Where is the horsepower? We have it here at Wiseco if you need it.

So, do you really know about horsepower? Luckily, the engineering team at Wiseco is well versed in horsepower. In fact, it's probably up toward the top of their lists of favorite things. We have a FAQ section on Wiseco.com in our customer service section. Here is a question regarding horsepower. It leans toward the automotive side, but has some good general info as well.


What are the other factors to consider when maximum horsepower is the goal?

Compression ratio and Dome/Dish volume determine combustion efficiency and resistance to detonation. Detonation can and will destroy any piston in short order. Lean conditions will melt any piston as any aluminum alloy melts within a few degrees of each other. Most of a piston's heat is dissipated through its contact with the cylinder wall and oil splash. Very short pistons and excessive clearance will melt a piston sooner. Static compression varies more than most people would believe. A piston running .020 down in the cylinder at tdc as opposed to "zero-deck" on a 64cc combustion chamber headed 350 Chevy changes the compression ratio from 10.25:1 TO 9.8:1.

People running compression ratios higher than 14:1 are not making more power if it means an increase in dome rise. More dome rise only hurts combustion efficiency which will loose more power than is gained by increasing compression. The current trend in Pro Stock, Winston cup, and others with big-budgets for engine development is to make the combustion chamber smaller and go to 12, 14, or 18 degree heads to make that happen. They are going for the shortest dome rise that gives them the compression they are looking for. The trend is to also use a bigger bore with a shorter stroke to put an engine at its best power potential for a given cubic-inch limit. One point to remember is a pro engine builder will never trade ring-seal for cubic inches from making a cylinder wall too thin.

Figuring Compression Ratio

Compression ratio is the volume of the cylinder when the piston is at the bottom of the cylinder compared to where it is when the piston is at TDC. A 100 cubic inch cylinder would have its volume squeezed into 10 cubic inches with a 10:1 ratio. The easiest way to keep track of it is to think of every thing as volumes that are stacked on top of one another. The factors that stack up are the displacement of the cylinder (bore and stroke), the volume of the deck clearance (getting back to the zero-deck issue from before), the volume of the gasket (which is basically a short-round cylinder), and the volume of the combustion chamber. The net combustion chamber volume means you must subtract dome volume add the dish volume. Use the formula (bore x bore x stroke x .7854 x 16.4) to get the volume for a cylinder in cc's. Stack up the cylinder + the deck volume + the gasket volume + the net chamber volume---take this number and call it A…Stack up the deck, the gasket, and the net chamber volume and call it B….. Take the big number A and divide it by the small number B and it will give you the compression ratio.

Tech questions come up in every rebuild whether you are an experienced engine builder or completing your first rebuild. When you purchase a Wiseco product, we provide technical support on our products to assist with the questions that may come up. Our technical team- Ron, Tom, Adam, Dwayne, Vic, Brian, Chris, John, Jeff, Al, Sue, and Sean- are ready to help you out. We’ve asked our team to put together a few questions they answer on the phone frequently.

What kind of piston-to-wall clearance can I run?

The factors that affect piston-to-wall clearance are cylinder wall thickness, whether the block is filled, the overall compression height of the piston, piston material and thickness, and whether a marine engine is to see fresh-water cooling. Most small blocks get .004 piston-to-wall clearance and most big blocks get .005 due to the use of our 2618 high-strength alloy. For heavy blower and nitrous applications, Wiseco recommends adding .001 to the standard clearance. Special note: Clearance numbers are obtained from measuring the largest diameter of the piston, typically at the bottom of the skirt. All measurements should be taken 90 degrees from the pin centerline.

Motorcycle/ ATV/ PWC piston clearances are printed on the label on the front of the piston box.

When I install my Wiseco piston, which way should the arrow on top of the piston face?

On most Wiseco Powersports pistons, the arrow will point toward the exhaust. If you are installing pistons in a v-twin or automotive application, this will differ depending on the application. Checking the installation directions included with your Wiseco product will verify the direction. But, if you still need assistance, our technical sales team will be happy to help.

I have a 4-stroke ring package that I received with my piston. I have the top oil rings, but am unsure of which rings are the Top and 2nd. How can I tell?

Some Wiseco 4-stroke ring packages are interchangeable between Powersports and automotive applications. Therefore, you may have additional rings that are not required for your application. In general, the silver/ gold/ shiny ring is the Top ring, while the black ring is the 2nd. This can be verified in the ring installation instructions included with your ring pack.

Is there a technical question that you would like to see posted on our blog? Leave us a comment! We will try to answer as many questions as possible.

We have also just added a technical section to our bi-monthly newsletter. Sign up on our website http://www.wiseco.com to check it out. You can also see our past newsletters.

Wiseco is #1 for Tech

So, you've already ordered all your parts for your engine rebuild. You've torn the engine apart so now it's laying all over the garage floor. You start putting in the new parts and you suddenly have a question on piston clearance. Luckily, you bought Wiseco pistons from your dealer.

Wiseco strives to provide the best customer service in the industry. Whether we sell you a powesports, marine, or automotive piston, we want to give you the best service. Our technical sales team has experience on many levels and comes from diverse backgrounds. Most of them have experience racing dirt bikes, ATVs, or cars. Others are have been mechanics at multi-line dealerships. Still others have worked their way up from the Wiseco production lines, actually making the products. Wiseco is dedicated to its customers.

We also just rolled out a new website! If you haven't seen it, check it out at Wiseco.com. We have made our website a resource for you! You can check out our latest project bike, get info on our full line of products, and so much more. We have a new Customer Service page. This page has installation and technical information. You can find engine calculators to prepare for your next rebuild and installation manuals. We hope to expand on our technical information during the coming year. We would like to hear your thoughts on our new website, as well as our customer service. And, as always, if we can provide you with any technical assistance, please give us a call.