Things I Hate About 80's GM Tech: Y-Pipes

Owning an older car for more than a decade gives you a window into the minds of the people who designed and built the thing. Parts break, and when you fix them, you see the handy work that went into the original part. You see the purpose and execution of the design. Some of these things make you think “Oh, I see what Mr. Engineer did there! Clever girl.” Others make you think, “Meh, must of done it to save costs.” But every so often, you come across something that just makes you think: “WTF were they thinking!”

In this post, I want to discuss a system that has yet to make sense on my 1982 Trans Am: The Exhaust System. Namely, The Y-Pipe

The Y-Pipe

Now I know what some of you are thinking! “My car’s got a super powerful straight 4, all I got is a straight pipe; What’s a Y-Pipe?“ or “My Supercharged Mustang Turbo V8 Stroker Coyote Fastback Coupe has X-Pipes and H-Pipes and Cat-Backs and Mufflers-Deletes and Straight Pipes (And I think there’s a bendy bit in the middle), What’s a Y-Pipe?“ And for those of you from the 70’s, you’re probably thinking: “What’s a Matador?”

Well fear not confused readers, for I am here to explain! A Y-pipe is a section of exhaust piping which connects the exhaust flow from the driver’s side of the engine with the exhaust flow from the passenger’s side of the engine into a single flow which exits at a muffler. If you look at the image above, you will see two “Shorty” style headers and the appropriate Y-Pipe for a 305 or 350 V8 in a Third Generation Camaro or Firebird. In fact, this is the very product I have bought to replace the stock manifolds and factory Y-Pipe in my 305 or 350 V8 in my Third Generation Camaro or Firebird!

Y-Pipe Flow

Above you can see how the flow is supposed to work. A little exhaust from the left gets placed smoothly into the little exhaust flow from the right, and combine into a single large exhaust flow. This minimizes back-pressure, which in turn, can increase the performance of your engine. Having a single large pipe rather than dual pipes from the headers back saves space, cost, and weight. It was probably done for packaging reasons, and so long as the single pipe is large enough, I see no problems with a single exhaust from the headers to the muffler.

Now I don’t proclaim to be an Exhaust Design Savant, but I do believe smooth transitions of airflow are better than rough ones. So, the aftermarket system turns the flows from the left and right side to be parallel before combining them in a relatively smooth manner. Good, everyone’s happy. But now we get to the factory setup…..

Factory Manifolds

So the first thing you notice about these is that they are not long tube headers. In fact, they are not even shorty headers. Hell, they aren’t even headers! What you see here is an example of factory manifolds.

But just what is a manifold? “In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point.”. Duh guys.

But actually, exhaust manifolds are just big chambers the exhaust valve empties into, rather than specific pipes per chamber as in headers. It’s a common thing for manufacturers to do to save costs and weights and emissions and stuffs, but not exactly optimal for powers. There are many reasons that headers are better than manifolds, but I’m sure there are reasons to use manifolds over headers. For a N/A V8 smog motor, I believe headers to be the preferred method of exhaust disposal, so let’s pretend that is absolutely, irrevocably, and decidedly correct. Therefore, these manifolds fall into the category of “Hmmmm, Mr. Engineer must have done it to save costs. Meh.” So they aren’t the issue. The issue is what they are connected to….

Factory Y-Pipe

And even closer.

And closer still.

Do You See The Problem Yet?

This, my friends, is the topic of today’s discussion. This is a design decision that made me say “Mr. 80’s GM Engineer…. WTF?”

This is not a Y-Pipe. This is a T-Pipe. A Freaking T. T. Right Angles. Perfect for smooth airflow. It’s not like a T will greatly impact the smoothness of the exhaust flow. This must be genius! Adds 50hp! Should have thought of this sooner! I can imagine the design team now….

1980's GM Design Team

Bob Boberson just needs his team of 1980’s GM Engineers to finish the design phase of the exhaust system, and all their ideas so far have been crap. Stupid things like “Power” and “Efficiency” keep coming up, but Bob won’t be fooled. Bob is a smart, experienced businessman. Bob knows what the public really wants is a cheap, poorly made, and incorrectly designed product. Arnold is smart enough to suggest a cheap manifold, rather than stupid, newfangled “Headers,” whatever those are. No one puts a head on an exhaust system; what rubbish. Betsy want’s to connect the two sides with a T-Pipe. Good, less metal means less costs. Plus, the air will stay in the exhaust pipe longer because it’s restrictive. Now that’s making the most of the materials we have! But darn Steve wants to put “Free-Flowing Exhaust” and “Performance Mufflers” into the design. Stupid ideas. He’s fired.

But thirty years later, I just look at their handy work and think to myself “Why Betsy, why?!?!”

The manifolds don’t bother me. I get it, saves cost, and it’s something for me to replace down the line. Good show. And the single pipe from the headers to the muffler doesn’t bother me either, saves space, good for packaging, I get it. But the gosh darned T-Pipe?! I have to draw the line somewhere. On what is supposed to be a “performance” model, you want me to believe a T-Pipe is the best way to go?

GM even realized their mistake, because by the midpoint of the decade, Thirdgens were equipped with something resembling a properly designed Y-Pipe, a later just dual pipes all the way back. They must have realized what they had done was stupid, but they did it anyways. Must have fired Bob a few years later. A sad day for Bob, sure, but it was a sad day for GM when they decided a T-Pipe on a Trans Am was a good idea.

The Fix

Companies make replacements for this mistake, and I have installed headers and a new Y-Pipe onto my Trans Am. And while I wouldn’t expect anything more than 4-5 hp increase if I were to put shorties on a modern car, like my 2012 Scion Tc, but I am very inclined to believe stories of people gaining 20hp, just from replacing these stupid manifolds and T-Pipes with a proper exhaust setup.

I would love to meet Bob, Arnold, or Betsy, just to see if they realized their mistake. And then, I’d go see Steve, and give him a cookie. Chocolate Chip.

The Best Kind of Manifold

This concludes my half rant/half description on the early 80’s F-Body Y-Pipe, and so, I will leave you with my favorite type of manifold. The best kind of manifold. The Calabi-Yau Manifold! Behold the majesty!

I have several other gems of early GM engineering I could post/complain about, so let me know if this was interesting enough to want to read similar articles. Or, tell me it’s complete hogwash. Either would be equally acceptable.