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November 2012 Top Tech Questions

You've Got Questions? We've Got Answers!

Text By Diesel Power Staff, Photography by Diesel Power Staff

Welcome to Top Tech Questions. Oftentimes, readers contact us with questions about articles, or to praise us on what a good job we are doing. But our favorite form of reader communication is tech questions. Our Top Tech section is a place where you ask what’s on your mind, and we answer it. Got a trouble code? Wondering how to get your engine to make more power? Send us an email at jason.sands@sorc.com and we’ll do our best to answer it.

Programming Overload
Question: I own an ’11 GMC 2500HD with the 6.6L Duramax and an Allison 1000 transmission. It’s a workhorse with 17,000 miles that I use to pull my 28-foot camper trailer. I would very much like to add a dash-mounted monitor that can also add power, but there are so many to choose from, I am overwhelmed with data. I am also worried about voiding my factory powertrain warranty. I don’t need a huge amount of power, just a little bump, plus some mileage.
Bill Hartsell
-via email

Answer: The diesel market has exploded in the past few years, and yes, there are a whole lot of choices out there. Many choices are tailored to a certain need that a customer might have; but you’ll have to be careful, as not all programmers or analyzers will work with the ’11-and-newer trucks, which will narrow your options. Many programmers are available now with display units, which also saves the end user from having to buy gauges. Bully Dog, Edge, and H&S are companies that offer this type of product.

The warranty end of things is a tricky one. Most people who install tuners or programmers on their vehicles take them back off and use the programmer to turn the truck back to stock before having any warranty work done. Sometimes this works, other times it doesn’t. The best way to handle the warranty situation is to work a deal out with a dealer in the area. If you’re just honest about modifying the truck, most dealers will still cover other warranty issues that aren’t caused by any type of programmer (like worn ball joints). If you decide to try and tow at 80 mph on a 300hp tune and melt your engine, though, that will probably be on you.

If it were us, we’d only add about 60 hp to your existing combination—since you tow so often—and we’d also get a deep transmission pan to help the transmission handle the extra horsepower. As for programmer options, any of the ones mentioned above will work well, and it just depends on whether you want gauges, something in your dash, or the truck to still look completely stock.

Ford Turbo IDI?
Question: I have an ’89 Ford F-250 with the 7.3L IDI engine. I want to install a turbo to get more power, but I am unsure of where to start. This is my first diesel truck, and I want it to look and drive great but also have some power.
Martin Ochoa
Woodburn, Oregon

Answer: Early Ford IDI trucks are vehicles for use around town, off-road, and on the jobsite. They’re good on fuel and good at hauling a load. Two things they’re not super at are making power and towing up long grades—but that doesn’t mean they can’t do it. Problem is, most turbo kits for these trucks (unless you can find them used) are $2,000 to $3000, which is usually more than the owner paid for the truck. If your truck is in pristine condition or is something really unique, the turbo kits from ATS Diesel, Gale Banks, and Hypermax are all great options.

If, on the other hand, the truck is in rough shape, it’s your play toy, or you traded some scrap metal for it—we’d consider building your own turbo system for it. Try flipping the stock manifolds forward, relocating the oil cooler, and mounting the turbos in front of the engine. Stock Mercedes diesel turbos, or those from ’80s Volvo turbos, should get the job done, and they are already wastegated to around 10 psi. Depending on how much you (or your buddies) can weld, we’d expect this type of kit to run about $500 to $1,000.

Also, limiting the truck to less than 15 psi of boost is a good idea. Any more than that, and you’re pushing the stock engine to its limit. With a compression ratio drop, boost pressures as high as 20 to 25 psi can be run, and with an upgraded injection pump, larger injectors, and good tuning, 300 rwhp is possible. Keep in mind, Ford also offered turbocharged IDIs from the factory (using ATS Diesel parts) for ’93 and ’94 models, so often it’s just cheaper to start out with one of those trucks.

’55 Cummins swap
Question: I have a ’55 Chevrolet 210 four-door car I am restoring and modifying. My nephew says we should put a Cummins diesel with an Allison transmission in it. The more I think about it, the more seriously I am considering it. What would we need to modify to put that engine into our ’55 Chevy? I put a ’67 Camaro 10-bolt rearend in it with 3.08 gears. Would that work, or do I need to do a 9-inch Ford with a lower gear ratio? Would I need to beef up the frontend for the added weight? If it seems too much trouble, I’ll just go with a crate 350ci gas engine.
Loyal Tripp
Peyton, Colorado

Answer: No! Don’t go with a boring, old crate engine. We’ll help! An old 5.9L Cummins 12-valve (’89 to ’98) would be the perfect choice to power your Chevy. The ’89 to ’93 engines have a rotary-style VE injection pump and were limited to about 160 hp (flywheel) from the factory. The good news is, they can be pumped up to about 300 hp for free, and with different injectors, an upgraded turbo, and turned-up pump, they can make about 450 hp for a few thousand dollars. The ’94 to ’98 5.9L engines have an inline-style P7100 injection pump and can also make 450 hp for a few thousand dollars. However, if you’re willing to build a drivetrain that can take it, you can continue past that power level and make 800 to 1,000 hp (flywheel) on a fairly limited budget. Either of these engines is very simple to wire; just send power to the starter and the shutoff solenoid, and you’ve got it.

If you do decide to do this type of swap, purchasing a wrecked, rolled, or rusted complete truck is usually your best bet, rather than going parts hunting. Miscellaneous parts—especially if they are from the dealer—can really add up. If you buy a complete rig, you’ll get a transmission, which can also be used.

While we’re a fan of the Allison, you’d need to integrate a computer to run it, which is beyond most enthusiasts. Instead, we’d use whatever transmission came behind your engine. It should be noted that early first-generation Dodges (with non-intercooled 5.9L Cummins engines) used a TF727 three-speed transmission, while later (’91½ to ’93) models came with an overdrive transmission, and ’94 to ’02 models came with a lockup-converter-equipped four-speed unit. If it were us, we’d definitely try and get our hands on an overdrive transmission, and one with a lockup converter if the budget allows.

Acquiring a ’94 or ’95 engine and transmission model is most preferable, since those two years came with a hydraulically activated overdrive transmission, versus later years that have an electronic overdrive that has to be wired in. Whatever transmission you decide to go with, your 3.08 rear gears will hold up fine, provided you don’t put too much strain on the rear axle.

Another thing we’d do (but isn’t mandatory) is an engine setback. The 5.9L Cummins is very heavy compared to a 350ci gas engine. Although it may be tough to cut up a flawless firewall, a very nose-heavy car is detrimental to both handling and straight-line performance. It’ll also keep front suspension modifications to a minimum, as much of the extra weight will be toward the center of the vehicle.

In closing, we’re not saying a Cummins swap would be easy, but the time and effort is worth it, considering you’d have a 500,000-mile engine that would get 30 mpg, make more power than a small-block Chevy, and draw a crowd wherever it went.

By Diesel Power Staff
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