I had a 2005 f-250 5.4l with true dual exhaust and no muffler. All i had was the stock cat converter and straight pipe.I want to do this to my 2004 f-350 v-10. does this hurt the motor with no muffler on it.Also i wonder how much louder the v-10 would be.Anbody know????????

 

No, it will not hurt the motor. However, I don't think you want to mess with the V-10. They tend to sound strange, and they get worse sounding as they get louder in my opinion.

 

do you know of anybody that has done it????

 

v10's have the same issue as the v6's do.. people say both cant sound good because of their "even firing order".. people go putting the same mufflers/exhaust systems on both thinking theyd sound good cuz they do on the muscle car/truck v8's but they wont... what you need for the 2 engines are mufflers that kill off the high frequency sounds.. thats what gives them that ricer tone.. flowmasters original recipe mufflers help with this.. itll kill off the high frequency tones leaving the deeper tones people like.. supposedly cherrybombs new vortex muffler uses the same tech but in a different style and freer air flow..

another thing that will help with the sound is to lose the cats and run an off-road pipe... but its not "legal" to do it.. and pretty much wont pass inspections with that.. what alot of muscle car guys end up doing is having 2 mid pipes and swap them when inspection time comes around... but less you have either MIL eliminators or get a tune to turn off your rear o2 sensors your just going to be throwing codes without the cats...

 

There is absolutely nothing to gain by eliminating the cat on a newer vehicle with computer controls.
It will be extremely loud and sound kind of off, like the previous OP said.
Even running no mufflers is very loud and makes no sense really...
unless you are deaf already and dont care about your neighbors.
Run a good single exhaust, no bigger than 3" with a Flowmaster muffler of your liking and forget about all the rest. It will sound good and keep you legal. Consider a K&N intake, headers, etc. also.

Rent-A-Man! lawn & tree
Killeen, TX

 

running with no mufflers wont actually hurt the engine but engines like having a little bit of back pressure... its been proven that flomaster mufflers make more hp then straight pipes.

 

Thanks for the info, I will be doing my pipes in a few days

 

Destroying a myth.

Some say that "an engine needs backpressure to work correctly." Is this true?

No. It would be more correct to say, "a perfectly stock engine that cannot adjust its fuel delivery needs backpressure to work correctly." This idea is a myth. As with all myths, however, there is a hint of fact with this one. Particularly, some people equate backpressure with torque, and others fear that too little backpressure will lead to valve burning.

The first reason why people say "backpressure is good" is because they believe that increased backpressure by itself will increase torque, particularly with a stock exhaust manifold. Granted, some stock manifolds act somewhat like performance headers at low RPM, but these manifolds will exhibit poor performance at higher RPM. This, however does not automatically lead to the conclusion that backpressure produces more torque. The increase in torque is not due to backpressure, but to the effects of changes in fuel/air mixture, which will be described in more detail below.

The other reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.

The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.

Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.

Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust because of the way that backpressure caused air to flow backwards through the carburetor after the air already got loaded down with fuel, and caused the air to receive a second load of fuel. While a bad design, it was nonetheless used in a lot of vehicles. Once these vehicles received performance mods that reduced backpressure, they no longer had that double-loading effect, and then tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.

The truth about exhaust backpressure and torque

 

Auto Exhaust Science

More...

 

Why is it then if you dyno a car with straight pipes and then put flowmasters on it and dyno it again there will be an increase in power and torque? All you've done is create a little bit of backpressure

 

For the same reason people pick up .2th of a second or more at the track with exhaust cut-outs?

Mufflers are just one part of a much larger equation. If a restriction in the exhaust increases your performance you need to take a look at what's wrong upstream. Especially when your talking about three or four hp on a dyno.

In the case of an otherwise stock truck it won't help or hurt anything appreciably. What does a V10 rev to? 4,500rpm?

 

this one says pretty much the same thing about backpressure.. but talks about it for other reasons...

Performance Unlimited 4-Wheel & Off Road Center - Hartford, Wisconsin - USA Technical Documents

its under the exhaust piping selection diagram...

 

An 04' 6.8l with the automatic trans and stock tuning will not rev above 5100rpm. The tach goes to 6 grand with no redline but the rev limiter in both neutral and drive is well shy of 6k rpm.

I got Doug Thorley long tube headers/y pipe, dynatech 3" cat, to a Flowmaster ForceII catback all mandrel bent 3" pipe. The velocity of the exhaust is great, the low end is great and the top end is great and I lost nothing with the combo.

I've had all kinds of exhaust configurations on my 6.8l over the years and my current setup works and sounds better than anything I've had. Best bet for the V10 is to use a chambered muffler with a decent amount of capacity to it. If you want to put more power to the ground get a tuner with a good tune for the truck, a good tune (like 5 Star tuning) will do more than screwing with catback exhaust systems. The exhaust manifolds and y-pipe on the 6.8l are also horrible and hurt power a lot.

A V10 with no mufflers will be loud and have very noticeable drone, it will be annoying.
Not necessarily. Ford trucks like the SD run stoich all the time except for over temp conditions. The factory tuning is setup to switch into open loop under extended periods of engine braking at which the fuel injectors are shut off to save fuel. The stock tuning leaves a lot to be desired and can be improved on greatly.

 

wow i didnt know anyone made long tube headers for the v10's.. all i could ever find were short tubes... got a link for that site man??

 

Basically short tubes just bolt up to the factory Y-pipe. Long tubes replace the entire Y pipe assembly. Doug Thorley, Banks, Borla and Hedmann al make/made long tube headers for the 2V 6.8l. Borla stopped making them years ago and Thorley just recently discontinued their headers also. Banks makes a set of long tubes for the 3V 6.8l but they are only for the large motorhome chassis. The Thorleys are the only tri-y headers for the V10, they make lots of torque but still make good HP.

SummitRacing.com

Banks Power | 99-09 Ford - 6.8L V-10>>PowerPack® System