I really want to do my own exhaust and i have decent fab skills BUT something really intimidates me about tackling exhaust. Anyone have a link to some very good vids or resources that highlights those little tricks that makes life 10X easier?
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Where are all my exhaust fab experts at?
- Thread starter jtrux
- Start date
Nope, YouTube academy 
Well there’s always the “don’t get in a hurry” method.
1) Plan, plan, plan
Know your start points, cross over, muffler, and outlet locations
2) research your sizes, directions of flow and flaring
3) consider modular. I switched to V bands, one at the collector, one at the muffler, one in the cross over. This not only allows you to remove any piece to say pull the transmission. It allows you to weld everything outside
I use black silicone instead of gaskets, and even a thin layer on the V band mating surface
4) use a zip tie around the pipe to mark your cuts. Ensures the cut face is linear.
5) blue sharpie all your joints not only for orientation but pipe depth
6) lots of jack stands and pre weld assembly mock
I use the tack-tack system on pipe. Seems to work better
I got this system last time I built one and it really helped make life easy. It’s just a bunch of pipe that you have to assemble but just having pre bent and flared parts made it a lot easier for me to see what I needed and where I needed to go.
I too use copper gasket rtv. I also use V-bands. Grab some extra bends to.
Try to keep in mind serviceability of anything you may need to service in the future without taking the exhaust off.
Also, if you have really tight spaces you can use the round to oval tube adapters. That can sometimes get you out of trouble. https://spintechmufflers.com/oval-round-tubing/oval/ or the like.
Try to keep in mind serviceability of anything you may need to service in the future without taking the exhaust off.
Also, if you have really tight spaces you can use the round to oval tube adapters. That can sometimes get you out of trouble. https://spintechmufflers.com/oval-round-tubing/oval/ or the like.
Last edited:
Compliments of beags86
I will say, I gained power, at this altitude, going to 3” dual on 400HP
Stepped headers have the effect of lowering the pressure where the pipe size increases. This creates some air mass acceleration at that point, making a vacuum effect upstream
This effect can be used to great advantage in the main line of the pipe.
If you run 2.5” past the cases, then go up to 3”, it will help pull the upstream charge out
Run at least 18” of pipe coming out of the muffler for the same reason
This effect can be used to great advantage in the main line of the pipe.
If you run 2.5” past the cases, then go up to 3”, it will help pull the upstream charge out
Run at least 18” of pipe coming out of the muffler for the same reason
Lets nerd out a little more
Here's a variable to consider when doing straigh math as a resolution to sizing:
It's all done at ambient air temp. say 70*F
That's not the actual temperature of the exhaust.
Since air expands as it is heated, using the intake volume as your out-take volume would require you to multiply that by an expansion factor based on heat
density @ 70 is appx 2.4
density @ 300 is appx 1.6
This expansion rate would be appx 1.5
So is 100 cfm of cold air is enough as tested in the pipe for your HP, 150 would be closer to reality with 300*
Here's a variable to consider when doing straigh math as a resolution to sizing:
It's all done at ambient air temp. say 70*F
That's not the actual temperature of the exhaust.
Since air expands as it is heated, using the intake volume as your out-take volume would require you to multiply that by an expansion factor based on heat
density @ 70 is appx 2.4
density @ 300 is appx 1.6
This expansion rate would be appx 1.5
So is 100 cfm of cold air is enough as tested in the pipe for your HP, 150 would be closer to reality with 300*
From there we also need to know other changes
each turn in the exhaust changes the speed and pressure area
Works the same on air as water, and why engineers figure the number of bends in a plumbing system
For a better visual of that, see how air flows though a cylinder head port
You also need to figure the coefficient of loss due to the resistance of the air against the inside wall of the pipe, and any intrusions such as weld penetrations
Most of these air flow tests are conducted on a straight shot of pipe
They also use vacuum to test CFM numbers as it is easier to generate 500cfm of suction than compression
Muffler tests using "tested CFM" numbers are usually total garbage, as they are pulling air out of a muffler rather than forcing it through.
At ambient temperature
Light reading for you if needed:
each turn in the exhaust changes the speed and pressure area
Works the same on air as water, and why engineers figure the number of bends in a plumbing system
For a better visual of that, see how air flows though a cylinder head port
You also need to figure the coefficient of loss due to the resistance of the air against the inside wall of the pipe, and any intrusions such as weld penetrations
Most of these air flow tests are conducted on a straight shot of pipe
They also use vacuum to test CFM numbers as it is easier to generate 500cfm of suction than compression
Muffler tests using "tested CFM" numbers are usually total garbage, as they are pulling air out of a muffler rather than forcing it through.
At ambient temperature
Light reading for you if needed:
F it going straight pipes now 
Long sweep zoomies out of the hood
Muffler = classic chambered exhaust
Have disconnects somewhere so you can get it out of the way if needed to drop the T-case or transmission. If you're using stainless or thicker-wall pipe, those loan-a-tool pipe expanders are worthless, but if you mark the pipes some local shops will put them on their hydraulic expander for cheap. Unless you're a great welder and end up with lots of room around the joints, do the welding off-vehicle. Just tack it where it should be, then pull it down (another reason for my first point).
Just wing it. Backpurge your headers, v bands, let it build itself where it wants to be.
mixing SS and aluminized steel ? Is this do able ? I was looking at v band kits and only seeing SS
I hope so. It's what I have on ReTonkulous.
No big deal. I did TIG it all with stainless filler.
No big deal. I did TIG it all with stainless filler.
Dan says wing it
