Induction Part II

Last section dealt with the basic primary induction (filters and cold air systems). In this new portion we will address the following additional induction components: throttle body, air foils, MAF, and runners.

The Mass Air Flow Sensor (this induction is not found on Speed Density systems) ( MAF is found on 1989 and before TPI Camaros, LT1, and LS1)

The MAF is the component directly located after the air box and its job is to help the onboard computer calculate fuel and spark ratios. The MAF achieves this by measuring the amount of incoming air and relaying that info to the computer. Unfortunately, anything that is in the induction track is an obstruction. Our job is then to make this restriction as free flowing as possible and necessary.

Modifiying the MAF: the MAF has two restrictive mesh screens one located on each end. These have been put into place by the manufacturer as a last way to defend the MAF from damage that may be caused by incoming debris. I personally do not think that these mesh screens do a good job of that. Lets face it that should be the job of your air filter. All of the camaros that are featured on this web page have no sceens and none have seen any problems. Other sources have also agreed with me, however I still warn the user of that slight chance of damage.

Here is a high flow MAF from Granatelli

The LT1 and LS1 engines have available to them, either a low restriction housing or a full MAF without screens and better electronics. The housing is made of a polymer and costs about 50 bucks. The full sensor from Granatelli costs about 340. They can both be found at jegs.com or Summit racing.

The Throttle Body (not recomended for V6 engines)

Increased Diameter:

The throttle body from LT1, LS1, and TPI engines can be upgraded to larger opening diameters. The installs are easy ( 1.5 hours ) and are straight forward. One thing to keep in mind is that stock throttle bodies are usually more that adequate for delivering air to a stock or mild engine. For example a stock TPI (48mm) throttle body from 1989 flows about 630 cubic feet per minute of air. That means that this throttle body is good for engines producing up to 320 hp. I would not recommend using a larger TB unless an after market cam or better roller rockers are used. I feel this way because a larger TB will decraese torque on the lower part of the RPM band while increasing it in the higher ranges. In a street car low RPM is what matters the most ( 0-60 times). Cars with heavily modified engines will produce enough low end torque to justfy this modification. In addition, keep in mind that this piece is only as strong as your weakest. That means that a bigger TB will not help that much if you do not change the rest of the air pathway such as the upper manifolds, lower manifolds, and runners (runners in TPI). These items usually run in the $340-400 range.

Pictured here is 52mm TB from BBK

Porting and Polishing:

Porting and polishing is also a way to modify the stock piece without spending a lot of cash. Porting can be achieved by grinding and polishing th metal that is inside of the stock TB to enlarge the opening. This procedure can be done by anyone but I would leave it to experts like Lingenfelter. Usually, the fee will be around a 100 dollars and you can bet its going to be perfect! I would recomend this to any car with an exhaust and air intake mods (Bored out to 50mm).

Air Foils:

Another way to modify these on TPI and LT1 but not LS1 engines is the use of AIR FOILS. They are inserts that go on the inside of the TB and are said to straighten and smooth out the incoming air. The theory makes sense as these can get you to flow 17 to 20 more CFM in your STOCK system. This flow is enough to shave a .1 off a quarter mile and give a crisper smoother TB response. Installation, takes about 30 minutes and they cost about an avarage of 35 dollars.

An SLP Air Foil

Runners:

On TPI engines (only), tube runners can be found between the upper and lower manifolds. Their length and design is largely responsible for the powerful low- and mid- torque of these engines. It is also why they seem to be restricted on the upper RPM band. Runners can be rewarding if the right design is used. Stock and mild applications should stick with the larger tube types while more radical engines should go with siamesed design from SLP. The large tube type seems to be better at not loosing low RPM torque while giving a 10-12 hp increase. The siamesed type gives more high end hp about 15-20 but at the cost of some low RPM torque. The truth is that both of these will work in any application above but we just try to see what works best. Stock to mild 305 engines should be more prone to using tube types as the 350 (stock or mild) has the displacement necessary to use either design. A 350 owner should buy the type that best suits their like, either fast or quick.

Pictured here from left to right: SLP siamessed runners and Accel runners

A recent test on a stock 350 TPI Camaro car revealed these test results:

Baseline: 14.452
Accel Air Filter: 14.397
Accel Runners: 14.283
Accel Throttle Body: 14.381

The air filter, and then adding the runners both decreased ET. The 58mm throttle body slowed it down. See, what we have been talking about?