1 - Gauges!

Like a doctor does when you first come into the hospital, you need to know your trucks vital signs. A good, quality set of gauges should be the very first item that you purchase on ANY diesel truck.

Ask yourself this. Would I rather spend a few hundred dollars on preventive measures or $10K+ on a new engine or $4K+ on a new transmission?

So what gauges do we really need? Well, that depends on the year and options on YOUR truck. At a bare minimum, EVERY diesel owner needs to be able to monitor Boost and EGT. These are common to all turbo diesel engines.

In addition to Boost and EGT, there are several other gauges that you will want one or more of. Depending on the year and your transmission will determine your next choices.

For the owner of an automatic transmission, the third gauge in your package should be tranny temp. Whether your truck is a daily driver, tow rig or a full blow race truck, knowing if you are frying that expensive automatic transmission is critical.

For owners of 1998.5 - 2002 VP44 fueled 24V Cummins, the next most critical gauge for you is Fuel Pressure. One of the most common failures in this series of Cummins is caused by lack of fuel pressure to your $1K+ VP44 injection pump. Knowing when your relatively inexpensive lift pump (which is the root cause of the failure) is giving up is CRITICAL to avoiding this problem. Seeing less than 7 psi of fuel pressure to your VP44 means shortening it's life span.

For owners of 2003 and up 5.9L and 6.7L CP3 fueled, common rail Cummins, the next gauge for you is Rail Pressure. Above anything else, your rail pressure can be THE single biggest indicator of your CR Cummins performance. You should be seeing approx 6800 psi at idle and up to 20,000 psi under a load. Less than these numbers, especially at idle, can indicate a fuel injection problem that could leave you stranded. Your OEM fuel rail is equipped with a relief valve that opens at approx 24,200 psi. If this relief valve blows, it will leave your truck dead in the water. Some of the aftermarket performance modules and programmers can significantly raise the rail pressure and need to be monitored.

These are the bare minimums. Gauges above and beyond those noted above are not necessary on your average street driven truck.

2 - Intake!

Quite simply, the stock air intake on your truck just doesn't cut it. For a fleet of trucks that are going from job site to job site and needs to have a commonly available part to ease maintenance and reduce costs, it works okay. But as far as performance and allowing your turbo to work at it's maximum potential, it just doesn't make the grade.

Now, let's be honest. Air intake systems DO NOT increase horsepower or torque. They simply free up a restriction that exists with your OEM intake system and allow your engine to breath easier, thus allowing it to make closer to it's true potential.

Your stock intake is designed to do several things, last of which is provide good performance. It is designed to be cheap, easily serviceable, reduce intake noise and filter effectively. Meeting those goals has a cost.....your trucks performance! To increase the performance AND help your turbo work more efficiently, we need to let it get more air. This is where the aftermarket air intakes come in. They allow more air flow, provide less restriction, reduce intake turbulence to the turbo and, in turn, help it to lower your exhaust gas temperatures (EGT's).

For the record, Doghouse Diesel Performance DOES NOT recommend one of the very popular brands of oiled filters that are commonly seen in most auto parts stores. They simply allow too much excess dust and debris to pass through and effect your turbo and engine.

The two filter manufacturers that have proven both very effective and very popular are AFE and S&B.

3 - Exhaust!

Like your OEM intake, your stock exhaust is designed meet OEM noise requirements, provide for "adequate" removal of spent gases and, as is the case of 2004.5 and higher 5.9 and 6.7 liter Cummins, meet emissions.

Getting rid of the backpressure and increasing flow is what we are looking for in a good exhaust system.

Now the 3.5" and 4" exhaust systems that come on most of our trucks is not necessarily bad; the worst part is the muffler. This is THE single most restrictive piece in your exhaust system and replacement of this one piece alone will yield you the best bang for the buck. There are many folks that like to remove the catalytic converter as well. This is actually not necessary and is also illegal under federal emissions laws. The benefits of removing the catalytic converter are negligible on the average truck with a stock turbo, as it is actually a very free flowing design. It also help control some of the drone that many Cummins owners have experienced with free flowing systems.

There are advantages and disadvantages to removing the muffler, and /or installing a 4" (or larger) free flowing or straight pipe exhaust system. The main concern we have is expelling the spent gases efficiently. The average 5.9L Cummins exhaust flow can range from 1435 CFM to over 2871 CFM at wide open throttle depending on boost pressures, RPM and exhaust gas temperature. A 4" straight pipe exhaust can flow approx 2200 CFM of air and not exceed 3" hg of back pressure, which is the maximum you want in a turbo diesel application. But, add in the stock muffler and the back pressure rises significantly and severely limits your engines ability to get rid of the spent gases. In the case of most 3rd Gen (2003 - 2009 Cummins) this can lower the exhausts maximum flow to approx 1700 CFM and not increase back pressure. This causes excess heat and hurts your turbos ability to make boost.

Now there are disadvantages to an open exhaust as well and the married folks can understand this better than anyone......noise. While we all want our trucks to sound mean and aggressive, you need to keep in mind that what sounds great driving around town, can become annoying on a long highway drive.....especially with a significant other or "in-law" riding with you. Those stacks look great, but be prepared for some of the consequences. The drone that is often associated with these type of exhaust should also be a consideration in which one you choose.

Where to from here?.......

So, we can see what's going with our engine and transmission, we helped out engine breath easier, we helped it evacuate the spent gasses better, so now we're ready to start adding power, right?

Wrong!

Transmissions and clutches:

Before we start throwing a bunch of HP and torque to the ground, we need to GET it to the ground, so keep this in mind. Your stock automatic 47 or 48 series transmission can only handle about 40 HP over stock before the OEM torque converter starts to slip. This generates heat and shortens your transmissions life. Not only that, but if you have added performance modules, programmers, big injectors, etc., you aren't putting the power to the ground due to this slippage. All your extra HP and torque is doing is generating heat as your TC and clutch packs slip under the increased power.

The stock TC has limits of approx 360 HP and 700 lb/ft of torque. Beyond this, it simple cannot cope with the power. Most aftermarket TC's are rated for over twice, and up to nearly triple, this power level. For torque converters and valve bodies, Doghouse Diesel Performance recommends SunCoast Converters and Goerend Transmission.

Now you manual guys aren't much better off. Start exceeding 60 - 90 extra HP and your OEM clutch is gonna give way also. The good thing you have going for you is that, for the most part, the manual transmissions in our trucks are pretty bullet proof, other than the clutch.

The stock clutch behind your Cummins has limits of approx 400 HP and 800 lb/ft ot torque. Some of the aftermarket clutches available are rated for up to 2000 lbs of torque. Picking the right one for you is critical, as some of them can be very grabby and require excessive pedal pressure to disengage the clutch. Picking the right clutch will make your driving experience much more enjoyable. South Bend and Valair and two good manufacturers to look at when considering a clutch upgrade.

So what do we need to do?

Automatic transmission owners, you have a little work cut out for you. You need a MINIMUM of three things here. A good triple disk torque converter, a good valve body and if you intend to tow heavy or occasionally drag race, a billet input shaft. These three items will help keep a good majority of your transmission woes at bay.

Manual transmission owners, you have it a little easier. You can get away with a new clutch (possibly a flywheel for some applications), a billet input shaft and possibly upgraded hydraulics. With those three items, you're getting ready to handle some power.

NOW we can start adding some power. This comes in all sorts of forms; mechanical, electrical and even chemical. What your intend to use your truck for is gonna be the main decision maker here. Give us a call and we'll help you make a good decision for where you see yourself taking your truck in the future.

Turbochargers and intercoolers:

Your stock turbocharger, when applied to a stock Cummins engine is very good. But, like other stock components, it has its limitations. It is really only efficient up to approx 32 psi of boost. This works fine under MOST stock conditions as, depending on model year of your Cummins, it’s wastegated at approx 18 - 26 psi of max boost. Beyond 32 psi, all it’s really doing is heating up the air due to it being outside the efficiency map of the compressor. Upgrading your turbo is one of THE best ways to control EGT’s and GREATLY improve the performance of your engine.

Now, with the understanding that you want to try and keep your engine operating at a maximum SUSTAINED exhaust temperature of 1250* or less and the fact that you can effectively cool your exhaust temps by approx 10* for every pound of boost, you can see where an aftermarket turbocharger comes into play. Some of the aftermarket turbochargers that are of the same size as your OEM turbo are efficient at ranges up to 60 psi and have much higher lbs/min ratings than your stock turbo.

Bigger is not always better when it comes to upgrading your turbo. A very large turbo will certainly help keep EGT’s down, but the lag and lack of response at low RPM’s can make it perform poorly in day to day driving. Picking the right size turbo for the power range that you are looking for is very important to getting good power, response AND good drivability. Go too big and you’ll have a hard time getting it spooled. Go too small and you won’t be able to effectively control EGT’s.

Below are some recommended turbo sizes for desired power capabilities. For a daily driven truck that doesn’t tow often, look at the lower numbers in the range. For trucks that tow often, look in the middle of the range. If you use your truck as weekend warrior / occasional drag racer or sled puller, look at the high side of the ranges.

Up to 300 HP, the stock turbo is fine, but upgrading to a 57mm will help greatly.

400 HP, look at 57 – 62mm’s

500 HP, look at 60 – 64mm’s

600 HP, look at 64 – 66mm’s (This is where we start to recommend compounds on daily driven or towing applications)

700 HP, look at 66 – 71mm’s (compounds are recommended)

800 HP, look at 74 - 80mm’s (compounds are recommended)

Over these HP ranges, you're looking at applications that are highly customized.

Aside from your turbo, your intercooler is the next item that helps keep the EGT's in check. Like everything else we've discussed so far, it has it's limits. The intercoolers on some of the 3rd Gen trucks (03 - 05 models) are most in need of an intercooler upgrade. The end tanks on these intercooler are plastic and prone to failure as boost pressures increase.

Larger intercoolers, with higher fin counts, wider and deeper cores, larger end tanks, larger inlets and outlets and heavy duty aluminum construction can help lower your intake charge as it comes out of your turbo by as much as 300*. This can translate into a 150* drop in EGT's.

Intercoolers are a very easy swap and can be done in less than an hour.

In order to provide enough fuel to get these turbos spinning, we’ll look at fuel system and injector upgrades next.

Fuel systems:

With upgraded power comes higher fuel demands. If you start exceeding 100 - 120 HP over stock, you are probably exceeding the capabilities of your OEM lift pump. This is a critical piece for you VP44 guys, less so for CP3 owners. Both of these pumps are cooled and lubricated by the fuel, so you can see why a lack of pressure or volume can be extremely detrimental to it's longevity. A good fuel pump (AirDog or Raptor) will go a long way in keeping those big injectors and hot tunes fed and your EXPENSIVE injection pump happy.

Dodge addressed one of the problems with the lift pump when they moved it from the engine mounted pump to the in-tank pump that is currently used. The in-tank pump is much less likely to fail then the engine mounted pump was, but it still falls short when you start demanding greater than stock fuel flow.

For stock and lightly modified applications, an AirDog or Raptor 100 are a good choice to help increase fuel flow, remove air from the fuel and provide increased filtration. These pumps are available with 2 micron fuel filters, which greatly exceeds the required 7 micron rating that the factory filter uses.

For higher HP applications or if you think you'll do more upgrades in the future, we suggest going with an AirDog 165 or Raptor 150. Both of these pumps are capable of supporting all but the highest fuel demands, offer increased filtration, air removal and have life time warranties on the pumps. Filters are widely available and have a much longer service life than the OEM filters. These 150+ GPH pumps both provide approx 17 psi of pressure for your VP44 and CP3 powered trucks, which is perfect to keep them supplied and lubricated.

Injectors and Injection Pumps:

Now that we've upgraded our fuel system, we can address the injection of that fuel. This is where our injection pump comes into play.

The VP44 (98.5 - 02) and CP3 (03+) pumps take the low pressure (17 psi) fuel from your lift pump (hopefully a FASS or AirDog by now) and turn it into the high pressure (up to 23,000 psi) fuel that is needed for efficient combustion in your engine. These pumps differ slightly in operation.

The older VP44 controls everything to do with the injection. It does the injection timing, duration and creates the pressure. All of this is done based on the demands from the ECM.

The CP3 has an easier job. All it is responsible for is creating pressure. The injection timing and duration of the injection pulse is controlled electronically by the computer by way of signals sent to the individual injectors.

There are several options for upgrading your injection pump. These range from a bag of parts to highly modified single pumps to dual pumps for high HP applications.

Lets talk about injectors...

Your injectors are the final critical piece in your injection system. They need to matched correctly for not only the application that you have intended, but also to the turbo you intend to use. Small injectors and large turbos equal poor power and lots of turbo lag. Large injectors and small turbos equal lots of smoke and extremely high EGT's. Getting the correct mix is critical.

Injectors range in size from 25HP to 200HP from most of the major manufacturers. Custom sizes are available and can be created by most of them.

So how do we know we are getting the most power but not overloading our turbo? Look at your exhaust when you are at wide open throttle. If there is no smoke at all, you can go with bigger injectors. If you are pouring out black smoke, you don't have enough turbo. If you can get to where you have just a barely visible haze at WOT, you are getting all the power that your setup can produce. Remember, lots of black smoke it just HP going out the tail pipe.

For the average daily driven truck that runs a stock turbo, you can get away with running up to 25HP to 50HP larger injectors, as long as you don't tow heavy (i.e. 10K lbs or more). For a little more power with a slightly larger turbo, you can look at 75 - 90 HP injectors. For bracket racers or occasion sled pullers that are using 62 - 64mm turbos, 100 - 120 HP injectors work well. For higher HP trucks with large singles or compound turbos that don't tow often (and when they do it's less than 10K lbs), 150+ HP injectors are the ticket.

Other mechanical upgrades to consider:

After this, we suggest you look at some mechanical upgrades. Two things to look at here; valve springs and head studs. There are some options on these and we can help you decide if you need them or not. A good rule of thumb is that if you are making more than 48 psi of boost, you need head studs and heavier valve springs.

The stock head bolts can be replaced with much stronger studs. These studs will allow you to get your engine up into the 60+ psi range without worrying about head gasket failure. If you are upgrading to a bigger turbo, these should also be purchased at the same time.

Along with the head bolts, your stock valve springs need to be replaced as your boost levels increase. The stock springs only have approximately 60 lbs of seat pressure, so as you approach this in boost pressure you can slow down how quickly the valves react. Once you get to around 52 psi, you can actually blow the valves open and this can cause valve / piston contact resulting in MAJOR damage. Upgrading to a stiffer set of valve springs will not only allow you to run more boost, but also allow you to exceed the factory RPM limit of 3200 and push your engine up to 4000 RPM's without worry of engine damage.

From here, we can have some fun. So if you want to take your truck a little further, give us a call so we can discuss some plans and get you on the right path so you're only buying parts once.

Remember, BUY THE PART YOU WANT THE FIRST TIME! Otherwise, you'll just spend more to get it later.