lipe1 -- Howdy and Welcome to TheDieselStop!
Only two things are required for power enhancement on the 7.3L Power Stroke: more fuel and more air.
But, as they say, the devil's in the details. HOW you go about adding fuel and air, and the support modifications required, ultimately determine the level of power enhancement. Of course, how much money you're willing to spend also is a factor.
A good power enhancement plan should start with gauges to give you a baseline on the vitals of your powertrain and also help guide you through additional upgrades. The pyrometer measures exhasut gas temperature and should be mounted pre-turbo (generally in the driver side exhaust manifold) to measure exhaust gas temperature. Anything more than 1300° for extended periods of time is bad. The boost gauge measures, well, boost pressure. About 25-35 psi of boost is about all the stock turbo can handle. Boost pressures higher than about 40 cause the head gaskets to pop. As you approach higher levels of exhasut gas temperature and boost pressure, it's time to upgrade! Finally, if you have an automatic transmission, a transmission temperature gauge to monitor the transmission fluid temperature. Heat kills a transmission and as temperatures get higher, additional cooling is required.
The next step involves getting more air in, and out, of the engine. It's time to upgrade the intake and the exhaust! An open element filter replaces the stock air filter assembly with an big paper filter allowing more, clean air into the engine. Replacing the exhaust from the turbocharger back eliminates the extremely restrictive factory downpipe. Modificaiton of the passengerside firewall is required to fit a downpipe. A 3" diameter downpipe and a 4" diameter exhaust are the "standard" exhaust upgrades. Replacing the exhaust will also require replacement of the muffler and most exhaust kits include a new muffler.
A high-pressure oil crossover hose ties the high pressure oil rails in the cylinder heads together to eliminate 'pulsing' and helps provide a more even flow of high pressure oil between the cylinder heads.
Now it's time for more fuel. That calls for a chip or programmer. There are any number of companies selling chips and programmers. My recommendation is a reprogrammable adjustable chip. For example, I have a 4-position chip with tow, economy, daily driver power, and more power settings. If I make any additional modifications to the engine, the chip can be reprogrammed to accomodate those modifications. The majority of the programmers are a one-size-fits-all type of product and would be good for a relatively stock truck.
Now you're at an impass. You've done all the standard "cheap" modifications. The wife or significant other is probably upset with you spending so much time with your truck. It's time to replenish the piggy bank for some more modifications. And maybe buy some new curtains or a sofa to keep the wife/significant other happy.
Seriously though, virtually any other modifications are relatively expensive compared to what you've done so far. At this point there are two paths: more power or more supporting modifications. If your transmisison is still okay, now would be a good time for some larger injectors. If not, it's time for some transmission upgrades.
If you have a manual transmission, a new single-mass flywheel is probably in order. If you have an automatic transmission, it's probably time to rebuild the transmission. You can drive the truck until the transmission starts to fail or flat-out fails or you can be pro-active. It's your choice. And your pocketbook!
I recommend Brian's Truck Shop in Lead Hill, Arkansas rebuild your E4OD. A transmission rebuild should include a new torque converter, additional clutch packs, and better fluid flow through the transmission. If you get to the point where a new transmission is in order, it's time for a new thread! Transmissions are a topic unto themselves...
Fuel injectors. They're typically the next stop for more power. Generally speaking there are three stages of fuel injectors (four if you cound stock fuel injectors). Stage I enlarges the fuel injection holes in the injector nozzles. Stage II enlarges the fuel injection holes even more. Stage III are generally a 'hybrid' style injector combining parts from injectors in other International engines to provide more fuel to the combustion chamber. A safe approach is to start with Stage I injectors and then upgrade those injectors to later stages as you modify further. Stage II injectors require more, cooler air (different turbocharger and an intercooler) and Stage III injectors require more, cooler air and internal engine modifications. Adding any style injectors require reprogramming of your chip to account for the additional fuel or the different style of injector.
Now would be a good time to modify or replace the turbocharger. The standard in replacement turbochargers is the Hypermax H2E. Just about every other replacement turbocharger is measured against it in, for instance, air flow. Replacing the stock Garrett turbocharger with a larger turbocharger allows you to flow more air to go with the more fuel you added with your injectors.
Before you add the larger turbocharger, or after; your gauges will tell you; would be the time for an intercooler. The intercooler cools the air on the intake side of the turbocharger which in turns leads to cooler exhast gas temperatures. Cool air is also denser than warm. Denser air = more air for the engine.
Now would be a good time to upgrade the fuel system. The '94-'97 7.3L Power Strokes have a mechanical fuel pump which is replaced with an electric fuel pump (or pumps). The also involves removing the fuel filter/water separator assembly on top of the engine and replacing with pre- and post-fuel pump filters. This also involves running new fuel lines from the fuel pump to the cylinder head. There are a myriad of kits and ways to go about upgrading the fuel system.
If you started with Stage I injectors, you have have the modifications to support Stage II injectors. And guess what? It's time to re-program your chip!
Think of the high-pressure oil pump on the 7.3L Power Stroke like an injection pump on the older 7.3L Indirect Injection engines or the 5.9L Cummins. The high-pressure oil pump is NOT an injection pump but it helps to think of it like one when in comes to modifications. Each fuel injector on the 7.3L Power Stroke has it's own injection pump. That's why the 7.3L Power Stroke fuel injector is physically larger than that of, say, a 5.9L Cummins. Upgrading the high-pressure oil pump can be as simple as replacing it with one from a 2000+ 7.3L or upgrading to a dual-pump setup. Upgrading to a dual pump setup usually requires the fuel filter/water separator assembly be removed. Oh, and you'll probably want to re-program your chip.
By now you've got almost all the supporting modifications for Stage III injectors. One last things remains: head studs/head gaskets. There are multiple strengths of head studs and multiple thickness/syles of head gaskets available. At this point, what's recommended depends on the specific modifications you've done or plan to do. Now you're ready for those Stage III injectors.
3" intake manifolds can be done when you upgrade your turbocharger or add an intercooler. At this point you've done just about everything you can do externally. A girdle can strenghen the lower end of the engine if you plan to get extreme with your modifications. You can also install multiple turbochargers or replace the exhaust manifolds with exhaust headers.
Once you decide on a particular modification, call vendors and ask them questions about their products. Go with a vendor with which you're comfortable and you trust. Make sure they answer your questions honestly and are straight-forward with you. TheDieselStop.com is a great resource and there's a wealth of information in the forums and archives.
Cheers from Claremore, OK!
Dave
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