How to decide what size DP? - Ford Mustang Forums : Corral.net Mustang Forum
 3Likes
  • 1 Post By TomR
  • 1 Post By wytwolf
  • 1 Post By 97stanger97
 
LinkBack Thread Tools Display Modes
post #1 of 17 Old 06-30-2016, 08:35 PM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
How to decide what size DP?

Ive been trying to research online but can't really find much. Is there a specific formula or anything I should be considering when deciding what size DP to run? Obviously every car is different, but it seems like most people just run a certain size and end up changing it down the road and seeing how the car responds. My build is a built 2v 4.6, 10:1, TF 38 cc heads with MHS stage 3 turbo cams, edelbrock manifold, and E85. Planning on the turbo setup to consis of a PTE 7675 CEA and CG Fab hot side. The hot side comes standard with a 3" DP, and I will most likely just run open DP. Does anybody have any thoughts if the 3" would be good enough or should I look to be going bigger? Goals for the car are 800+ through an auto.


1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
Sponsored Links
Advertisement
 
post #2 of 17 Old 06-30-2016, 11:06 PM
Registered User
 
KEVIN$'s Avatar
 
Trader Feedback: (8)
Join Date: Nov 2001
Location: Lincoln NE
Posts: 3,892
IMO, For "only" 800hp with your combo I don't think it's going to matter a whole lot whether you go 3" or 4" if you're running open DP. A bunch of people making well over that with a 3" so I would run whatever fits. Where do you plan on dumping the exhaust?

ks



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Kevin Slaby
2002 GT 2V 902hp/820tq through the muffs.
http://baselinesuspensions.com/Projects/balrog.htm
KEVIN$ is offline  
post #3 of 17 Old 07-01-2016, 01:33 AM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Quote:
Originally Posted by KEVIN$ View Post
IMO, For "only" 800hp with your combo I don't think it's going to matter a whole lot whether you go 3" or 4" if you're running open DP. A bunch of people making well over that with a 3" so I would run whatever fits. Where do you plan on dumping the exhaust?

ks
I will either dump it right at the turbo or run it out the front bumper
97stanger97 is offline  
Sponsored Links
Advertisement
 
post #4 of 17 Old 07-01-2016, 08:40 AM
Registered User
 
TomR's Avatar
 
Trader Feedback: (2)
Join Date: Aug 2009
Location: Macon, GA
Posts: 4,947
Garage
Watch local rules if you want to race heads up. Around here they ban front exits and sometimes require exhaust to the back axle or behind driver.
97stanger97 likes this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
89 LX. 363, single turbo, Super Vic EFI, TFS high port heads by TEA, solid roller, glide. Holley HP EFI. (exact combo varies)
TomR is offline  
post #5 of 17 Old 07-01-2016, 04:42 PM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Quote:
Originally Posted by TomR View Post
Watch local rules if you want to race heads up. Around here they ban front exits and sometimes require exhaust to the back axle or behind driver.
Thanks for the heads up, this will 99% be a street car though so I'm not too concerned about race requirements. Appreciate the looking out though.

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #6 of 17 Old 07-01-2016, 04:43 PM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Since the CEA 7675 has a 3" outlet, would there be any benefit to going with a 3.5" or 4", or would it be most efficient to stick with the 3" to match the outlet?

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #7 of 17 Old 07-01-2016, 07:09 PM
Registered User
 
KEVIN$'s Avatar
 
Trader Feedback: (8)
Join Date: Nov 2001
Location: Lincoln NE
Posts: 3,892
I don't think I've ever heard of anyone losing power from a too large of DP since it's not being used to scavenge the exhaust. I would think that the larger one would help by eliminating any potential back pressure.

ks


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Kevin Slaby
2002 GT 2V 902hp/820tq through the muffs.
http://baselinesuspensions.com/Projects/balrog.htm
KEVIN$ is offline  
post #8 of 17 Old 07-01-2016, 11:31 PM
Registered User
 
Weather Man's Avatar
 
Trader Feedback: (0)
Join Date: Jul 2014
Location: MN
Posts: 128
I had horrible back pressure issues with 3 inch down pipe. I had to buy a boost controller that could handle duty cycle to keep the boost from tailing off. Went to 4" off the turbo and all my problems went away.

This is my current setup. I am running custom Lunati turbo cams... 225/229 at .050, .494/.496 Lift, Cut 115 LSA With A 105 ICL

Cold Side With Mishimoto R Line Intercooler, Garrett GT4094R Ball Bearing Turbo 1.06 A/R With Tial "Q" BOV & Dual F35 Wastegates, Swaintech Coating On Hotside Piping & Turbo Hotside Housing,

707 HP on 13 psi.

Good luck with your build.

2008 Mustang GT
Weather Man is offline  
post #9 of 17 Old 07-02-2016, 08:40 AM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Quote:
Originally Posted by Weather Man View Post
I had horrible back pressure issues with 3 inch down pipe. I had to buy a boost controller that could handle duty cycle to keep the boost from tailing off. Went to 4" off the turbo and all my problems went away.

This is my current setup. I am running custom Lunati turbo cams... 225/229 at .050, .494/.496 Lift, Cut 115 LSA With A 105 ICL

Cold Side With Mishimoto R Line Intercooler, Garrett GT4094R Ball Bearing Turbo 1.06 A/R With Tial "Q" BOV & Dual F35 Wastegates, Swaintech Coating On Hotside Piping & Turbo Hotside Housing,

707 HP on 13 psi.

Good luck with your build.
Thanks for the info man. I'm getting complete different answers as to which size to go with, but at the end of the day it's not a difficult swap or expensive change so if its something I have to play around with it's not the end of the world. Just would have liked to address the correct parts up front. If the outlet of the turbo is 3", how would say a 4" provide any different benefit than a 3"?

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #10 of 17 Old 07-02-2016, 09:50 AM
Registered User
 
Weather Man's Avatar
 
Trader Feedback: (0)
Join Date: Jul 2014
Location: MN
Posts: 128
Quote:
Originally Posted by 97stanger97 View Post
Thanks for the info man. I'm getting complete different answers as to which size to go with, but at the end of the day it's not a difficult swap or expensive change so if its something I have to play around with it's not the end of the world. Just would have liked to address the correct parts up front. If the outlet of the turbo is 3", how would say a 4" provide any different benefit than a 3"?
It is the power of Pi! The outlet on my Garret is 3". The area of 3" is 7.069. The area of 4" is 12.556, almost 44% increase.

CPRsm uses a initial 5" down pipe on their coyote kits that run in the 1,000 HP range. That make ridiculous power at low boost and going big on downpipe is one of the keys.

I tried running 3" to just the oil pan area and dumping and I still had issues.

Pic of my 3" bell to 4" downpipe.




2008 Mustang GT
Weather Man is offline  
post #11 of 17 Old 07-02-2016, 04:03 PM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Quote:
Originally Posted by Weather Man View Post
It is the power of Pi! The outlet on my Garret is 3". The area of 3" is 7.069. The area of 4" is 12.556, almost 44% increase.

CPRsm uses a initial 5" down pipe on their coyote kits that run in the 1,000 HP range. That make ridiculous power at low boost and going big on downpipe is one of the keys.

I tried running 3" to just the oil pan area and dumping and I still had issues.

Pic of my 3" bell to 4" downpipe.

Good stuff. Thanks again for the info and picture. I think for what my goals are it will probably make most sense to start with a 4" and see how the car responds in the beginning. If I ever need to step down to a 3", which I've never heard of anybody going smaller on a DP, than I can change that no problem.

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #12 of 17 Old 07-03-2016, 11:40 AM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
About to pull the trigger on the hot side. So if I did go with the 4" DP, how exactly will I get this to work with the 3" outlet of the turbo?

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #13 of 17 Old 07-03-2016, 11:51 AM
Registered User
 
Weather Man's Avatar
 
Trader Feedback: (0)
Join Date: Jul 2014
Location: MN
Posts: 128
Quote:
Originally Posted by 97stanger97 View Post
About to pull the trigger on the hot side. So if I did go with the 4" DP, how exactly will I get this to work with the 3" outlet of the turbo?
This is one way. You could also get a 3 to 4 inch exhaust transition.

EDIT: I see they give you the option to have them weld a 4" flange on. I would go that way. No muss, no fuss.

Flanged Stainless Transition, 3" to 4" : atpturbo.com

2008 Mustang GT
Weather Man is offline  
post #14 of 17 Old 07-03-2016, 01:23 PM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Quote:
Originally Posted by Weather Man View Post
This is one way. You could also get a 3 to 4 inch exhaust transition.

EDIT: I see they give you the option to have them weld a 4" flange on. I would go that way. No muss, no fuss.

Flanged Stainless Transition, 3" to 4" : atpturbo.com
Ahh okay, that makes sense. Pretty simple solution

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #15 of 17 Old 07-04-2016, 03:56 AM
Corral Elite Member
 
wytwolf's Avatar
 
Trader Feedback: (8)
Join Date: Feb 2012
Location: CA, OR, WA
Posts: 796
Just remember, size matters.
97stanger97 likes this.
wytwolf is offline  
post #16 of 17 Old 07-04-2016, 09:35 AM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Quote:
Originally Posted by wytwolf View Post
Just remember, size matters.
Touche
wytwolf likes this.

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
post #17 of 17 Old 07-05-2016, 07:26 AM Thread Starter
Registered User
 
97stanger97's Avatar
 
Trader Feedback: (19)
Join Date: Oct 2006
Location: NJ
Posts: 2,962
Went with a 4"

1997 Mustang GT
1997 Mustang GT
10:1, TF heads, Turbo cams, 7675, E85, 4R70W, Holley EFI
97stanger97 is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Mustang Forums : Corral.net Mustang Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Cobra Caliper Banjo bolt size? and caliper mount bolt size? xalier General Mustang Tech 5 10-25-2012 07:32 PM
Please help me decide what size turbo to choose. Blk4V00GT Turbochargers 15 04-29-2012 11:55 AM
Questions on Injector size for new build.. Leftyroc1 Superchargers 14 04-02-2012 07:52 PM
what size slicks on what rims? sgarcia89lx Wheels and Tires 10 02-15-2002 06:52 PM
What size wheels and slicks to buy? Brian97vobra GT & SOHC 4 01-08-2002 04:42 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome