When to decompress - Competition Diesel.Com

Goinbyyabig · 09-28-2015, 07:42 AM

I was wondering about opinions on when it's really beneficial to decompress a CR motor. I have an 06 Cummins, ported head, and have had a few sets of twins on it. Makes around 900/1600 fuel limited, due to stock rods, still. When I did the head install, many years ago, I did a bit of research and decided to use a .020" over head gasket to decompress, and now wonder if I should be stock compression. Looking to gain bottom end/driveability/transition into boost from none better, and wondering if a bump in compression might help. Please discuss...

chris lang · 09-28-2015, 08:26 AM

In on it for information.
My guess would be stock for a street drivability and decompress for competition obviously.

Marq92 · 10-06-2015, 11:07 PM

I would agree with Chris. Might be a good idea to put in some billet rods while you're at it.

09-28-2015, 07:42 AM	#1
Goinbyyabig Name: Goinbyyabig Title: Free Thinker, Innovator Status: Not Here Join Date: Apr 2009 Member`s Gallery Posts: 185	When to decompress I was wondering about opinions on when it's really beneficial to decompress a CR motor. I have an 06 Cummins, ported head, and have had a few sets of twins on it. Makes around 900/1600 fuel limited, due to stock rods, still. When I did the head install, many years ago, I did a bit of research and decided to use a .020" over head gasket to decompress, and now wonder if I should be stock compression. Looking to gain bottom end/driveability/transition into boost from none better, and wondering if a bump in compression might help. Please discuss...

09-28-2015, 08:26 AM	#2
chris lang Name: chris lang Title: Too Much Time Status: Not Here Join Date: Jun 2010 Member`s Gallery Posts: 843	In on it for information. My guess would be stock for a street drivability and decompress for competition obviously. __________________ Don't take what I post seriously; 60% of the time I'm drunk all the time

10-06-2015, 11:07 PM	#3
Marq92 Name: Marq92 Title: Too Much Time Status: Here Join Date: May 2012 Member`s Gallery Posts: 953	I would agree with Chris. Might be a good idea to put in some billet rods while you're at it. __________________ 2001.0 QCLB 3500 4x4 3.55 Toyo M-55 255/85R16 Brown's/Goerend 48RE sonnax shafts/maxed count Alto clutches Carli/Deaver 3.0 EMF BJ's PSC 6 bolt box Synergy steering TheRetroShop HID projector retrofit VLED's DC Power 180A alternator W-T ground mod ISSPRO EV2's