[95psdF250]

After seeing "AggiePSD" pictures of his home made downpipe I decided to go ahead and do a little more work on mine today at my work since I was doing nothing. I decided to take the flex pipe off and went ahead and dropped the hard pipe below the firewall and put the elbo back on pointing towards the rear. I did not have to make any modifications to the firewall.

Since I went ahead and done this I was not able to finish putting in the straight 4" pipe all the way back with the 5" chrome tip. I will have to tackle that Monday morning.

My question is: How much back pressure does the motor actually need. The way I am doing the exhaust now there will only be about 2 feet of 3" pipe and then it will go to a 4" straight pipe all the way back behind the tires and then turn out to the stock position with a 5" chrome tip. Will this be good or do I need a muffler of some sort to create more back pressure?

Since I was unable to get the rest of the exhaust done today all I have is about 3 feet of 3" pipe coming off the turbo for exhaust right now. Will this short open exhaust hurt anything until I get the rest on Monday?

I will say that it REALLY sounds AWESOME this way and you can REALLY here the turbo sing.

All your thoughts and info is GREATLY appriciated!!

I will have to say this is an AWESOME sight and all of you guys are GREAT.

I may have just joined a couple days ago but, I have been visiting this sight and learning for almost 2 years.

Thanks for all your HELP,
95psdF250

 

[RickHredf250]

[ QUOTE ]
All your thoughts and info is GREATLY appriciated!!

[/ QUOTE ]
Well here's mine....
None, its a good trade off for cooler egt's. If ouy could stand it and get away with it, run just the down pipe!
The Diesel is just one big air compressor, the more in and more air out (adding fuel of course helps!).
Rick H...

 

[Gone Fishen]

If it were legal there would be nothing except straight pipes. Backpressure causes shortened engine life.[excessive pressure]. Best to have very little or none.

 

[ford86]

[ QUOTE ]
Since I was unable to get the rest of the exhaust done today all I have is about 3 feet of 3" pipe coming off the turbo for exhaust right now.

[/ QUOTE ]

That is all i have been runnin fer a long time now and i love it... aint hurt nothin and prob. wont... but do what you like best ... remember its all about custumizin it /ubbthreads/images/graemlins/cool.gif

 

[AggiePSD]

Yep, the turbo creates plenty of backpressure itself. Speaking of backpressure, HERE is a good article explaining the facts and myths about needing backpressure for low end power. I learned quite a bit, seems to have more to do with exhaust velocity and scavenging than backpressure. Granted it talks about N/A engines, but it still applies. Kinda hard on the eyes, but good reading.

95psdF250, if you can snap some pics of what you are doing, I am curious and don't quite understand your description. /ubbthreads/images/graemlins/cool.gif

 

[johndeerebones]

While you're in there I would highly recommend an EBPV gut unless you intend to make a brake out of it, If you need info on how to do it PM me or make a post asking about it. If you think the turbo sounds good now you should here it without that nice big butterfly valve in its throat. You also drop your egt's a little and maybe get a bit faster spool up. /ubbthreads/images/graemlins/wink.gif

 

[stroker101]

i can see how a 3" constant diameter turbo outlet can be beneficial but, would an exhuast that has a diameter of 5" (or greater) really add any benefits to a fairly stock 7.3L PSD? other than sound?

 

[milner351]

I think you will reach a point of diminishing returns with larger and larger pipe diameters.
The area of a circle is Pi*r^2, so, when you increase the diameter of the pipe (D=2r) the area of the pipe increases by the sqaure of the radius.
The max volumetric flowrate through the pipe increases in direct proportion to the area....so.... for a nearly stock truck with stock injectors, turbo, and open element air cleaner, anything more than 4" is pure overkill.
For those lucky enough to have the money for huge injectors and turbos, running 35+psi of boost and what not, well, do what the tractor pullers do, come off the turbo and go through the hood straight toward the ski with the biggest pipe you can find!
/ubbthreads/images/graemlins/grin.gif

 

[RickHredf250]

[ QUOTE ]
The area of a circle is Pi*r^2, so, when you increase the diameter of the pipe (D=2r) the area of the pipe increases by the sqaure of the radius.
The max volumetric flowrate through the pipe increases in direct proportion to the area....so....

[/ QUOTE ] <font color="red"> You just gave me a HEADACHE! </font> /ubbthreads/images/graemlins/zombie.gif
[ QUOTE ]
for a nearly stock truck with stock injectors, turbo, and open element air cleaner, anything more than 4" is pure overkill.

[/ QUOTE ] <font color="blue">
That's the idea!</font> /ubbthreads/images/graemlins/crazy.gif
But in the end you are right... /ubbthreads/images/graemlins/smirk.gif
Rick H...

 

[95psdF250]

Well, I am only putting the 5" chrome tip on for looks. The basic exhaust will be about 2 feet of 3" from the turbo to about 4 feet of 4" and then about a 16" X 5" chrome tip coming out infront of the rear wheel. I seen a truck the same year as mine today with the exhaust coming out in front of the wheel and I thought it looked great so that is what I am going to do now.

Thanks for all of your info,

 

[ThreeStarJR]

Dang John, that hurt my wittle head! /ubbthreads/images/graemlins/biggrin.gif /ubbthreads/images/graemlins/biggrin.gif

 

[95psdF250]

[ QUOTE ]
While you're in there I would highly recommend an EBPV gut unless you intend to make a brake out of it, - If you think the turbo sounds good now you should here it without that nice big butterfly valve in its throat.

[/ QUOTE ]

What real advantages will I gain and will gutting the EBPV make enough difference in the turbo sound, EGT's, and spoll up to be worth the hassle?

I am very interested in doing this but I need to know exactly what all it will gain me before I decide to tackle it.

Thanks,
95psdF250

 

[masami]

Absolutely! /ubbthreads/images/graemlins/biggrin.gif