Your Chevelle came with a 180-degree stat from the factory. We didn't see the 195-degree stats until years later with the advent of smog controls. Yes, the engine will have less wear running at a higher temperature, and the engine oil will run cleaner because you burn out the condensation better, but unless the whole package is designed to run at a higher temp, you will see lower performance at a higher operating temperature. With a cast-iron-headed big-block, the higher temperature will lower your knock sensi-tivity. The engine will heat the incoming charge of fuel and air more, decreasing performance. The hotter the charge temp, it's easier to pre-ignite, which isn't a pretty place to be. You will have one cylinder that likes to knock first, creating much higher combustion temperatures, setting off a vicious cycle.
We would drop in a 180 stat and enjoy the days when the temps are lower. Drag racers will bring their engines to the line in the 100-140 temp range to extract the last amount of performance out of those engines. For every 10 degrees of inlet air temp increase, you lose around 1 percent of horsepower. Combine that with the fact that the hotter the engine runs, the less spark advance the engine will tolerate; they run them cool. If they came to the line at, let's say, 190 degrees, I would doubt they would make it a quarter-mile before the engine expired!
TPI BoogieQI have a question on the TPI system on an '87 Camaro with the L98 350. I was thinking of putting in a ZZ383 425hp crate engine from GM; however, I read that the runners choke off the air to the engine around 4,000 rpm. So what can I do to make this work? For example, putting larger runners or larger injectors, or is this TPI system not the right way to go? I really want this car to be a 5-second performer from 0 to 60. Thank you.Kent TatarinVia e-mail
A The original TPI system used from '84 through '92 did exactly what GM wanted it to do, give you gobs of torque and plant you in the seat! And it did, while knocking down some very impressive fuel economy numbers for its day. The horse-power wars had not fully set in back then, and based on the theory that torque moves the car, they had a killer system. As the horsepower wars set in, the engine speeds needed to go up. To support the power bogies the marketing department required, along came the LT1 engine design with its short-runner manifold. Is the TPI a good design for performance? It certainly can be with the correct match of components, and running the engine speed where it gives you the most benefit. There is one company that probably has more time in developing the TPI systems for performance use than anyone else. Myron Cottrell at TPI Specialties married himself to the TPI systems back in 1984 when the Corvette came out with the system. He raced them, won with them, and developed a full line of components to support their performance use.
Yes, in stock form on a 350-cid engine, the TPI intake system will fall off in power over 4,000 rpm. Add 33 more cubic inches to the engine with high-flowing cylinder heads and a performance cam-shaft and that airflow wall comes into play earlier in the rpm range. You can either upgrade your TPI with large-tube runners (PN 500-503), a big mouth base (PN 500-509), a 52mm throttle-body (stock is 48mm), and a modified mass airflow sensor to move the air required for your 383, or step into one of TPI Specialties' Mini Ram manifolds (PN 500-530). The Mini Ram looks very much like a GM LT1 inlet manifold, and some say it's a copy of an LT1; however, Cottrell released the Mini Ram a full year before the LT1 engine was released. The bottom line is that TPI Specialties can support you with all the components and calibration necessary to drop the ZZ383/425 into your '87 Camaro.Source: tpis.com