Header/Exhaust System Design

[DEFIANT 7M]

The OBX is the same. Cylinder's 1, 2, and 3 in the first collector, and cylinder's 4, 5, and 6 are in the second collector. I'll try to get some primary to collector lengths, and the first 2 collectors to the last collector lengths.

So, you're saying 1, 3, and 5 should go into the first collector, and 2, 4, and 6 should be in the second collector? That would be a much harder header to create, I think, especially if you were trying to keep all the primaries the same length. Would you want to keep them as short as possible, or make a long tube header?

Oh yeah, I think the reason the available headers are the way they are is ease of manufacture.

Oh yea since our firing order is 153624, it's wrong and we are loosing out. Really a long tube header suites a 7M N/A, shorties work but we need every little bit. Your right it's got to be a manufacturing thing. The "equal length" idea is a little over used. We can make this right and not notice the little gain we would make if all the pipes were equal.

 

[DEFIANT 7M]

Longest primary on the Pacesetter is 21" (#1). I'm going to make them atleast 31", pulled this from the SS header link.

"On today's cars, with space virtually nonexistent, crossing four tubes either under the oil pan or around the front or rear of the engine presents major problems. On racing applications where it is possible, there is still the problem of keeping the tube length down to a reasonable 32" long. If that's not enough challenge, then try to arrange the tubes into each collector so they fire in a "Rotational Firing" pattern. Then you have, what has been called "A Bundle of Snakes". "

Being an in line six it's not so bad. I'm not much of a welder, hell my welds look like "bird shit". So I am going to improvise..( I mean pay somebody)

 

[BLACKCAT]

My Australian Hurricane brand has the same cylinder collector setup.
The primary ID is only 1 1/4" but I still make good hp running 2 1/4 from end of header to end of first muffler followed by 3" to second muffler & end.
At least the flange is nice & thick plus the O2 sensor is at the bottom measuring three cylinders not one.

 

[DEFIANT 7M]

My Australian Hurricane brand has the same cylinder collector setup.
The primary ID is only 1 1/4" but I still make good hp running 2 1/4 from end of header to end of first muffler followed by 3" to second muffler & end.
At least the flange is nice & thick plus the O2 sensor is at the bottom measuring three cylinders not one.

Nice header, I wonder how much hp/tq we are leaving on the table with the collector/primary issue

 

[AJ'S 88NA]

Nice header, I wonder how much hp/tq we are leaving on the table with the collector/primary issue

I wouldn't think it would be that much, maybe around the 5 - 10 hp range, but 5-10 hp is 5-10 hp add that to what you would normally pick up with the change to headers and it all adds up.
Wouldn't be better, and easier, to put the 0-2, farther down to read all the cylinders? Also to prevent any heat soak problems with being too close to the hottest parts of the header? I know the stock location is closer to the head, but they are cast.

Also with the stock 0-2 sensors it might be ok that close to the head, but I think with a WB 0-2 it might be too close. I believe CRE had a problem with his WB in the stock location. I sure would like to know the best place to mount the WB to make sure I haven't screwed up by mounting mine farther down on the collector, but not as far down as Pacesetter had it.

 

[Tire Shredder]

Alan,

I believe this link will be very helpful. Seamus on CS.com did a comparison of all the headers he could get ahold of. Included in that thread is a link to pictures of every header.

http://forums.celicasupra.com/showthread.php?t=17157&highlight=header

there was some talk of using 5M designed headers on a 7m and visa versa. The flange and bolt pattern are the same on both models. The difference lies in the rest of the exhaust. If putting a 7m header on the 5m, you will find that the "midpipe" section will be too long and the angle off. Likewise, using a 5m header on a 7m, the midpipe section will be too short and angle slightly off.

The OBX 7m header on a 5m: Robert pina has some comments regarding the flange quality, 02 sensor location and fitment into a mk2 here: http://forums.celicasupra.com/showthread.php?t=18673&highlight=header

George at Raptor racing has recreated the Tri-mil header. He made some modifications so it fits well, had proper 02 sensor location and a wideband bung.

He gained 10whp with just the headers alone. full 2.5" exhaust and cat stayed on for both the stock manifold and his header dyno runs....so these gains are from the header alone. it should be noted that the headers you are speaking of are designed for a 160hp 5m....

dyno results and video here: http://forums.celicasupra.com/showthread.php?t=25569

pictures from the now ended group buy here: http://forums.celicasupra.com/showthread.php?t=25872

 

[DEFIANT 7M]

Alan,

I believe this link will be very helpful. Seamus on CS.com did a comparison of all the headers he could get ahold of. Included in that thread is a link to pictures of every header.

http://forums.celicasupra.com/showthread.php?t=17157&highlight=header

there was some talk of using 5M designed headers on a 7m and visa versa. The flange and bolt pattern are the same on both models. The difference lies in the rest of the exhaust. If putting a 7m header on the 5m, you will find that the "midpipe" section will be too long and the angle off. Likewise, using a 5m header on a 7m, the midpipe section will be too short and angle slightly off.

The OBX 7m header on a 5m: Robert pina has some comments regarding the flange quality, 02 sensor location and fitment into a mk2 here: http://forums.celicasupra.com/showthread.php?t=18673&highlight=header

George at Raptor racing has recreated the Tri-mil header. He made some modifications so it fits well, had proper 02 sensor location and a wideband bung.

He gained 10whp with just the headers alone. full 2.5" exhaust and cat stayed on for both the stock manifold and his header dyno runs....so these gains are from the header alone. it should be noted that the headers you are speaking of are designed for a 160hp 5m....

dyno results and video here: http://forums.celicasupra.com/showthread.php?t=25569

pictures from the now ended group buy here: http://forums.celicasupra.com/showthread.php?t=25872

Hey thanks, this is some really useful information. It has also made me think the basic design for the Pacesetter has been used since MKII days. They just changed it to work on a MKIII. As with the other makers. The Trust/GReddy is just typical of them doing a little extra to out pace the competition. Raptor wow...10hp/10tq with a factory cat, is a great increase for sure! Plus he got the "pulse firing" right!

 

[DEFIANT 7M]

OK, I just got off the phone with Burns. Just in material(mild steel), I will spend close to $800. Flange included in that price from a local machine shop(they are very high). But very good I used them when I turbo charged a Sentra..any way. I wanted to get an idea what using the best would cost. I want to make a long tube 6 into 1 header with 1 5/8" primaries. Maybe it will make 5-7 or more hp/tq than a Tri-mil. I know Tri Ys' make more low end hp/tq not much but more. But a good "race style" 6 into 1 should be stronger in the upper and mid rpms, somewhat of a even trade off.

 

[AJ'S 88NA]

OK, I just got off the phone with Burns. Just in material(mild steel), I will spend close to $800. Flange included in that price from a local machine shop(they are very high). But very good I used them when I turbo charged a Sentra..any way. I wanted to get an idea what using the best would cost. I want to make a long tube 6 into 1 header with 1 5/8" primaries. Maybe it will make 5-7 or more hp/tq than a Tri-mil. I know Tri Ys' make more low end hp/tq not much but more. But a good "race style" 6 into 1 should be stronger in the upper and mid rpms, somewhat of a even trade off.

Ouch!!6 in to 1 might be a problem with fitment trying to get 6 primaries to fit along side, the motor and tranny, IDK maybe.

 

[DEFIANT 7M]

Ouch!!6 in to 1 might be a problem with fitment trying to get 6 primaries to fit along side, the motor and tranny, IDK maybe.

You think? I mean it will be shaped similar to the Pacesetter.

800 bucks? DAMN!

Yea, but that is the good stuff. Is there anyone here who makes the exhaust flanges? My guy wants $250-275!

 

[AJ'S 88NA]

You think? I mean it will be shaped similar to the Pacesetter.



Yea, but that is the good stuff. Is there anyone here who makes the exhaust flanges? My guy wants $250-275!

The flange should be the easy part. $250 sounds quite steep to me.

I think if you are making the primaries around 32" long, you might have some trouble getting 6 1 3/4" pipes to fit in the narrow area they have to go in down to the collector. The collector would have to be pretty large to get 6 pipes in also. I think it would work the best, it's just you might have some problems. Maybe if the primaries are a little shorter you could collect them before it goes into the area around the bellhousing. I think I'll make some measurements and see how much room we have in that area.

 

[DEFIANT 7M]

The flange should be the easy part. $250 sounds quite steep to me.

I think if you are making the primaries around 32" long, you might have some trouble getting 6 1 3/4" pipes to fit in the narrow area they have to go in down to the collector. The collector would have to be pretty large to get 6 pipes in also. I think it would work the best, it's just you might have some problems. Maybe if the primaries are a little shorter you could collect them before it goes into the area around the bellhousing. I think I'll make some measurements and see how much room we have in that area.

That's what I thought on the flange...just said okay thanks and hung up. The collector is $350 from Burns (mild steel), should I even mention $$tainless! That would be great I'm going to take a look at my car sometime tomorrow.

 

[Ma70.Ent]

Well, depending on what happens, Allan will be sending me his version of the pacesetter (modified etc.) and I'll be putting it on my car and taking it to the dyno. Right now I'm running the stock exhaust manifold so I'll compare the results. My exhaust system isn't stock, but we can factor stuff like that in later.

 

[DEFIANT 7M]

First thing is to fix the routing problem with cylinders 2 & 5. I will probably replace the collectors with a merge style to increase the velocity. I like this site, I'll give them a call in the morning. Page thru till you see the 6 into 1 collector:aigo:

http://www.spdexhaust.com/pdfs/02-11_Merge_Collectors.pdf

 

[Ma70.Ent]

I cleaned up the thread of stuff that really didn't have to do with the designing. Hope you don't mind

 

[AJ'S 88NA]

First thing is to fix the routing problem with cylinders 2 & 5. I will probably replace the collectors with a merge style to increase the velocity. I like this site, I'll give them a call in the morning. Page thru till you see the 6 into 1 collector:aigo:

http://www.spdexhaust.com/pdfs/02-11_Merge_Collectors.pdf

If you talk to them find out the dia./width of the 6 tube collector. The area the tubes go thru by the bellhousing is approx. 6".

If you were to run the primaries around 32 inches long they would all be in that area and collect from what I can guess around a couple inches past were the block meets the bellhousing.

The distance from the bellhousing and what I believe is a "ear"of the sub-frame protrudes towards the block, is close to 6". If a collector could be made stacking the tubes 2 wide and 3 high making a rectangle collecting down to the collector size of 3", clearance would not be a problem. Total collector size would be, with 1 5/8" ID pipe probably 1 3/4 OD, around 3 3/4" by 6".

The collector on the site you referenced above would probably work as long as it's not over 6" wide at the widest point. Either way could be rotated to cut down, if you will the cross-section width to give a little more space. My Pacesetter almost touches the "ear" of the sub-frame, really could have been pivoted a little more towards the block. I think I've heard the header hit the "ear" a couple of times it's that close.

 

[DEFIANT 7M]

Cut the flanges off today and fixed the primaries (2,5). Really we heated the #2 and moved to the #5 spot. We cut #5 off at the flange and ran it under everything to the #2 spot. Not too bad, this is just a mock up to see what is what. I have my shapes know I have to make the final pipes. The collectors are the formed style not a "merge". Basically it slips over the pipes and welded up filling in any gaps not the best. But 98% of the headers out there are made this way. A true merge 3 into 1 cost $150-219 each:aigo:. I have some ideas that should work out great for the finished product. Right now two redesigns can be made, but the cost for the second is a bit rich. Plus the performance gain might not out weigh the cost of the second design. So I will stick to the plan.

 

[AJ'S 88NA]

You talking about the pre made collectors you referenced yesterday? They're $150-$200 for the 3into 1? What about the length you were talking about 32"? The cut off pacesetter you cut the pipes look to be about 20", I know is just a mock up, but are you going to extend the primaries?

 

[DEFIANT 7M]

You talking about the pre made collectors you referenced yesterday? They're $150-$200 for the 3into 1? What about the length you were talking about 32"? The cut off pacesetter you cut the pipes look to be about 20", I know is just a mock up, but are you going to extend the primaries?

Yes and yes, I was like DANM! The length.. I see what your asking this is going to be a modified Pacesetter. The 32" primaries will be the long tube header 1 5/8" primaires with a Burns 6 into 1 for "Mythical". That other place is out of this world $$$$$. Never thought I would find someone higher than Burns:aigo: Right now I'm making something everyone can use. When I'm done Ma70.Ent is going to dyno it to see what we get. Here is a better shot of number 5. A friend of mine reminded me that his uncle makes headers/exhaust and has a mandrel bender! So he dropped it off tonight, I'll have it back in a few days.:icon_bigg

 

[cuel]

The OBX primaries range from 18" to 21". The collectors(2 3into1) are about 10" long. Here's a link to one: http://cgi.ebay.com/ebaymotors/OBX-...-Supra-NT_W0QQitemZ370007202242QQcmdZViewItem

I like the idea of swapping 2 and 5. Been looking at the header trying to figure out an easy way to do it. Might have to do that when I get the new motor done.