Ok fine, you got us. We have a thing for the LT series of motors, we just do. Sure, the trend is shying away from the LT1 right now for the more popular LS series of engines, but for a good number of you out there, the LT1 is in your ride right now. We are here to put some of the popular simple bolt-ons on the dyno and show once and for all what's worth what in terms of your dollar. We set out on a field trip to TPIS in Chaska, Minnesota, home to a group of LT1 gurus who've been racing the plucky little engine since its inception. TPIS put together a test mule and operated the dyno while we made changes and recorded the results.
Test 1 – Baseline Stock Engine
Max Power: 367tq, 316hp
Average Power: 330tq, 264hp
First, let's go over what our test motor is and get that out of the way. The motor is a .040-inch over-bored LT1 block with a lot of the standard stock parts such as the crank, heads, cast exhaust manifolds, intake, 1.5-ratio rockers, oil pan, 48mm throttle body, stock 24-pound injectors and stock (43psi) fuel pressure. Coolant temps were a constant 175-180 degrees throughout our testing and oil temp stayed right at 180-190 degrees. For reliability reasons several aftermarket parts were added including Scat rods (stock length), Speedpro hypereutectic flat top pistons (with valve reliefs), and the block was zero decked with a 10.5:1 compression. Fuel was your standard 91-octane from the local Gas-n-Blow gas station.
Our motor was broken in with the standard methods and then given 20 solid pulls to first make sure the motor was ready for our tests, and secondly to create a baseline. Our baseline pulls netted us a healthy 316 horsepower and 367 lbs-ft of torque completely naked, no accessories or cats. The following tests were progressive, which means that each item was added in order and left on the motor to see the cumulative effect of each part. Each part was given three pulls on the dyno to ensure that it didn't get a bum pull and we could be as accurate as possible.
Test 2 – Plugs and Wires
Max Power: 365tq, 320hp
Average Power: 332tq, 266hp
We replaced the stock plugs and wires with a set of Bosch Platinum plugs and a set of TPIS proprietary wires. Most stock engines come with a pretty flimsy set of wires; sure they get the job done, but they don't allow for a greater spark. Upgrading the wires to a thicker, spiral bound core will improve spark plug discharge, thus creating a stronger ignition source and in theory, more power. Our plugs were gapped to 0.050-inch with a stock heat range, but the upgraded platinum plug has greater efficiency. While we may have lost a bit of max torque, we did make slight gains in our average power numbers. Sure, the power per dollar cost here may not seem worth it, but if you plan on bigger upgrades in the future, these are a must.
Test 3 – MSD 6AL and Coil
Max Power: 364tq, 324hp
Average Power: 337tq, 270hp
The transitional style ignition system on the LT1 is perhaps the most maligned aspect of the engine, so a few basic upgrades in this area seemed appropriate. We found an old MSD 6AL ignition box lying around and decided to throw it on the dyno to see what it could do in conjunction with a high-output coil. As with the plugs and wires, a stronger spark will create a more efficient burn of the fuel and air mixture. We decided to test the MSD 6AL and coil to see what effect, if any, a more efficient ignition source could gain us. In theory, a stronger spark will create more power by fully igniting all of the fuel and air in the combustion chamber. In most cars, the stock ignition works just fine, however when cylinder pressure increases you'll need a greater source to ignite the mixture. On a stock engine the power from an MSD box and coil will most likely be nominal, but it is virtually a requirement for high performance engines. We saw small gains in both horsepower and torque pretty much all the way through the powerband. Again, this is an upgrade that is more effective in avoiding issues further down the road than it is making power on its own.
Test 4 – TPIS AirFoil
Max Power: 373tq, 327hp
Average Power: 343tq, 275hp
The TPIS AirFoil has been around for quite some time, almost as the first LT1 rolled off the line, TPIS had this neat piece ready to go (thanks to its TPI predecessor). Smoothing out the intake path by diverting air more efficiently to each throttle bore allows more air to flow into the intake manifold and heads. The cool thing is that it's fairly inexpensive and takes less than 15 minutes to install. The price per power gained on this unit makes it a no-brainer. We saw some significant gains with this, almost a 20% gain in both average HP and TQ in this test. Not too shabby!
Test 5 – Airaid Air Filter
Max Power: 365tq, 329hp
Average Power: 340tq, 273hp
For those with a sharp eye, you'll notice that this isn't the stock LT intake. Instead this is an air intake from an LS1 Camaro that was very similar to the Ram Air LT1 intake. Try as we did, we could not find a stock LT1 air box to test, we asked friends, neighbors and even the mail man! We even ordered one off of eBay, but it showed up cracked and broken, definitely not usable. Sure, the air flow is different, but this air box was used on all of our tests, so we feel the test was fair as we were only comparing a stock paper air filter versus a performance filter.
The stock paper filter is typically inefficient, as it does not allow air to flow as freely through the element as it could. An engine is basically a glorified air pump. The more air you can shove into the engine, the more power you'll be able to make. So, with that in mind we decided to test a performance style filter that boasted greater airflow over the stock paper filter. We're not quite sure what happened with the Airaid air filter. To be frank, we weren't expecting miracles here, but we were anticipating some small and modest gains going from a stock style paper filter. Our theory is that our exhaust system is the real limiting factor and while we are able to make the engine breath in better, it's really not doing much for us since it can't breathe out.
Test 6 – MAF Housing
Max Power: 365tq, 332hp
Average Power: 338tq, 272hp
Often over looked is the MAF housing itself. The stock MAF is quite constrictive as the main entry point for air that feeds the engine. This version from TPIS increases the size to 3-inches and removes the center divider, which can reduce airflow. The point again is, more air in, the more power we can expect. From our tests, it's not a huge increase, however with high-output motors and boost, this MAF will make a much more significant increase.
Test 7 – Electric Water Pump
Max Power: 380tq, 336hp
Average Power: 345tq, 277hp
We decided to throw in an electric water pump because it has no mechanical drive linkage to the engine. This decreases parasitic loss and allows the engine to generate more torque. Every little bit counts and this addition certainly will prove bigger gains as the build continues. Before you get your under pants in a bunch, we know that $270 feels like a lot for roughly 15 extra pounds-foot and 5 horsepower at peak power, but (again) we know from experience that this addition will make bigger power gains with larger upgrades.
Test 8 – Octane Booster
Max Power: 374tq, 335hp
Average Power: 345tq, 277hp
Ok, calm down and count to ten. We had a bottle of this stuff on the shelf and gave it the ol' college try. We've heard for years that these things are scams in bottle form and at first glance, the rumors might be right. However, think about our combination. It's a strictly stock engine; it really doesn't need any additional octane. If this motor had some big heads, high compression and a wicked cam it would certainly benefit from added octane. But, since our tests had 91-octane to begin with, the added octane was wasted on our motor. So does this stuff work? Yes, it does raise the octane level of your fuel, but is it worth it for this particular motor at this particular time? That's debatable.
We learned a lot of things from these tests. Clearly all of the little tricks will only add up to so much when the motor is still restricted by the factory exhaust, throttle body, intake, heads, and valvetrain. The common wisdom of 10hp from this and 10hp from that equals 20hp, just isn't true. The engine is an air pump, but more than that it is a system of interacting parts – each one affecting the other. When you modify your engine, you should do so with purpose and intent. For example, don't bother upgrading the throttle body and heads if you still have a stock air intake. Don't add octane booster or race gas unless you are running high compression or boost that requires you to pull timing. Knowing that our LT1 still has a few restrictions in it, we'd like to uncork it a bit more to pull out its potential before we start opening it up to see how far we can push a stock cube motor.