2" into 5" stacks
Thread Starter
|
New User
Joined: Aug 2010
Posts: 22
Likes: 0
2" into 5" stacks
Bought the 94 F350 7.3 turbo dually last august , done all the 'usual' mods like turning fuel up , tweeking injector pump timing , increasing boost pressure , installing pyro/boost gauge , got rid of throttled intake scoop , K&N filter...................last on the list is to replace the restricted down pipe off the turbo , problem being the down pipe goes into a 2" 'Y' branch , both exhausts run off the 2" Y branch & connect into the two 5" stacks which go through the bed ....just wondering if the 3" down pipe is worth the aggro? , the other problem being if i replace the crushed down pipe with 3" is it ok to still use the 2" exhusts into 5" stacks? , what i was thinking is to use a 3" X 2" X 2" Y branch , any ideas?............i realise EGTs will drop when getting rid of the existing down pipe but wondering if the 2" exhausts will still be restricted , stacks are coming through bed directly behind double cab.
Thanks.
Thanks.
Thread Starter
|
New User
Joined: Aug 2010
Posts: 22
Likes: 0
Problem i got is the base of stacks are real close to chassis rail where they come through the bed , the 2" coming off the stack is real tight to get in there...
Elder User
Joined: Feb 2010
Posts: 724
Likes: 0
So either redo your stacks, or don't run stacks at all.
If I had to pick between letting my truck breath better, getting more power, and lowering my EGT's, or having stacks?
It's a no brainer for me.
But do what you want man, at the end of the day it's your truck.
Postmaster
Joined: Apr 2009
Posts: 4,086
Likes: 1
From: Malahat/Cowichan Valley
hooah!! well said dave! pulling numbers from places no one wants to think about, a dave specialty! hahaha
Trending Topics
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
I am teachng myself surveying and survey math right now.
So many blueprints we get have bad information on them, I will be able to check their numbers before summer gets here.
And when I draw an "as built" print, it will be exact.
56 and still learning new stuff.
So many blueprints we get have bad information on them, I will be able to check their numbers before summer gets here.
And when I draw an "as built" print, it will be exact.
56 and still learning new stuff.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Thread Starter
|
New User
Joined: Aug 2010
Posts: 22
Likes: 0
Well , got down pipe out without cutting , just disconnected trans cooler line off tranny & out she came , took around 15 minutes , most time was spent getting to the clamp between turbo/downpipe...............the downpipe measures around 1" where it's flattened 
, cut the floor seam with a recipro saw so the 3" should clear nicely , will take the truck out later & see how it goes , the engine is no louder without a downpipe , only difference is you can hear the turbo spooling.
Thanks.
, cut the floor seam with a recipro saw so the 3" should clear nicely , will take the truck out later & see how it goes , the engine is no louder without a downpipe , only difference is you can hear the turbo spooling.Thanks.
Posting Guru
Joined: Dec 2005
Posts: 1,528
Likes: 0
From: Peterborough, Ontario
One distinct advantage I have with my toolmaking background when it comes to dirt playing, drawings and math are strong points in my experience. I do have to work more on figuring volumes and the like with some of this stuff, but so much of my work is small stuff, it's guesstimate and go anyway.
Thread Starter
|
New User
Joined: Aug 2010
Posts: 22
Likes: 0
Took the truck out without a down pipe fitted , seems to of lost some power
, can't see why this would be as the turbo has to be spooling quicker...........drove the truck up an incline & found boost to be the same (15psi) , also EGTs remained the same as they were before , should be making more power as this truck belches black smoke out the stacks when initially floored , can't comment on the smoke with the down pipe off as i can't see the turbo outlet............maybe it has picked up but i just can't feel it due to it running slightly louder.
, can't see why this would be as the turbo has to be spooling quicker...........drove the truck up an incline & found boost to be the same (15psi) , also EGTs remained the same as they were before , should be making more power as this truck belches black smoke out the stacks when initially floored , can't comment on the smoke with the down pipe off as i can't see the turbo outlet............maybe it has picked up but i just can't feel it due to it running slightly louder.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
The 3" downpipe is already a lot better than the crushed stock one, you might not be loosing that much running the dual 2" pipes, look at the amount of work/cost to redo how the stacks are versus the 0.781 square inches of flow. Is it worth it to you?
thats your decision.More math to help (or confuse) you, can you fit 2 1/4 pipe between the chassis to the stacks? two 2 1/4" pipes will be 7.952 square inches, better than a single 3".
two 2 1/8" pipes would be 7.093 square inches, about the same as a single 3".
Cargo Master
Joined: Feb 2010
Posts: 3,493
Likes: 3
From: NY
Dude, I think you are confused. Cross sectional area of a circle is pi r squared. The radius of a 2 inch pipe is 1 inch, square 1 inch and you get 1 inch, then x it by pi and get 3.14. I agree with Dave
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
Remember that we are talking about taking a 3" pipe, then splitting it into two smaller pipes. Currently the OP has two 2" pipes EACH is 3.1415926... square inches, COMBINED they are ~6.283 square inches.
I'm not saying Dave is wrong, I'm just throwing some more facts for the OP to consider since he would need more modifications to change the 2" pipes going into the stacks.