Compression on 12 and 24v's?

[Devan Manis]

Is the compression on a 24v higher than on a 12? Because my truck a 24v is louder at idle than my friends, a 12v. Mine is quieter out of the exhaust but I think that is because mine has the small mbrp muffler thing. Just curious

 

[JFaughn]

Compression is the same & not related to how much noise you can hear .
Many variables for that , additives ect.

 

[rbattelle]

I've always thought the 24v engines were a bit noisier than the 12v. Both engines sound nice.

Ryan

 

[MCummings]

The biggest noise difference is adjustable timing and injection pressures.



The 24V runs very high timing at idle, and has higher injection pressures.



The 12V is a much "softer" motor with retarded timing at idle, and low injection pressures. Listen to a 1st gen idle. They are very quiet at idle. Lower injection pressure, and even lower timing.



Merrick

 

[KCloward]

Is the compression on a 24v higher than on a 12? Because my truck a 24v is louder at idle than my friends, a 12v. Mine is quieter out of the exhaust but I think that is because mine has the small mbrp muffler thing. Just curious

Needless to say they both sound great at WOT. :-laf



I've also noticed his is higher at idle lately but now we know why.



Bryce

 

[16919]

Actually, it may be the same for a 12v and a SO 24v but the HO 24v has slightly higher compression than the SO. If I remember right it is like 16. 8 for the SO and 17. 1 for the HO ... ... .

 

[jwgary]

Most of the noise at idle is caused from the injection pump. As stated above, the higher pressure from the 24v pump will be louder. I was thinking that the compression of a 24v might even be lower?

 

[raychem]

Injection pressure for a p-pump is 17k plus psi at full load

vp-44 is 14k plus at full load



Depending on timing. . you can make a p pump as loud as a vp truck. What your hearing is the difference in timing for each motor since the vp advances timing up to 6* if I remember correctly and has higher injector opening pressure. The p-pump is FIXED timing with lower a lower injector opening pressure. Also a 24v is central injection while a 12v os offset injection. I am speaking stock for stock, when you start to mod the motors, everything changes.



Richard

 

[MCummings]

I coulda swore the Injection pressures were lowest in the 1st gen, and progressivly higher untill the current '08's... .





Merrick

 

[JoeBioDiesel]

from the Dodge Cummins Student Workbook:

Injector pop pressures.

12V VE Pumped 3,625 psi

12V P7100 Pumped 3,770 psi

24V VP Pumped 4, 500 psi



From Snap-on Shopkey Information System

24V with Auto Trans and 5 speed 16. 3:1

24V with 6 Speed 17. 0:1

2nd Gen 12V 17. 5:1

1st Gen 12V 17. 5:1

Common Rail 17. 2:1



Joe

 

[Devan Manis]

Actually, it may be the same for a 12v and a SO 24v but the HO 24v has slightly higher compression than the SO. If I remember right it is like 16. 8 for the SO and 17. 1 for the HO ... ... .

Yeah I've noticed a difference in mine and my dads. Dads is an 01, but also an HO. Mine isn't an HO and they do sound slightly different, but there isn't a huge difference.

 

[16919]

My #'s were off but in the end still right.