August 2011 Chevy High Performance Q&A

Performance From Around The World

Kevin McClelland Jun 30, 2011 0 Comment(s)
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A: Nitrous is the only answer! Seriously, your stock LS1 is in the 350-370hp range, but more important is the amount of torque your engine makes at or below stall speed. Yes, you have a 4L60E trans with its low First gear, but you have C4 Corvette IRS rear suspension. We’d have to believe that your very nice ’55 street rod build is not the lightest ’55 around. When you stand on the throttle from a stop, we bet your car squats on the IRS and plants the 295-plus rear tires into the ground. We’re not surprised that it doesn’t spin the tires; it accelerates pretty hard from a dead stop, though, doesn’t it?

Now, back to burnout school. Have you tried to power-brake the car to get the engine farther up into the torque curve? (Of course, we don’t condone this type of activity.) With the brake bias correct, all of the brake power goes to the front brakes, with 50 to 60 percent going to the rear brakes. This allows you to hold the brake, press the gas, and spin the rear tires. Again, the IRS is going to squat and transfer more load to the rear tires than a conventional live-axle rear suspension. You may have to try a couple of strategies to break the tires lose. Again, this isn’t something you should be doing on the street; take the car to the track and have a blast in the burnout box.

Notch Away

What is the proper way to notch a ’68 Camaro front subframe for an oil pan clearance? I have front rollcage extensions and use a front motor plate on my 509 big-block Chevy. Thank you,

Gerry Schweg

Exeter, RI

A: Get the oil out! Yes, most of our standard-frame passenger cars are not the best for crankcase windage. Stock-type oil pans are too close to large stroke crankshafts, and the bay-to-bay breathing that must happen within the oil pan is hindered. You’ve all heard that an engine is just a large air pump. Well, the bottoms of those pistons in the crankcase move the same amount of air around in the crankcase. If the oil pan restricts airflow within the crankcase you lose power. Notching the factory subframe on your Camaro will allow you to utilize a racing-style oil pan.

Notching the subframe to fit a larger oil pan is rather straightforward; however, you must have the proper tools and welding skill to pull this off. First, mock up and measure several times before you cut anything. As the old saying goes: measure twice, cut once. Make sure you include adequate clearance for the oil pan and the thickness of the material you are going to plate the openings with. We recommend 0.090-inch cold-rolled steel plate. This material is easy to work with and will be at least as thick as the material you’re removing.

Once you have outlined the material to be removed, you can use a plasma cutter, which will leave you a relatively clean straight line to replate your crossmember, or you could use an oxyacetylene cutting torch. This would make a big mess and put a ton of unwanted heat into the crossmember. After cutting, you will need to clean up the edges with a high-speed grinder and sander to prepare the area for welding. A great tool for cutting out sections of frame is an abrasive cutoff wheel on a high-speed grinder. This cutoff wheel will leave a very clean, straight line with a steady hand. If you don’t have a local source for cutoff wheels, check out MSC Industrial Supply, which carries everything under the sun, including 3M abrasive wheels and mandrels. Try 4x1/16-inch-thick wheels on a high-speed die grinder. After you have notched out your crossmember, install your engine with the new pan. Double-check that you have the clearance you’re looking for, then remove the engine and create cardboard templates for your reinforcement plates.


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