It is fairly common to hear from people who think that simply installing a bigger camshaft, a smaller supercharger pulley, a high flow exhaust or a better intake will be “THE” answer to more performance. The often-used statement that the internal combustion engine is a simple ‘air pump’ never seems to get the point across. The engine is really a complex number of components that MUST work together to produce the power to turn the crankshaft, which turns the transmission, which turns the wheels, which move the car. It is simplistic to think that changing one component without considering the rest will result in the optimum performance increase.

A factory engine design team makes a major effort to make all things work together well, while working within cost, performance, drivability, reliability and emissions design constraints. They establish a target for performance and each component is chosen to optimize towards that point. If they target to have “X” horsepower, they can then adjust each and every component to that point. Everything from boost pressure, throttle body port size, exhaust system, valve sizes, etc. all are established to meet the target. Changing any one of the many options may indeed gain some performance, but the result is by no means optimized.

Going back to the 'air pump' analogy, let's consider the single most popular upgrade done to the Mini Cooper "S": increasing the boost pressure. There is no question that there is horsepower to be gained by simply increasing the amount of air being forced into the combustion chamber. While the factory must be conservative in their choice of components and thus will always build-in a margin for error in favor of reliability, there are real engineering limits to what we can expect from a single simple component change. Increasing boost pressure consumes horsepower and generates heat which must be dissipated by the intercooler. The capacity of the stock intercooler on the MINI is easily exceeded, negating the potential gains of increased boost pressure. The real question regarding performance enhancements, is how to know when we exceed the point of diminishing returns, where we no longer achieve optimum performance from an upgrade.

The MINI supercharger might be thought of as a multiplier. It takes horsepower to make it rotate and in return it forces more air/fuel mixture into the combustion chamber, which in turn results in more horsepower. The intent is to get more than you give.

But increasing the air out of the pump is only the first step; you then have to get it into the combustion chamber, and to do so you have to pass it thought the ports of the cylinder head and then past the valves. As we increase the blower’s output, we can quickly approach or exceed the head porting design limit established by the factory. Getting back to a more optimum balance of components will have many beneficial results. If we make it easier for the supercharger to deliver the desired amount of air, it will work less and since the basics tell us the work equals horsepower, we will consume less horsepower for the better results. And if the pump is not working as hard it also can deliver a cooler air mixture, which results in a more dense mixture, which again equals more horsepower.

So what can we do to the cylinder head to regain some of the balance of components? Air flows into the valves by ways of ports. The shape and size of these ports control flow and velocity. These are the two critical components of port design. The optimum design will yield the highest flow (volume) of air while maintaining the highest velocity (speed). If you think of the port as a straw it is easy to understand that as the diameter is increased the flow will increase but with the same input pressure, the velocity will have to decrease. The result of flow and velocity might also be thought of as low RPM verses high RPM performance. You need the velocity at low engine speeds to produce the HP but if the volume is not there at the high RPM, the engine will not achieve maximum horsepower and torque. This is why we leave porting to the professional with access to the proper flow testing equipment. An amateur with a die grinder will tend to make the ports way too big, drastically dropping the intake charge velocity and ruining power (not to mention ruining the head).

When building a full race motor. it is not uncommon to give up low end performance in favor of total HP at high RPMs that can be maintained on a race track. Since most of us also want to be able to use our cars on the street or least need a wider RPM range, then we MUST balance Flow and Velocity.

This is the real ‘art’ required to get the optimum performance from a port job. As we have probably already increased the pressure from the blower (with a 15% reduced pulley) we now must modify the cylinder head to again re-establish that optimum balance of flow and velocity. The ‘art’ typically requires not just an understanding of how to do it but also often requires a number of hours of very intensive hand operation with high powered die grinders followed by hand sanding to finish the job.

Why isn’t this level of attention given at the design and manufacturing process? While the factory engineers well understand the benefits of porting cylinder heads, it is one of the engineering/cost compromises that must be made in modern production engines.

The general practice In cylinder head porting is to carefully reshape by hand both the intake and exhaust ports to enlarge them slightly while straightening out the airflow path and reducing obstructions that result in any sort of pumping loss. As you reduce the turbulence you increase air flow. This is also a balance as a perfectly smooth mirror finish port wall can result in a loss of performance if the fuel atomization is compromised. Most cylinder head tuners will leave the intake port looking rougher than the exhaust for just this reason. It is very common for a good porting facility to test both their progress and their finished product on a flow bench. This device is the best way to quantify the gains, short of putting the head on an engine and engine dyno to prove the results. A good port technician can establish a baseline on a flow bench and then be able to do many ports and heads to the exact results that can be verified on the flow test bench.

The next step in the process is to get the air past the valves. There are two levels of performance that can be considered. The first hurdle is how to get the best flow from stock valves. The more important hurdle is how to balance increased pressure from the supercharger by increasing the size of the valves. It has been proven that 50% of the gain typically found in cylinder head tuning is achieved by the simple process of doing a high performance valve job. The factory again accepts compromise for cost and manufacturability, and thus you will find single angle valve seat in a production head. These are typically a wide area 45-degree cut on the edge of the valve and corresponding seat area in the head. These are easy to do and as the valve size, etc. has been designed for x-horsepower there is no need for the factory to spend more money.

Just as we reshaped the ports of the cylinder head to improve flow, we can do the same with the seat area of the standard size valves. A ‘multi-angled valve job’, typically 3 or 4 angles will result in smoother transition for the air and greatly enhance flow, while maintaining adequate valve seating area for the necessary dissipation of combustion heat. This precision process is considered standard practice in performance tuning shops.

Multi-angled valve seats are one improvement that does not require the trial and error ‘art’ that is found in cylinder head porting. Requesting a 3-angle valve job should be considered the minimum that you would ask from your machine shop. Typical 3-angle valve jobs include an angle cut on either side of the actual sealing area of the valve seat. The high accuracy required of this technique means that the seat area is kept to a minimum (often less than half of the original seat area). The net result is that the gasses are encouraged, or funneled, through the valve-to-seat opening. The flow increase is dramatic. The intake seat width is typically about .040” while the exhaust is kept a little wider (.050”) to allow for better heat dissipation. It is critical that the corresponding cuts in the valve seats be matched and thus it is important not to switch valves between cylinders.

A 15% pulley reduction increases boost by 10%, from a max pressure of 10lbs to 15lbs. As a positive displacement pump this means you get a higher velocity of air sooner although not much increase in flow or volume. Porting and a good valve job will still leave you short of the needed improvements to reach optimum potential provided by the pulley size reduction. The next logical step is to increase the size and lift of the valves. Again, this must be done with the understanding the need to balance flow and velocity. Remember that we have said the flow is more important at high RPMs while velocity is critical at the lower RPM. Since the blower upgrade mostly produces more velocity, then in order to keep this balance the focus needs to be on flow. This is best accomplished with increased valve sizes. Another compromise that we must keep in mind is the need to keep the correct ratio between intake and exhaust flow. In the ideal cylinder head the exhaust should flow at about 70% of the intake. This balance is maintained both in port design and in valve sizes. For the MINI we have discovered that by increasing the intake valve size by 2% and the exhaust by 6% we not only can regain the ideal balance of intake verses exhaust, but the increased flow (combined with a top quality porting job and valve job) allows you to get much closer to reaching the potential benefits of the reduced the pulley size.

While all this head work provides great benefit in and of itself, a performance camshaft, with properly engineered duration, overlap and lift, will put the finishing touches on your re-engineered, high performance MINI cylinder head. With other engines, the available space above the head allows for many variations in camshaft design. Discussing these choices and the resulting performance and drivability impacts is a subject for another paper at another time. Suffice it to say that for the MINI, the physical limitations of the camshaft area on top of the head limits the performance gains and potential impact to drivability. These limitations include taller lobes interfering with the metal spark plug tubes, and the need to maintain the stock base circle diameter of the lobes because of the integral rocker-arm/hydraulic lifter design. As a result, there is very little difference in performance between the camshaft upgrades we are aware of for the MINI.

We hope this discussion has shed some light on the 'why's' of cylinder head work, and you can now decide whether to trade in your stock head for a ported cylinder head, or undertake the project yourself with the help of a local 'head guru', or leave the pursuit of serious power to more hard-core enthusiasts. Whatever your choice, you are sure to have many happy motoring miles ahead of you!

Part No Applications: NME6026, NME6010, NME6001, NME6045, NME6026

Don Racine
Article Date: Dec 30, 2005
Car Accociations: NEW_MINI
Hits: 16713

Order and Shipping Information

Worldwide Shipping Charges
Shipping Address Policy
Worldwide General Shipping Information
Shipping Schedule
When Will I Get My Order?
Entering APO/FPO Addresses
Backorders

World-Wide Shipping Charges

How can I get a shipping estimate?

Just click "Buy Now" on the product page to add it to your cart. Continue shopping and when ready for the shipping estimate, begin the checkout process. Shipping charges for most items are calculated and displayed during order checkout. You will NOT need to log in or create an account to use the 'shipping quote' button.  If you're not ready to order, simply use you browser's "back" button to return to previously viewed pages.

Shipping Methods appropriate for your destination are displayed to you during order checkout. Once you've decided on the items you'd like to order, consider how quickly you would like to receive your shipment(s), evaluate the shipping cost displayed, and choose a shipping method.

What if no shipping charges are displayed?

Shipping charges are calculated at time of shipment based on the actual package weight and dimensions. In some cases, we may not have weights or dimensions in our computer system for one or more of the items you ordered. In this case, shipping is not quoted. The amount you will be billed is the carrier's standard charge. We don not charge any handling fees. The cost of shipping your order will be sent to you in a confirmation email message at the time of shipment. No action is required on your part.

Shipping Address Policy

When you order product using your credit card we initiate a process to check the address information you enter to see if it matches the address that your credit card issuer has on file and matches your billing address. If they do not match then the issuer of the credit card will not approve the transaction 100%. This is because much of credit card fraud occurs by having products shipped to the address of the person who stole the credit card instead of to your address – the billing address. The fraudster steals the credit card, orders products and has those products shipped to the fraudsters’ address and you don't know anything about it until you get your credit card bill.

This works great for those people that have products shipped to their home address and their credit card bill is also mailed to that same address. But some people use a PO Box or their personal credit card to order products for business. In those cases they want the product shipped to their office but the statement (billing address) is still being mailed to their home address or PO Box. This normally would be a rejected transaction because of the two legitimate, but different, addresses.

The way to get around this is with an Alternate Shipping Address. You can add an Alternate Shipping Address to your credit card so that orders will be accepted at both addresses. The alternate shipping address does not have to be your business address but is used here simply as an example.

Simply use the toll-free number on the front or back of your card to contact your credit card company and create an Alternate Shipping Address which is simply a note on your account authorizing purchases that are delivered to a destination other than your billing address. With the Alternate Shipping Address feature in place you can have credit card orders shipped to two different addresses but your credit card bill will continue to be mailed to the original billing address.

Add the Alternate Shipping Address to your credit card account before placing your order. After your credit card company has updated your credit card account you can then order products with your credit card and have them shipped to the alternate shipping address you have on file with the credit card issuer.

* Please note that on your initial order items must be sent to the billing Or ‘Alternate’ address as registered with your credit card company. See this Policy for more details or contact our sales staff at 800-946-2642.

Mini Mania, Inc. primarily uses FedEx, UPS and the US Postal Service to ship orders world-wide, each of which may be available only in certain areas. Truck freight items may be shipped using our choice of a variety of motor freight carriers. The customer pays shipping costs unless stated otherwise.

When choosing a shipping method, remember that carriers charge considerably more for expedited delivery. Expedited delivery also generally requires the package be signed for at the time of delivery. Check with your selected carrier locally if you or your authorized representative may not be available to sign for the package at the time of delivery.

For some destinations, we offer the choice of Mail (USPS). While often less expensive, remember that items shipped via Priority Mail, while insured, are not always reliably delivered and cannot be tracked. By choosing Priority Mail, you accept responsibility for your order once it leaves our facility.

Customers outside the domestic United States should exercise particular care when selecting a carrier or expedited shipping methods. If in doubt, consult with your potential carrier for information about shipments to your country. Import duties, local taxes, customs charges, etc. are the responsibility of the customer. If Mini Mania is invoiced by any carrier for import duties, local taxes, customs charges, or similar fees, the customer's credit card on file will be charged immediately for these fees, and an invoice explaining the charges will be sent to the customer.

Shipping Schedule

Most orders phoned in to Mini Mania before 12 noon Pacific Time are shipped the same day; orders received later usually ship the next day. If you must receive your order by a specific date, please make this clear when placing your order.

Most Internet orders are processed the next business day and are shipped within 1-2 days.

If there is more than one item in your order, we will ship your items as they become available.

Depending on availability, your order may be sent in more than one shipment. You will be charged shipping for each shipment.

You may choose to contact us by phone or e-mail before placing your order in order to ascertain availability.

When Will I Get My Order?

For Ground shipments, see the maps below for approximate delivery times. For expedited shipping choices, please see your chosen carrier’s web site for details, terms and conditions. Note that in all cases, shipping times do not include the day the order ships, weekends or holidays.

UPS Ground Delivery Transit time Map for Domestic Customers

FedEx Ground Service Delivery Map

Entering APO & FPO Addresses Correctly

Having trouble entering an APO or FPO address on our order form? Following these steps should help:

• Enter the recipient's full name and address in the relevant fields.
• Enter "APO" or "FPO" in the City field.
• Enter "AE" in the State/Province/Region field if the recipient is stationed in Europe, Canada, Africa, or the Middle East. Enter "AA" if the recipient is stationed in the Americas. Enter "AP" if the recipient is stationed in Asia or the Pacific.
• Regardless of where the recipient is stationed, select "United States" from the Country drop-down menu.

  Following these steps will ensure that you're charged the correct shipping amount and that your order will be delivered in a timely fashion. All shipments to APO/FPO addresses are sent via U.S. Priority or First Class Mail. We estimate 5 to 7 business days for delivery once the order has been shipped; however, some destinations may take up to 21 days.

  
  
  
  
  
  

  Backorders

  We endeavor to stock most of the items we sell. The automatic shipment notification email you receive will identify backordered items and indicate the approximate date we expect to receive the item at our warehouse. Be sure to contact us if you wish to cancel your backorder to avoid unnecessary shipping and restocking charges once your backordered items are shipped.

  
  
  

We will match the published price of any US supplier* -- even their current sales prices! If you find an item advertised at a lower price, make a notation in your online order, call or email us your price match request (see terms and details below). We'll sell you the SAME item at the SAME price! If you've already purchased the item from us, we'll even price match (for store credit only) as long as you contact us with your request within 10 days of placing your order.

This offer is restricted to identical items offered for sale in writing or on the web. When making your price match request, you must provide us with a link to the competitor's Internet URL for the item, a copy of the written ad or written quotation, which must include suppliers part number, description and price.

Price Match Terms and Fine Print

We may choose not to price match in some cases; here are some reasons why:

• The competitor's product is not an exact match (identical manufacturer & model) with ours.
• The competitor with the lower price does not have the item in stock at their warehouse.
• The competitor's total price (including shipping, handling, rebates, taxes, etc.) is higher.
• The competitor's product is used, refurbished, reconditioned, or a display model.
• The competitor is not selling in US dollars.
• The product is a clearance or closeout item.
• The item is not found within the first 10 items listed on major search engine results.
• The competitor is not manufacturer authorized or has advertised below the manufacturers minimum allowed price for the item.

* Qualified U.S. Suppliers are established businesses that routinely and regularly sell the item to be matched from an established physical storefront or warehouse.

While we endeavor to maintain the accuracy of item availability, descriptions and availability, we reserve the right to correct errors. We reserve the right to choose not to honor this offer.

How to Request a Price Match

Place an order on-line and leave a comment at checkout. Provide the competitor's name, part number, item description, URL link to the exact item and the competitor's price anlong with your request to price match. If we agree to match the price, your order will be processed at that adjusted price. In the event we cannot match the price, we will notify you by email. We will hold you order for 3 business days.

Alternately, you may call us with your request. We'd love to talk with you. We will generally respond to price match requests within one business day.

SHIPMENT PROBLEMS?

Claims for missing items or error in shipment must be reported within 5 days of order receipt .

BACKORDERS

We endeavor to stock most of the items we sell. For Classic Minis, parts are frequently in limited supply and are difficult to keep on hand. the automatic shipment notification email you receive will identify backordered items and indicate the approximate date we expect to receive the item at our warehouse.

Be sure to contact us if you wish to cancel your backorder to avoid unnecessary shipping and restocking charges once the item(s) you’ve ordered is shipped.

Some items are made available on a Special Order basis. These are typically items with very low demand that we choose not to keep in inventory, or items that are custom built or built to order. These items are ordered from their suppliers solely to fulfill your order. As such, these items require a 100% non-refundable deposit at the time the order is placed (power-unit orders require a $1,000 deposit before work begins). Because of the nature of Special Order items, your order cannot be cancelled once your order is accepted and deposit taken, nor can returns be accepted once the item has shipped.