harley engine

This site describes Harley-Davidson compression and just how it affects the performance of the Harley.

Although elevated displacement, air flow, and revoltions per minute are secrets to creating more energy, more energy won't be recognized unless of course combustion chamber pressure is enhanced and utilized for at the maximum pressure around the piston. Everyone knows the car engine is simply an air mattress pump. However,


what we should mustn't forget is that it's a pump made to generate warmth and harness cylinder pressure. Making warmth and controlling cylinder pressure may be the secret to creating energy. For enhanced cylinder pressure to happen, warmth should be contained and changed into functional pressure around the crankshaft while reducing warmth loss towards the air conditioning. Obviously, an account balance should be accomplished between making the most of warmth and reducing its dangerous thermal and mechanical effects on components. When creating and building an electric train engine, keep in mind that it is advisable to maximize cylinder pressure around the energy stroke while reducing pressure around the exhaust stroke. This begins with optimizing the compression ratio towards the engine combination.

Remedied compression considers the point where the intake valve shuts after BDC around the compression stroke. The later the valve shuts, the low the remedied compression ratio. To have an enhanced engine, the remedied compression ratio ought to be matched up towards the vehicle's application and fuel octane. Generally, the later the intake valve shuts, the greater the mechanical compression ratio is always to conserve a given remedied compression ratio. To find out remedied compression, the mechanical compression ratio and also the cylinder displacement remaining from the moment the intake valve shuts should be known.

Compression Ratios
Cylinder pressure is vital to achieving a effective and enhanced engine. Growing volumetric efficiency
with large cams, greater-flowing cylinder heads, or bigger induction really are a couple of methods to increase cylinder pressure, but raising the engine's mechanical compression ratio (also called static compression) is yet another. Up to and including point, raising the compression ratio increases thermal efficiency because warmth and combustion pressure are elevated for greater gas expansion. Therefore, presuming an enhanced exhaust valve opening, more potential energy could be removed in the growing gases. Because the speed of combustion increases because the square of combustion pressure, doubling combustion pressure through greater compression boosts the speed of combustion with a factor of 4. It has several implications for that optimum ignition timing and also the needed fuel quality.

An electric train engine with aluminum heads usually can support a compression ratio of roughly 1. to at least one.5 points greater than a similar

cast-iron mind engine without taking on detonation. The reason being the aluminum functions like a warmth sink and pulls warmth in the combustion chamber. From the energy perspective, which means that everything being equal, such as the compression ratio, an iron mind engine can make more energy than an aluminum mind engine because more warmth will stay within the combustion chamber, thus creating greater cylinder demands. To replace with lost warmth and energy, an aluminum mind engine must operate a greater compression ratio than a similar iron mind engine. For example, it requires roughly a 15.5:1 compression ratio by having an aluminum mind Evolution engine to complement a 14:1 compression ratio by having an Ironhead Sportster. Another factor that's impacted by cylinder mind materials are fuel octane. For any given compression ratio, an aluminum mind engine requires less fuel octane to prevent detonation than a similar iron mind engine.

Combustion chamber design, thermal obstacles, and ignition timing all affect thermal efficiency. Although elevated compression boosts energy within the entire revoltions per minute range, it's particularly effective for low and midrange energy increases. Though many variables are participating, the utmost mechanical compression ratio is dependent upon the engine's detonation threshold. This threshold is mainly affected by fuel octane, volumetric efficiency, combustion chamber efficiency, and cylinder mind material. Engine compression is generally talked about when it comes to mechanical, remedied, and dynamic ratios. We'll have a brief take a look at mechanical and remedied ratios.

Mechanical Compression

An engine's mechanical compression ratio could be described as the amount of the total amount within the piston at bottom dead center (BDC) in contrast for the volume at top dead center (TDC). The Harley V- Twin engine

responds very well to some increase in mechanical compression. Really, many engines are poor artists since they lack sufficient mechanical compression.

The initial step to consider when determining the mechanical compression ratio is if the engine uses 92-octane pump gas or high-octane race gas. Once the engine will probably be work on pump gas, it'll be limited to roughly 9.:1 and 10.5:1 mechanical compression, according to variables for instance cam timing, combustion chamber design, ambient temperature, bike weight, and gearing. If race gas might be the fuel associated with preference, the effective maximum compression ratio will probably be limited to roughly 17:1, again according to several variables. Keep in mind, however, that after the compression ratio surpasses about 16:1, thermal efficiency starts to lower and parts breakage potentially becomes an problem.

Ambient temperature plays most in where detonation sets the engine's energy limit. A very good reason a drag racing engine can run high compression could it be only is employed by a while and doesn't finish track of hot. However, a street engine will get warmer substantially around the hot summer season day, especially while idling for extended periods in traffic inside the late mid-day. Where a street engine may not encounter detonation through the awesome spring and fall several days, detonation may be rampant throughout summer season several days, specially when riding double and beginning in the stop. If you are developing a street engine, save this reason behind mind when determining the engine's mechanical compression ratio.

General strategies for conservative mechanical compression ratios on 92-octane pump gas while using V-Twin engine would be the following: With Twin Cam and Evo Large Twin engines, you'll be able to run between 9.5:1 and 10.5:1 mechanical compression without going through detonation. The light Evo XL are equipped for between 10:1 and 11:1 mechanical compression. For your Ironhead XL and Shovelhead, expect 9:someone to ten:1 since the maximum mechanical compression ratio on pump gas. Fuel-injected models may deal with up to half point greater mechanical compression in comparison to values in the list above. Other variables, for instance combustion chamber design and cam timing, may even influence the specific compression limit. Since cam timing affects cylinder pressure when the engine is running, cam occasions and compression ought to be carefully matched up to increase energy for just about any given parts combination. This is where cured compression ratio is essential.

Cured Compression

When the mechanical compression ratio is made the decision, the assumption may be the intake valve is closed when the piston reaches BDC in the start from the compression stroke. When the were the problem, the whole cylinder volume might be compressed round the compression stroke. The simple truth is, however, intake valve closing is postponed beyond BDC, which results in the piston being part way around the compression stroke when the valve shuts. Therefore, under a whole cylinder volume is compressed, and so the actual compression ratio is correspondingly less. Calculating compression based on intake valve closing is called cured compression. Cured compression can be a more realistic way of determining an engine's compression ratio.

Since cam timing features a major impact on compression, cam occasions and compression needs to be matched up when designing a train locomotive. A train locomotive getting a extended-duration cam are going through a considerable insufficient low-finish torque unless of course obviously the cured compression is matched up up for the cam timing, particularly intake valve closing. Many street engines are deliberately built having a late-closing intake valve to bleed off cylinder pressure at low revolutions per minute to prevent detonation. However, that affects low-finish torque. Therefore, you need to coordinate gasoline octane, mechanical compression ratio, and cam timing when designing a train locomotive. The Three variables needs to be determined just like a matched up combination instead of three separate variables.

For just about any well-running V-Twin engine, ideally the cured compression ratio needs to be surprisingly than 9.:1. Experience has proven while on an enhanced combustion chamber, a Twin Cam or Evo Large Twin engine running on 92-octane gas supports between 9.:1 and 9.5:1 cured compression ratio (calculated at .053 in. tappet lift) before going through detonation. Therefore, to increase performance with pump gas, you need to design a train locomotive getting of a 9.2:1 cured compression. However, keep in mind that numerous factors, for instance ambient temperature, barometric pressure, altitude, humidity, dual spark plugs, gearing, and total bike weight could affect an engine's actual detonation limit. With dual spark plugs and optimum conditions, the limit is frequently up to 9.5:1. But overall, 9.2:1 cured compression can be a reasonable guideline to take advantage of.

The key facts to consider out of this discussion aren't a specific cured compression ratio to take advantage of, but the thought of cured compression together with an over-all range to goal when ever utilizing pump gas. The mathematical formula for calculating cured compression is kind of complex and beyond the scope from the discussion. However, the easiest approach to calculate cured compression is to apply the "Accelerator for Home home windows" engine simulator program or possibly a course particularly written for calculating cured compression.

Compression Ratio Factors

Following are a handful of details to think about when determining an engine's mechanical compression ratio:

Match the mechanical compression ratio to fuel octane, cam timing, volumetric efficiency (VE), combustion chamber design, gearing, and total bike weight.

Aluminum heads generally tolerate greater compression than iron heads.

Energy-adder programs (supercharged, turbocharged, and nitrous) require less compression.

At high altitudes or with low VE, raise the compression ratio.

Dual spark plugs may allow a larger compression ratio for just about any given fuel octane.

Greater compression requires a young exhaust valve opening.

A smaller compression ratio requires a later opening exhaust valve.

A small compression ratio benefits of a larger flowing exhaust port.

Greater compression offsets some negative affects of the large low-velocity intake port.

Greater compression requires less ignition timing.

Good fuel atomization cuts down on the chance of detonation, thus enabling a larger compression ratio.

Greater compression improves throttle response.

Reducing combustion chamber warmth loss is most critical with low compression.

Greater compression may require a greater-torque starter motor.