c7 upgrades

[jauguston]

I know from talking to Randy at TS Performance that the have done hunderds of dyno tests on all the engines they make programmers for. They have inhouse dynomometers. They sponsor dyno day weekends at their business where anyone can come and for a fee run their vehicle on their dyno's.

As I have posted on a previous thread on EGT's they ran a C-7 for one hour full throttle with the EGT at 1500 degrees. No issues at all with the engine.

There are so many variations to engines even between different engines of the same model I can understand why they would not publish before and after dyno data for any engine.

With the word of mouth advertising they get from the Over The Road Truckers and big tractor farmers they don't need to do much advertising. They sell thousands of them per year. I talked to a dealer in Montana that said he sells 400-500 per year to farmers in the Canadian prairies for their tractors.

[mbrandt1402]

If your C7 does not have a two speed fan clutch, adding one would seem to be a stone-cold reliable way to improve fuel mileage. There is a thread in the Freightliner forum with some info and a link to some really good info.

My impression of fuel savings with the MP-8 style "chips" rather precisely coincides with Jim's comment: you are better off using that money to buy fuel.

[jauguston]

I would also suggest that if your engine has a direct drive fan that instead of spend a LOT of money to have a two speed fan installed use that money to buy fuel also. It is highly unlikely that the conversion cost would EVER be recovered in fuel cost savings. Fuel is simply part of RVing. You put more in when needed.

Jim

[Ramzfan]

How do you know if your engine has a direct-drive fan or a two-speed fan...?

[jauguston]

If your fan is direct drive with the engine NOT running grab a fan blade and see if you can turn it. If it won't turn it is direct drive.

[1ciderdog]

Out of curiosity does anyone with a CAT C-7 have the "two speed fan" or a clutch fan on that engine? And if so are you satisfied with the fan set up?

[jauguston]

You will find that side radiator coaches generally all have hydraulic driven fans. Hydraulic drives can be variable speed and are expensive.

[moisheh]

jauguston: Your logic could be applied to your MP 8 as well. When it comes to Motorhomes there is never an ROI. They are like boats. You pour in money! But many of the mods are done for convenience or to make the trip more comfortable. All Freightliners since about 08 have viscous fans. It seems the cost would be under $1000. How much was your MP8? But really if you think that the MP8 gives you more power and you want or need that power then it was a good move! Same for a fan mod. If we wanted to save money we would stay home!

[jauguston]

I installed a MP-8 because I wanted more power and it did that. Fuel mileage had NOTHING to do with the decision to put it on.

The discussion on replacing fans seems to be all about attempts to increase fuel mileage. Different subject. It may be possible to slightly increase fuel mileage with a different fan but will there ever be a payback. Maybe.

Jim

[mbrandt1402]

The break-even isn't bad if you can install this yourself for about $600. At $4 / gallon and .7 mpg increase from 7.5 to 8.2 (moderately conservative numbers from the reading I've done), break-even comes at just over 13k miles.

[jauguston]

A .7 mpg increase from 7.5 mpg is nothing short of spectacular. What is this product.

Jim

[EDALLSAILS]

What is the cost for these upgrades? what are the real savings on fuel? And how long till the cost is paid for by the fuel savings?

[mbrandt1402]

Lifted from Bill Halberstadt's excellent write-up on fitting a two speed fan to a C7:

"During a trip from Delaware to Oregon in July and August of 2004, I was able to acquire good operation data, mostly via my laptop computer hookup to the engine and transmission data bus, via SilverLeaf’s “VMSpc” connector and software. This allowed me to monitor and log many engine variables, including coolant temperature, transmission temperature, intake manifold temperature,
road speed, engine rpm, engine load, boost pressure, and fuel MPG. Averaging many separate segments of constant speed on level roads, with the fan at high or low, I found a 1.0 (± .2) MPG increase in fuel economy (from 7.5 to 8.5 MPG). Several 0 to 60 MPH runs on level ground averaged 2.5 seconds faster (to 31 seconds) with the fan on low. Horton estimates an available horsepower increase of 25 HP with the fan at low."

This was on a 35' Safari towing a 4,400 lb Jeep Grand Cherokee. BH is a retired engineer, and the write-up reflects that sort of organized, documented evaluation. Note that he used level-ground segments, so if you drive up lots of grades that would push your cooling system temp up enough to require high fan speed, you won't see those savings. Any climb short enough that the fan doesn't come on until you are descending shouldn't significantly impact fuel savings - gravity is spinning your fan when it kicks in on descent. In those conditions, the cooling system is contributing to fuel economy sort of like the battery in a hybrid.

The write-up (and subsequent parts lists) were posted to the old Cat RV club website, which has recently morphed into the Diesel RV Club. Finding the files requires Yahoo and/or Diesel RV Club membership, or you can email me via my profile and I'll send them.

I seem to recall estimates that it takes 60 hp to move our rigs down the road. If you take even half of Horton's estimate of the hp savings when the fan is in low speed mode, that still is a significant amount of energy conserved compared to what it takes to keep us moving.

[moisheh]

Assuming you get the 1 mpg increase your savings would be almost 89 gallons or $320 per year. BUT why is everyone all hung up on payback. RV's dont save money. If you want a money saving hobby try stamp collecting or maybe a tin foil collection!