How Much Horsepower Does the Honda Vehiclesby Contributing Writer
Everybody's got to start somewhere, and Vehicles has long believed in hooking them while they're young. The Vehicles might seem like just a junior-scale version of the full-sized Vehicles dirt bike, but as usual with Vehicles it's all those little, perfectly balanced details that make it just right.
Under The Hood:
- How Much Horsepower Does the Honda CRF 80F Have?
- How Much Horsepower Can a Two-Bolt 454 Handle?
- How Much Horsepower Does a 2006 Dodge Charger RT Have?
- How Much Horsepower Do Headers Add?
- How Much Horsepower Does a Weber Carburetor Put Out?
The CRF 80F is an in-between kind of bike. Larger than a kid-scale minibike and smaller than a full-scale adult bike, it's designed for "tweens and smaller tweens." With tough construction and a conventional clutch and five-speed transmission, the CRF 80F is meant to help younger riders develop skills while still allowing for a fairly steep learning curve. The CRF's four-stroke, single overhead cam, 80 cc engine reflects that philosophy in microcosm; it's not a screaming race engine; however, it delivers 5.44 horsepower at 8,000 rpm and its peak 4.06 foot-pounds of torque at 3,500 rpm. That kind of powerband, stretching over an impressive 4,500 rpm, makes for very tractable power delivery that won't tax beginning riders with constant gear changes. Like the rest of the bike, this ruggedly designed engine offers a bit of "fudge factor," allowing riders to focus more on fun and safety and less on just keeping the thing moving.
The weak point of the 454's bottom end isn't the main caps, it's the block webs that the main caps bolt to. When a bottom end breaks, most often stress cracks start at the bolt holes and propagate through the web; the more holes in the web, the less material the cracks have to work through and the more opportunity for failure. For this reason, the parallel four-bolt arrangement that GM used for high-performance blocks isn't actually the ideal arrangement.
Serious race engine builders will often start out with two-bolt blocks and re-drill them to accept "splayed caps." A splayed cap places the outer two bolts at an angle to the center so the bolt holes go through the web near its base. This greatly reduces stress on the webs, and redistributes it to the block. But all that is really a redundancy; at the end of the day, the second pair of bolts only stabilize the caps. The center bolts actually hold them to the block.
With a decent set of chrome-moly studs and a well-balanced rotating assembly, a two-bolt block can easily hold 600 horsepower. A main cap girdle can take the two-bolt up to 900, because it essentially performs the same stabilizing function as a second set of main bolts without drilling into the block. Past this point, you're looking at splayed bolts for the extra holding power, and then an aftermarket block with thicker webs.
The 5.7-liter Hemi engine under the hood of the 2006 Dodge Charger R/T produced 340 horsepower at 5,000 rpm and 390 foot-pounds of torque at 4,000 rpm. With the Road/Track Performance Group or the Dayton R/T package, the output jumped to 350 horsepower and 390 foot-pounds of torque.
Horsepower Gains are Proportional
No two engines or systems are exactly the same, so results will naturally vary. The general rule is that you can expect from 5 to 20 percent power gain, but it is directly proportional to the engine and its output at the time the headers are installed. If a performance exhaust is installed on 100-horsepower, four-cylinder engine, for instance, the gain may only be five to 10 horsepower. Installing a header system on a 1969 hot rod with a big block, however, may net over 50. On top of the power gains, it is very likely that fuel economy will increase because the engine will not have to work as hard to produce horsepower and torque.
Brand and Type
The price of headers can greatly affect the power gains achieved. Quality materials and craftsmanship for the specific vehicle application will always produce better numbers than a Brand X header that doesn't fit right because it either was not designed correctly or has multiple vehicle applications. For this reason, it is important to purchase the best quality headers you can afford to ensure good quality and horsepower gains. Stock exhaust manifolds are normally very restrictive as far as flow goes, and headers open that path up so that the engine can breathe easier. However, going too big in tubing size, or the incorrect length, can actually result in the engine losing horsepower.
Headers vs. Complete System
While simply installing a good header or headers can definitely increase the power output of most engines, coupling them with a quality exhaust and muffler can further the gains. Adding a well-designed and effective set of headers that flow into a $16 muffler, for instance, probably could be improved upon. Popular quality muffler brands include Flowmaster, Dynomax, Magnaflow and Borla, although several others are on the markets that do the job well.
Some headers or exhaust systems may not be legal in all states, so check your local laws and ordinances before installing any aftermarket components. Some systems may require the use of the stock catalytic converter, so do some research on your make, model and year before making an expensive purchase. If installing the system yourself, be aware that some welding may be required. Never work on a hot exhaust system. Always wait at least 30 minutes for everything to cool down before digging in.
A carburetor is installed in the intake side of an engine and is responsible for mixing the air and fuel before delivering it to the motor, where the two are mixed with spark to ignite the enging. There are two primary Weber carburetor designs, downdraft (mounted on top of the engine) and sidedraft (mounted on the side of the engine). The best type to use depends on the engine on which the carburetor is being installed.
How much horsepower a Weber provides depends entirely on the type of engine it is being used on and state of the tune of that engine. For example, a single Weber used on a stock four-cylinder engine will not produce as much power as three Webers installed on a modified straight-6 engine. Typically, Weber carburetors can add from 5 percent to 20 percent more horsepower.
While installing a larger Weber carburetor on an engine may give an instant horsepower boost, for the carburetor to work to its maximum efficiency, the other components should be upgraded as well. A larger performance carburetor works by delivering more air and fuel to the engine, which should be matched with a more efficient intake manifold, exhaust and ignition system.