Header/Exhaust System Design

[DEFIANT 7M]

I think this is the header Tanya was referring to installed in a Australian Supra. That is the only picture I could find.

Oh yea, that's Ed's old set up. Someone on here has that car.

http://forums.performanceforums.com/forums/showthread.php?p=839439470#post839439470

 

[DEFIANT 7M]

:3d_frown: WE HAVE A PROBLEM:3d_frown: I just measured the primaries on my Pacesetter. "Inside diameter" which is what we have been talking about is 1 3/8" not an 1 1/2"!!

 

[AJ'S 88NA]

Cut em apart and make new pipes out of 1 1/2" I.D. pipe or larger. Didn't you want 1 5/8" I.D.?

 

[DEFIANT 7M]

The info I posted was outer diameter (o.d), but uhh...that sorta sucks. Now what?

No worries, this is why we are sorting this out:icon_bigg. Looks like a Pacesetter header BARELY can handle a STOCK 7M head exhaust flow! Put a ported head on it and you just wasted time and money:3d_frown: It's just old tech guys the thinking behind this header is just dated. Tanya's Trust header is 1 5/8" inner diameter. To put a visual perspective on it get a 3/8 wrench and a 5/8 and compare! The Trust is the header to get, in my opinion. But we have Pacesetters out there so we need to see how we can make it work better for most of the N/As

 

[DEFIANT 7M]

Cut em apart and make new pipes out of 1 1/2" I.D. pipe or larger. Didn't you want 1 5/8" I.D.?

Hell yea, I plan on it. But for the guy who wants to modify his 7M it's good to know if you are going to out grow your latest mod really quick.

 

[cuel]

Interesting discussion. I could see a need for larger primaries for you, Allen. Does that Pacesetter have a thick flange? Might just scrap the primaries, and build your own. You can get mandrel bends and straight tube in pretty much any size you want from Summit and prostreetonline.com.

The OBX seems to be more of a stepped primary design than equal length. What I liked about it was the mandrel bends, it's stainless, and the flange is over 3/8" thick. I would think the i.d. would be 1 3/8" as well, though. I did have to move the o2 sensor flange. I put it right behind the Y collector. Actually, I scrapped the one it came with, and put a standard o2 bung in.

 

[Ma70.Ent]

Here's some info about the stock exhaust manifold.

The ports at the flange are 1.295" avg., from the head. The first three runners all join together into a log style runner, while the back three are separate for a couple inches before joining together. The front and rear are divided all the way through the manifold, to the middle flange, just past the O2 sensor.
Here, we have the middle flange. At the bottom of the manifold, just under the O2 sensor, the 2 ports measure 1.573". Some port work here would be beneficial.
On the other side, there is two pipes, and they measure 1.550". These two pipes lead down, with some restrictive crush bends, to the main pipe. There is no "Y" connector, the pipes are cut and welded, horribly, to each other and the pipe that they join to. This pipe measures 2.227" at the flange for the cat. The 2.227" pipe is pretty bad. It has some flat spots in it, and is really restrictive.

Just for any random future reference

 

[DEFIANT 7M]

Interesting discussion. I could see a need for larger primaries for you, Allen. Does that Pacesetter have a thick flange? Might just scrap the primaries, and build your own. You can get mandrel bends and straight tube in pretty much any size you want from Summit and prostreetonline.com.

The OBX seems to be more of a stepped primary design than equal length. What I liked about it was the mandrel bends, it's stainless, and the flange is over 3/8" thick. I would think the i.d. would be 1 3/8" as well, though. I did have to move the o2 sensor flange. I put it right behind the Y collector. Actually, I scrapped the one it came with, and put a standard o2 bung in.

The flange is 3/8" thick @ best. Yea looks like a header build tread coming for "Mythical"(that's what my friends call my car):biglaugh: Thanks for the link. Sounds like the OBX is much better made than the Pacesetter.

 

[DEFIANT 7M]

Here's some info about the stock exhaust manifold.



Just for any random future reference

I'm going to dig one of mine out. Maybe even get it flow tested at the shop. My memory of a stock manifold is not good. Would Extrude Honing do anything here?

 

[Ma70.Ent]

You might wanna talk to PowerTrip Performance if you're looking for some good fabrication-type stuff. I remember I was asking him about the pacesetter but he said it would require an actual "model" or it would require me to bring my car to his shop.

 

[Ma70.Ent]

I'm going to dig one of mine out. Maybe even get it flow tested at the shop. My memory of a stock manifold is not good. Would Extrude Honing do anything here?

I've actually heard that the stock exhaust manifold flowed pretty well.

 

[AJ'S 88NA]

This is kind of bad news for the guys (me for one) that have Pacesetter headers. Makes me want to rip mine off and rebuild them. Maybe someday I will, maybe someday somebody will make a good set, hint hint, for the higher modified GE.

 

[Ma70.Ent]

This is kind of bad news for the guys (me for one) that have Pacesetter headers. Makes me want to rip mine off and rebuild them. Maybe someday I will, maybe someday somebody will make a good set, hint hint, for the higher modified GE.

I was actually thinking of using a Pacesetter Header too. Ouch.

I'm pretty sure that this topic is going to lead to the production of headers that are actually good for N/As though.

 

[DEFIANT 7M]

:3d_frown:WE HAVE ANOTHER PROBLEM:3d_frown: Most of you have heard of pulse firing. Here is a quick run down. This is what should happen, since we have a six cylinder. We have two collectors with three pipes in each going to one 3-2-1, known as a Tri Y design. Which makes the most overall usable hp/tq. So our firing order is 153624: collector #1 should have cylinders (1,5,3), collector #2 should have cylinders (6,2,4). In a rotational order.

http://www.ssheaders.com/header.htm Explains even more plus some.

COLLECTOR 1
1 fires creates a pulse (vacuum) ,next is 5 gets sucked out by 1, next is 3 gets sucked out by 5. Then is starts over as 1 pushes out 3.

COLLECTOR 2
6 fires creates a pulse (vacuum) ,next is 2 gets sucked out by 6, next is 4 gets sucked out by 2. Then is starts over as 6 pushes out 4.

This is also know as scavenging. Then off into the two secondary pipes.

WRONG!

Pacesetter has number 5 where number 2 should be. That causes "dead air" in the header which kills the velocity. Which I'm thinking reversion and a loss of torque/hp.

Quick fix would be too switch positions to correct this.

 

[Ma70.Ent]

Pacesetter looks worse and worse as this thread goes on....ouch.

 

[DEFIANT 7M]

Let me add a little: Collector #1 creates a pulse (vacuum) of it's own Which helps Collector #2 get started. So you see have if there are two cylinders out of sync it causes a train wreck so to speak.

 

[DEFIANT 7M]

I hear you guys throwing hints at me..Who makes exhaust flanges on for the turbo guys?

 

[AJ'S 88NA]

I hear you guys throwing hints at me..Who makes exhaust flanges on for the turbo guys?

Don't know who makes them. The flanges should be easy to make and make right, not the half-ass job Pacesetter does. Especially if you have one to go by. I would think the proper length, right bend tubes would be the hard part. IDK. Once you had a pattern to go by.....

 

[DEFIANT 7M]

Looking at Tanya's Trust header number 2 and 5 aren't right. I'm thinking old design (made prior to the knowledge of pulse firing), or ease of manufacturing. Also be inherit design the 5/6MGE headers will have larger primaries, the ports are bigger I believe. If I'm right, first step for a 7M guy is to buy a 5/6M header.

 

[cuel]

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.