straight through exhaust

[prawnfarmer]

Is it bad for a Ford 7.3 PSD (or any diesel engine) to run a straight through exhaust? Some buddies were saying that diesels require back pressure?

 

[john_Bud]

(quoted from post at 05:55:54 11/27/08) Is it bad for a Ford 7.3 PSD (or any diesel engine) to run a straight through exhaust? Some buddies were saying that diesels require back pressure?

Your buddies are incorrect. A turbo diesel wants as little exhaust pressure as possible. Straight thru is ok for them. Neighbor's work truck a dodge 3500 cummins dropped it's muffler and picked up 2 mpg and a lot of low end grunt when pulling 20k of trailer.

jb

 

[Fordfarmer]

Only drawback to a straight-through exhaust I've ever heard of is in gas engines, where super free-flowing exhaust systems can actually reduce power (mostly torque) by pulling some fuel/air mix past the exhaust valve, due to intake/exhaust valve overlap. (especially true with engines running "big" cams) TUrbo diesels love low (or no) backpressure.

 

[john in la]

I can give you the biggest reason to not run straight threw exhaust.
Your ears!!!!!!!!!!!!!

 

[Anonymous-0]

I have st. ex on my 01 Dodge dsl., sounds great when under a load and is not too noisy in the cab.

 

[Welding man]

You can get by with it on the older models but the newer engines with cat. converters and down stream O2 sensors will turn on the Check engine light and set a code in the computer if you unhook them.

 

[jd plowboy]

i put a straight through exhaust on my 05 dodge and it gained 2 to 3 more mpg and a little more torque. mine runs fine and check engine light has not come on.

 

[prawnfarmer]

Some of my breakfast buddies said it would burn the exhaust valves. Apparently they had diesels mixed up with gasoline engines.

 

[jd plowboy]

that might be right on a ford but on my dodge i havent had any problem. you know ford has the better ideas

 

[Brian Jasper co. Ia]

Only the new diesel engines with a particulate filter in the exhaust will set DTC's if you remove the trap and catalyst. With older stuff, it's just illegal to remove the catalyst. If you have to pass emission testing, thats when they catch you...

 

[unioncreek]

jd plowboy,

Did you gain much noise in the cab? I have a 96 and have wanted to pull the cat, but don't want the noise.

Bobg

 

[jd plowboy]

it is alittle louder in the cab but not real bad unless you gas on it. mine sounds pretty good when it is under a load

 

[gtx1967jewison]

u betcha thats why all racers do it! to loose power! any 4-stroke engine will produce more power with free-er flowing exhaust. more fuel & FRESH air (read OXYGEN to burn more fuel) in equals more power & economy out. duh. it takes power to produce backPRESSURE.

 

[Fordfarmer]

Race engines are running at HIGH RPM's - not the lower RPM's where torque is most important. Yes, more fuel+oxygen in = more power (but not always economy) out... BUT gas engines (especially those with cams that have a lot of overlap on the intake and exhaust) CAN loose low-rpm torque if the exhaust is TOO free-flowing. The fresh fuel/air mix can get pulled right through without a chance to get burned. Torque and horse power are not the same... And even a straight-through exhaust will produce more back -pressure than running open headers like many race engines do.

 

[Orangefever]

diesels need to breath. most of the time you will gain a lil power and milage. If any of you wish to remove cat conv. off of late model diesels you do have to install whats called a blocker plate that plugs into your wiring harness this will keep your check engine light off

 

[jd plowboy]

i have a 05 dodge diesel and my service engine light is not on. all i did was cut converter off and added 4 inch pipe.

 

[Anonymous-0]

Your buddies are wrong! A diesel does not need back pressure. Only gasser's. The average, daily driven gasser, runs like crap with no mufflers. A diesel will run better.

 

[Brian Jasper co. Ia]

NOTHING needs back pressure. Properly functioning fuel injection will maintain proper air-fuel ratio. Older carbureted non feed back types may need a change in jetting to make up for increased air flow. Back pressure kills both mileage and performance. The mfr's do what's best for performance with sound level and life span being first concern.

 

[Orangefever]

I think it's more of a problem on chevy and fords
my 02 dodge had no problem but my 06 chevy it comes on it's ok without the muffler but the missing cat sets it off

 

[Anonymous-0]

GO TO A EXHAUST SHOP YOU TRUST AND PAY THEM TO PUT IN A (TEST PIPE) MAY COST $50.00 RUN IT FOR 1 MONTH TO LET YOU GET USE TO IT AND IF YOU DONT LIKE IT THEN YOU CAN REPLACE THE STOCK STUFF. RESIGNATION OF SOUND IS MOST OF THE PROBLEMS WHEN YOU ARE INBETWEEN A PULL AND COST.

 

[BLinWMI]

evidently you have never driven a Cummins, it makes absolutely no noticable difference in the Db with a straight pipe. I had the shop that put the pipe on mine do a sound test and it was within .5 Db of the muffled sound.

 

[JT]

I put a 4" turbo back open exhaust on my 2000 7.3ps, runs a lot better, is not that loud, sounds kinda cool at low rpm, you can hear the turbo whistling. Not a lot of noise at cruising speed either.
Jim