Saw this in a post. I've never heard of TRI Y headers. What were they on originally or are the an aftermarket item? ______________________________________________________________ Like I told the kid, "Your music's not too loud, it just sucks and so does OKC!"
Tri-Y headers have two pairs of primary tubes going into two single tubes into a collector on each side of a V-8 or one side of a four. They give increased torque at lower RPM's. I have only seen them in the aftermarket mainly, for four wheel drive applications.
Tri-Y's were offered as aftermarket options on musclecars too, the mustang being the one that stands out in my mind. If I remember right they sacrifice some low end torque for high end flow...
If you look at a typical V8, say, a 289 the ideal is to split the firing order up in two with a 180 deg headers. Left bank 1234, right bank 5678. firing order 15426378 one header combines 1-4-6-7- -5-2-3-8 in the other one. Thats ideal but not possible without tubes crossing over from bank to bank. The next best thing is a Tri Y. It combines 1&2, 3&4, 5&7, and 6&8. So that gives ( with the same firing order ) 1--2----1--2---- --4--3----4--3-- -5----7--5----7- ----6--8----6--8 And then it combines Y 1&2 with 3&4, and 5&7 with 6&8. ( and sometimes not like on the Cobra Daytona Coupes, where they left them with 2 pipes on each side ) Not as good as a true 180, but the next best thing with a lot less of a plumbing nightmare...
There is a difference between "Tri Y" headers and 2-2-1 headers. These are 2-2-1 headers. 2 adjacent cylinders are yoked together and then they are yoked together again farther down the line. The firing order doesn't come into play. Just the proximity of the cylinders. Even though there are 3 Ys, these are not considered "Tri Y" headers. These are "Tri Y" headers. You can see on the bottom one that the second cylinder and the 4th cylinder are yoked together and the first and third are yoked together. This was done to try to space out the pulses in the system as they pass through the exhaust system. All of the Tri Y headers that I've ever seen were different on each side because the firing order determined which tubes should be yoked together. Usually one side will yoke the side by side tubes together but the other side would yoke every other one together like the lower one above. My recollection was that Tri Y came along first and then someone carried it a little further to the 180 deg headers that yoked cylinders from opposite sides of the engine together as pictured in an earlier post. My feeble memory bank wants to say that Ford had the first 180 deg headers (GT-40 maybe?) but they could have copied it from someone else. I used to help a 1/2 mile circle tracker years ago and one of his competitors built a true 180 deg header system for his 1/2 mile asphalt car. 180s have a sound all their own. We called it the bumble bee due to the sound. It almost buzzed at high RPMs. You could tell from the pits if he was on the track with the other competitors just by the sound. Tri Ys don't sound any different than conventional headers. I love them and built them for some of my old hot rods just because they are different and have that old timey feel to them. I never bothered to learn the matematical theory behind it all. No I never reached the ultimate potential of the design but I'm sure that mine are better than a stock cast iron manifold and I'm not scrounging for tenths of a second at the race track either. Like the big cam debate, technology has come a long way and passed them by but if looks and nostalgia mean anything to you they are cool and hard to beat. I've collected these pictures because I plan to build a set for my FE in a 56 Ford.
Tri Y headers became popular with the original Mustangs and Shelby's and that was still probably the most famous use for them. Doug Thorley, through his Doug's Headers brand really popularized this type of header and Doug's Headers still makes them today. When Doug got divorced his ex wife Betty started Doug Thorley Headers and used the idea for trucks and motor homes also. This next statement will probably cause some controversy, but it is the truth - For just about every American V-8 on the street, the Tri-Y design is optimal for overall power production. Today Tri-Y design pipes are favored by road racers and NASCAR Winston Cup teams, in addition to many of the top NHTA and IHRA Pro Stock engine builders. One of the largest errors street enthusiasts make is in running too large of a primary pipe, and too large of a collector. For example, NHRA Stock teams using Tri Y headers in H/SA in traditional small-block powered muscle cars are running 1.5-inch diameter primary pipes- much smaller than many street machines are trying to use with a conventional 4 into 1 design. 4-into-1 headers do not have secondary pipes, and secondary pipes are the key to the proven reality that Tri-Y designs make more overall power over a broader rpm range. Street enthusiasts have known that Tri-Y pipes make more bottom-end torque, but further research has resulted in Tri Y headers making more power all across the rpm range. With more pipes in the Tri-Y design, more tuning possibilities exist, and therefore more potential for power. The secondary pipe diameter is determined by considering both pressure waves and reflective waves throughout the system. Since the pipes are paired according to the firing order, these waves can work together or against each other. The pressure wave travels the length of the primary pipe in a 4-into-1 header, then is reflected from the collector where the area changes from the small-diameter primary into the larger-area collector. A reflection of negative pressure goes back up the primary pipe. In a Tri-Y design, the pressure of additional area changes (where the primary pipes become secondary pipes) produces additional reflections, so the Tri-Y must be designed in a different manner with respect to wave control. Given this, the area of the Tri-Y header between the first and second collectors becomes critical, and tunable. The entire header is affected by this crucial length of pipe, and can be fine-tuned accordingly through proper sizing for optimal broad-range performance. 4-into-1 headers also are affected by altering pipe lengths. But, without these secondary pipes it is impossible to tune with the same level of precision as with a Tri-Y. Tri Y headers also weigh less and with less tubes in the lower area are much easier to package in tight areas. Proper Tri Y headers are actually more difficult to design and more expensive to build , which is why you don't see more offerings in the market.
Tommy, if you are collecting photos of the Tri Y headers you should look at the www.fordpowertrain.com site. click on headers and look at the Tri Y's for the FE in a 60-64 Galaxie. Those are some wild looking Tri Y's. Scott...
In 1964 I bought a set of Doug's (Doug Thorley) Tri-Y headers for my 327 powered '55 Chevy gasser. Stock 365 horse short block, Mondello double humps, Chet Herbert #70 roller, Edelbrock cross ram with 2 500 cfm Holley's, 5:57 Pontiac rear with Henry's axles. Dump the clutch at 8,000 and power shift at 8,500, ran 11:20 at 121. The combo worked as all components were closely matched. As time has passed the Tri-Y design is still valid, and I agree with Horroddon most current thoughts on exhaust design are incorrect, bigger is not better. Bigger diameter tubing reduces velocity which has a direct effect on cylinder scavenging. Everyone will have their own opinion on this complex subject. The FOGGER
Pontiac Tri-Y headers made by H-O Racing back in the early '90s, for round-port Pontiac Super-Duty, HO and Ram Air heads. Seen here bolted on a set of Edelbrock heads which are based on the '69-'70 RAIV heads. These ones have 1-3/4" primaries, 2" secondary tubes and 2-1/2" collectors. Perfect for the low end and mid-range powerband of Pontiac street/strip engines. I have set of these on my 8.6:1 compression 455 HO '64 GTO, ran 12-flat times at 110 MPH in the 1/4 mile with a 5200 RPM shift point.
I had a set on a 55 chevy back in the mid 60's. They seemed to work well and sounded cool with glass packs.
Mustang Tri-Y's. Dirt cheap at under $150. Should work in many early frame applications. They tuck in very close to the block/trans. Specs: 16 gauge steel with 1/4" flanges, 1-1/2" primaries, 1-3/4" secondaries & 2-1/2" collectors. Includes collector reducers, gaskets, hardware.
63 1/2 427 Galaxies had a beautiful (but really heavy) set of cast-iron tri-y manifolds. One of the recent Engine Masters competitors ran them on an (admittedly very tricky) flat-tappet 427 FE with a single four barrel to make over 600 hp. Motor made about 650 with headers and an electric water pump.
Tri Y headers were simply a way to separate the firing impulses of adjacent cylinders 90 (or 60 in a six cylinder) degrees apart in the firing order and build mid range torque. The factory Ford and Pontiac cast iron examples both date back to the VERY early 60s. One of the more famous examples of a 180 degree exhaust system was the so called "Basket of Snakes" setup in the pushrod engined Lotus Ford Indy car of 1963. Although it didn't win the race, it did place 2nd.
I'm a big fan of Tri-Y'S and have a set of Belangers' on my 2003 Z06 Corvette. Yeah, I know, a new car but still the same principle. This was a set of $1300 headers but luckily I found a used set for less than half of the original price. Some great explanantions in the above posts, especially the part about them being much more difficult and expensive to manufacture. They may fall off just slightly in the upper RPM ranges, but when you do those gear shifts that tachometer drops right into the sweet spot of the mid-range where these things really shine. That's how you win races! Oh yeah, don't forget that Flowmaster makes a universal 4-2-1 header collector that you can add to any header to get the close to the same affect. Helps with chassis clearance too sometimes. If a manufacturer makes a true Tri-Y for your vehicle, it should be your FIRST CHOICE for your street-driven car!
The Jalopy Journal
