Turbo "j-pipe" angles for making a new pipe...

[merlot566jka]

What are the angles?

I can obviously see the lower "j" part of the pipe is two 90s. What about the bend right before it comes up through the fender and turns into the stack? (45*? 30*?) what about the one that goes into the engine bay? (???)

I am thinking about fabricating a larger diameter of pipe, and for cost estimate purposes I would like to know the angles.

I looked at the dual exhaust threads... not what I am after.
I dont watn to run it under the cab and out the back either.
I like the stock location, just want a bigger pipe (from the turbo to the stack)

I cant measure them on my truck cause I am somewhere in the Pacific Ocean (again!).

Thanks for any help folks!

-Jonathan Anderson

 

[merlot566jka]

ttt!

 

[jatonka]

If you are gonna do all that work, why not get it right and put it back horizontal and exit on the right, ahead of the forward tandem? The noise is fun when you're young but you won't be young forever. It's pretty nice to be able to talk to your passenger. JT

 

[merlot566jka]

Several reasons actually,

1. I like the look of the fender exhaust.
2. There are mufflers if its too loud, plus I have a 'D' turbo.
3. I dont like the exhaust down low
4. I am 27 and not ready to be mature about the exhaust noise and my hearing
5. I do not like to talk, or listen to my passengers while I am driving.
6. The work involved in welding a few bends together isnt much work to me at all, I enjoy welding.
7. Shorter and larger exhaust tends to lower EGT and increase available power.


I do appreciate the response from such a well known member! thank you!

 

[aaron379]

Several reasons actually,

1. I like the look of the fender exhaust.
2. There are mufflers if its too loud, plus I have a 'D' turbo.
3. I dont like the exhaust down low
4. I am 27 and not ready to be mature about the exhaust noise and my hearing
5. I do not like to talk, or listen to my passengers while I am driving.
6. The work involved in welding a few bends together isnt much work to me at all, I enjoy welding.
7. Shorter and larger exhaust tends to lower EGT and increase available power.


I do appreciate the response from such a well known member! thank you!

i agree on 1-7 love number 5 so do u want biger exhaust from turbo out or just turbo to bottom of fender with stock stack?

 

[merlot566jka]

Bigger from turbo back. Including the stack. I have found a place to get everything at a very reasonable price, I just need to know what angles I need.

 

[frodobaggins]

What is the purpose of the larger pipe, just looks ?

 

[mightymanx]

There will be no performance gain from that mod. The limiting factor is the Turbo not the pipe by wide margin.

 

[aaron379]

i just redid my exhaust the u part i got 2 90s but when it was off looked like 2 45s one turbo side and one stack side but i wouldnt be surprised if they werent stock angles im sure there some kind of weird angle u cant get but if ur a good fabricator/welder and u ordered those im sure u could make them work if u had to.... what size were u doing?

 

[merlot566jka]

Purpose of the larger pipe is #7, "Shorter and larger exhaust tends to lower EGT and increase available power"

Mightymanx, no performance gain? could you explain your reasoning?
The "D" turbo is better sized than the "C", but yes I'll agree neither is the best for making the most power. But if we do some simple size comparison, a little bit of math, we see that the "D" turbo isnt too far off its rocker here. Whichever turbo may be on there, we can also observe the 3.5" exhaust pipe. Thats a bit too small for the size of the engine and its displacement with a turbo. (I've read it was designed that way to help accelerate the air up and away from the troops).
When a larger pipe is used, the exhaust gas tends to flow our with less restriction (back-pressure). From the basics we know that the more a gas moves, the lower its pressure is. The easier and faster evacuation of the exhaust gas will reduce the amount of heat that is sustained in the pipe. This lowers EGT. The turbo is no longer using some of its force to "push" the exhaust gas away and out the pipe...instead the gas has plenty of room to expand and move out of the pipe. Once we have lowered the EGT, we can add more fuel to increase power until we get to the point the turbo is too far out of its range or there isnt enough fuel to go any further.

(note: this is BASIC. I could do an advanced writeup in another thread, lets keep this on subject)

Aaron379, Thats what I was thinking, that they were like 45*. But I didnt want to goof it and order the wrong angles. I can get 15*, 30*, 45* and 90* bends. I was looking at 5" pipe. You just redid your own... from scratch or did you just put on a new J-pipe?

so does anyone have a Jpipe thats off the truck right now and can measure the angles?

thanks,
Jonathan Anderson

 

[aaron379]

Purpose of the larger pipe is #7, "Shorter and larger exhaust tends to lower EGT and increase available power"

Mightymanx, no performance gain? could you explain your reasoning?
The "D" turbo is better sized than the "C", but yes I'll agree neither is the best for making the most power. But if we do some simple size comparison, a little bit of math, we see that the "D" turbo isnt too far off its rocker here. Whichever turbo may be on there, we can also observe the 3.5" exhaust pipe. Thats a bit too small for the size of the engine and its displacement with a turbo. (I've read it was designed that way to help accelerate the air up and away from the troops).
When a larger pipe is used, the exhaust gas tends to flow our with less restriction (back-pressure). From the basics we know that the more a gas moves, the lower its pressure is. The easier and faster evacuation of the exhaust gas will reduce the amount of heat that is sustained in the pipe. This lowers EGT. The turbo is no longer using some of its force to "push" the exhaust gas away and out the pipe...instead the gas has plenty of room to expand and move out of the pipe. Once we have lowered the EGT, we can add more fuel to increase power until we get to the point the turbo is too far out of its range or there isnt enough fuel to go any further.

(note: this is BASIC. I could do an advanced writeup in another thread, lets keep this on subject)

Aaron379, Thats what I was thinking, that they were like 45*. But I didnt want to goof it and order the wrong angles. I can get 15*, 30*, 45* and 90* bends. I was looking at 5" pipe. You just redid your own... from scratch or did you just put on a new J-pipe?

so does anyone have a Jpipe thats off the truck right now and can measure the angles?

thanks,
Jonathan Anderson

5 inch would be nice it would have a deep rumble... mine was rusted out at the bottom so i cut the u part off and got 2 90s and welded them on to the stock stack and the par that goes on the flex a new j is like 180 and my fix costed me 70

 

[mightymanx]

You can take the pipe completley off and gain nothing this is why a biger pipe won't help in this case yes I agree with the theoory this is why Step headders and pulse timing are also important in advanced aplications. In practice on this application the turbo so innefficent that it is a wasted effort to try and improve it with a propper sized turbo you would see benifits from ehaust tuning. But a T-6 on a 465 engine just does not really make a difference. This is why the only way to get the turbo to make any worth while boost is to up the fuel to the point that there is combustion in the exhaust. While it works but it is most definatly not the right way to do it.

This is why I am still tryng to graft a HX-35 in with an intercooler and a wastegate that way I can adjust boost and fuel levels like you are suposed to. Then if I notice a need I will try and tune the ehaust. but I am 99% positive that there will simply never be that level of performance in this engine (at least for what I want to do with it) This way I can get a usable 15psi of boost with out having to try and make a turbo ainto some form of ghetto jet engine. (I am slacking due to looking for a post military retirement job, but I do have all the pieces parts staring me in the face.)

I am not trying to disuade you from doing it but if it is for performance vice looks and sound I think you will be disapointed. I gained nothing when I tried it with an unmuffled 4" long turnout, vice the stock setup with a dynomax muffler on it.

 

[merlot566jka]

Pulse timing uses helmholtz theory to tune intake and exhaust runners to take advantage of 3 different "pulses" that occur in a running engine.

Step headers are mostly used to keep velocity up and reduce back pressure where space isnt a luxury.

Neither of those concepts are applicable to a turbo diesel. The pulses are ruined in the turbo itself. And stepping the headers is ridiculous when the runners are inches long... But I think I get what your saying, "tuning is important"

Increasing the volume on a turbo diesels exhaust reduces back pressure, we know this. It reduces pumping loss (pumping of the turbo, and in turn the VE of the engine increases). So yes, it does increase power. In no way do I think this engine is capable of making decent power. I do think some minor modifications would lower EGTs. I am fairly certain it would improve MPG as well.

But this should all probably be put in another thread... As this has totally gone off topic!

Back to the original question...

What angles are on the exhaust?

 

[Cleptomaniac]

lol Gotta love it on here!! I would measure mine but it has been chopped off and flex pipe has been run to dump it under the truck. But when you get it done let us know what the results are. I was thinking of the same mod. The fumes are really bad with it under the truck!!