How To Turn Up a Cat C7: Horsepower Upgrade (Helpful Guide)

Many RV owners want to squeeze more power out of their CAT engines. They look for just about any trick they can use to boost their power and tow more weight. This behavior may not be as simple as some people may think.

Some C7 engines may have a low power problem. If the fuel pressure is not kept between 65 and 85 psi, you may not be getting all the power you can. Fix this problem and you should turn up the C7 engine a little bit more.

To learn more about turning up the C7 engine, just continue to read our article. It has the information you want to know about if you own or are thinking of buying this model. It may not be possible to squeeze more power out of this engine.

What is Robbing Your C7 Of Power?


Before we get into this discussion, there are a couple of simple things that need to be discussed first. There is a maximum power boost you can get out of this engine with after-market options. Although, those are not that good.

But if you do not feel that you are getting all the HP out of the C7 then the problem may lie elsewhere. For example, the fuel pressure is one of those low power sources. If it is not maintained, you will not have all the power this engine can produce.

The low fuel pressure can be found in either a weak fuel transfer pump or a faulty fuel pressure regulator. But this is not the only source of a low power problem.

If there is a leak in the air piping or air cooler, you could be suffering from a low boost condition. Or the turbocharger has excessive shaft end play. A third source will be worn injectors. If everything else is okay then this may be your problem area.

Before going out and spending money on a boost kit, etc., check these parts out first to make sure there are no problems with the engine.

How Much Horsepower Does a C7 Cat Engine Have?

This engine was produced between 2003 and 2009 and was designed for medium-duty trucks and vehicles. That means that you are not going to get ‘blow the doors off the competition' horsepower.

The official data sheets say that this engine’s maximum HP was set at 300. But we have read a mechanic who stated the maximum amount of HP you can get out of a C7 is 350 HP. If you are already at that level, then you won’t be able to go higher.

After-market boosters may eke out a little more power but you can damage your engine in the long run. This may be why CAT has disallowed Banks Engineering to install one of their kits in the C7 like they do with Cummins’ motors.

But you would have to ask CAT about that. This engine was not made to have a lot of horsepower and you may have to be content with what it produces and look to tow or haul lighter loads. This is a medium-duty engine and not a heavy-duty one so keep that in mind.

C7 Cat Engine Performance


Before anyone jumps on us about the maximum HP in the C&, this model of the engine was released with 8 different power settings. It went from 210 to 360 HP, with torque ratings between 520 to 925 lb-ft. The higher HP-rated engines were given limited duty.

They were placed in RVs and firefighting trucks. Its B50 rating was between 400,000 and 500,000 miles before it may need an overhaul. The ACERT technology of that time was one of the reasons this engine had the reputation of being low power.

There were a lot of problems with this technology and along with that low power came low fuel efficiency. But it has been said that the engineering of some CAT engines during those early 2000 years was not well thought out.

Another problem affecting performance was that the cooling fan did not turn on till 235 degrees F. But drivers reported overheating at 200 degrees F. That created many problems for CAT.

The ACERT technology had so many problems including numerous issues with maintenance, fuel economy, and lowered horsepower, that they decided to not continue in the over-the-road engine market. Nor did they want to meet the 2010 emissions regulations.

They stopped building these types of motors in 2009.

How To Turn Up a Cat C7

This action will depend on a few factors. For example, if you have a C7 210 HP engine, then the most you can go up would be to 230 or 250 HP. But the ECM software needs to be changed and you would have to upgrade the injectors.

According to one source, you can only rerate CAT engines as long as they belong to one family, (whatever that means). the C7 is supposed to have families from A to F.

However, the solution is the same, you have to flash the ECM or reprogram it. Then only if the transmission can handle the extra HP. That is another factor you have to take into consideration. If the transmission is not built for more HP, for example, 210, or 330, etc., then you can’t turn up the C7.

There may be other parts that would need to be upgraded as well. You would need to talk to CAT as they may be the only ones who can do the re-rate for you. From what we understand, CAT is very protective of its engines.

The word is that you are not going to get a lot more power out of a CAT engine. The company is pretty strict about after-market applications.

Cat C7 Horsepower Upgrade


There are different aftermarket kits you can buy. One from Brazels RV Performance shop has one on sale for $500 approx. They advertise that you can get 30% more HP and between 10 and 20% more fuel efficiency. The HP option is adjustable and you can set it for a 10, 20, or 30% increase in HP>

This kit is supposed to not flash the ECM but get its data from that part. Then it optimizes that signal to increase the power and the fuel performance. There is something called ‘The Edge’ and some trick boosters you can find floating around the different marketplaces.

But the Edge does not provide a lot of extra power and those trick boost sensors may give you a little more power as well. But they also damage your engine given enough time.

There are companies that sell upgrade kits but their results are also questionable. There is only so much power you can get out of your CAT C7. You should check with CAT to see what they can do for you first.

CAT dealers seem to be the only ones who can re-rate the ECM so your options may be limited.

Cat C7 Turbo Upgrade

This is a possibility. There are companies that advertise and sell CAT C7 turbochargers that are considered an upgrade over the stock turbocharger. The PDI Big Boss Stage 1 Turbo is one option but its cost may take a long time to recoup.

If you go this route, you are looking at paying $2450. Another option would be the JM Turbo Technology’s model 300AG072. They advertise that you can get up to 330 HP once it is installed.

The keywords are ‘up to’. There is no guarantee that you will get that top amount after you purchase it. This option is more reasonably priced at $400 approx.

Both models come with a 1-year warranty. But what most owners have reported is that CAT dealers will not do any work that is not listed in their book. They seem to be very firm on this principle and that frustrates many CAT C7 owners. That means you will not get re-rated for anything higher than 330 or 350 HP unless policies have changed over the years.

Cat C7 Tuner


There is a place called Heavy Diesel Tuner and it seems that they carry different tuners for many of the CAT engines. The list is fairly long for engines that are compatible with their products.

The company has 3 that they advertise and the prices are included- Power and Fuel Economy Tunes - $1499.00; Custom Programming Including High Performance Tune - $2899.00; Fuel Economy, HP/TQ, and Twin Turbo Delete tune - $3299.00

It is a tough decision to spend that much money at one time. Then PDI has an ECM power tune option but they too are quite expensive. They are asking $2200 approx. for their tuner.

You may have to do a more local search to find any of these custom shops in your area. Then you need to ask if they will work on a C7. There are complications in squeezing out more power from these motors and more technical research is needed.

There is not a lot of chatter on this project out there. Most people are finding it hard to go beyond the maximum HP output of 350. CAT has designed their engines well and does not want anyone else messing with them so you need to check with CAT before you go too much further.

Cat C7 Rerate Chart


You should be able to enlarge this chart. It is the only one we could find on the internet. It comes from a mechanic over at Just Answer and you should find the original at this link.

Pay special attention to those little boxes underneath the charts. They provide some important information. Also notice, that any of these uprates do not go past 350 HP.

That is what one mechanic said was the maximum amount of HP you could get out of this engine. But talk to different people. They may have found ways around that limitation and can get a few more HP than that.

Just be cautious as you do not want to add any parts that will damage the motor as you use the new uprate parts.

How do You Adjust The Valves On a CAT C7?


According to CAT, you do not adjust the valves on a diesel engine. You need to adjust the valve mechanisms, for example, the lifter, push rod, and rocker arm assembly.

The process starts with-- the intake is 0.015 and the exhaust is 0.025

Turn to top dead center on number 1. adjust intake on 1,2,4 and exhaust on 1,3,5

Turn 360 then adjust intake on 3,5,6 and exhaust on 2,4,6

This link will take you to a web page with diagrams and detailed instructions. We double-checked those instructions and they are the same as the one a mechanic sent to a customer.

This is what CAT has to say about a valve adjustment:

The valve mechanism is adjusted to provide a specific lash (or looseness) necessary to regulate the opening and closing of the valve. If the lash is too loose, the opening and closing of the valve become very abrupt which will eventually lead to damage to the valve and/or valve mechanism.

If the lash is too tight, the valve cannot close and seal properly in the cylinder head and exhaust gases will leak past the valve. With the incorrect lash adjustment, the engine may not operate at full power, fuel consumption may be high and the exhaust smoke and exhaust temperature may be excessive.

If left uncorrected for an extended period of time, a catastrophic failure of the valve and engine is likely to occur.” (source)

Some Final Words

No matter how hard your try, you may only get a little extra power out of your CAT C7. CAT has made their engines to work in a certain way and then kept the re-rate information to themselves.

Regardless of the engine's construction, etc., you may only end up with 350 HP after spending all of that money.

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