We decided to only use items that could be easily bolted on and able to be installed outside under the proverbial shade tree. They had to be over-the-shelf items, and be able for the average do-it-yourselfer to do the work. Pretty tough rules, but hey, this is a pretty tough project!
A Word About Camshafts - Things go bumpity-bump in the night
Performance camshafts try to compensate for the problem of getting more air in and out of the cylinder by allowing the exhaust and intake valves to stay open longer by increased duration and overlaps in an attempt to "air out" (scavenge) the cylinder. Unfortunately this provides more opportunity for the fresh mixture to also escape along with the exhaust gases, thereby improving power, but not without the sacrifice of fuel mileage and low end torque
Cams can be of great benefit to performance minded machines, but not the first choice of modification in situations where economy is a factor, and certainly not for newer more sophisticated computer controlled rigs. That can always come later when all is said and done. This is also true with other internal engine modifications. Anything can be had for the right price and effort, however we are going to concentrate on the external bolt-ons and tricks that will help no matter what you have tucked under those valve covers. It'll always help even more, later.
Most people forget about the basics while spending way too much on unnecessary modifications. Since most of these procedures and products in this series will not only help performance as well as economy, they could be considered as "freebies", as they will eventually pay for themselves in the long run. Interested?
Back To The Basics
One of the first lines of defense against the power robbing residual fraction of exhaust gases remaining in the cylinder, is to get more fresh, dense air into the cylinder. A Colder intake charge makes the air molecules more dense, thereby allowing more oxygen particles to make their way into the cylinder. Similar to the principle behind supercharging, many have experienced this power gain late at night on a cool, humid evening at the track- the times and speeds always increase. That's the cold-air charging effect at play.
In order to harness this advantage, getting in as much cool air as easily as possible is the key. The vacuum pulse produced by an internal combustion engine is not necessarily very strong, and it doesn't take much restriction to decrease it's signal, thereby inducing significant power and economy losses. One consideration to keep in mind is not only how un-restricted an air filter is, but also how well it flows when it's slightly dirty. Very few filters live in pristine, perfect dirt free environments, so this is where a premium filter really proves it's worth. Therefore, having no filter at all is not a fair comparison, however the K&N Air Filter Company did just that.
Send in the Air Force
Their tests show that K&N's Filtercharger air filter actually flows better than with no filter at all, due to the fact of the 'straightening' effect the K&N has on the incoming air stream. Their wider pleats and free-flowing filter material allows for maximum unrestricted air flow into the engine. Due to the filter material being oil impregnated, their filter cleans the air much better, as well as allowing this reusable filter to be cleaned over and over again by the user. K&N claims upwards of a 12 h.p. gain with their filter, and it was easy to see why. Again, look on this as being nothing less than a 'freebie', at only 50 bucks or so for this 10 minute drop-in add on.
(Photo of OEM replacement K&N air filter next to the old one next to it): We did a comparison test to find the difference between the stock air cleaner and filter system to the K&N filter in the stock air box, as well as the K&N Fuel Injection Performance Kit (FIPK). The K&N OEM replacement filter was simply installed in the original location in just a few minutes. Note the tightly placed pleats in the restrictive OEM-style paper filter compared to the open free flowing K&N version. You can also see that only a small portion of the paper filter was being used (indicated by the black spot on the filter) due to the inherently low flow configuration of the stock air box.
(Photo of K&N panel filter beside a stock filter with light behind it): With a 100 watt light behind the stock paper filter on the left and the K&N on the right, it's obvious which one flows more air. Even though more air can flow through, the oil suspended in the element fibers of the K&N traps even more dirt than the more restrictive paper version. Best of all, it can be cleaned, re-oiled and used over and over again… for up to one million miles, as warranted by K&N. Theses filters further protect your engine from possible damage due to the oil impregnated filter material naturally repelling water, thereby reducing the chance of hydraulicing an engine!
(Photo of temp sender in air box with readout close by): We set out to see how well the 'cold air' box really works, and measure any benefits of the theoretical cooling advantage on the system's overall performance. To accomplish this, a remote digital temperature probe was placed inside the air box directly under the filter element to measure the intake charge within the air box. Another probe just outside the air box will measure the under hood temperature while yet another probe measures the ambient outside temperature as a control number. We ran the engine to normal operating temperature during all our tests while driving under load at highway speeds.
(Photo of stock air inlet by radiator): Originally just the K&N OEM replacement air filter in the stock air box was planned. But after talking with K&N Racing Events Manager Kirk Peters, it was soon evident that the so called "cold air" box was prone to being "pre-heated" anyway, due to the close proximity of the air inlet to the radiator, as well as absorbing heat via the plastic air box housing. As consequent tests have shown, there were no significant gains to be had by the stock 'cold air' box, other than the notable silencing effects it had on engine noise during hard acceleration.
(Photo of stock air box removed, compared to the new K&N system. & Std. Filter Charger): Here one can see the air flow advantages produced by the K&N FIPK system shown in the middle, with the stock box on the right and the direct replacement K&N filter on the left. Even though warmer "under hood" air is being consumed, it's not that much warmer than the "pre-heated" air box, however, taking advantage of the increased air flow cancels out any negative effects to the power output of the warmer air at medium to higher engine speeds.
(Photo of installed FIPK air cleaner sys): The much higher flowing capacity of the Fuel Injection Performance Kit (FIPK) air filter element is obvious, however it does eliminate any added benefits from a cold air intake system by drawing hot air from within the engine compartment. K&N claims the increased flow of the filter out weighs and benefits lost from losing the cold air feature. K&N reports a 3% performance and economy increase for their replacement filters and a 7% increase in their complete FIPK systems. Best of all, we never have to buy another filter with either system.
(Photo of C.A.R.B. decal on air cleaner system): Here's the important part. With this certification tag, the K&N F.I.P.K. filter system is 50 State emission legal. Our tag was visibly and proudly displayed for all to see. However, we also noticed that the FIPK open element cleaner actually read a higher intake temperature than the engine compartment due to the fact it was 'vacuuming' out the hot under hood air and sending it directly into the engine. We also noticed a healthy performance growl let out from under the hood whenever we added a good amount of throttle.
(Photo of grinding internal baffles out of air box): After careful consideration we decided to once again try the stock air box system in hopes to achieve the quietest operation as well as gain maximum performance while under extreme load conditions and pulling up hills. First off, we modified the inside of the stock air box for maximum flow to make up for the horsepower loss over the open element system.
(Photo of grinding radiuses from air inlets): Additional gains could be attained by making the filtered air path as smooth as possible by radiusing any sharp edges or transitions within the air box. Careful attention must be paid as to not grind through the thinly designed box.
(Photo of location of air restriction): Here is where the factory intake noise silencer is located on our Ford, which theoretically restricts the intake air from the air cleaner as well. In order to improve performance along with comparing filters, it was originally thought that this restriction was needed to be eliminated.
(Photo of air restriction being sawed): On our Ford we needed to simply cut off the reducer cones designed to eliminate intake noise during acceleration. After cutting the plastic restrictors off with a hand saw, the edges were filed smooth and reinstalled into the factory location. Noise was slightly increased under half throttle, but it was a 'racy' sound to be appreciated. However, after the first few runs back when we were just beginning Project M-P-G, it was apparent that the performance actually dropped, therefore we reinstalled the cutoff pieces and instantly seen the return of a notable increase in bottom end torque and midrange performance. I guess Ford did have a better idea here. We tried again later to see if removing the silencers would help when other performance products were added. Only until the exhaust modifications were installed did the removal of these silencers pay off. However, ours were very smooth flowing and the removal of other more restrictive designs may prove beneficial if removed sooner.
(Photo of air restriction removed): Now that we eliminated the factory air tube silencers (above), a notable decrease in the intake restriction was realized. Many fuel-injected vehicles have these noise baffles located in various places and significant performance and economy gains are claimed to be had by increasing the air flow here. We found our engine to be running slightly lean across the entire fuel curve due to the increased airflow. By simply turning up our adjustable fuel regulator 2 psi we were able to compensate and further increase power and economy while reducing pinging and the need for higher-octane fuel.
Since you already know that cool air is happy air, then what about all that under hood engine heat? The cooler you can make that engine compartment, the cooler the air intake system will be, and the more aircharge can be had. Wrapping the exhaust manifolds with insulation or having them ceramic coated will help, as will venting the hood with a scoop will also help.
Another neat and cheap trick is to insulate the air intake tubes with a heat reflectant tape in order to keep the incoming air as cool as possible. Even though the metallic intake manifold will undoubtedly transfer heat throughout the intake system, the rushing air of the incoming intake charge will inherently cool the insulated components from within.
DEI makes a product called "cool Tape", which is an adhesive backed 1.5 inch wide tape with a metallic silvery heat resistant exterior. This tape is available in 15 foot lengths and sticks to almost anything. Dyno reports have confirmed that at least one percent of the overall horsepower is gained for every 10 degree decrease in temperature, and even more if the coolant temperature is stabilized under load. We could feel the difference, even though ever so slight. However, we could really see the difference in the fuel mileage increase. Not too bad for just a couple of rolls of tape.
(Photo of insulating the air box): Keeping the incoming air as cool as possible will also help in the power and mileage area... at approximately 1% horsepower gain per 10 degree reduction of intake temperature. To do this we wrapped the entire air box and inlet tubes with a heat reflective adhesive tape. This product was specifically designed by DEI for this application, and is certainly not pipe insulation which is designed to keep heat "in" and not "reflect heat away", which this situation requires.
(Photo of insulated cleaner system underhood): Over 120 feet of tape was used in this one operation, and the tape adhered to every nook and cranny to appear as if we have our service work done at NASA. Fuel injected, or "dry air" systems, benefit much more from this since they do not enjoy the inherent cooling effect of the atomized fuel flow through the intake in a carbureted, "wet" air system. A cooler intake charge will also reduce the potential for detonation and "pinging", along with the need for a higher octane fuel.
(Photo of temp gauge readouts side by side with air box and underhood temp readings): Measuring the inside and outside air box temperatures as compared to the non-insulated version showed a dramatic decrease in temperature inside the box, thereby increasing power and economy. Several horsepower and a significant amount of torque was gained in addition to the benefits of the K&N, however, top end power was still not as much as that of the open element. We felt that particular performance edge is best left to the Mustangs and Camaros to enjoy, while we gain maximum benefit at lower towing engine speeds with hotter under hood temperatures.