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 couple of months ago I wrote about our good friend Ian Smith from Australia’s adventure going to the Las Vegas Bracket Nationals with us. I got a phone call from Ian recently. He was right at home at the dragstrip, and even more so watching the McClelland family enjoy all that Las Vegas had to offer. He was also able to spend time with NHRA Division Director Mike Rice to learn the inner workings of one of our large bracket races.

During his visit he noticed that almost everyone that was racing the electronics, or Super Pro, bracket would run their cars wide open, or, if I could be so bold to say, all out! He runs their Beretta on the throttle stop in Super Gas, and they had never run the car wide open. The Beretta started life as a tube-chassis Competition Eliminator car with a blown small-block and a Lenco transmission. One of the strange things for me is that even their race cars are righthand drive. When Ian bought the car, he called Reher Morrison and purchased one of the early crate Super Series 509 big-block Chevys. This engine was one of the first crate Super class engines you could buy and it produced somewhere in the low 800hp range. After the weekend I had talked him into going to one of their local (five hours away) bracket tracks to get more seat time for his son, Warren. Also, he wanted to see what the old Beretta would do wide open.

Another thing Ian took away from his visit was a ton of parts. In the weeks leading up to his visit he ordered parts and had them shipped at the Mac home, saving him quite a few dollars in freight. He packed several bags for the return trip and we filled them right to the weight max limit. With all his new parts home and installed in the car they made the trek to test the car. Not only did he service the car with several new parts, I talked him into adjusting his four-link suspension to get the car to leave more aggressively. Between Friday and Saturday, they got six time runs in, but unfortunately, they were rained out on Sunday for eliminations. Ian was thrilled with a best 60-foot of 1.294, and an eighth-mile time of 5.79 seconds at 120 mph. This should put them right in the high 8.70s at 153 mph. This makes total sense to the car’s performance in Super Gas trim running 149 mph.

It doesn’t matter if you’re in Australia, Santa Pod Raceway in England, or the new Qatar Racing Club, we all love drag racing. Car is a universal language that brings us all together. Until next month, have fun and be safe.

496 Build

1108chp 02 O  August 2011 Chevy High Performance Q A 2/2

Q: I am planning a 496 big-block Chevy build for my ’97 Cavalier Pro Street project, and it will weigh around 3,000 pounds. I totally gutted the Cavalier and installed a Morrison tube frame with a strut front suspension and four-bar rear with a Strange 9-inch. It will have an automatic and run on 93-octane fuel. I have a ’77 454 engine, which is probably a two-bolt main. I plan on using a forged rotating assembly from Scat or Eagle and an Edelbrock Street Tunnel Ram manifold (PN 7115) with dual 4150 series carbs mounted sideways (for its look). It will have a COMP Cams mechanical roller. I plan to race it, but I want to build this as radical as I possibly can for occasional street cruising. After a little research on the head choices, I think the Air Flow Research CNC-ported 0-290 has the best flow across the board compared to others. The other components will match the limitations of what I have chosen so far. A couple of initial questions: Considering the two-bolt main (with ARP premium main bolts or studs) and 93-octane, what would be the compression ratio and max rpm? What do you think about this setup so far? I know more questions will come as this build plan proceeds. Thanks,

Lance Olson

Via email

A: Boy, does this bring back some memories. Around 1983 we were running our ’57 Chevy in Super Gas. We had gone through all the four-bolt 427 blocks we had. Everything was junk and had been run for too many years. We’d heard of folks running two-bolt blocks with good success. They would run main studs and everything was just fine; they weren’t trying to move a 3,000-pound ’57 Chevy at 9.90 seconds at 135 mph. Nothing like trying to push a brick through the wind. Well, only having 440 cid (0.060-over 427) we’d buzz the engine to 8,500 rpm in the lights. Even with taller gears (4.88s versus 5.14s) the little engine just couldn’t pull the weight with the higher gearing. Everything was going just fine until we “drove over the crankshaft” at Orange County Raceway at the 1983 Super Chevy Sunday race in the semifinals! The front main cap pulled right out of the block, breaking the crankshaft right in front of the third main. As you can well imagine, this broke just about everything we owned. Luckily, we were able to get the car stopped safely and race it another day.

Your build would not be as radical as our early 427, but with the quality of components these days, it’s very easy to make power. The main reason we killed the big-block was from the high rpm required to run the e.t.’s. If you can keep the rpm in the 6,500-7,000 range, it will live. But again, building horsepower is way too easy these days. Also, you’ll have 1/4-inch more stroke than we were tossing.

To give you peace of mind, either find a core four-bolt block or have four-bolt caps installed on your current two-bolt case. Milodon offers four-bolt retrofit caps machined from high-strength ductile steel material, which has the proper balance of strength, yet is not too rigid like a billet main cap. The caps come in both straight and angle side bolt configurations. The angle side bolts are much stronger than the standard vertical main bolts. These caps will require a standard line bore and are designed for 0.030 inch of material removed from the main cap mating surface on the block to clean up any existing damage. This is an easy swap, and you should line hone the block anyway to prep for a performance build. The main caps are sold under PN 11200 for the center three mains, and PN 11210 for the front main. While you’re at it, pick up the main studs, PN 81133 for non-windage tray applications, and PN 81134 if you have a tray. This upgrade will strengthen your standard block to allow you to make the power you’re looking for today or in the future.

If you are going to do much street driving, limit your compression ratio to the 9.5:1 range. We’re currently running 10:1 with my 524 in the Super Gas roadster. We pull out of the lanes at 150 degrees, and pulling off the end of the track the temps have climbed to 180 range—all of this with 32 degrees of total spark with no detonation. We’d be concerned with the higher ratios for street driving if you can’t keep the temps under control.

Your selection of components is spot on for your application. The AFR heads will work great as an all-around torque monster. These heads, in conjunction with the long-runner Edelbrock Tunnel Ram manifold will move your Cavalier quite nicely. Enjoy the torque and don’t spin the thing over 7,000 rpm. It’s a waste of time—e.t., that is!

Burnout School

Q: Last year, my ’55 Chevy Bel Air came out of a two-year build, an awesome, beautiful car and fun to drive. It has a stock LS1, 4L60E, an aftermarket frame with C4 Corvette suspension front and rear, and a new GM Performance computer. The car runs great, but it will not spin the tires. Other cars with this engine will burn the tires up. What could be the problem? Any suggestions would be appreciated.

Gerry Kennon

Via email

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.

The final step in this process is welding everything back together. You should use either a wire-feed MIG welder or a TIG welder. Again, you must have the proper skills and equipment to do this properly and have a safe outcome for your modifications. First, tack-weld all of your plates into position. Then weld small sections at a time to prevent putting too much heat in to the base metal. For instance, you could weld across the length of the crossmember, then let the area cool for a period, until the area is just hot to the touch. Then do the vertical welds on each end and let it normalize again. Continue until you’re fully welded.

Hopefully this is what you were looking for. If any of this sounds like it’s beyond the scope of your skills, please look up a chassis or 4x4 shop in your area. The off-road crowd makes serious modifications to their trucks. They can possibly help you out with your fabrications. Good luck.

Source: mscdirect.com

Torque Monster

Q: What do you think about this engine combo? It is a 489-cid big-block with a 4130 steel crank, rods, and Probe pistons with 10:1 compression. The cam is a COMP Cams Xtreme Energy solid that specs out at 244/252 degrees duration at 0.050-inch tappet lift, and has 0.590/0.598-inch max lift on 110 centers. The heads are 781 casting oval ports with 2.19/1.88-inch valves, ported and polished. My intake is a Professional Products Crosswind dual-plane, which has a powerband of 1,500 to 6,500 rpm, and a Pro-Systems 980-cfm double pumper carb. For spark, I’m using an MSD distributor and Procomp box, and Hooker Super Comp headers. To transmit the power I’m running a TH350 trans with a 3,200 stall and 373 rear gears. This powertrain is going into an ’83 Monte Carlo. What do you think it will run in the quarter-mile? Is this a good combination, and should it have good torque and power? Thanks!

Tommy

Via email

A: We think your Monte had better be ready for its new engine. The component package you’ve spec’d out is great and the torque from your little 489 will move your Monte very well. As long as your cylinder heads were prepped, we see no reason you shouldn’t make around 580 hp and over 600 lb-ft of torque. With the oval ports and the dual-plane manifold, the horsepower peak should come in around 6,600 rpm, and torque peak should be in the high 4,000 rpm range.

We hope you’ve added some traction-enhancing components to the chassis and more than street tires on the rear. There is no reason this engine shouldn’t push your Monte into the high 10s—if your chassis can apply the torque to the track. There are many suspension packages on the market to hang the front wheels of your Monte in the air. Have fun with it and be careful.

LS1 Power

Q: I recently had my ’55 Chevy dyno’d at a local shop. My car was incomplete (no glass, front clip, decklid, and interior). It has an LS1 from a ’98 Camaro (I was told) with a six-speed from the same year. The only modification done to the engine was a COMP Cams 63LS 212/218 duration at 0.050-inch lift, valve lift 0.522/0.529 inch, with a separation angle of 114 degrees. The valvesprings are COMP Cams PN 26918. The intake has been changed to an LS6 of the same year. The oil pump is a 99-LS1-OP from Thunder Racing. Custom Jet-Hot–coated headers were installed from Art Morrison and left open for the test. The computer is what was used in 1998 and mapped to look like an LS6. I don’t even know if this is possible. Finally, I have a 9-inch Ford 3.50:1 posi and P275/40ZR18 GY Eagle ZR tires on the rear. At first I was going to use a 4L60E, but I switched to the stick. I assume I won’t be happy with those gears, but I am going to try them at first.

How much power do you think this combination should make? The shop, using a PowerDyne Mustang dynamometer, came up with these numbers: 381.2 hp at 5,265 rpm/109.9 mph in Fourth gear or 400 with WCF (whatever this means), and 398.6 torque at 4,746 rpm/98.8 mph and 418.2 with WCF at the rear wheels.

Based on this info, do you think it is possible to make this much horsepower? The shop owner is the nicest guy in the world and very honest and reasonable, but I find this a little hard to believe. He said these LS motors always make more power than they are rated. What gears would you recommend? I am near retirement and plan on touring with the ’55, and therefore want the best mileage I can squeeze out of her.

Love your magazine and look forward to it each month. I would greatly appreciate your thoughts.

David Schrumpf

St. Louis, MO

A: The topic of engine power derived from chassis dynos is a subject that is constantly being challenged. Our sister publication Hot Rod had a great article in their Mar. ’11 issue. They took at “Ford Product” to five different reputable chassis dyno shops around the Southern California area in one day. They tested the car on a Mustang, DynoJet, Superflow chassis dynos, and Dynapack axle-mounted brake system, and the procedures varied from shop to shop. The recorded output varied around 100 hp among the five different shops. Testing procedures, equipment used (dyno brand, cooling fans), and exhaust ventilation varies at each facility, all reasons for wildly varying power numbers from the same car on the same day. As you shouldn’t race dynos and flow benches, use them both as tuning tools unto themselves. If you stick to this you will be very happy with the outcome.

The correction factor is used by a dyno to correct the power numbers for atmospheric weather conditions. We believe the “WCF” the dyno operator is referring to is Weather Correction Factor. All dynos will give you “observed” power and torque numbers from a dyno run. The correction factor is to adjust the data to standard weather conditions. The Society of Automotive Engineers (SAE) has adopted several correction factors. The most widely used correction factor used in the performance aftermarket is the SAE Standard, which adjusts all power numbers based on these atmospheric conditions: 29.92 in-hg, 60 degrees F, and dry (zero humidity) air. The next would be what is called the SAE J1349 correction factor, which all of the OEM auto manufacturers have used since 1971. This correction factor uses 29.234 in-hg, 77 degrees F, and 0 percent humidity. Using the SAE J1349 correction factor alone will adjust the power number around 5 percent lower than if you used the SAE Standard correction factor. This is another reason not to race dynos unless you are sure how the data was corrected from shop to shop.

As for the power you saw on your dyno adventure, we’d speculate that they are slightly higher than we would expect from your listed modifications. The LS engines are very powerful and respond well to minor bolt-ons. With open headers and the components you listed, we would expect to see around 425-430 hp from your engine. If you assume that you will lose around 15 percent from parasitic and driveline losses, that’s around 365 hp at the tires. Since you saw 381 hp on your dyno test we’d be pretty happy. Again, from the listed dyno tests that Hot Rod did you could see the larger variances that you have.

The 3.50 rear gear should work very well with your T56 six-speed transmission. With the overdrive in Sixth and your tires, the cruising rpm should be around 2,200-2,300 at 75 mph. This will put your engine right in its sweet spot to knock down some decent mileage. You can expect low 20 mpg with your brick of a shoebox. Don’t worry about the power numbers, and finish your toy. CHP

Source: hotrod.com

Technical questions for Kevin McClelland can be sent to him at chevyhi@sorc.com.

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