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Discussion Starter #1
Hello everyone
If to saw my post on eliminating the 90 bends in the exhaust it explains in great detail what I did.
So you can refer to that post.
As I mentioned before in other post I’ve had a lot of different car builds. One of the cars I had was a turbo T/bird from back in the 80’s. Which is why I was excited about the Ecoboost. Anyway to the point back then when we modified those Ford turbo cars, we found out that the best exhaust you could have on those cars was a single 3 inch turbo back with as little bends as possible. When I saw the two 90 degree bends
in the stock exhaust and how it went to a pipe
to flattened flex pipe to being chocked down to
the resonator inlet I was like you got to be kidding. So after I eliminated the two 90 degree
bends, the flattened flex joint and the chock down to the resonator. Some wonderful things happened like the cars performance was improved. Currently my mods are air raid tube
from factory air box to turbo, AEM drop in filter,
Cobb v2 Catt back exhaust CPE stock location
intercooler, Adam tune spark plugs and Cobb Accessport stage two 93 otc map. So like I said
after I did the exhaust mod noticed a real difference in car performance it’s explained in the other post.so just for ha ha’s I switched to the Cobb stage three 93 otc map. The car had a nice
jump in performance no check engine light set up
the accessport to check timing, Knocks everything is fine I did pulls in 2,3,4,5 gears
red lining all gears multiple times and at time just
beating on it and I hate beating on my cars but I wanted to make everything was fine. Plus doing a fifty mile ride highway and back roads no problems. No dyno yet but its coming soon. so you can keep your factory cat and have good performance.
Feel free to ask any questions but please read my
eliminating the 90 degree bends post first, it explains why I did the mod.
 

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i admire the idea. it opens whole new fantasies to consider. bc my knowledge is limited atm when i see something interesting i consider basics first. The hanger normally located at tip of DP= are you using that support now?

and perhaps somewhat ironically, future modders with eBay $150 DP may consider where to cut the 2.25" off and weld piece to fit their aftermarket 3" catback.
image.jpeg
 

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Discussion Starter #3 (Edited)
Hello
I did start to search for exhaust pieces on summit racing, you can do it that way but keep in mind your going to have to buy a
flex section piece of exhaust. The thing is
doing that way you also start using quite a
few clamps which start to add up and you
have more potential for exhaust leaks. There
are hangers you can buy that have a long rod on them that you clamp on the exhaust pipe and you slide the rod in the rubber mount. I would use all the factory mounting points because the exhaust is right below the drive shaft so you don’t want the exhaust bouncing around under the car or hanging to low. The section of exhaust after the cat is 2.50 after the resonator it goes to 2.25. Honestly it’s not a hard job for a custom exhaust shop to do if your at $150.00 now I would say you probably over
halfway there for a shop to do it. I used the Cobb pipe because I already had the Cobb cat back. Like I said i was trying to figure out
where the gain was coming from with a down pipe obviously without a cat there will be a difference but those options at least the ones I found still kept the 90degree bends.
Then there’s Cobb that uses a free flow
cat but eliminates the 90degree bends. I done enough car builds and had header back custom exhaust made at the shop. There isn’t that much difference from factory
cat and free flow. So I think anyway it comes
down to ether or eliminate the cat with a 3.00 inch pipe keeping the bends and choking it down to the factory exhaust the rest of the way or keeping your factory cat
eliminating the 90degree bends going to a
after market cat back the rest of the way. Of course another combo would be eliminate
the factory 90bends, keeping the factory exhaust the rest of the way. I don’t know how that would work out as far as performance. If you have any question feel free to ask.
 

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bends that aren't excessively tight and are proper mandrel bent do not add much restriction at all. nothing compared to a catalytic converter.

Having a full 3" inch exhaust with NO cat is the #1 key to exhaust gains... everything else is pretty insignificant in comparison to that.
 

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Discussion Starter #5
bends that aren't excessively tight and are proper mandrel bent do not add much restriction at all. nothing compared to a catalytic converter.

Having a full 3" inch exhaust with NO cat is the #1 key to exhaust gains... everything else is pretty insignificant in comparison to that.
mandrel bent pipes are important, but don’t mean much until you get to around
500hp
i know everybody sells mandrel bent. Also car manufacturers have went to stainless which isn’t as forgiving when your bending it.
Like I said no cat obviously is less restricted
than any kind of cat.
If your going for as much power as possible
you have to do it with no cat. But if want to keep your car legal that’s not an option.
What’s your definition of excessively tight?
 

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mandrel bent pipes are important, but don’t mean much until you get to around
500hp
i know everybody sells mandrel bent. Also car manufacturers have went to stainless which isn’t as forgiving when your bending it.
Like I said no cat obviously is less restricted
than any kind of cat.
If your going for as much power as possible
you have to do it with no cat. But if want to keep your car legal that’s not an option.
What’s your definition of excessively tight?
its not that simple. the diameter of the tube is the biggest factor in how much hp it can reasonably support but if its not mandrel bent its not going to flow like the size pipe it actually is because the curved areas of the tube will be a smaller dia than it would be if they weren't bent.

so unless your exhaust tube is already oversized for your application then it actually is very important to have a mandrel bent exhaust for ANY hp application if you want your exhaust to not restrict compared to mandrel.
 

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Discussion Starter #7
its not that simple. the diameter of the tube is the biggest factor in how much hp it can reasonably support but if its not mandrel bent its not going to flow like the size pipe it actually is because the curved areas of the tube will be a smaller dia than it would be if they weren't bent.

so unless your exhaust tube is already oversized for your application then it actually is very important to have a mandrel bent exhaust for ANY hp application if you want your exhaust to not restrict compared to mandrel.
I have always found It fascinating how GM,Chrsler,Ford I’ll just stay with big three
have been researching and developing automobiles for over hundred years with state of the art labs. But some how a vendor
selling performance mods who basically is an after the fact company with no where near the resources and engineering talent all seem to know more than a combined 300
years of experience.
 

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How bad is the smell off a catless downpipes? I drive with windows down 90% of the time, would I smell terrible at stop lights? would drivers behind my car be upset smelling my fumes? ive been behind one or two catless cars that smelled like pure fuel.
 

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Keep in mind that prior to 1980 there were no catalytic converters and cars did not smell. As a matter of fact cats tend to smell worse than no cats because of the sulfer biproducts. If the car is tuned properly it shouldn't stink.

Dave
 
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