Headers vs Manifold discussion

[Zach]

Hello, I am currently looking into a full new exhaust system for my 1977 400 trans am with a 4 speed. Currently discussing with my dad whether we go with headers or a manifold. Personally I want headers for the performance improvement and people recommend them all the time, but I also love the sound of the stock trans am and how muted it is in the engine bay as well as it isn't gonna annoy people miles away going down the road. My dads reasoning for manifolds is to also preserve the sound and the structural integrity of a manifold coming off the block. His experience with putting headers into is 68 firebird didn't go well so we need some convincing if we stick with a manifold for the sound, or go to headers for performance. The car is pretty much all stock and we aren't gonna be throwing any extra power into it besides a carb rebuild and other small performance fixes.

TLDR Headers vs manifold, sound over performance. Convince us.

[5th T/A]

Depending on what you decide on for an exhaust system would determine how much gain you would get from headers. If the engine is mostly stock and your not going to race it, I would go with Ram Air exhaust manifolds. Some people say you don’t lose that much running the log type manifolds. The extra heat from headers and aggravation of working around them is not worth it for me. Ram Air Restorations has nice aftermarket reproductions, but I heard they are on back order.

[DynoLee]

This is testing I performed. 

455, stock "66" pressed-stud heads with better valve springs installed, HUGE chambers made the compression ratio right at 7.8:1 at this time.  Q-jet, Performer intake, HEI.  I used a wide-band to monitor the AFR, and the presented graphs were after correcting the fuel ratio for each configuration (and the carb required much richer metering rods with the headers).  The camshaft is a mild custom HFT, with rather low lift (.443/.435).

Stock 2nd gen Firebird exhaust manifolds for the first test, with the factory head pipes.  The head pipes were about 2.0" in diameter, feeding into 2.5" pipes that ran to the mufflers.  The mufflers were 3" Flowmasters, and the tail pipes were 2.25".



The 2nd test was performed with a set of tri-Y headers.  To the best of my knowledge, these are no longer available new, so I'll refrain from even mentioning the company.  [a friend paid for a set and never received them]  I suspect any quality regular header would have similar results.

The headers eliminated the 2" section of pipe, but for this test they were connected directly to the remaining existing pipes.  Other than tuning for proper AFR, no other changes were made.

I have thread on here, where I detailed the testing and some other changes I made as well.

[Wallington]

A good comparison showing that there is very little to gain vs the dramas that headers come with. On a street engine, depending on type, I'd nearly always go with manifolds. As mentioned, cabin heat alone is enough of a reason. Exhaust sound comes down to far more than that. As you mentioned, a close to stock car won't see the improvements available from increases in exhaust flow, an improved exhaust behind that will do just as much, select muffler/s to suit.

[scarebird]

That looks like the best headers vs. the worst manifolds.

I ran the RA III manifolds on my 71 - the issues with headers were not worth the extra 20 or so HP.

[DynoLee]

A good comparison showing that there is very little to gain vs the dramas that headers come with.

Improvements of 45rwHP and 75rwTQ are over 20% gains.  Far from what I'd consider "very little gain". 

Scarebird, to the contrary, those manifolds are the same as what Zach is going to have on his car.  It is about as hard (and expensive) to find a set of 2.5" RARE manifolds right now as a set of tri-Y's.  I had a set of RARE's, a friend bought them back in the 90's and sold to me in a package.  I put them up for sale for (what I thought was excessively high) $650 - not thinking I'd sell them, but to get an idea of what they were worth.  I had 2 buyers for full price within hours.

[5th T/A]

Here is an interesting article comparing various combinations of headers, exhaust manifolds and down pipes on Pontiac engines.

https://www.motortrend.com/how-to/hppp-0312-headers-vs-manifolds/

As I initially mentioned, in my case for a streetcar, I don't think headers are a worthwhile trade off. I do think shorty headers with exhaust wrap could be livable compromise. I will not argue that open headers provide the most power and a higher performance engine will gain more power with a good header/exhaust system. If you have to go to headers, buy quality, not cheap. They fit better and are less likely to give you problems.

[jk79ta]

I have headers on my 79 w/ a 400 engine. Just a stock rebuild. I like the sound, but, what a pain in the you know what! Hard to get the oil filter off because one of the pipes is right there. They have been on the engine for maybe 10 years and have had a leak for quite a while now. Hard to get to the bolts to tighten, changing the gaskets with the motor in the I think would be darn near impossible, at least for me. And you can't hook up the backup lights ( which I got busted for this year on inspection). I don't know about everybody else, but I think I would go with the ram air or maybe even stock manifolds with true dual exhaust and decent mufflers. Just my 2 cents.

[ryeguy2006a]

Whenever I read posts like this I always like to ask what are the goals for the car? From your first post it seems like you are going to be keeping the car very stock and not doing any performance upgrades. Given that you aren't going to add a cam, headers or anything that would require increased exhaust flow, I'd keep your stock manifolds. That's at least what I'm gleaning from your post.

Now, if you are planning for the future you could always do the headers now and then future upgrades would be that much easier.

Another alternative to doing a full length header would be a shorty header. The gains will be less than long tubes, but you would get the sound that you are after. Additionally you would be able to retain the reverse light linkage, less floor board heat, and easier maintenance items like were suggested above.

[roadking77]

I have ram air III manifold, Pypes exhaust, car has plenty of power and sound. I have never had headers, and from what I have heard I will never put a set on any of my cars.

I need to order a set for my current build. I saw them maybe on the RA website and they said they were in stock. I too heard they were back ordered but that has just been word on the grape vine to date.

[TammyTA]

Are you keeping the single cat?  Duals might give you a boost as well.

[Wallington]

Very little to gain....vs the dramas, is what I clearly said. And similar gains on a stock engine mentioned, not worth it.

[roadking77]

FYI. I just got off the phone with Ram Air Restorations. The parts are in the foundry right now, they expect to be able to start shipping the first part of Oct. I got my order placed 

[5th T/A]

I should add that Ram Air Restorations offers an option to ceramic coat the inside and outside of the manifolds. Like everything else it's not cheap, I think about $200.00 when I had mine done. The advantage is it will keep your manifolds from rusting, they also claim it reduces under hood temps.  If your one of those people who cares about how good your engine compartment looks it is worth it. I had mine done in cast gray, after 2,000 miles they still look new but have a very slight brown tint.

[Zach]

I appreciate all the information , after reading all this I'll most likely stick with manifolds. Not going for a race car just want something that runs really well, compared to a stock emissions era trans am, that also isn't a pain to work on. I will be doing a full exhaust repipe, mufflers, manifolds, etc. Currently have a leak from self removing the cat years ago.

Thanks!

[glenn911]

Honestly my headers have been on the car since around 2009, never had an issue with them, I can get to the filter, no leak, no heat issues, and the back up lights you just have to remember to twist the column if you want back up lights.  Ram air manifolds I would never run those again.  I put a set on a fresh rebuild numbers matching 400 in a ta/ta.  They were so close to the starter I had to wait 20 min to restart the car.  I found out there was a heat shield for these and installed that with no improvement.  Brand new starter, brand new over sized cables, timing set correctly.  The issue went away when I put logs back on.  A mini starter would probably be the ticket, that's what I have on my current ta with the hooker headers. 

[roadking77]

I had hot starter issues with my 77. I put a mini starter on, and heat wrapped it. Have not had a problem since.  I was under the impression that is a problem regardless. The new set I am ordering will be ceramic coated for added protection.

[b_hill_86]

For what little it’s worth I have headers on my 77 T/A. I had hot start issues for a while till I wrapped a heat shield around the header pipes near the starter. Wrapping my factory starter did little but prevent the starter from cooling but wrapping the header in that area made all the difference. Probably pushing 10 years on the factory type starter with no issues other than I haven’t made a more permanent looking wrap.

Also, probably could rig something similar to an auto shifter but I added a micro switch to the shift linkage of my 4 speed for backup light operation.

[tajoe]

This is always a "fun" topic to discuss. I know I'm a little late to the party, and I'm sure my opinion is similar to some of the posts above. But I'll throw mine out there too, just for the points.
I've always loved the sound of hedders, especially when they're open. (Of course we're talking about a performance V-8) And the 4 spd just brings out the sound, so much better. In my younger years, I always had hedders on my cars, which were basically street/strip. I put up with the leaky flange gaskets, and the low clearance, and the fussing with starters, and oil filters. And the absolute "fun" of putting bolts into a Pontiac head/hedder flanges  All for the status of being able to say, "I've got hedders".
As years went on, and was more into "street, than strip", I've found the factory RA manifolds to be worth the money. Performance wise, with a full exhaust, you won't know the difference. And all the other benefits from having something smaller, and more rigid, than hedders. As for the factory "log" manifolds, I hate the way they look, and don't care how much I wouldn't know the difference between the logs, and the RAs. If I'm gunna be dipping into my secondaries, I want "at least" RA manifolds, if not hedders. The logs can go on grandmas 4 dr grocery getter. (but hey, that's just me)