| 2005 Gmc Sierra Duramax smokin
Perhaps the most common question we get in the diesel industry is, "What can I do next?" Most people are daring enough to buy a programmer and maybe make a few other modifications, but then they stop and leave the full race stuff like cams and ported heads to the really hard-core drag racers and sled pullers. We knew there had to be a middle ground, so we set off to find out just how fast you can go with bolt-on parts.
While we were out looking for a truck that would satisfy our needs, one found us. At the '07 DHRA Vegas Nationals, the winner of the 12.0 class was Joe Komaromi from Pacific Performance Engineering (PPE), and he did it with all bolt-on parts. It seemed like exactly what we were looking for, so we got Komaromi to give us the inside scoop on what makes the white monster tick.
| Joe Komaromi is loading PPE's level 6 programming into his truck. One of the best things about new diesels is that you can adjust power up or down based on your driving needs.
Step One: The BasicsMany of you may have already completed step one, which includes gauges, an exhaust, and a programmer. A lift pump can also keep the injection pump supplied with plenty of fuel, so that's not a bad idea. But be warned-even a programmer can roast a stock Allison transmission on the highest settings. The PPE Hot + 2 Xcelerator has settings for an extra 40 hp (at the crank) all the way up to 350 hp, so if you run the higher settings, your transmission may be on its way out. Komaromi recommends no more than PPE's 160hp Stage 3 tune-about 100 rear-wheel horsepower (rwhp)-with a stock transmission. It's a bummer to pay a lot of dough up front, but a performance transmission is the next step you have to take before you can add more horsepower.
Step Two: TransmissionKeeping in mind our lofty goal of 650 rwhp, a simple torque-converter swap isn't going to cut it. For his truck, Komaromi uses a Stage V transmission kit, which includes a new converter, a valvebody kit, a power valve, and upgraded clutches. The kit retails for approximately $4,100, plus the labor to install the parts, but at such a high power level, there is no way around the expense. What you'll get for your money, though, is a transmission that will live through almost any upgrade you can throw at it. Better to do it once and get it over with than to have to take the Allison apart every time you want to add more power.
| With a serious programmer, your transmission will be living on borrowed time. Despite the expense, upgrading the transmission as power increases isn't optional, it's mandatory.
Step Three: Turbocharger UpgradeWith a programmer cranked up to its highest level and a transmission that can handle the power, your truck should now be at the 450-rwhp level. The stock Duramax turbo can only spin enough air to support about 500 rwhp, so a turbo upgrade is next on the to-do list. On his truck, Komaromi uses a Garrett GT4094R turbo, which flows enough air for almost 700 hp at the wheels.
Step Four: Dual FuelerAir and fuel are still related, even in a diesel, so with more air from an upgraded turbo, more fuel can be added. For this, Komaromi uses a dual-fueler kit, which adds a second CP3 injection pump on the top driver side of the engine. The second CP3 helps the engine keep its rail pressure up and ensures the engine will get all the fuel it needs with the addition of the turbocharger. Komaromi also uses his Duramaximizer on this step, which increases rail pressure so the thirsty CP3s, turbo, and programmer can work as one big, happy family.
The Results: 641 Rwhp!The results of combining all the proper parts speak for themselves. While the truck didn't make 650 rwhp as we had hoped, we'll let Komaromi off the hook because it made 641 hp and 1,146 lb-ft of torque on the chassis dyno, and 99 percent of our goal is good enough for us. Not only that, but on regular street tires, the truck ran an astounding 11.83 at 115 mph in the quarter-mile at a race weight of about 6,700 pounds. The estimated cost of all the parts you would need to replicate this truck is about $13,000, which may seem like a lot until you realize that amount of money will get you a truck that reliably makes more than 800 hp at the flywheel, gets good fuel mileage, tows whatever you want, and is off-road capable. What vehicle other than a hopped-up diesel truck can do that?
| 2005 Gmc Sierra Duramax autoclub Dragway
Diesel Vs. SupercarsTo give you an idea of what kind of performance bracket a truck will put you into, we compared Komaromi's '06 LBZ truck with some of Europe's finest. We tracked down a list of new '06 vehicle prices, then added $13,000 to a basic-optioned '06 GMC 2500HD to arrive at our hot-rodded diesel price figure. All we could find were crank horsepower numbers, so all power ratings are at the engine, not at the wheels.
VEHICLE
PRICE HORSEPOWER `0-60 MPH
QUARTER-MILE ’06 LBZ Duramax with upgrades $56,000 800 hp 3.3 seconds 11.8 at 115 mph ’06 {{{Ferrari F430}}} $202,000 483 hp 3.5 seconds 11.7 at 120 mph ’06 {{{Lamborghini Gallardo}}} ${{{200}}},000 520 hp 4.1 seconds 12.1 at 117 mph ’06 {{{Porsche 911}}} Turbo $125,000 480 hp 3.6 seconds 11.9 at 118 mph As you can see, the modified diesel truck hangs with all of them in terms of performance while costing half of what the Porsche does and a quarter of the Ferrari and Lamborghini prices. In addition, the diesel has more seating capacity, gets better fuel economy, has a bed to carry things in, and can tow more than 10,000 pounds. Try that in a Ferrari. Still want an exotic car? We don't.
| With a new turbo in place, more fuel can be added and the rail pressure can be turned up. Komaromi uses a second CP3 along with his Duramaximizer to give him all the fuel he can handle.
Driving ImpressionsNow that we've showed you the steps to build an 11-second Duramax, you probably want to know how it drives, right? Well, Komaromi was nice enough to let us take his '06 LBZ for a spin around the block.
Our first impression as we puttered around was that the truck still felt pretty stock under normal driving, even with the programmer on level 6. Once we rolled into the throttle, it felt pretty fast, but not as fast as we might have hoped. What was funny is that we could look in the rearview mirror and see two black marks whenever we laid into the throttle-in two-wheel drive, all our forward momentum was just going up in tire smoke. We tried accelerating from 30, 40, and finally, 50 mph, but the vehicle would still break the tires loose as soon as the boost came in. As silly as it seemed, we pulled over and put the truck in 4WD because we realized we needed all four wheels to grab at anything under freeway speed-the truck is that fast.
With all four wheels doing their job, the acceleration was intense. The truck would launch hard, and by the time we would get a second to look down at the speedometer, we would already be going 50 mph within a few hundred feet of where we started. As long as we eased into the throttle instead of flooring it, smoke really wasn't that bad, and the big turbo cleaned things up to just a light haze. The real surprise was the lack of turbo lag. Once rolling, the larger turbo felt just as responsive as a stock unit. We were very impressed with the overall package, and we honestly believe someone could drive a truck at this power level on a daily basis.
