Again, drone isn't much of a concern when it comes to the MBRP system.

I negelected to mention a few details regarding my MBRP system when I had it: The muffler was mounted in the usual spot and driving down the freeway or even around town, I never heard any type of drone. Believe me, I listened for it and listened for it, but never heard it.

The only time I heard any type of drone is when I modded my exhaust and deleted the MBRP muffler in favor of the Aeroturbine Muffler I have now. I mounted the muffler in the recommended position which was as close to the downpipe as possible. Then and ONLY then did I hear a drone, even then, it was gone not long after.

So once more, drone isn't much of an issue with the MBRP system. Can't speak for others though...

 

I am going to order either the Silverline or Diamond Eye with HushPower Pro Muffler. Have herd a lot of mixed reviews about MBRP on the drone levels. So thought I will try something else. I like the description of the HushPower and here they are pretty quite. Have not herd one with my own ears though.

Silverline Single Outlet-Turbo Back 7.3L Ford PowerStroke Excursion FS102

Diamond Eye 4" Aluminized Turbo Back Single 01-02 7.3L Ford Powerstroke Excursion K4332A

 

After sitting on the fence for a while, I decided to order the MBRP today. Looking forward to the benefits when towing.

 

Long term "test" report on MBRP Cat back system:

I installed this system back in September 2012. I've been to Phoenix two times from Oklahoma since then, and one time at max trailer weight of 11,000 lb (Gross weight 19,500 lb).

With the Cat in place, I do not have any intrusive drone.

I'm using SCT tuner with Matt's "8K Tow" tune. The EGT still can exceed 1400F, unless I take action (pull out of cruise control and work the throttle) to reduce towing speed up very long mountain grades. I must say that towing a big rig north on I-17 from Phoenix to Flagstaff is quite a test. There are some climbs there that go for miles at 6%.

Those very long grades can easily be held at 60 - 65 mph in 3rd gear. It is really a question of timing my passes around the big trucks. I don't like blocking the left lane for those cars coming up at 70 mph, but I sure hate cutting the speed to 40 mph for those big rigs trundling along in the right hand lane.

The only problem I'm having with the MBRP has to do with fasteners. I don't think it is MBRPs fault. I had the truck in to solve an oil leak and the mechanic had to pull the turbo (and I presume had to loosen the down pipe). Since then, the nuts at the downpipe to Cat connection keep backing off. I get a metallic rattle noise after just a few hundred miles of driving. Then, I find the nuts have backed up. I wonder what happened when he took the downpipe off? Maybe some sort of lock nut or washer was left off? Does anyone have an MBRP that they could photograph these fasteners for me? I'd rather just do this simple fix myself than take it back for work.

 

I would use lock tight, not sure if you should use blue or red. When i tow out west i use mats slr+ tune and change to the 8k tow tune, when beginning to climb. You might want to use the 8k tune until you get to those passes. Any mpg comments with those tunes?

 

It could be that things just weren't lined up properly when they were reassembled. If simple SS split lock washers behind the nuts won't keep it tight, you might want to try and get things straightened out. Loosen every clamp(even the turbo/DP connection) from the turbo to the tip, and make sure nothing is binding. Shaking things around will help everything settle. Then re-tighten it all starting at the turbo.

I-17N in the summer is a rough one.

 

Thanks for the loc-tite idea.

I'm getting about 9.5 mpg with no wind, set on 70 mph (2000 rpm).

 

Those temps look pretty good to me! Last week pulling my 9200 lb TT back through the Ozarks (highway 65 north out of Branson) I saw ECT up to 228 and EOT up to 246.

I question these temps slightly. I am using an Edge insight. sometime last year they did aoftware update and ever since it has registered higher temps regardless of situation.

My unloaded 75 mph empty highway temps are ECT 180 EOT 195.

 

Why did you just go with a 'cat back?' And since it didn't help your high EGT's will you be replacing the turbo to cat pipe with a larger size?

 

I am surprised no one has brought up are you using the tow/haul feature of the transmission. I find that using tow/haul I can drop the temps.

 

I think you are correct. I do definitely use Tow/Haul. I'll confess that I use cruise control most of the time. The engine is powerful enough to keep up with about any grade up to about 5% in cruise. I think my high EGTs may occur because I wait a bit too long to drop out of cruise when the grade steepens. Perhaps engine is defueling(?) and leaner mix causes EGT to rise(?)

The 4" MBRP system seemed to help some, but it does not seem as dramatic as I was hoping. I'm unwilling to remove the Cat at this time. I am wondering if a less restrictive aftercooler would help any.

 

Sorry I did not clarify.. I did use a new 4" downpipe. All that stayed original was the Cat.

 

Depending on your RPM when you approach the hills, you may be beginning to lug the motor. As the grade steepens, the load placed on the engine increases. As you, or the cruise control tip in the throttle, the PCM will first command fuel/boost. More fuel can be commanded and the RPM and speed can still drop as the grade steepens.. If speed can't be maintained, it will eventually downshift to put the motor in a more efficient part of it's powerband. The PCM/TCM are smart enough to keep the motor from destroying itself, but getting the RPM's up before you enter the grade is easier on the drivetrain, and avoids the high EGT situation as you start to climb. You'll also have better speed control as you should have more available HP/TQ to pull up the hill.

 

This brings up a question that I have and been meaning to ask for a while now...How do you do that with the 5 speed auto?? With the 4 speed auto in my V10 Ford chassis motor home, I would downshift to 3rd gear just before climbing a grade by taking it out of overdrive with the button at the end of my column shifter.

The 5 speed auto appears to have no mechanism to manually drop in to 4th gear??

 

With a Torqshift tranny 4th is only available while the TFT is low. You can't positively select it with the shift lever. The actual gear ratio of 4th compared to 3rd is very close. Digging into the accelerator is the easiest way to get it to DS. Once you're in the grade, the load should keep you from upshifting, and cruise will maintain your speed.