Well I've made it home for the summer and it's time to start tearing this thing apart. I will begin tomorrow, but yesterday I took it to the dyno. Laid down 503 / 1215. I was very pleased with the numbers, but the knocking is getting worse to it's time to take it apart.

 

I still cannot see a reason to go to 4" or 5" exhaust yet. I'm running 400 HP at the flywheel calculated and very controlled EGT's and extremely good MPG's. With a flow through muffler its pretty quiet in the cab now. The only way I would got to 4" is when mine finally rots off the truck but it will be muffled. I really do love the sleeper style everyone just assumes its a stockish Dodge till the beast is unleashed...

I changed from a 5" down pipe to a 4" and saw no difference. Even pushing some higher power I don't see a problem with 4".

Looking purely at the CFM capabilities a 4" exhaust is perfect for most users. 3" gets restrictive with any decent airflow over about 2000 rpms and why OEM went to 4". 5" is really only needed at high rpm and high airflow. 

 

The mufflers are also a big factor in the restriction.  

 

A 380 flywheel hp 5.9 at 3000 rpms and 30 psi of boost can move 1700+ CFM of exhaust. Obviously the cam can have a big effect of CFM/boost as does rpm and turbo to a lesser extent. 

 

5 inhg is the max back pressure Cummins wants and less than 3 inhg is preferred. 

 

My big 40" muffler has the flow I need but many mufflers don't. 1800 CFM @ 1inhg. 

Edited July 5, 20168 yr by AH64ID

So what muffler are you running? I was just driving my 99 with straight back 4in exhaust and love the sound, but towing on longer trips would be not ideal.

I run the Donaldson  M085171  and it sounded great by itself but the exhaust brake was deafening so I added an OEM megacab resonator. I'll likely go with a slightly quieter muffler next time but it's hard finding good flow at low restriction. I may have to go 5" in/out with reducers for 4" pipe. 

 

Go to the page with the M085171 and look at the blue lines with 3" in/out and 4" in/out and you can see how much is gained with 1" of change. The same muffler in 4" flows 78% more exhaust at 1in hg. 

 

https://www.donaldson.com/content/dam/donaldson/engine-hydraulics-bulk/catalogs/Exhaust/North-America/F110028-ENG/Exhaust-Product-Guide.pdf

 

 

So looking through that massive pdf made my head hurt! lol

 

I think my ideal setup is going to be a 4in diamond eye that I'll run straight through for around town day to day stuff and use diamondeye's quick connect clamps to swap out the muffler delete and put one in for long trips. Now I just need to find a decent muffler that's 30in!

5 minutes ago, notlimah said:

So looking through that massive pdf made my head hurt! lol

 

I think my ideal setup is going to be a 4in diamond eye that I'll run straight through for around town day to day stuff and use diamondeye's quick connect clamps to swap out the muffler delete and put one in for long trips. Now I just need to find a decent muffler that's 30in!

Why would you go through the pain of changing out exhaust components regularly.... Sounds like a terrible idea

It wouldn't be all that regular. I would only swap on a muffler if I were going to tow longer distances with the family. Personally if it were just me in the truck by myself all the time. It'd be a 5in straight back the whole time! 

 

If you watch the YouTube video diamond eye has about those quick connects it really looks like a 5 minute deal. 

Edited July 6, 20168 yr by notlimah

I'm going to install the 5" kit when I pull it off the other truck and run it for a few trips towing and running empty. Then I'll decide on a resonator or just do a 4" like I ori planned 

Did some work on the truck this weekend. Put a little shiny and black on

 

 

I also changed the coolant out to Zerex G05 instead of DexCool.

First thing I did was put the rear up on ramps and drain the coolant from the radiator. I got just over 4.5 gallons out of it. From there I took the thermostat out of it and bolted the housing back down. From there I stuck a hose in the top of the radiator and ran the engine on high idle. With the hose on full, I repeatedly pulled the top hose off of the radiator and let the pump remove all of the water from the system. I did this for probably 30 30 minutes. for 10 min the coolant was completely clear, but I wanted to make sure I got everything out. From there I let the last of the water drain from the bottom of the radiator. Then I filled through the thermostat housing with distilled water and concentrated Zerex G05. The first thing I noticed was how much thinner the zerex was! Noticeably thinner than the Dex-cool. I then drove around and got the thermostat to open up. Once all of the air was in the radiator I topped it off again. Driving, I noticed the temperature cools off much faster than it did before. If I held it WOT for a while before it would jump to 199 then slowly come back down to 199. Now it's jumping to 197 and jumping back to 193 quickly. I haven't towed with it yet, so we'll see about that. Fan clutch is still shot though......

Looks good. 5in pipe to 6in tip?

 

And not to start a huge coolant debate but Zerex and Dexcool can mix in SMALL amounts and not cause issues right? IE, like you were doing, if some Dexcool was left in the system, it's not going to cause problems mixing in with the Zerex whatever small amount that would be right?

It's a 5 to 7 tip. Made the exhaust much deeper since the twins muffle everything.

 

I'm not sure if they are compatible or not, but there wasn't anything left in the system. 30min with a hose on full blast and the engine running cleaned it out!

Very interesting to hear that the tip made the sound deeper. I would like mine to be deeper, maybe a 4-6" would do the trick...

 

btw what color is the Zerex and where did you get it?

Edited July 18, 20168 yr by leathermaneod

3 minutes ago, leathermaneod said:

Very interesting to hear that the tip made the sound deeper. I would like mine to be deeper, maybe a 4-6" would do the trick...

 

btw what color is the Zerex and where did you get it?

 

4-6 does make a difference! I had one on my old exhaust.

 

It's a light yellow color, and I got it at the local Napa. $20/gallon for the concentrated stuff

Just now, TFaoro said:

 

4-6 does make a difference! I had one on my old exhaust.

 

It's a light yellow color, and I got it at the local Napa. $20/gallon for the concentrated stuff

Was it a good difference? How did it affect the sound? 

 

How much did you need? About 3 gallons?

1 hour ago, leathermaneod said:

Was it a good difference? How did it affect the sound? 

 

How much did you need? About 3 gallons?

It made the rumble deeper than before. The 4in with a 6in tip was deeper than just the 5in without a tip.

 

Yes, about 2.5 gallons of concentrate. You'll have some extra for refilling. 

Is that an mbrp exhaust? I've noticed that those exhaust systems seem to exit the bed at more of an angle where as the diamond eye is more perpendicular to the truck bed. Wondering if that makes things more tame inside the truck and keeps drone down.

11 minutes ago, notlimah said:

Is that an mbrp exhaust? I've noticed that those exhaust systems seem to exit the bed at more of an angle where as the diamond eye is more perpendicular to the truck bed. Wondering if that makes things more tame inside the truck and keeps drone down.

No, it's a diamond eye. I just cut the curved piece off of the end so the tip would fit. I haven't noticed an in-cab difference

Oh ok you just cut it further towards the axle? I like the way it turned out. I was just thinking of how the stock exhaust looks and then what @CSM was saying about the angle of exhaust tip making a difference in sound and drone. 

2 hours ago, TFaoro said:

Yes, about 2.5 gallons of concentrate. You'll have some extra for refilling. 

 

That doesn't sound like enough, especially if you had some leftover. 

 

I have found two different sizes for the cooling system; however, even using the smaller size 2.5 gallons of coolant isn't enough. 2.5 gallons in a 6 gallon system is 41% coolant and it sounds like you didn't have quite 2.5 gallons of concentrate in there. 44% coolant is the minimum needed to prevent corrosion and pump cavitation.

 

At 40% coolant it only has freeze protection to -12°F as well. The lower %age of coolant does transfer heat better and that could be part of why you are seeing the quicker cool off temps. 

 

I know it was discussed earlier about tap water, but if you have a 6 gallon system where only 4.5 gallons drain out you have 25% tap water. IMHO that's a lot of tap water, especially with G-05 which is known to not play nicely with other coolants so hopefully any minerals in tap water don't have issues with it. 

 

6 gallons was the smallest size I found for the cooling system and I found some references that put it at 7.4 gallons.