X Pipe vs Headers
10-07-2008, 12:06 PM
#31
Addict
Rennlist Member
Rennlist Member
I'd say that if you have an X pipe and no Sharktuning, then adding (Devek) headers would get you some gain. I didn't see the gain from headers on a car that was already sharktuned for the X pipe, but not sharktuned for headers. The Sharktuning difference with the headers was more than I thought it would be.
10-07-2008, 12:37 PM
#32
Rennlist Member
In other words, just slapping the headers on the car will not yield much of an improvement, correct? In order to benefit from the addition of the headers, you need to sharktune the car?? I already have the X-pipe, but did not consider the headers due to the post suggesting that there was no power gain or advantage. I am mechanically challenged, and would depend on my local 928 mechanic.
I'd say that if you have an X pipe and no Sharktuning, then adding (Devek) headers would get you some gain. I didn't see the gain from headers on a car that was already sharktuned for the X pipe, but not sharktuned for headers. The Sharktuning difference with the headers was more than I thought it would be.
10-07-2008, 04:08 PM
#33
Three Wheelin'
Thread Starter
Greg was referring to the profile of the intake trumpet, not its cross-section.
An article in Race Engine Technology magazine tested several trumpet profiles (elliptical, circular, "aerofoil" and a plain pipe end) to determine which yielded the best mass flow and pressure recovery. The elliptical bell profile was found to be the best (the cross-section of the duct and bell mount was circular).
For a duct diameter, d, the best ellipse shape had a mouth of diameter 2.13d, and length (from the lip (ie normal to the direction of the duct) to where it necked down to the duct diameter) of d (hence Greg's description of "short and fat". There also was a radius outboard of the lip (leading edge) to smooth the flow of air being ingested from the side. I don't recall how much effect that radius was found to have.
In the article, the duct used for the tests was 23mm in diameter, so the mouth of the optimum elliptical trumpet profile was 49mm (2.13d) in diameter, length 23mm and the radius outboard of the lip was (I think) 3 mm (so 0.13d if I remember correctly).
An article in Race Engine Technology magazine tested several trumpet profiles (elliptical, circular, "aerofoil" and a plain pipe end) to determine which yielded the best mass flow and pressure recovery. The elliptical bell profile was found to be the best (the cross-section of the duct and bell mount was circular).
For a duct diameter, d, the best ellipse shape had a mouth of diameter 2.13d, and length (from the lip (ie normal to the direction of the duct) to where it necked down to the duct diameter) of d (hence Greg's description of "short and fat". There also was a radius outboard of the lip (leading edge) to smooth the flow of air being ingested from the side. I don't recall how much effect that radius was found to have.
In the article, the duct used for the tests was 23mm in diameter, so the mouth of the optimum elliptical trumpet profile was 49mm (2.13d) in diameter, length 23mm and the radius outboard of the lip was (I think) 3 mm (so 0.13d if I remember correctly).
Ok, I see what Greg meant. The cross section of the opening is an eliptical shape. It's not to the dimensions you cite though. I couldn't have the air horns that wide. Because of the inward angle, if the air horn diameter is too large the outer edge would be higher and interfere with the top of the air box. I had to settle for compromise. If I understand your dimensions, my air horn diameter at the top of the mouth is a factor of 1.7 to the ID, or 3.4". The outer edge does recurve downward with a radius of about .16D. I got a lot of this from fluid dynamics engineering books and doing some flow testing using a smoke trail to see the path. The eliptical opening cross section was strictly by eye. The recurved outer edge was seen to be important because air (smoke trail) will flow upward toward the opening, then around the lip and down into the opening. With a sharper edged opening, the air isn't so eager to go up and around the sharper edge.
This is a picture of the tool I made to form the male plug (from Delrin) I used to make the CF air horns. The eliptical opening shape is on the left side and the constant radius recurved section is the right side.
https://rennlist.com/forums/attachme...1&d=1223405664
Last edited by Louie928; 06-13-2013 at 05:13 PM.
10-08-2008, 09:52 AM
#34
Instructor
Right; a V8 would require a big airbox to accommodate trumpets that large! It sounds as though you have achieved a good compromise.
10-08-2008, 04:07 PM
#35
Rennlist Member
Hi Louie,
I thought you might be interested in this. Unfortunately they don't use stainless.
Building your 2-into-1 System
RACING PRODUCTS, INC.
N50 W23001 BETKER DR. • PEWAUKEE, WISCONSIN 53072
Phone 262-246-8577 • Fax 262-246-7371 • Internet www.castheads.com • E-mail: castiron@execpc.com
Your starting point for extra power
The most important item to remember when building your system is this; primary pipes need not be routed in any particular way to gain the added horsepower of the 2-into-1 effect.
★Optimum Primary Pipe Length - Keep the pri¬mary pipes as short as possible. Systems are designed around individual 90 and 45 degree bends, which are 12" long. Do not use more than 72" of pipe on each side. This translates into a maximum of 6 pipes per side.
Three horsepower will be lost for each additional 12" section beyond 72". These recommendations are based on dyno tests with stock and modified Corvette, Chevy II and Log manifolds.
★Unequal Length Primary Pipes are OK - Now go back and read that again. Our dyno tests have concluded that variations up to 30" in primary length have no adverse effect on power when a collector is used. Primary pipes equal in length, or as close as possible, are preferred, but in some applications this is just not possible. So if your pipes going into the collector are not equal, don’t worry. If you are restricted to a dual pipe system, pipes must be equal in length.
★Secondary Pipe Length - After the collector run a minimum of 12" of secondary pipe. Adding more length has no effect on power. In other words, “We’ve run 1 to 6 feet of secondary pipe and noticed absolutely no power difference.”
★Mufflers - The main challenge in designing a muffler for the 2-into-1 system rides in the fact that the entire engine is exhausting out of only one pipe. Most mufflers are designed to handle only half of a V-8 engine. When passing the entire exhaust through one outlet, other mufflers become very restrictive, scrubbing off 10 - 15 horsepower.
Our muffler is able to handle the extra volume because of its physical size. Being 9" in diameter and 10" long enables it to quiet the engine while not stealing valuable horsepower. Horsepower with and without the muffler is the same. No other muffler can make that claim. Run a foot of secondary pipe between the collector and the muffler.
I thought you might be interested in this. Unfortunately they don't use stainless.
Building your 2-into-1 System
RACING PRODUCTS, INC.
N50 W23001 BETKER DR. • PEWAUKEE, WISCONSIN 53072
Phone 262-246-8577 • Fax 262-246-7371 • Internet www.castheads.com • E-mail: castiron@execpc.com
Your starting point for extra power
The most important item to remember when building your system is this; primary pipes need not be routed in any particular way to gain the added horsepower of the 2-into-1 effect.
★Optimum Primary Pipe Length - Keep the pri¬mary pipes as short as possible. Systems are designed around individual 90 and 45 degree bends, which are 12" long. Do not use more than 72" of pipe on each side. This translates into a maximum of 6 pipes per side.
Three horsepower will be lost for each additional 12" section beyond 72". These recommendations are based on dyno tests with stock and modified Corvette, Chevy II and Log manifolds.
★Unequal Length Primary Pipes are OK - Now go back and read that again. Our dyno tests have concluded that variations up to 30" in primary length have no adverse effect on power when a collector is used. Primary pipes equal in length, or as close as possible, are preferred, but in some applications this is just not possible. So if your pipes going into the collector are not equal, don’t worry. If you are restricted to a dual pipe system, pipes must be equal in length.
★Secondary Pipe Length - After the collector run a minimum of 12" of secondary pipe. Adding more length has no effect on power. In other words, “We’ve run 1 to 6 feet of secondary pipe and noticed absolutely no power difference.”
★Mufflers - The main challenge in designing a muffler for the 2-into-1 system rides in the fact that the entire engine is exhausting out of only one pipe. Most mufflers are designed to handle only half of a V-8 engine. When passing the entire exhaust through one outlet, other mufflers become very restrictive, scrubbing off 10 - 15 horsepower.
Our muffler is able to handle the extra volume because of its physical size. Being 9" in diameter and 10" long enables it to quiet the engine while not stealing valuable horsepower. Horsepower with and without the muffler is the same. No other muffler can make that claim. Run a foot of secondary pipe between the collector and the muffler.
10-08-2008, 05:41 PM
#36
Three Wheelin'
Thread Starter
Hi Louie,
I thought you might be interested in this. Unfortunately they don't use stainless.
Building your 2-into-1 System
RACING PRODUCTS, INC.
N50 W23001 BETKER DR. • PEWAUKEE, WISCONSIN 53072
Phone 262-246-8577 • Fax 262-246-7371 • Internet www.castheads.com • E-mail: castiron@execpc.com
Your starting point for extra power
The most important item to remember when building your system is this; primary pipes need not be routed in any particular way to gain the added horsepower of the 2-into-1 effect.
★Optimum Primary Pipe Length - Keep the pri¬mary pipes as short as possible. Systems are designed around individual 90 and 45 degree bends, which are 12" long. Do not use more than 72" of pipe on each side. This translates into a maximum of 6 pipes per side.
Three horsepower will be lost for each additional 12" section beyond 72". These recommendations are based on dyno tests with stock and modified Corvette, Chevy II and Log manifolds.
★Unequal Length Primary Pipes are OK - Now go back and read that again. Our dyno tests have concluded that variations up to 30" in primary length have no adverse effect on power when a collector is used. Primary pipes equal in length, or as close as possible, are preferred, but in some applications this is just not possible. So if your pipes going into the collector are not equal, don’t worry. If you are restricted to a dual pipe system, pipes must be equal in length.
★Secondary Pipe Length - After the collector run a minimum of 12" of secondary pipe. Adding more length has no effect on power. In other words, “We’ve run 1 to 6 feet of secondary pipe and noticed absolutely no power difference.”
★Mufflers - The main challenge in designing a muffler for the 2-into-1 system rides in the fact that the entire engine is exhausting out of only one pipe. Most mufflers are designed to handle only half of a V-8 engine. When passing the entire exhaust through one outlet, other mufflers become very restrictive, scrubbing off 10 - 15 horsepower.
Our muffler is able to handle the extra volume because of its physical size. Being 9" in diameter and 10" long enables it to quiet the engine while not stealing valuable horsepower. Horsepower with and without the muffler is the same. No other muffler can make that claim. Run a foot of secondary pipe between the collector and the muffler.
I thought you might be interested in this. Unfortunately they don't use stainless.
Building your 2-into-1 System
RACING PRODUCTS, INC.
N50 W23001 BETKER DR. • PEWAUKEE, WISCONSIN 53072
Phone 262-246-8577 • Fax 262-246-7371 • Internet www.castheads.com • E-mail: castiron@execpc.com
Your starting point for extra power
The most important item to remember when building your system is this; primary pipes need not be routed in any particular way to gain the added horsepower of the 2-into-1 effect.
★Optimum Primary Pipe Length - Keep the pri¬mary pipes as short as possible. Systems are designed around individual 90 and 45 degree bends, which are 12" long. Do not use more than 72" of pipe on each side. This translates into a maximum of 6 pipes per side.
Three horsepower will be lost for each additional 12" section beyond 72". These recommendations are based on dyno tests with stock and modified Corvette, Chevy II and Log manifolds.
★Unequal Length Primary Pipes are OK - Now go back and read that again. Our dyno tests have concluded that variations up to 30" in primary length have no adverse effect on power when a collector is used. Primary pipes equal in length, or as close as possible, are preferred, but in some applications this is just not possible. So if your pipes going into the collector are not equal, don’t worry. If you are restricted to a dual pipe system, pipes must be equal in length.
★Secondary Pipe Length - After the collector run a minimum of 12" of secondary pipe. Adding more length has no effect on power. In other words, “We’ve run 1 to 6 feet of secondary pipe and noticed absolutely no power difference.”
★Mufflers - The main challenge in designing a muffler for the 2-into-1 system rides in the fact that the entire engine is exhausting out of only one pipe. Most mufflers are designed to handle only half of a V-8 engine. When passing the entire exhaust through one outlet, other mufflers become very restrictive, scrubbing off 10 - 15 horsepower.
Our muffler is able to handle the extra volume because of its physical size. Being 9" in diameter and 10" long enables it to quiet the engine while not stealing valuable horsepower. Horsepower with and without the muffler is the same. No other muffler can make that claim. Run a foot of secondary pipe between the collector and the muffler.
