians at Lohen, has been tuning his Gen 1 R53 for around 2 years.His aim has always been to have a MINI that can handle both the track and the road, and one that can run rings around the other technician’s cars. Jack’s R53 was kitted out with some pretty awesome modifications prior to the performance head development, these included a CAE Short Shifter, a set of Sparco Sprint Seats, a set of Lohen Door Cards and a Janspeed Manifold to name just a few (a full spec list of Jack’s awesome R53 Cooper S is listed below). Wanting to increase the bhp of his MINI he had toyed with the idea of fitting a performance head for a while and when the opportunity came up to test one of these at Lohen he jumped at the opportunity, and since his Gen 1 MINI was still running the standard W11 engine, his R53 gave us the perfect opportunity to put the Lohen Performance Head to the test.

As always, we began this development process by doing some Pre Dyno runs to see what power this MINI made before the work was carried out, this gave us a base figure of 249 bhp and 280 Nm of Torque. The new Lohen Performance Head was then fitted and Jack hoppedback on the dyno to see what difference the porting and big valves made. This time the MINI made 269 bhp and 289 Nm of Torque, as no other performancemodifications had been made during this time, we knew that this 20 bhp increase in power was solely down to this bolt-on performance head.

After fitting the new head, Jack has been putting some miles in and the difference is huge. According to Jack “It feels MEGA! It pulls a lot harder and quicker and you can watch the speedo just keep climbing between gear changes”. Jack has also found that the acceleration is better and the top end pull has increased, which can both be seen in the Dyno Graph (Figure 1) below.

What modifications are recommended along with the head?

Depending on where you are in your MINI modification journey, there are certain modifications we recommend you get alongside the Lohen Performance Head so your MINI performs at its best.

If you are at the start of your MINI modification journey then we recommend that you make modificataions to your MINIs engine bay. A performance intercooler, supercharger pulley and uprated spark plugs will keep your MINI running smoothly under high pressures and will allow you to get the most amount of power from your R53 before you port your MINIs head.

If you have already added these modifications to your Gen 1 MINI then we recommend that you fit a PH2 performance camshaft and bigger injectors alongside the Lohen Performance Head. We offer both a Schrick and a Newman Camshaft for the R53 MINI, both of these camshafts offer increased performance, as they are profiled to make the inlet and exhaust valves stay open for longer. By increasing the length of time that the valves are open for, you increase the amount of air and fuel going to the cylinders. This increase in air and fuel in the cylinders increases the power and torque of the MINI. A PH2 camshaft is the best option if you do not want to remap your R53 as it gives a good increase in mid-range torque and has no effect on idle, while a PH4 camshaft will give you more power it also requires a remap.

Using bigger injectors over the standard ones will allow a greater volume of fuel into the cylinder and help improve the MINI’s engine performance and running quality. The MINI R53 JCW 380cc Injectors offer an upgrade over the standard 340cc injectors, and are available to purchase on our website. Using a larger injector will allow a greater volume of fuel to be delivered into the cylinder, which helps create a greater power increase. Engine performance and running quality are also enhanced when using a larger injector.

Newman Camshaft

Schrick Camshaft

MINI JCW Injectors

As you can see from the spec list listed below, Jack had made all these modifications prior to getting the performance head. Following our recommendations will allow you to have a Gen 1 MINI your friends will be jealous of.

Jack is thrilled with the difference the performance head has made to his MINI and the 20 bhp extra means he has a little something to boast about to the other technicians.

We hope this blog will be the first ‘port’ of call for all your Ported Head questions, but if you want more information about our Performance Head and the benefits it can have on your MINI then our team are more than happy to provide more information, simply contact them on [email protected] 01785 859999.