HELP! Cat C7 performance and ScanGuage D

[dredel]

Just bought a 2005 Winnie Journey 36G with a Cat 350 C7 (S# KAL 52801). The performance while climbing long grades seems real poor - about 35mph. I installed a ScanGauge D to try and monitor what is going on. Boost is usually showing 23-24 psi climbing under load. HP rarely climbs above 250. Coolant temp stays consistently at about 185-190 degrees. I would love to get some feedback from you C7 350 owners.

What top speeds are you realizing on 5-6% grades (towing dinghy and not towing)?

For you with 350hp C7s and monitoring HP with a ScanGauge, what are the max HP readings you have seen? Do you think the ScanGauge is giving you an accurate HP reading?

Thanks

[FIRE UP]

Originally Posted by dredel

Just bought a 2005 Winnie Journey 36G with a Cat 350 C7 (S# KAL 52801). The performance while climbing long grades seems real poor - about 35mph. I installed a ScanGauge D to try and monitor what is going on. Boost is usually showing 23-24 psi climbing under load. HP rarely climbs above 250. Coolant temp stays consistently at about 185-190 degrees. I would love to get some feedback from you C7 350 owners.

What top speeds are you realizing on 5-6% grades (towing dinghy and not towing)?

For you with 350hp C7s and monitoring HP with a ScanGauge, what are the max HP readings you have seen? Do you think the ScanGauge is giving you an accurate HP reading?

Thanks

Well Sir,
We have a very close sister ship to yours. Ours is an '04 Itasca Horizon 36GD with the 330HP CAT. One thing you may want to check before going nuts on trying to up the performance on your CAT is, THE WEIGHT of the coach. I've been running at the maximum amount of weight, i.e. GVWR of the coach, now for years. I hover around 6.1 - 7.5 in fuel mileage. We tow either a 2011 GMC Sierra 1500 4x4 Extended cab which, is carrying a 275 lb. motorcycle lift which, is carrying a 900 lb. Honda GL 1800 Goldwing or, we tow a 2015 Jeep JKUR. Both of which are fairly heavy.

Now, climbing grades, with either the 300, 330 or 350 C-7 CATs is what it is. None of them have the ability to ZOOM right up ANY GRADE. Your "35 mph" is not that unusual. I've seen that many times in ours. I've also seen 55 up some of the grades too but, that's rare. My turbo psi hovers right at 25-27 psi, depending. That C-7 of ours doesn't burn any oil, runs about as good as any CAT that I've experienced driving and, just keeps on going. We now have 83,000 on it and, I've recently done the major maintenance on it like fan hub bearing, all hoses, new water pump, CAT regulators, and more.

I have two buddies with the 350 version C-7s. One has it in a 34H Meridian and one has it in a 36' Meridian. I've driven along side, in front and behind both of them at various situations. We've tackled grades at the same speed at the bottom of those grades. Both of them were towing heavily modified Jeeps at that time. However, at the tops of those grades, they have me by no more than 1.5 lengths of the coaches, period. They were full throttle as well as I was. None of us are running the Scan D system so, monitoring all that info was not possible. Due to ours being the Horizon, one step up from the Meridian and Journey, it has the turbo gauge which, like stated earlier, tells me the turbo pressure.

Now, is there something not quite right with yours, who knows? If your temp stays steady, and you're making grades even at the 35 mph, I don't know that you could get any real improvements without consequences. I say consequences because, there's been a few on here that have tried the use of the MP-8 Chip in their CATs and, when used in the highest settings, all kinds of bells, whistles and alarms start going off. Not to mention, these darned engines are EXPENSIVE to fix, rebuild or replace. So, for me, I'm happy with it being bone stock and lasting for a long, long time. Your choice.
Scott

[1ciderdog]

Originally Posted by dredel

Just bought a 2005 Winnie Journey 36G with a Cat 350 C7 (S# KAL 52801). The performance while climbing long grades seems real poor - about 35mph. I installed a ScanGauge D to try and monitor what is going on. Boost is usually showing 23-24 psi climbing under load. HP rarely climbs above 250. Coolant temp stays consistently at about 185-190 degrees. I would love to get some feedback from you C7 350 owners.

What top speeds are you realizing on 5-6% grades (towing dinghy and not towing)?

For you with 350hp C7s and monitoring HP with a ScanGauge, what are the max HP readings you have seen? Do you think the ScanGauge is giving you an accurate HP reading?

Thanks

I'd think it depends on the grade - I-5 in Northern CA and Southern Oregon I'm usually down to 4 gear and about 45 mph. On some of the state highways with steeper grades I'm slower. Mine has the 330 CAT. For awhile I had an MP8 power boost but I really had to watch exhaust temps and back off the throttle. Seems without the MP8 the exhaust temp doesn't get extremely high. on edit: I forgot to mention boost gets up to about 28 max.

[Mr_D]

One thing to remember is that NONE of the electronic devices like a ScanGauge or VMSpc actually measure HP or torque. The gauge output is programmed in from the engine stats and is just an approximation taken from RPM, throttle position and boost pressure.

[dredel]

Thanks guys for your input. From your replies it looks like my slow speed climbing grades is not unusual or anything to be concerned about. I used to have a 2001 35' Rexhall Anthem with a Cummins 270HP engine. That coach typically climbed grades at 45mph and I thought my Cat with the extra 80 horses would better than match the power of the Cummins. But as one of you commented, if I consider the GVW of my Winnie Journey 36G I see it is certainly higher than the Rexhall Anthem. I realize the HP indicated on the ScanGauge is a programmed number and not an actual reading. But if other members with the same C7 Cat are using ScanGauges to watch HP, and are seeing "approximate" peak readings close to 350HP, it seems logical that something may be causing less than optimum performance.

Papa Dave

[JaminSamin]

Dave - you said you just bought this coach...do you know how long has it been since the fuel and air filter were changed?

[dredel]

Jamin, Fuel filter was just changed and the air filter "minder" monitor indicates minimal loss of air flow. Thanks for your interest.

Papa Dave

[1ciderdog]

Originally Posted by Papa Dave

Jamin, Fuel filter was just changed and the air filter "minder" monitor indicates minimal loss of air flow. Thanks for your interest.

Papa Dave

Dave, one thing to keep in mind (so I'm told) is the air cleaners can age out and the paper element inside the air cleaner can start coming apart and cause damage to engine and turbo. I do replace mine every two or three years. If yours hasn't been replaced in a few years you may want to consider replacing it.

[2 Stroker]

When it comes to air filter I use Donaldson Blue, cost more but worth it.
https://www.donaldson.com/en-us/engi...-blue-filters/
2 stroker

[zproud]

My coach cat 330 empty 25,000 lbs, long 4% grade ran up the hill at 70 75 , speed limit.

It was my first attempt on a hill I was happy, will have to wait and see how it does loaded and towing.

Rpm needs to be 1900 to 2200 for max preformance

[Cat]

Boost spec on your engine is 27.7 in hg which is 28 psi. This what your engine tested at the dyno at the factory June 18 2004. You should see this boost at full load rpm of 2395rpm. If you have your foot to the floor and you are at 2395rpm to approx 2340rpm and are not too much above sea level you should get 28 psi boost. Many things can cause low boost, boost leaks, fuel filter, dirty air cleaner and more. But 23-24 psi boost is low for a 350hp engine.

[dredel]

Wow - lots of great suggestions! Thank you everyone. I will start by replacing the air filter and see what difference that makes.

Papa Dave

[TonyMac]

Originally Posted by Papa Dave

Wow - lots of great suggestions! Thank you everyone. I will start by replacing the air filter and see what difference that makes.

Papa Dave

While you are in the air cleaner, make certain there is no air bypassing the filter thru loose connections from the air cleaner all the way to the turbo, then from the turbo, thru the cooler to the intake.


I'm pulling 50+ on similar hills with my C7, passing semis. If there are three lanes, I'm solidly in the middle lane.

[JaminSamin]

I don’t have a C7 but my 3126 coolant temp would be closer to 200 at the top of a climb like that.