Mitsubishi Evo6 4G63 Cylinder Head

I would like to share a recent cylinder head I just finished. The cylinder head came out from a Mitsubishi Evolution VI with a 4G63 turbocharged 2.0L engine. The client came to our workshop complaining of severe oil burning and lack of power.

After we took out the head we found that the head had badly worn valve guides and digged seating’s and also we found out that the cylinder head was badly ported by a prior tuner compromising the durability hence the severe oil burning.

After cleaning, we made some testing on the in house Superflow flow bench and I went to the conclusion that the head needed some serious work to be able to make it better as the cylinder head was flowing less than an original standard head. What we did first was removing the standard cast iron valve guides, and had some special ones we use on the flow bench so we could test the flow after each porting modification. To solve the heavily digged seatings we decided to increase the valve sizes on both the inlet and exhaust valves by 1mm, to further try and make the port more efficient. After several hours the finished head was completely restored and flowing more than 30% more than when it came and i would like to point out that this was not a competition porting job but a street one and had to have full durability.

Below are some finished pictures and flow bench results.

Some More Cylinder Head Porting Background

The cylinder head is the most important part in an engine where substantial time and effort is spent by a professional tuner. There is more power to be gained in correctly porting the cylinder head than in any other modification that it can be done to an engine.

Cylinder head porting is the process of grinding material from the ports and chamber of the cylinder head to increase the airflow and thus improve performance of an engine.

The flow efficiency of the cylinder head will determine the horsepower potential that an engine can achieve and by correctly porting the cylinder head, higher level of efficiency is achieved and the engine will extract more power.

The cylinder head consists of three important areas which are the intake section, the combustion chamber section and the exhaust section. It is very important that all three sections are modified to work in conjunction with one another as power will suffer and engine efficiency will decrease considerably. I cannot stress this enough as every day I come across ruined heads after being ported badly and my point is that it is useless to have a huge high flowing polished inlet port and the combustion chamber is all shrouded and will not burn it efficiently or the exhaust port does not flow enough air or has a bad shape or the inlet/exhaust flow ratio is out as the engine will not produce more power or even worse decrease its power after being ported.

Another important topic is engine characteristics. Cylinder head porting needs to be accustomed to the usage that the engine will operate at. A head modified for drag racing operating between 7,000 and 10,000rpm will be useless to a rally engine needing more midrange torque and operating between 3500 and 7500rpm.

When a new client comes to our workshop with a cylinder head to have a porting job we ask several questions so that we can tailor the porting appropriately the type of driving the engine will operate in.

If the engine is going to be built in house then we know most of the answers but if a client come with just the cylinder head than we need to make sure to have all the required information so the cylinder head porting will be done accordingly.

Just to give you some idea these are some of the questions that we ask:

a)Is the engine for street use, off-road/rally, circle track or drag racing?
b)Is the engine normally aspirated, turbocharged, supercharged, NOS, or a combination?
c)Engine size, Bore, stroke, connecting rod length?
d)What type of fuel is going to be used? Pump fuel, racing leaded fuel, alcohol?
e)Is the engine carbureted or electronically fuel injected?
f)Will the car have a full exhaust system or open headers?
g)Is the camshaft still stock, and if not we need full specification.
h)What is the weight of the car and type of transmission and gearing is used? Manual, auto, sequential?
i.etc

After all the questions are answered then we can start the cylinder head analysis and port the cylinder head accordingly.

Next time we will post some information and pictures of a Mitsubishi Evo 4G63 turbo head we just did for street racing.

If you would like some help or require my service please contact me at cjpowertuning@yahoo.co.uk

Great Cylinder Head Porting Info:

I would like to share some great information I use when porting my cylinder heads. Some time ago I came across a great package of nine great cylinder head porters and have shared their knowledge on a 10 CD package. This is a must have for the serious enthusiast and more for the professional head porter.

The name of the product is AirFlow Experts and is available in here.

Racing Secrets - Click Here

Some of the subjects covered:

• What are your core beliefs on air flow?
  
• How do you get the most out of a head?


• How do you shape the all important short turn?


• How would you design a port from scratch?


• How do you calculate the following?




• Valve size needed


• Port size needed


• Window size needed


• Bowl size needed


• Seat ring ID needed


• Where are the biggest airflow restrictions?


• Differences in porting the intake port and exhaust port?


• Take us through the steps you take when porting a head.


• What are your favorite airflow formulas?


• How does porting a four valve head differ from a two valve?


• Air Flow Testing Tools:




• Flowbench - Best? Cheapest? Building your own?


• Diagnostic tools (flow balls, pressure probe, velocity probe, etc)


• Getting accurate results


• Duplicating your work (Templates, gauges, et)


• Modifications - Area Specific:




• Gasket - Area? Shape? Height?


• Pushrod - Area? Width?


• Roof - Width? Tip? Angle?


• Floor - Width? Tip? Shape?


• Walls - Shape?


• Window - Area? Shape?


• Short turn - Height? Width? Corners? Radius?


• Bowl - Width side to side? Width front to back? Depth? Shape?


• Guide - Shape? Height?


• Seat - Shape? Transition to bowl?


• Combustion chamber - Squish side? spark plug side? valve shrouding? Shape?


• Valves:




• Diameter - How do you decide?


• Face - Angle? (45', 55', etc) Width?


• Back cut - Angle(s)? Width?


• Shape? (Nail, Tulip, etc)


• Fixing flow problems:




• Poor low lift - What areas to focus?


• Poor mid lift - What areas to focus?


• Poor high lift - What areas to focus?


• CFM backs up at upper lifts - What areas to focus?


• Turbulent (noisy) - What areas to focus?


• Reverse flow - How to test? What to do?


• Swirl - What is it and how do we use it to improve power. You might be surprised by his answer


• Epoxy - When to use?


• Welding - When to use?


• How to get the most out of engine simulation software


• I hear Winston Cup teams are using Extrude Hone in a different way, what are they doing? This was a real eye opener.


• The biggest head porting mistakes you've seen?


• Current trends in porting?


• Biggest discoveries you’ve made working on cylinder heads?

Racing Secrets - Click Here

Cylinder Head Porting Tools 2

Cylinder head porting requires more specific tools and now we will continue to review them so people can learn what tools we use.

What we need after the cutting section are some grinding stones and polish assortment kits. These come in different shapes and like the cutters we use various shapes to help us shape and contour the ports better and here are what they look like.

5 Pc Mounted Grinding Stones 1/8


And a great professional abrasive assortment for cylinder head porting I use is here.
DPK-100 Porting and Polishing Deluxe Kit

Now its the time to start reviewing the special tools we use to make winning heads. Of all the tools that we use the most import one for cylinder head porting is the Flowbench. The flowbech is used so we can measure the actual amount of airflow that is flowing inside the ports and without it you can not know if a certain modification done on the port will result in an improvement or not and finally into actual power increase.

Flowbenches can be bought in various sizes and also if one wishes and wants to save some money can even build one himself. There are alot of DIY flowbenches out there and if one wishes to go that way please let me know. For myself I use a Superflow flowbench which is a great piece of equipment and is calibrated and I can check and compare my results with others too.

A flow bench can flow in either direction, that is intake and exhaust and with other special attachments, operators can determine the flow direction traveling into the cylinder so they can optimise the air/fuel mixture.

www.superflow.com

I would also like to point out on some great books on this subject and a definite buy for the serious enthusiat wishing to have more knowledge and start porting his own heads.

Four-Stroke Performance Tuning 3rd ed: A practical guide

How to Build, Modify & Power Tune Cylinder Heads

How to Build and Modify Chevrolet Small-Block V-8 Cylinder Heads (Motorbooks Workshop)

Ford Sohc pinto & sierra cosworth dohc engines high - performance manual

Cylinder Head Porting Tools 1

Cylinder head porting requires certain tools that without them the ends result can or will be compromised and so now we will discuss what professional tuners use to modify the cylinder heads.

The first tool that is used for porting by hand is a straight high speed die grinder, and these come in two types, electric and pneumatic type.

Electric type:

Pros......powerful, variable speed (not all) and unstallable

Cons.......heavy, bulky to manoeuvre in tight areas

Milwaukee 5192 4.5 Amp High-Speed Die Grinder

Pneumatic type:

Pros....... light thus less tiring and easy to manoeuvre

Cons......power depends on compressor size/volume and can stall easily

Ingersoll Rand 3108 Super-Duty 1/4-Inch Pneumatic Die Grinder

Of great use is a flexible coupler that can be used on both grinders but usually on the electric type so it will alleviate from the weight of the tool and be less tiring to do the job.

https://www.allprotools.com/Accessories-p-38-c-273-sort-title-sdir-0.html

Now we delve into the cutting, grinding and polishing tools that we use.

Porters need to choose from different shapes and sizes of cutters for the required cut that is needed and also since there are two types of materials for cylinder heads that are Cast steel and cast aluminium that the appropriate cutter is used. Normally the best are Tungsten Carbide burr cutters and although they are more expensive they are very durable and make a better job.

Neiko Tools USA 8 piece Double Cut Carbide Rotary Burr Set

The shapes that we usually use are the straight, round, rounded cone and rounded straight. The difference between the cutters from material to be used on is the amount of flutes they have and normally for aluminium the less flutes the better so it will not clog up and in my experience i tend not to use the same cutter on different materials as it will shorten the life of the tool.

Next time we will continue to talk on the tools we use for cylinder head porting as there are some interesting tools coming up........

Cylinder Head Porting

Cylinder head porting is the most rewarding process that a professional tuner or DIY individual (if individual have enough knowledge and appropriate tools) can do to an engine to increase the power output/potential of any 2 or 4 stroke or even rotary engine on this planet and there is more to be gained by correctly porting the cylinder heads than by any other single modification you can do to the engine.

Why port the cylinder head?

Cylinder head porting is performed on engines being built for racing purposes or even done to an average Joe car were he demands more power from his vehicle. Porting is the process of increasing the airflow or smoothing the intake path that the air has to travel to fill the cylinder more efficiently and thus the more airflow the engine can inhale in any given time the more power the engine can produce and then also to expel the exhaust out more efficiently from the chambers thus minimising the power to take out the exhaust gases.

Cylinder heads as manufactured are normally not biased toward power potential but more on economy and emissions and even standard high performance cars that look to have power to the normal individual will benefit from extra porting the intake, chamber and exhaust ports and even if more economy is what the individual wants porting can help in that area too.

Next time we will talk on the tools used for cylinder head porting so to help DIY porters out there.