primary and secondary lengths for headers

[sheepers]

i have searched the forums of and on for about 3 weeks now and im not finding allot of info about primary and secondary length for you average tri-y headers.
ive been on the header design site but i cant seem to find a way of getting length for anything except 4 into 1.
ive found plenty about pipe diameter but bugger all about length.
as best as i can remember without looking it up the general consensus is 1 1/2" primaries, 1 3/4" secondary and 2" collector going into a single 2 1/2" tail pipe, but nowhere can i find any info about lengths for these pipes.
im not looking for massive performance, i just want to build a nice mild streeter. i have two cars, one for going fast and my 1uz will be for street.
so thats all im after. can anyone please give me some advice??

cheers,
sheepers.

 

[JBrady]

Here's is some data from my copy of PipeMax


--- Tri-Y Header Design Specs --- for 241.647 CID from 4000 to 6500 RPM

1st Y-Segment Dia.= 1.407 Length= 12.7 to 14.1 inches long
2nd Y-Segment Dia.= 1.532 Length= 12.7 to 14.1 inches long

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 2.160 to 2.410 Tuned Lengths= 16.8 best and 8.4 or 33.5

H-Pipe= 16.8 X-Pipe= 67.1 distance behind end of Primary Tube ends

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 16.8 , 33.5 , 67.1 , 134.1 inches long

Worst HP/TQ Loss Collector Lengths= 25.1 , 50.3 , 100.6 , 201.2 inches long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

---- Primary Pipe's Harmonics ----
3rd Harmonic = 25.3 inches long, both Y-Segments combined Length, best TQ + HP

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 134.1 inches long ... longest with Mufflers and TailPipes
2nd Harmonic = 67.1 inches long ... longest recommended with Mufflers
3rd Harmonic = 33.5 inches long ... more bottom-end Torque
4th Harmonic = 16.8 inches long ... highly recommended , best Torque Curve
5th Harmonic = 8.4 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 4.2 inches long ... reduced Torque , not recommended


************** Metric Units ******************


--- Tri-Y Header Design Specs --- for 3.960 Liters from 4000 to 6500 RPM

1st Y-Segment Dia. MM= 35.742 Length= 321.6 to 357.2 MM long
2nd Y-Segment Dia. MM= 38.917 Length= 321.6 to 357.2 MM long

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter MM= 54.865 to 61.215 Tuned Lengths= 425.8 best and 212.9 or 851.6

H-Pipe= 425.8 X-Pipe= 1703.2 distance behind end of Primary Tube ends

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 425.8 , 851.6 , 1703.2 , 3406.4 MM long

Worst HP/TQ Loss Collector Lengths= 638.7 , 1277.4 , 2554.8 , 5109.6 MM long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.

Note-> all Pipe Diameters are OD and based-off 1.588 MM Pipe thickness

---- Primary Pipe's Harmonics ----
3rd Harmonic = 643.2 MM long, both Y-Segments combined Length, best TQ + HP

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 3406.4 MM long ... longest with Mufflers and TailPipes
2nd Harmonic = 1703.2 MM long ... longest recommended with Mufflers
3rd Harmonic = 851.6 MM long ... more bottom-end Torque
4th Harmonic = 425.8 MM long ... highly recommended , best Torque Curve
5th Harmonic = 212.9 MM long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 106.5 MM long ... reduced Torque , not recommended

 

[-Nemesis-]

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 425.8 , 851.6 , 1703.2 , 3406.4 MM long

Worst HP/TQ Loss Collector Lengths= 638.7 , 1277.4 , 2554.8 , 5109.6 MM long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.

I don't know much exhaust tech, but I especially didn't know the overall length of an exhaust effects power? How can 425mm and 851mm be good, while 638 is bad?

 

[sheepers]

thanks heaps man!!!
thats exactly what im after!!!!!

is there any specific reason why the header calculator thingy only has the option for 4 into 1 design? or am i just missing something really obvious?????
im aware of the different principals of each design but is there a bigger argument about the two types of system i.e "4 into 1 is better for all applications" or something like that???

thanks once again.
sheepers.

 

[Jaco]

Y headers

Mabe this can help. Note wich cylinders is joined together.

 

[JBrady]

Jaco,

Welcome to Lextreme.

Please elaborate on your post. What is your understanding of cylinder joining?

Most designers seem to join cylinders to isolate each exhaust pulse. Some find that joining or overlapping has benefits. The picture you posted may fit the latter. Again, your thoughts?

 

[Jaco]

To optimize your exhaust it is best to join the cylinders that does not fire directly after eachother, to minimize exhauat rivision. With he 1Uz`s firing order, the best spacing is the 180 degree desighn. This is joining the outer cylinders of one bank to the inner cylinders of the other bank, but this neccesitates long runners, wich might be a trade off.
here is a pick of 180 degree desighn.

 

[JBrady]

Yes, I agree MOST design to isolate. That said the FIRST picture you post shows headers joining #4 and #8 cylinders which OVERLAP.

The JUNCTION (collector) between 2 high pressure flows or one high and one low pressure flow is critical in how the 2 interact. With a merge collector design (like you show in the first picture) the high pressure blow down from cyl #4 can actually PULL a vacuum on the lower pressure return exhaust phase on cyl #8. This is why I pointed that out and asked your imput.

Exhaust design can often be an example of what seems "right" may be "wrong" and vice versa.

 

[camaro68]

The THOR RACING engine with the ITB’s shown as an example above should not be followed as the correct way to pair the pipes. It was used at a show as part of a display. The exhaust manifolds are from an off road 4WD car where the engine is mounted backward and behind the driver. The manifold were mounted on the opposite side of the engine for display purposes only.

 

[sheepers]

yea, i saw that they were paired wrongly (for a run of the mill type system) at first i thought the photo had been flipped, but its not.

i haven't come to a decision about my headers as yet, i would like to build a tri-y system but the above mentioned pipe sizes are just not practical and i think i might not have enough space, it might be 4 into 1 for me....

anyone else with some dimensions for middle of the range tri-y headers???

cheers,
sheepers.

 

[Jaco]

tri y sizes

Hi sheepers.

Acording to me the 1uz`s fireing order is 18436572. I am not entirely sure how the cylinders is numberd, but if you are standin in front of the engine and no1 is in fornt at your right, and 2 in front left ect. Then the cylinders in the Thor picture is right? If you seperate the banks according to fireing order then: Right is 1357 and left is 2468. From this you can see that the pairs is : Right 1&5, 3&7. and Left 2&6, 4&8.

Then, According to the book of A. Graham Bell, I made a quick calculation and the sizes for a tri y is:
PRIMARY
Length: 420mm to 450mm
Diameter: 40mm to 42mm

SECONDRY
Length: 410mm to 470mm
Diameter: 50mm to 55mm

The total length(primary + secondry) should be between 830mm and 920mm
This should give good midrange torque for road use with std cams.

Wile I can`t promise you this will work, I can say that i have used this formulas in the past with sucsess, but they were all 4-1 headers, havent build my own tri y`s yet.

 

[Jaco]

tri y sizes

Hi sheepers.

Acording to me the 1uz`s fireing order is 18436572. I am not entirely sure how the cylinders is numberd, but if you are standin in front of the engine and no1 is in fornt at your right, and 2 in front left ect. Then the cylinders in the Thor picture is right? If you seperate the banks according to fireing order then: Right is 1357 and left is 2468. From this you can see that the pairs is : Right 1&5, 3&7. and Left 2&6, 4&8.

Then, According to the book of A. Graham Bell, I made a quick calculation and the sizes for a tri y is:
PRIMARY
Length: 420mm to 450mm
Diameter: 40mm to 42mm

SECONDRY
Length: 410mm to 470mm
Diameter: 50mm to 55mm

The total length(primary + secondry) should be between 830mm and 920mm
This should give good midrange torque for road use with std cams.

Wile I can`t promise you this will work, I can say that i have used this formulas in the past with sucsess, but they were all 4-1 headers, havent build my own tri y`s yet.

 

[sheepers]

thanks for that, i too have a book by Graham Bell, his books are very good. thanks for the information, ill look into it.
as for the pairing, the first photo you posted is definitely wrong. the header shown on the VVT engine is on the wrong side.
sheepers.

 

[Jaco]

Hi Sheepers.
I hope you make a sucess of your exhaust project. The std design is very restrictive, and i think opening it up can yeild good gains.
Going the tri y route should give impressive midrange, and for street use its the best in my opinion.
keep me updated.

Jaco

 

[Zuffen]

Past testing has shown only nominal gains with headers.

The heads and inlet tract are the main restriction.

You can expect 20hp or so from headers.

 

[Jaco]

Makes sence, Your motor is onley as good as the next restriction.
And the heads and intake does not look very free flowing.
I think the std cams also doesn`t allow large amounts of air to flow through improved manifolds.
To me 20hp is a worth wile gain. On my Bmw i changed the whole exhaust system for a noticable 13Hp.

 

[ed_ma61]

Makes sence, Your motor is onley as good as the next restriction.

that engine philosophy will build you an expensive, underperforming engine every day of the week

 

[Jaco]

that engine philosophy will build you an expensive, underperforming engine every day of the week

Sounds stupid I know.
I was trying to point out is that for example its no use in putting on a super fowing pro stock part if the other parts in the system cant flow nearley the same amount. Everything has to compliment eachother, every day of the week.

 

[LEXUSA]

I realize this thread is old and that JBrady has all but retired from the Exhaust Design business but my version of PipeMax, 3.8 came up with smaller and longer calculations I'm wondering what values I have that are different, and possibly incorrect, that could be causing the differing results.

Here's is some data from my copy of PipeMax


--- Tri-Y Header Design Specs --- for 241.647 CID from 4000 to 6500 RPM

1st Y-Segment Dia.= 1.407 Length= 12.7 to 14.1 inches long
2nd Y-Segment Dia.= 1.532 Length= 12.7 to 14.1 inches long

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 2.160 to 2.410 Tuned Lengths= 16.8 best and 8.4 or 33.5

H-Pipe= 16.8 X-Pipe= 67.1 distance behind end of Primary Tube ends

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 16.8 , 33.5 , 67.1 , 134.1 inches long

Worst HP/TQ Loss Collector Lengths= 25.1 , 50.3 , 100.6 , 201.2 inches long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

---- Primary Pipe's Harmonics ----
3rd Harmonic = 25.3 inches long, both Y-Segments combined Length, best TQ + HP

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 134.1 inches long ... longest with Mufflers and TailPipes
2nd Harmonic = 67.1 inches long ... longest recommended with Mufflers
3rd Harmonic = 33.5 inches long ... more bottom-end Torque
4th Harmonic = 16.8 inches long ... highly recommended , best Torque Curve
5th Harmonic = 8.4 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 4.2 inches long ... reduced Torque , not recommended