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.
Hot-Rodded Common-Rail
Question: I have an ’06 Cummins- powered Dodge that I would like to modify to make about 550 hp. I’m looking into buying a Smarty programmer, and I know I’ll also need a turbocharger, but I don’t know which one to buy. I only tow once in a blue moon, so I’m mostly just going to use the truck to hot-rod around town.
Kevin Giddens
–Via email
| If you own a 6.7L Cummins and not a 5.9L—not to worry, plenty of hop-ups are available for the newer 6.7L versions also. Aron Nick’s hot rod is a good example of how a built 6.7L can make plenty of power. How about 771 rwhp and 10-second quarter-mile passes on a 66mm turbocharger?
Answer: To get a good handle on the quickest and easiest way to make your power goals (550 hp at the wheels), we contacted Brown’s Diesel in Riverdale, California (www.brownsdiesel.com). Brown’s is used to building common-rail Dodges ranging in power from 400 hp all the way to 1,100 hp, so it knows what combination of parts it takes to achieve a given power level.
Since you’re looking for more of a hot rod than anything else, we’ll give you the bare minimum it would take to make the type of power level you’re looking for. Then we’ll give some suggestions as far as making your truck more reliable at that power level.
The Smarty programmer is a good choice, but you’ll need a little more help in the fueling department to reach your goals. Brown’s suggested a set of 75hp or 90hp injectors would get the job done without making the truck too undriveable (smoky). Other than the injectors, a 62mm-diameter-inducer S300-based turbocharger will get the job done and spool very quick—although the exhaust gas temperature will get pretty toasty.
If you’re looking to play it cooler on the EGT side and bump up the power even more, a 64mm turbocharger, a hot rod CP3 kit (such as the Arson kit from Wicked Diesel, or the Bag O’ Parts from Industrial Injection), and a lift pump will make sure your truck isn’t starving for fuel or dropping rail pressure once you’re into the throttle for more than a few seconds. If it were us, we would start out with the more conservative approach and go with the smaller turbo. Then if you decide to go big, we’d install twin CP3 injection pumps and an 80mm S400 under the 62mm turbo. Whichever route you take, you’re in for one fast ride.
Clutch Fan Conundrum
Question: I’ve wanted to install electric fans on my ’04 Dodge for a long time, and in your October ’11 issue I finally saw an article on them. The problem is, when I contacted Summit and Flex-a-Lite, both companies said these fans are not for use on trucks with electronically controlled fan clutches. Is there some sort of solution to this that wasn’t mentioned in the magazine? I’m curious about how to solve this problem before I go buy a set of electric fans.
Levi Foss
Ashland, Ohio
| Electric fans are proven to gain about 1 to 3 mpg while driving, so on-road warriors who put lots of miles on their truck will like them. Electric fans deliver about 5,500 cfm, compared to a typical mechanical fan’s capability to pull approximately twice as much. For example, Ford’s new 6.7L Power Stroke has a mechanical fan that moves 9,300 cfm to allow the truck to tow at its maximum GCWR up steep grades—even in the desert. So the more you tow, the more you should lean toward keeping the stock fan.
Answer: It is in fact possible to install electric fans on an electronically controlled fan- clutch-equipped Dodge with the Cummins engine, and there’s good and bad about this. The bad is the truck will throw a code when the electric fans are installed because it thinks the stock fan clutch is malfunctioning. There is good news, however, because this code doesn’t reduce engine power in any way. If you’re not willing to live with a check engine light that’s on all the time, we’re told that in the near future users might be able to disable simple check engine functions such as these with EFILive, which has just been released for the Cummins engine. So in your case, we’d buy the fans if check engine lights don’t bother you; otherwise, we’d keep close track of the EFILive software and keep our ears open for when code disable software is released for non-power derating codes.
Give me a Line
Question: I was looking at doing a 5.9L Cummins 12-valve swap into a Suburban and was wondering if you could tell me which type of tank, fuel line, filters, and pump I need to convert from gasoline to diesel fuel.
Ken Dennity
Los Angeles, California
| Editor David Kennedy has a Cummins-powered ’91 Suburban project he’s begun on page 138 of this issue. We’ll have all his trials and tribulations in upcoming issues for all you conversion-lovers out there.
Answer: When we think of conversions— especially Cummins converions—the first place we think of is Auto World in Great Falls, Montana (www.autoworldmt.com). Owner Ken Kraus has been doing 12-valve and 24-valve conversions for more than 20 years, and diesel conversions since 1972. Ken told us the gasoline tank is OK to use as long as it’s in good shape and not rusted out or filled with junk. It should be drained completely and left open for a day or so to let every last bit of gasoline evaporate. As for the fuel lines, the stock lines can be maintained, and filters can be adapted, but in reality it is a lot cheaper and easier to buy a complete kit from FASS or AirDog. For about $600, you’ll get a pump, 2-micron filters (which are needed for diesel use), a water separator, and lines. If you want to get really fancy, you can also buy a fuel sump from Hellmann Performance (www.hellmannperformance.com) to avoid suction problems at low fuel levels. In summation, yes you could probably cobble something together with junkyard truck filters and stock lines, but unless you’re on a nickel-and-dime budget, you’re probably better off going with a full aftermarket system. It’ll also give you a lot more room to grow.
