Header/Exhaust System Design

[Ma70.Ent]

It seems this has died.

 

[amichie]

Why not modify the OBX headers. They are stainless and the primaries are mandrel bent and nice and long. You could have a collector made that just bolts straight on to the cat and also still slips on to the twin two-inch output from the headers.

They do seem to be well made. TIG welded with very nice baffle style 3 into 1 collectors.

 

[AJ'S 88NA]

Why not modify the OBX headers. They are stainless and the primaries are mandrel bent and nice and long. You could have a collector made that just bolts straight on to the cat and also still slips on to the twin two-inch output from the headers.

They do seem to be well made. TIG welded with very nice baffle style 3 into 1 collectors.

OBX doesn't have a collector that comes with the header?

 

[amichie]

OBX doesn't have a collector that comes with the header?

So what do you call the bit between the headers and the cat that came with my OBX headers. It's a 2 into 1 section with a cat flange on the end.

 

[AJ'S 88NA]

So what do you call the bit between the headers and the cat that came with my OBX headers. It's a 2 into 1 section with a cat flange on the end.

Yeah that's a collector, got confused when you said "you could have a collector made"

 

[MrWOT]

Just for grins I ran the numbers as the 7M has a great deal of potential for a powerful N/A motor, but the lack of torque on the bottom end would just make it a damn dog to drive unless it was track only. I decided to calculate for the full exhaust system considering the specs of a stock 7MGE. This is calculating pressure wave timing for the 3000-5500 rpm band, and is simulated, but the software is usually quite accurate.

If you want the cleanest pulses you need to use a 6-2 system with two seperate collectors and join 123 to 456 after the collector at the H-pipe, then again at an X-pipe further down the system. You can use a 6-1 if you want with a single tailpipe, but two smaller pipes aren't that hard to fit if you already have the resources to do this and are better. It is also important that you chose a tailpipe and muffler based on it's FLOW capability not it's physical size or sound in order for the below calculations to work. You want to meet the flow requirement at peak rpm and not much more or less.


--- Single Primary Pipe Specs --- for 180.393 CID from 3000 to 5500 RPM
Diameter= 1.226 Length= 26.5 to 29.5 also 18.0 to 21.0 inches long
Note> Maximum Primary's Tuned Length= 45.2 to 48.2 inches long

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 2.500 Tuned Lengths= 19.7 best and 9.8 or 39.4

H-Pipe= 19.7 X-Pipe= 78.7 distance behind end of Primary Tube ends

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 19.7 , 39.4 , 78.7 , 157.5 inches long

Worst HP/TQ Loss Collector Lengths= 29.5 , 59.1 , 118.1 , 236.2 inches long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.
H-Pipe is located at end of Collector, and X-Pipe is located
usually half-way between end of Primary Pipes -to- tailpipe end

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

---- Primary Pipe's Harmonics ----
1st Harmonic = 121.7 inches long ... typically never used
2nd Harmonic = 45.2 inches long ... longest recommended
3rd Harmonic = 26.5 inches long ... highly recommended , best Torque Curve
4th Harmonic = 18.0 inches long ... shortest recommended
5th Harmonic = 13.1 inches long ... typically never used
6th Harmonic = 10.0 inches long ... typically never used
7th Harmonic = 7.8 inches long ... typically never used
8th Harmonic = 6.2 inches long ... typically never used

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 157.5 inches long ... longest with Mufflers and TailPipes
2nd Harmonic = 78.7 inches long ... longest recommended with Mufflers
3rd Harmonic = 39.4 inches long ... more bottom-end Torque
4th Harmonic = 19.7 inches long ... highly recommended , best Torque Curve
5th Harmonic = 9.8 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 4.9 inches long ... reduced Torque , not recommended


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


--- Single Primary Pipe Specs --- for 2.956 Liters from 3000 to 5500 RPM
Diameter MM= 31.148 Length= 671.9 to 749.0 also 456.5 to 533.5 MM long
Note> Maximum Primary's Tuned Length= 1148.4 to 1225.5 MM long

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter MM= 63.500 Tuned Lengths= 500.0 best and 250.0 or 1000.0

H-Pipe= 500.0 X-Pipe= 2000.0 distance behind end of Primary Tube ends

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 500.0 , 1000.0 , 2000.0 , 4000.0 MM long

Worst HP/TQ Loss Collector Lengths= 750.0 , 1500.0 , 3000.0 , 5999.9 MM long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.
H-Pipe is located at end of Collector, and X-Pipe is located
usually half-way between end of Primary Pipes -to- tailpipe end

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


---- Primary Pipe's Harmonics ----
1st Harmonic = 3091.9 MM long ... typically never used
2nd Harmonic = 1148.4 MM long ... longest recommended
3rd Harmonic = 671.9 MM long ... highly recommended , best Torque Curve
4th Harmonic = 456.5 MM long ... shortest recommended
5th Harmonic = 333.7 MM long ... typically never used
6th Harmonic = 254.4 MM long ... typically never used
7th Harmonic = 199.0 MM long ... typically never used
8th Harmonic = 158.0 MM long ... typically never used

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 4000.0 MM long ... longest with Mufflers and TailPipes
2nd Harmonic = 2000.0 MM long ... longest recommended with Mufflers
3rd Harmonic = 1000.0 MM long ... more bottom-end Torque
4th Harmonic = 500.0 MM long ... highly recommended , best Torque Curve
5th Harmonic = 250.0 MM long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 125.0 MM long ... reduced Torque , not recommended

This software is pretty accurate, I used the following values for head flow

intake exhaust


lift " cfm lift " cfm
.100" 84.3 .100" 83.0
.200" 146.1 .200" 122.9
.300" 177.4 .300" 134.7
.350" 180.5 .350" 139.8
.400" 182.4
.450" 181.7

 

[Ma70.Ent]

That's some interesting info, what software is this though?

 

[MrWOT]

PipeMax, written by Larry Meaux

 

[benchwarmer]

Does this mean we're back on for an NA header group buy?:naughty: Christmas is coming and I've been a good boy. Okay, that's a lie, but I still want a header.

 

[935motorsports]

So what is the plan?

 

[Ma70.Ent]

Does this mean we're back on for an NA header group buy?:naughty: Christmas is coming and I've been a good boy. Okay, that's a lie, but I still want a header.

A group buy is highly unlikely. There isn't really much support for this because N/A guys just don't care about being N/A, or they have already bought a header and don't want to/can't shell out cash for another one that might cost a decent bit.

 

[A-to-the-J]

TRUST header

1 5/8" inner diameter. My only gripe about the design is where the O2 sensor is located, but that can be easily modified.

Only sold in Japan, you can contact Greddy USA. There is no part number listed for the 7MGE, but if it fits a 5M, I assume it'll be fine for the 7M as well.
http://www.trust-power.com/01exhaust/tr_na_mani.html
MA61 part # 10510550
I was quoted $525 shipped to my door from Greddy in NY (when I lived in NY)

Those Trust headers look awfully similar to the HKS Headers I have. Mine are originally for the 5/6M but fit perfectly on the 7M.

 

[935motorsports]

Nice, feel free to sell me that header at any time

 

[A-to-the-J]

Nice, feel free to sell me that header at any time

Well Robert, I'm still undecided, but my car may be up for sale soon. It's almost ready to run, just a few loose ends i need to take care of. I want to hear this thing! I'll throw in those headers with the sale

 

[Ma70.Ent]

Bump for anyone who's interested in headers.

 

[Tanya]

Those Trust headers look awfully similar to the HKS Headers I have. Mine are originally for the 5/6M but fit perfectly on the 7M.

How did you come to find out those were HKS headers? Is there a marking on them of any kind?

I've seen Greddy/TRUST knock-off headers on yahoo Japan, painted in that same yellow color.

 

[A-to-the-J]

How did you come to find out those were HKS headers? Is there a marking on them of any kind?

I've seen Greddy/TRUST knock-off headers on yahoo Japan, painted in that same yellow color.

It was stated by our engine supplier. Plus the engine it was on had a bunch of other HKS goodies, so there was no argument. But from what you say, i guess it might be possible?

pm'd.

 

[Tanya]

PM'd ya back.


Gosh, I love header talk. Now that I know (kinda) how to MIG weld, I'd love to fab up my own someday just for giggles.

 

[935motorsports]

I'm still voting for the 2jzge style. It is already done, so it is just a matter of adapting it to the M engine.

So we could have the long runner 2jzge style, raptor racing, and the trust. That would be plenty of options I think.

There are a few guys over 200rwhp NA with that style of header, so it must work somewhat.

 

[toy fanatic78]

I'm still voting for the 2jzge style. It is already done, so it is just a matter of adapting it to the M engine.

So we could have the long runner 2jzge style, raptor racing, and the trust. That would be plenty of options I think.

There are a few guys over 200rwhp NA with that style of header, so it must work somewhat.

I have an old raptor racing from my first mk2,seemed to add a decent amount of power w/2.5" all the way back.Just cut it up last night,had to move/change the collector a little,and tuck it closer to the bellhousing to clear the steering arm in my cressida('84,proud 5M owner,absolutely love that engine)Is the company that makes the raptor racing around still?I tried to fit it to my 86.5 supra a few years back,but it hit the motor mount and floorboard.I had only paid $110 for it though so it isn't that scary to cut/modify.I bought an OBX new for $160 for my mk3,curios to feel differance between 6-1 and 6-2-1.Should this header be heat wrapped?Where is the optimal place for a stock O2 sensor on a header?