Upgrading C7 HP from 300 to 330

[ambyn]

I'm told that I can have a CAT dealer up my 2004 300 hp C7 to 330 hp with a computer firmware change.

I like the idea of having more torque (less drop off) as the RPMs increase. But I wonder what the down side might be. The cost is around $450 now that the warranty has expired.

I'm wondering what you think of this Mr Moderator?

Thank,

Amby N.

[wolfe10]

I'm told that I can have a CAT dealer up my 2004 300 hp C7 to 330 hp with a computer firmware change.

I like the idea of having more torque (less drop off) as the RPMs increase. But I wonder what the down side might be. The cost is around $450 now that the warranty has expired.

Thank,

Amby N.

Amby,

First, peak torque does not change -- it remains 860 lb-ft at 1,440 RPM.

Any time HP is increased, it means two things -- you will burn more fuel and you will produce a greater heat load on the cooling system.

The first issue is one that you can answer -- am I willing to pay more fuel for a little more performance?

The second issue is more complex. Basically, you are asking if the chassis maker originally "OVER-SIZED" the cooling system enough to handle additional heat loads. Where most would use the extra HP is climbing those long grades -- exactly the same place that your cooling system is already stressed.

Another way to approach the decision is to ask what you want to achieve? For most, if it will not allow you to go 5 MPH faster up those 6% grades, it is likely not worth it.

Caterpillar Corp has an excellent document to determining FACTUALLY, what additional HP will do for you in terms of speed on a 6% grade.

https://ohe.cat.com/cda/files/287140/7/LEGT5364.pdf

Go to page 7. Determine which coach (GCW) you have and see how much additional HP it would take to get you those 5 extra MPH. Note: the HP in the table is all "AT THE REAR WHEELS" HP, as Caterpillar had no idea what size A/C compressor, alternator, cooling fan, etc your chassis maker would fit. Figure about 1.30 engine HP= 1.00 HP at the rear wheels.

After looking at the FACTS, the decision on "what it is worth to you" is-- indeed yours.

Brett Wolfe

[ambyn]

Thanks, Brett.

I was told that the chassis would support the HP upgrade. Someone along the way had told me that there might actually be some improvement in mileage on the order of .1 to .2 mpg.

I have not been out west yet so that mountain climbing performance was not considered. I was more thinking about having the increased torque at highway speeds (about 61 or 62 mph) for passing. Usually this is about 1700 rpms with the C7 and Alison 6 spd on economy. I have been looking at the torque in this rpm range and realize that the reduction in torqe roll off with the increased hp is not worth the $500 to mi right now especially since I just spent $2K to have 9 of my SE-GI windows fixed.

You commented about increased fuel consumption. Would this be due to the computer requesting more fuel be injected at a specific rpm to get the increased HP and torque?

Amby N

[wolfe10]

Thanks, Brett.

I was told that the chassis would support the HP upgrade.

You commented about increased fuel consumption. Would this be due to the computer requesting more fuel be injected at a specific rpm to get the increased HP and torque?

Amby N

I don't know what chassis you have, but if you read comments in the summer, there are a LOT of overheating complaints, particularly from rear radiator chassis (especially if the inter-cooler is not cleaned frequently). Making more HP/burning more fuel does increase the amount of heat an engine produces AND that the cooling system must dissipate. Agreed, the rest of the drivetrain itself (Allison 3000 and rear axle) will be fine.

Yes fuel consumption will go up. No free rides. To produce more HP/torque any engine requires more fuel.

The only conditions where MPG could go up is if you drive in areas where you don't have sufficient power and.even in economy mode. the transmission is constantly downshifting to 5th to pull grades. Adding just enough power to keep it in 6th all the time would save a little fuel. But overall, consumption will NOT go down.

Brett Wolfe