GM 60-degree V6 Power Tricks: Solutions for Corralling More Horses
|Text and Photography By: Dr. Sean Michael|
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GM 60° V6 Power Tricks: Solutions for Corralling More Horses - Page 2
Trick #3: Flip Your Lid
A trick that addresses part of the weakness of the factory air filter housing on these engines is extremely easy, yet makes a real difference. Flip the lid of the air filter housing and resecure it with the original wing nut. This allows air to reach the filter more readily, streaming in from all sides rather than squeezing through the intake hose. The drawback is that filters get dirtier far quicker -- a good reason to consider trick #4. Another drawback is the increased engine noise, but that is a drawback or a plus, depending who you ask.
Performance gains are most noticeable at high RPM's, where the stock motor runs out of air less after the flip. Low-end response is also slightly improved. You may also notice less impressive changes in summer because the flipped lid allows hot engine compartment air to be drawn in. With estimates of one horsepower lost for every 10 degrees Fahrenheit increase, consider flipping the lid back to the stick position when visiting Death Valley trails.
Trick #4: Hi Flow Filters
Depending upon the condition of the existing air filter, switching to a reusable air filter may provide impressive flow rate increases. Reusable filters fall into two main categories: gauze and foam. K&N made the gauze type famous, and K&N makes a simple 10-inch ring style filter that drops right in place of the stock Trooper filter. K&N also has a new high-performance filter that utilizes a filter element on top, allowing even better air flow. Be sure to use K&N's own filter cleaner and treatment to take full advantage of their product, though. I'm not just repeating the party line - I did not follow their recommendations and learned the results the hard way.
Some competing companies suggest that oiled gauze filters actually diminish filtration. Amsoil is the company credited with marketing the first synthetic oil and a long-time innovator in air- and oil-related automotive products. Amsoil claims that their reusable foam filters pass a volume of air equivalent to gauze filters, while filtering damaging particles down to the 5-15 micron range. They claim that quality paper filters do capture these particles and that gauze units do not. As a result of these claims, and because I have used and been pleased with Amsoil products in the past, I switched to their foam filter. It was cheaper than a K&N filter and also provided a nice performance increase.
Trick #5: Fiddling with Filter Housings
Another way to maximize air flow is to use a larger-than-stock filter. Several approaches exist for this:
-- Use a cutting wheel on an angle grinder to remove the vertical wall around the filter housing, allowing use of a filter almost the same diameter as the housing. Larger diameter filters provide a big gain in filter surface area, and as a result, much-improved air flow.
-- Fabricate a hose intake system that securely fits the TBI and route a three-inch diameter hose to a cone-shaped filter.
-- Obtain a larger air filter housing from a similar motor.
I selected the last of these options, and used a much-larger air filter housing from an early seventies Chevy 402. This allowed use of a larger 14x4" filter. I made this swap at the same time as I installed the larger Amsoil foam filter, and the combination made a noticeable improvement over the smaller K&N filter, especially below 3000rpm. The key to making it all fit is Trick #12.
Trick #6: Throttle Body Spacer
The flow of air/fuel into the intake bores can be smoothed through the use of a simple spacer. Carl Barrett was kind enough to machine a batch of these in varying sizes, and there was a small but perceptible gain in throttle response. I experimented and ended up using the one inch spacer. This seems to be the maximum thickness that will fit without applying excessive torquebefore torque on the rigid fuel lines that connect to the throttle body. Theoretically, at low RPMs a lengthened passageway may induce turbulence, and conversely, the longer passageway may smooth out the airflow at high RPMs. This is a very simple modification if you have someone who can machine the spacers for you. I recommend 3/4-inch aluminum spacers sandwiched between thin-profile 4.3L TBI gaskets. Turbo City sells several different thicknesses of spacers.
Trick #7: Intake Bores
|The bored and ceramic coated intake being installed on the motor|
Another trick that works in conjunction with other air flow enhancements is machining the twin intake manifold bores to match the 1.68” diameter of the TBI. Leave this to a machinist with the right tools -- exactness of fit is critcal. The intake manifold also contains casting cavities, that, if nicked, wreck the part. In my area the going rate for this relatively simple task seems to be about $50.
Performance results from this trick are instantaneous as the motor begins to breathe more. Gains are particularly evident at higher RPM's when the motor was previously starving for air. Because removing and re-installing the intake is a fairly labor intensive process, at minimum, pair this trick with at least Trick #8. Consider buying a used manifold to allow a machine shop to bore it without disabling your rig.
Trick #8: Roller Rockers
The 2.8 responds well to substituting roller rockers for the stock rockers. At a bit over a hundred bucks for the basic version, manufacturers claim that switching from 1.5:1 to 1.6:1 lift ratio rockers yields about a 10% hp gain. Because the rocker arms require a removal of the valve covers, intake and TBI, this trick is ideal to link with trick #7. If you plan a subsequent cam change, you may want to stick with the stock 1.5:1 ratio, but upgrade from tappet rockers to roller rockers.
|Close-up view of the roller rockers||All the lifters installed and lubed|
Both Crane Cams and Competition Cams make roller rockers for this motor. Crane Cams produces the affordable Magnum Roller Rocker, which I installed, as well as the Gold Race full roller rocker. At twice the price, it offers twice the zoot, using needle bearings for the fulcrum, an aluminum body, and replacement studs (the 2.8 used 10mm vs. the more common 3/8"). The full bearings certainly decrease friction, but the power gains over the Magnum are less obvious.
Trick #9: HyperTech Power Pulley
The Camaro/Firebird often upgrade their 3.4L F-body engines by installing underdrive pulleys. A replacement crank pulley and, on some motors the alternator pulley, reduce the load on the motor, freeing up a few more horses. A relatively simple trick, the gains are modest, but of enough interest to strongly consider. The drawback is that the alternator produces proportionately less power because of the underdrive pulley, which may be problematic with the current requirements of winches and driving lights.
Trick #10: Cams
|Here the new cam shaft is being slipped into place|
Trick #10 is ideal when coupled with a performance cam shaft. A number are available for this bow-tie block, but you’ll want to keep your eye out for one that is sold with the matched lifters, valve springs and all the locks and seals. The 2.8 uses flat tappet lifters, so you must replace them too when adding a new cam. If ground to match the owner's driving profile the gains from this modification are both impressive and an improvement on the placement of the power band. Companies such as Competition Cam can work closely with you to assure that you get the ideal grind. And that's important when you're talking this much labor to get down to the cam on the 2.8L. Still, yields from the cam are also going to be in the 15% range and so any problem requiring pulling the motor is a good reason to consider a cam swap. Remember that depending upon the cam grind, any use of new roller rockers with it may demand that you not use a 1.6 ratio rocker.
Trick #11: Computer Chips
Super Chip's replacement chip proided a perceptible gain -- the manufacturer claimes 15 horsepower, but recommends using high octane fuel to reap these benefits. This chip is a mixed blessing; it is easy to install and produces tangible gains, but always does more damage at the pump. Fortunately, the chip does not reduce fuel efficiency or preclude using lower octane fuels, although some folks report an increase in motor knocking. The chip may also end up being better able to to handle changes like cams or roller rockers. The chip can also be reprogrammed to support subsequent changes, if necessary. Jet Chips also markets replacement chips for 60-degree V6s.
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