Performance and Accessories 2nd gen only Talk about Dodge/Cummins aftermarket products for second generation trucks here. Can include high-performance mods, or general accessories.

Twins v. Compounds

Thread Tools
 
Search this Thread
 
Old 07-10-2009 | 08:12 PM
  #1  
CODODGE2500MAN's Avatar
Thread Starter
Chapter President
 
Joined: Oct 2004
Posts: 978
Likes: 0
From: Highlands Ranch, Colorado
Twins v. Compounds

So what's the difference?

Advantages/disadvantages of each?

Thanks....
Old 07-10-2009 | 08:55 PM
  #2  
kevellis32's Avatar
Registered User
 
Joined: Oct 2004
Posts: 584
Likes: 0
From: Fort Collins CO
I may not be correct, but from what I think I know is that in order to have true twin turbos you have to have one turbo on each side of the exhaust manifold(each of the same size) which isn't possible on a truck like ours. Its more of something that you see on gas vehicles with two headers. Compounds are what our trucks really run. One smaller turbo that feeds a much larger turbo. I say I have twins for two reasons. Its faster to say, and a lot of people have no clue what compound turbo's are.
Old 07-10-2009 | 10:18 PM
  #3  
1-5-3-6-2-4's Avatar
Registered User
 
Joined: Oct 2006
Posts: 3,142
Likes: 0
From: Okotoks AB
exactly what he said people slang the term "twins" on cummins but they are in fact compound turbocharging different sized turbos in series. twins on the V8s and any V engine twin turbos 1 bank 1 turbo. same sized turbos in parrallel. don't get hung up on the terminology. theres enough of the grammer and etiquette police around.
Old 07-11-2009 | 12:35 AM
  #4  
Mike D's Avatar
Chapter President
 
Joined: Nov 2003
Posts: 3,807
Likes: 1
From: Rural Hall, NC
One smaller turbo that feeds a much larger turbo
It's actually the other way around. The big charger is the primary and it feeds the secondary/small charger. The secondary does drive the primary with it's exhaust.
Old 07-11-2009 | 01:04 AM
  #5  
1-5-3-6-2-4's Avatar
Registered User
 
Joined: Oct 2006
Posts: 3,142
Likes: 0
From: Okotoks AB
that is correct. follow the compressor path. I do know that. I was in a rush. point there was unequal charger sizes in SERIES in compounding. Equal chargers in PARALLEL in twins.
Old 07-11-2009 | 01:17 AM
  #6  
kevellis32's Avatar
Registered User
 
Joined: Oct 2004
Posts: 584
Likes: 0
From: Fort Collins CO
Yea, my bad. I knew I was going to mess something up in my explanation. I can put the stuff together pretty well, but explaining how it works isn't my strong point.

And I have one question for y'all that are good with compound tweaking. I would like to get a little better low end spool. I've heard that I want to tighten my waste gate a little bit. Is that correct?
Main reason I ask is because if I get on it to get goin when I pull out in traffic I will smoke out a city block and I don't feel like being responsible for an accident. And I cannot turn down my fuel anymore or I will loose my top end.
Old 07-11-2009 | 04:10 AM
  #7  
j-fox's Avatar
Registered User
 
Joined: Mar 2002
Posts: 2,541
Likes: 1
A closed wastegate has nothing to do with spool up.
An open one will pretty much prevent spool up too.
Old 07-11-2009 | 11:28 AM
  #8  
pickupman96's Avatar
Registered User
 
Joined: Dec 2007
Posts: 308
Likes: 0
From: Danbury, Ct
Just a idea but how would it work if you were to split the manifold and and run true twins. I know there would be more to it than just that but in my head atleast it sounds good.
Old 07-11-2009 | 12:03 PM
  #9  
j-fox's Avatar
Registered User
 
Joined: Mar 2002
Posts: 2,541
Likes: 1
That has been tried, compounds work better.
Do a search and read up.
Old 07-11-2009 | 08:55 PM
  #10  
dieselman2300's Avatar
Registered User
 
Joined: Aug 2007
Posts: 1,133
Likes: 1
From: Beautiful USA!
Originally Posted by kevellis32
Yea, my bad. I knew I was going to mess something up in my explanation. I can put the stuff together pretty well, but explaining how it works isn't my strong point.

And I have one question for y'all that are good with compound tweaking. I would like to get a little better low end spool. I've heard that I want to tighten my waste gate a little bit. Is that correct?
Main reason I ask is because if I get on it to get goin when I pull out in traffic I will smoke out a city block and I don't feel like being responsible for an accident. And I cannot turn down my fuel anymore or I will loose my top end.
You need to set your top turbo wastegate to open around 25-30psi.
That will get them to spool faster.

If you are smoking that bad, you need to adjust your pre-boost fuel on the back of the pump. It will not effect full fuel at all. If they are smoking that bad, you are actually hindering spoolup by "putting ou the fire".
Old 07-11-2009 | 09:23 PM
  #11  
kevellis32's Avatar
Registered User
 
Joined: Oct 2004
Posts: 584
Likes: 0
From: Fort Collins CO
Is it possible that I have any bit of a timing issue. I have tried different star wheel adjustments for probably about 12 hours and too low I run out of fuel and too high it snuffs it out like you said.
Old 07-11-2009 | 11:08 PM
  #12  
dieselman2300's Avatar
Registered User
 
Joined: Aug 2007
Posts: 1,133
Likes: 1
From: Beautiful USA!
Originally Posted by kevellis32
Is it possible that I have any bit of a timing issue. I have tried different star wheel adjustments for probably about 12 hours and too low I run out of fuel and too high it snuffs it out like you said.
You should set your afc to fuul fuel at around 25psi.
You take your afc off, use shop air where the afc boost line goes into and adjust the starwheel so it afc arm will slide forward at 25psi.

On the back of the afc right next to the boost line is anothe metal cap with 2 screws one being tamper proof. Cut that cap off and that is the pre boost screw. Loosening it cuts fuel down before boost hence pre-boost fuel.

Your starwheel controls WOT full fuel load.
The pre-boost fuel screw controls the fuel before boost.

Hope this helps.

If you cant find it, I will take a picture for you as I have an extra AFC. PM me and let me know.

Also, have you done all the AFC mods?
Old 07-11-2009 | 11:12 PM
  #13  
dieselman2300's Avatar
Registered User
 
Joined: Aug 2007
Posts: 1,133
Likes: 1
From: Beautiful USA!
Here is an excellent thread about AFC mods and the 4th pic. shows the pre-boost screw without the cover on it.

http://competitiondiesel.com/forums/...ad.php?t=11047
Old 07-11-2009 | 11:12 PM
  #14  
kevellis32's Avatar
Registered User
 
Joined: Oct 2004
Posts: 584
Likes: 0
From: Fort Collins CO
No AFC modification done at all. I have a good feeling that may be my main issue. If possible could you please send a picture of that screw you are talking about. My email is Laxboy3211@hotmail.com if that makes it easier.
Thanks a bunch for your help!
Old 07-11-2009 | 11:16 PM
  #15  
kevellis32's Avatar
Registered User
 
Joined: Oct 2004
Posts: 584
Likes: 0
From: Fort Collins CO
That is one of the most informative threads I have seen ina while...I will get on doin that when I get home from work.


Quick Reply: Twins v. Compounds



All times are GMT -5. The time now is 01:35 PM.