C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

H,X or straight pipes?

Thread Tools
 
Search this Thread
 
Old Jul 12, 2019 | 11:22 PM
  #1  
pooled's Avatar
pooled
Thread Starter
Advanced
 
Joined: Mar 2019
Posts: 60
Likes: 2
From: Euless, TX
Default H,X or straight pipes?

I am installing my long tube headers, I just got them back from getting ceramic coating. Right now my exhaust is separate straight exaust with flow masters at the rear. My question is, should i pay to have my local exhaust shop add a cross to make an H pipe mid way, keep it the way it is? Also, if i came across a cheap used X pipe would that be better option?

This is on my C-4, basically stock, minus air pump, no frisbee, TB coolant bypass. In the future maybe a year I will be getting better heads and a better intake.

Thank you
Reply
Old Jul 12, 2019 | 11:41 PM
  #2  
Tom400CFI's Avatar
Tom400CFI
Team Owner
Pro Mechanic
20 Year Member
 
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Default

I think there should be some connection between the two sides...I think the location in the system is far more important than if it's an "H" or and "X".
Reply
Old Jul 12, 2019 | 11:50 PM
  #3  
sstonebreaker's Avatar
sstonebreaker
Le Mans Master
15 Year Member
 
Joined: Mar 2006
Posts: 5,775
Likes: 585
From: Texas
Default

Engine Masters did a show on this. The X and H pipes both made about 10 HP more than the straight pipes, and both Freiburger and the other guy (I can't remember his name) liked the sound of the H pipe the best, as I recall.
Reply
Old Jul 12, 2019 | 11:53 PM
  #4  
pooled's Avatar
pooled
Thread Starter
Advanced
 
Joined: Mar 2019
Posts: 60
Likes: 2
From: Euless, TX
Default

Really, do you remember what vehicle they did the test on, just curious? I had no clue it made that big of an effect over straight pipes, i always thought they would be maybe 2-3 hp over straight, and 10 over a Y pipe.
Reply
Old Jul 12, 2019 | 11:53 PM
  #5  
pooled's Avatar
pooled
Thread Starter
Advanced
 
Joined: Mar 2019
Posts: 60
Likes: 2
From: Euless, TX
Default

Do you know where it should be located? like maybe 2 ft past the end of the headers?
Reply
Old Jul 13, 2019 | 12:36 AM
  #6  
Tom400CFI's Avatar
Tom400CFI
Team Owner
Pro Mechanic
20 Year Member
 
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Default

Maybe. Testing or exhaust calc's would give you a good idea.

Do a search for exhaust design and there are some good articles about it to let you do your own calcs and design.
Reply
Old Jul 13, 2019 | 08:14 AM
  #7  
C409's Avatar
C409
Le Mans Master
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
Default

….. I have an X on mine … on a C4 , positioning is determined by the transmission and the tunnel … 3" pipes , Summit bullets , and 50 series Flowmasters … great sound , NO drone … and they run 6.7's @ 100+ in the eighth …..



Reply
Old Jul 13, 2019 | 08:39 AM
  #8  
pooled's Avatar
pooled
Thread Starter
Advanced
 
Joined: Mar 2019
Posts: 60
Likes: 2
From: Euless, TX
Default

Im going to take a photo of how mine is laid out today, and post it on this thread.
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

10 Ugly Corvettes That We Still Kinda Love

 Joe Kucinski
story-1

Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

 Brett Foote
story-2

10 Things Every Corvette Owner Needs (2026 Edition)

 Michael S. Palmer
story-3

8 Most "Only Corvette Owners Understand" Quirks and Problems

 Pouria Savadkouei
story-4

10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

 Joe Kucinski
story-5

How Much Horsepower Every Corvette Engine "LOST" in 1972

 Joe Kucinski
story-6

Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

 Michael S. Palmer
story-7

Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

 Joe Kucinski
story-8

150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

 Joe Kucinski
story-9

8 Coolest Corvette Pace Cars (and Replicas) of All Time

 Verdad Gallardo
Old Jul 13, 2019 | 02:47 PM
  #9  
sstonebreaker's Avatar
sstonebreaker
Le Mans Master
15 Year Member
 
Joined: Mar 2006
Posts: 5,775
Likes: 585
From: Texas
Default

Originally Posted by pooled
Do you know where it should be located? like maybe 2 ft past the end of the headers?
It's not that critical. Optimum placement will net you a couple more hp, but in reality you're going to have to put the X-pipe where it will fit under the car. Unless hundredths of a second at the drag strip are important to you, a 4 or 5 hp difference isn't going to be noticeable.
Reply
Old Jul 13, 2019 | 03:23 PM
  #10  
65Z01's Avatar
65Z01
Team Owner
20 Year Member
 
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Default

I've read that the X should be placed (as close as possible) to where the pipes are the hottest.

My question is do you prefer the sound of the old (say C3) Vettes vs newer Vettes with a connection between pipes.
Reply
Old Jul 13, 2019 | 08:22 PM
  #11  
Kevova's Avatar
Kevova
Le Mans Master
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
Default

It depends a little on how you.layout you exhaust. It was recommended to paint 18 in of pipe attaching to header collector, crossover goes as close as possible to where the paint stops burning .
Reply
Old Jul 14, 2019 | 09:26 AM
  #12  
vader86's Avatar
vader86
Team Owner
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Default

It doesn't matter if its H or X, but a connection will help reduce resonance. It wont make much power difference on your car, and there is only so many places you can put it.

Preferably closer to the headers though.
Reply
Old Jul 14, 2019 | 03:41 PM
  #13  
cv67's Avatar
cv67
Team Owner
15 Year Member
 
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Default

Do what you can afford, had all and no crossover cant feel a difference from any
Ready to go back to straights with a very long turbo
'
Real mods are made INSIDE the motor same as usual

Last edited by cv67; Jul 14, 2019 at 03:42 PM.
Reply
Old Jul 14, 2019 | 04:56 PM
  #14  
project C4's Avatar
project C4
Pro
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Apr 2004
Posts: 621
Likes: 37
From: Texas
Default engine masters episode

I just found and watched the Engine masters episode with the straight vs H vs X pipe comparison. They used a carbureted 5.3 ls motor with a cam swap. 3/4' primary headers with 2.5 inch exhaust pipe and straight through Gibson mufflers. Peak horse power with the straight and the X was 362. The peak horse power with the H pipe was 360. There were slight gains in torque with the H and X in the lower RPM range.
Reply
Old Jul 15, 2019 | 10:18 PM
  #15  
pooled's Avatar
pooled
Thread Starter
Advanced
 
Joined: Mar 2019
Posts: 60
Likes: 2
From: Euless, TX
Default

did they dyno it without the h or x, just straight pipe?
Reply
Old Jul 15, 2019 | 10:33 PM
  #16  
Pwnage1337's Avatar
Pwnage1337
Tech Contributor
15 Year Member
 
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Default

I put an X on my car and the girls love it so much I can't drive my car downtown because they flock to it like bees to honey
Reply
Old Jul 15, 2019 | 10:33 PM
  #17  
Pwnage1337's Avatar
Pwnage1337
Tech Contributor
15 Year Member
 
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Default

Also my car is hella low because girls love a low low with 400 rwhp
Reply

Get notified of new replies

To H,X or straight pipes?

Old Jul 16, 2019 | 05:15 PM
  #18  
A95Y's Avatar
A95Y
Burning Brakes
Supporting Lifetime
20 Year Member
All Eyes On Me
Liked
Loved
 
Joined: May 2006
Posts: 985
Likes: 17
From: St. Louis Missouri
Default

Originally Posted by C409
….. I have an X on mine … on a C4 , positioning is determined by the transmission and the tunnel … 3" pipes , Summit bullets , and 50 series Flowmasters … great sound , NO drone … and they run 6.7's @ 100+ in the eighth …..


Where did you get the bends for your header pipes?

Thanks
Reply
Old Jul 16, 2019 | 06:01 PM
  #19  
06_LT1's Avatar
06_LT1
Instructor
10 Year Member
 
Joined: Aug 2010
Posts: 237
Likes: 17
From: San Diego CA
Default

I run a custom x-pipe my muffler guy fabbed up for me, installed in place of the factory resonator. With a stainless chambered exhaust, it's VERY quiet at idle but loud enough to frighten my wife (driving in front of me) when I get on it. No idea if it makes any more power, but it's significantly lighter than the piece it replaced.
Reply
Old Jul 16, 2019 | 10:37 PM
  #20  
C409's Avatar
C409
Le Mans Master
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
Default

Originally Posted by A95Y
Where did you get the bends for your header pipes?

Thanks
….. I bought a used Stainless Steel 3" B&B system for LT1 cars minus the resonator … the B&B mufflers were on the car for about 2 days and droned so bad that I couldn't drive the car … at one point , the car was idling in the driveway with the garage door open (attached garage) … I went into the house to get my sunglasses and the cupboard doors in the kitchen were all vibrating and making the strangest noises … I drove straight to the muffler shop that installed the mess and had 'em put the Flowmasters on … What a relief ! ….. The X was an E-Bay purchase …..

Last edited by C409; Jul 16, 2019 at 10:40 PM.
Reply



All times are GMT -4. The time now is 11:15 AM.

story-0
10 Ugly Corvettes That We Still Kinda Love

Slideshow: 10 ugly Corvettes that we still kinda love.

By Joe Kucinski | 2026-06-03 10:34:17


VIEW MORE
story-1
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

A lot of money has changed hands at the online auction house over the years.

By Brett Foote | 2026-06-03 10:21:50


VIEW MORE
story-2
10 Things Every Corvette Owner Needs (2026 Edition)

Slideshow: 10 great gifts Corvette enthusiasts actually want for Father's Day!

By Michael S. Palmer | 2026-06-03 15:43:40


VIEW MORE
story-3
8 Most "Only Corvette Owners Understand" Quirks and Problems

Slideshow: These are the quirks, annoyances, and oddly lovable problems that every Corvette owner eventually learns to live with.

By Pouria Savadkouei | 2026-05-28 09:31:39


VIEW MORE
story-4
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

Slideshow: 10 reasons why the C6 Z06 is still a performance benchmark after 20 years.

By Joe Kucinski | 2026-05-27 17:20:09


VIEW MORE
story-5
How Much Horsepower Every Corvette Engine "LOST" in 1972

Slideshow: How much horsepower every Corvette engine lost in 1972.

By Joe Kucinski | 2026-05-27 16:54:53


VIEW MORE
story-6
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-7
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-8
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-9
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE