danglerb

The complete reasoning behind Tri Y headers is a mystery to me, but it still seems like a good idea due to fewer pipes and simpler plumbing. Specifically two fairly small diameter pipes poking out past the constraints of the firewall area instead of four similar ones or one larger pipe with all the combining in the engine bay.

Firing order is: 1-3-7-2-6-5-4-8
Looking from front of engine to the rear cylinders are numbered:
Passenger side: 1-2-3-4
Driver side: 5-6-7-8

720 degrees in a full two revolution cycle of the engine, each cylinder's events 90 degrees apart. What seems ideal is to merge cylinders 360 degrees apart with equal lengths of pipe, the length being tuned so exhaust events have effect in the desired rpm range. As I understand it the high pressure burst from an exhaust valve opening travels down the exhaust pipe to the merge where it creates a low pressure wave in the other pipe that reaches the other cylinder exhaust valve somewhat prior to its closing reducing the amount of exhaust left in the cylinder. Being 360 degrees apart the exact same thing happens in the opposite direction.

Trouble is ideal matching is 1/6, 3/5,7/4, and 2/8, wrong side of the block for easy plumbing. Enter my reckless limited understanding of Tri Y, and consider initially pairing 1/2, 3/4, 5/7, and 6/8, which seems benign as the cylinder events are 270 degrees apart, no flow by both at the same time. Now combine those four pipes in an equal length fashion behind the firewall and clutch merging 1/2 with 6/8, and 3/4 with 5/7, and we more or less get close to the ideal matching.

I don't have a clue about the final merge or X, but somebody smart would know how to figure out where to put it etc. Should work shouldn't it?

Hilton

This old thread has discussion on pairing cylinders based on firing order, along with much discussion on both tri-y and "crossed" tri-y.

https://rennlist.com/forums/928-foru...ternative.html

toofast928

I have Tri-Y manifolds. Sounds great and lots of low end torque.

SMTCapeCod

it's messy~~
https://rennlist.com/forums/928-foru...ternative.html

danglerb

Thanks, and this is a link to the pipemax thread I forgot I started related to it, and now plan to update, "soon". https://rennlist.com/forums/928-foru...r-a-928-a.html

Lizard928

I would love to make a tri-y setup for myself.
But the materials to make 1 set (properly) are going to be around $800.
The labour to make them is not small either.
Add in the R&D, how many would be willing to pay $2k-3k for a set of headers?

danglerb

New ford V8's use the same firing order as the 928, so some amount of lifting of ideas can come from existing products. Jon Kaase had some interesting headers on the engine that won the 2013 engine masters challenge. http://www.stangtv.com/news/jon-kaas...asters-winner/

“Those headers really did help us score down low and we really didn’t give up anything up high,” says Kaase. “At one point it made 630 lb-ft at 3,200 rpm. That’s a lot of torque at 3,200 for a 409-cubic-inch engine.”

ptuomov

You'll get to the ball park by buying the materials from Burns Stainless and using their software. I don't know if they can use simulated or measured pressure traces in that program, but that information would help them get yet closer. Calvin Elston of Elston Exhaust is the triple-y specialist and works with Burns. He'll need the map of the available space. That's the way I'd go if I'd need one-off custom headers that would need to be right the first time. On the exhaust side, there's really no substitute for experience.

To answer your question whether someone would pay $2.5k for a set of SS tri-y headers, I think some people would if the headers would be the best they can be for a particular combination. For a compromise header, probably not so much. For it to not be a compromise header, it will need to be matched with the operating rpm, power production, intake tract, cams, and compression ratio. This will narrow the market significantly.

Compromise headers would have to be cheaper, but then the market would be bigger.

Thank God I have turbos. John will be casting Inconel manifolds for our cars next summer, which isn't the cheapest option. At least the turbo engines will make power as a return for the dollars invested...

That header uses the dual port structure. Furthermore, we don't know anything about what's inside that engine. We don't know if the exhaust valves are the same side on both sides, we don't know if the cam lobes are the same on both sides, etc. We don't know if it's just a marketing stunt to run eight pipes out of the head or whether it actually adds anything on top of a more conventional tri-y. I believe that copying without understanding will lead to disappointing results.

Rob Edwards

So for the Pipemax experts- here are the measurements off the Tri-Y's that were on Anderson's Zombie motor. Does anyone want to plug in the numbers to model and see whether the really long secondaries were useful or not?

All numbers are from the mounting flange on the head to the end of the pipe.

Primary tubes are 1.75" OD, individual lengths are:

1. 25”
2. 20.25”
3. 23.75”
4. 24.25”
5. 28.25”
6. 24.5”
7. 19”
8. 18.25”

The first merge pipes are 1.75" to 2.25" in diameter and are as follows:

1&4: 12.5”
2&3: 13.25”
5&6: 13”
7&8: 13.75”

Second merge pipes are 2.25" to 3" and are:

1-2-3-4: 13.5”
5-6-7-8: 13.75”

Once assembled, the total path length from the flange surface to where the 2nd merge pipes end as shown in this linked pic are:


1: 46-7/8”
2: 43”
3: 44-3/4”
4: 41-3/4”
5: 52-7/8”
6: 48-1/4”
7: 42-1/4”
8: 43-7/8”



Moar pics:

1-4:





5-8:






Exhaust pipe:



On-car:

ptuomov

I don't think you need pipemaxes or simulation programs to answer that question, you should go and ask Mark Anderson! He'll know if it worked better than other headers or not...

Just by looking at it, that's not at all how I would have paired the pipes. I would have paired 1&2, 3&4, 5&7, and 6&8. I would have also had a lot shorter primaries. Shows how little I know about what actually works in terms of exhaust...

Trying to read the designers mind here: The very long secondaries by my understanding help the torque at below peak torque rpms. Basically, closer to the exhaust valve you do something in the header, the higher the rpm at which its impacts show up. It could be, for example, that the primaries in those headers are very long and that takes care of the rpms above torque peak. Then, the pulses are intentionally combined in the first mergers in a way that gets them as much on top of each other as possible. This design intent would be the opposite of normal tri-y design intent. This pulses-on-top-of-each-other design may create a stronger pulse at low rpms despite the pretty large pipes, which may help get the wave tuning to work better at below torque peak rpms. The pretty large pipes may then flow a lot at high rpms.

Rob Edwards

Here are a couple of the dyno results from the period before the Tri Ys were installed, up to the addition of the Threshie intake. So the Tri-Y's were good for a little bit of hp/tq over the MSDS headers used previously (at least I think they were MSDS based on Mark's notes), though the benefit is small compared to the CF intake.

ptuomov

Based on those numbers, if the only difference between the 7/29/2002 and 5/6/2002 was the headers, they obviously work very well.

danglerb

Any idea who made the headers for Mark?

BTW the indication I get from more reading is that Tri Y optimizes low end torque, and other designs may work better on the top end HP. The Ford Coyote motor uses Tri Y with primaries about a foot long.

SMTCapeCod

I assumed they were Cloutiers' from back in the day. No?

Rob Edwards

They're not from Cloutier- Pretty sure they were built by Greg's header fabricator.