Engine/Transmission (1998.5 - 2002) Exhaust system questions

[TJMIV]

I did`nt get much of a response when I listed this topic as exhaust restrictions so I`ll try this a different way. My question was how much good can going to a 4" or larger system on the exhaust do if you still have a neckdown situation off the turbo housing? Seems to me to get the best benefits you would almost have to change out the turbo exhaust housing. I just re-read Joe Donnelly`s article about AIR+FUEL=POWER, and it seems that he also is saying that you would also benefit from a 16sq. cm. outlet. I am not an expert in this area by any means, but I am interested in a larger exhaust when I start my other mods. , any light shed on this subject may get me out of the dark. Sorry for such a long post but I gotta know. TIA Oo.

 

[fj40charles]

I agree with Joe Donnelly's assessment. You will not get the full benefit of a 4" exhaust with the stock exhaust housing on the turbo. I'd look at a 14 or 16 cm exhaust housing for the turbo. Or, you could upgrade to a HX40 with a 16cm housing so you'll have full 4" exhaust from the turbo out.



Be sure to have some additional fueling to help spin the turbo with the larger exhaust housing.



Hope this helps. .



Charles

 

[Ncostello]

Its true you wont get the "full" benefit of a 4" system with the turbo neck being smaller... you'll still get a lot. The neck is just one component of an entire system. If you change a large portion of that system you are going to get a correspondingly large benefit.



Flow for air, exhaust, liquid is very similar. A particular fire hydrant, for example, is capapble of flowing 1250 gpm. Hook up a 2. 5" diameter fire hose to the 2. 5" outlet and you will get perhaps 500 gpm at some distance away... maybe 750 feet. Hook up a 5" diameter hose to the same 2. 5" outlet and you will get the practically the full 1250 gpm some 750 feet away. (I did no math here... just from experience in using). Hook up the same hoses to the 4. 5" outlet and you will find similar results. The smaller line has too much friction to overcome for big flows... much more friction than the outlet at the beginning of the system.



The same could be said for the turbo outlet. The 4" system will provide much lower overall resistance to flow over the long run the exhaust has to take. While the larger neck will help... I wouldn't think it would be tremendously noticable unless your really putting down some big time power where every little bit helps.

 

[Mark Craig]

4 Inch Exhaust benefits

TJMIV,



Ncostello is correct as are the others here, to get max benefit you need to have a true 4 inch outlet etc. For most folks it's a difference that is pretty minor though. The difference for a typical member with say an EZ or maybe Super Chips tuner and an exhaust and air intake is way sufficient to lower the EGT's to a safe level and increase flow get the additional HP etc.



Now if youre going to really BOMB it with injectors and COMP box or maybe even more and you're going for all the HP available a true 4 inch outlet housing would be the best way to go.



What I'm attempting to say is you will get large EGT drop with a stock housing and a good flowing 4 inch system, you'll get some hp and torque, the turbo will spool up sooner etc etc all with a stock housing. For most folks thats all they need, if you're going for broke HP wise then a change is wanted and in some cases necessary as well. Call us if you need any more info.



Mark @ DPPI

 

[illflem]

The length of the restriction makes a big difference, sometimes the effect of a short drop in pipe size is negligible.

Relating it to water as Neil did, we use 2'' valves on a 4'' pipe flowing 250 gallons a minute with a minor pressure drop caused by restriction.

Common plumbing practice, sure beats spending $300 for a 4'' valve when a $40 2'' one will suffice.

 

[Car_nut57]

Exhaust Outlet

If you want to get more flow through the exhaust outlet housing on the turbo, replace it with a Banks Power Elbow and continue with a 4" exhaust. The Power Elbow reduces outlet back pressure and can be used with Banks exhaust or others.

 

[fj40charles]

Re: Exhaust Outlet

Originally posted by Car_nut57

If you want to get more flow through the exhaust outlet housing on the turbo, replace it with a Banks Power Elbow and continue with a 4" exhaust. The Power Elbow reduces outlet back pressure and can be used with Banks exhaust or others.

No offense to bank$, but for the money, I'd think you be better off spending your money towards a HX40 from PDR.

 

[Car_nut57]

Re: Re: Exhaust Outlet

Originally posted by fj40charles

No offense to bank$, but for the money, I'd think you be better off spending your money towards a HX40 from PDR.

You are right, an HX40 would out perform the Power Elbow, but also costs considerably more $.

 

[TJMIV]

Thanks to everyone that responded to my questions about this . I understand it a lot better the way you guys explained it in reference to length of the restriction. I don`t understand it good enough to know how much more fuel & timing it would take to push an hx40 without turbo lag. I don`t intend to dragrace or do any pulling, but just to have a little more fun, of course I am starting to feel how hard this bombing bug can bite and there are still a million questions that I want to ask. Oo.

 

[Car_nut57]

HX40 Turbo Lag

Originally posted by TJMIV

Thanks to everyone that responded to my questions about this . I understand it a lot better the way you guys explained it in reference to length of the restriction. I don`t understand it good enough to know how much more fuel & timing it would take to push an hx40 without turbo lag. I don`t intend to dragrace or do any pulling, but just to have a little more fun, of course I am starting to feel how hard this bombing bug can bite and there are still a million questions that I want to ask. Oo.

One of our Turbo Air Guide (TAG) testers has an HX40 and he has reported that the TAG made a significant improvement in his lag.

 

[KEarnest]

TAG w/ PDR HX40

I'm using a TAG with the PDR HX40 and it greatly reduces both turbo lag and black smoke and it increases my mpg's. I can still blow black smoke at low boost (<4psi) but if I am at 4psi or more, the smoke is all but non-existent, even with the PMax on level 4.



I posted some pics of the TAG installed in the HX40 in this thread https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=80321