Downpipe change
Downpipe change
Postmaster
Joined: Feb 2002
Posts: 2,773
Likes: 0
From: Bonney Lake, WA
It wouldn't probably be worth the effort. But, since yours is a SuperDuty, you can go with a 4" downpipe. That would make a difference, especially if you've got the rest of the exhaust system redone.
Senior User
Joined: Feb 2002
Posts: 444
Likes: 0
From: Carol Stream, IL
I have a 3.5" downpipe and even though its only .5 inch bigger is does flow more air than the 3 inch and will result in lower EGTS. Some say the 4 inch downpipe creates a loss of low end power.
Elder User
Joined: Dec 2000
Posts: 808
Likes: 3
downpipe
SBFD8,
The biggest restriction to our exhaust system is the stock muffler!!! If you upgrade your muffler to the BTM you will notice lower EGT's and somewhat better performance.
The 3.5 downpipe will help alot. IMO the stock DP is not a true 3"er. The first radius bend from the turbo down the firewall is about 2 3/4 to 2 7/8's. Sure it's not much, but it is a difference.
I installed the 4"er on my rig and I haven't noticed any loss of low end power. It would be interesting to know if those who did notice a loss of low in had 3.73 gears in the rear??? For I have 4.10's in my dually. In any case I have no regrets. My EGT's @ 70MPH on level ground has been 550 to 600. Pulls awesome.
Xaviar
The biggest restriction to our exhaust system is the stock muffler!!! If you upgrade your muffler to the BTM you will notice lower EGT's and somewhat better performance.
The 3.5 downpipe will help alot. IMO the stock DP is not a true 3"er. The first radius bend from the turbo down the firewall is about 2 3/4 to 2 7/8's. Sure it's not much, but it is a difference.
I installed the 4"er on my rig and I haven't noticed any loss of low end power. It would be interesting to know if those who did notice a loss of low in had 3.73 gears in the rear??? For I have 4.10's in my dually. In any case I have no regrets. My EGT's @ 70MPH on level ground has been 550 to 600. Pulls awesome.
Xaviar
Post Fiend
Joined: Jan 1997
Posts: 23,165
Likes: 18
From: Enjoying the real world.
A larger down pipe does two things to help lower EGTs:
1. evacuates exhaust faster
2. its a larger heat sink than the stock pipe.
1. evacuates exhaust faster
2. its a larger heat sink than the stock pipe.
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Elder User
Joined: Aug 2002
Posts: 772
Likes: 0
From: Salem USA
Exactly, I took Kens advice and went with one of his 3.5 downpipes and it did make a noticeable difference even with stock exhaust. The stock was not only .5 smaller but hammered almost flat... a pretty severe oval. With my truck the 3.5 would fit with a little bend of the lip where the firewall and floor pan meet, it would have had to trim it to get a 4" in there.
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