My Truck's a Slug
First off, great mag! I have been a faithful reader for some time now, but let's get down to business. I have a 1997 Chevy Silverado with a pathetic excuse for an engine, a 305ci V-8. My pickup struggles to go 60 mph up nearly any hill with 3.42 gears and 32-inch-tall tires. Worst of all, I live in Nodak and it's not exactly flat country. I am looking to rebuild the 305 with all the fun goodies like new heads, intake, flat-top pistons, cam, throttle-body spacer, and an air intake, plus anything else that could make my motor worthy. Or I am considering switching to a 350ci V-8 and building that the same way.
My question is if this was your truck how you would do it? I'm lost trying to figure out the best way to pull more power out of the motor. I would prefer to use what the truck already has and just build the stock 305 into a killing machine, but I also hate to waste the money doing that if I will not gain that much anyways. This is my project/daily driver, but I intend to put a 6-inch lift and 35-inch tires on it and have 3.73 gears as well. I just want a decent powerplant under the hood before I even start on any of that. I do not know much about engines when it comes to performance. I'm a mini-trucker at heart, but it's hard to drive a Mazda that's 2 inches off the ground in 12 inches of snow, so I put my mini aside for awhile and now am focused on my Chevy. Any help at all would be great. Thanks!
Tim C.
via email
You bring up a number of questions that are often overlooked when beginning to "pump up" your truck. It doesn't surprise me that your truck feels a bit anemic given your present tire size, gear ratio, and engine combination. By changing your tire diameter to 32 inches from the stock 29 inches, you have effectively changed your rear gear ratio to a 3.10. Combined with the 30 percent overdrive of the 4L60E trans, you are only turning the engine about 1,750 RPM at 70 mph, which is hardly ideal for power or mileage in a 4,000-plus pound truck.
In 1997, Chevrolet offered the C-series trucks with a 3.73 rear gear, which is a better all around combination for hauling, towing, and adverse terrain in my opinion. You mentioned changing to 35s in the future. A 4.56 rear axle ratio with a 35-inch tire would net the same final drive ratio as the 29-inch stock tire diameter and a 3.73 rear gear and would cruise 70 mph at a comfortable 2,150 RPM. This will drastically improving acceleration and driveability.
Now, onto the muscle part of your question. There are multiple choices for your engine package, including everything from stock replacement crate engines to turbocharged big-inch strokers. As usual, the extreme end of the spectrum costs bundles of money and presents many challenges. In almost every case, a daily driver deserves some upgrade, but not to the extreme, unless you're prepared to deal with the headaches that typically go along with it. For my money, I want good driveability, good power, and to be reasonably trouble-free. In the case of a 4,000-plus pound truck, bigger is better (especially when starting with the 305). GM currently offers the HT383E replacement long block (part # 17800393), which retails for $6,378.00 (our local GM parts manager indicated almost every dealer has sale pricing) and is emissions-legal. While advertised as a 383ci, high-torque, direct replacement for the 350ci, it would most likely require some custom tuning You will have to address the computer tuning issue with any upgrade, which should include engine tuning, transmission shift points and pressure, as well as speedo calibration to optimize your new drivetrain package.
After the tuning, you'll have an engine that makes much more torque down low in the rpm band, which means your truck will turn those big tires and climb those hills much easier. You may be able to save some bucks with other crate packages or your local engine builder. Whatever choice you make, do your homework, be clear on what you expect, and what someone is selling, consider local emission laws, and then dive in.
This question was answered by Steve Brule', General Manager and Director of Technical Service's at Westech Performance Group in Mira Loma, California. Steve's been a professional in the performance industry for over 30 years and has a wealth of knowledge when it comes to engines and trucks. You may recognize the name from the numerous dyno tests conducted at Westech.