For Your Street Motors: Who Here Chose Manifolds And Who Here Chose Headers?

[Runcharger]

Ground clearance is the issue for me. If the headers are tucked up I have no problem running them. Honestly on a 383 they won't make much of a difference performance wise unless you modify it. If you run them check flange flatness and port matching to gasket and head port before mounting them and use good gaskets.

 

[Dennis H]

TTI. Less weight too.

 

[71RRHI]

When I got my convertible It needed a new exhaust. I knew I wanted to order exhaust from TTI but had a hard time deciding to order with headers or keep the HP manifolds. I kept the HP manifolds. Main reason was my other two cars have headers, so I didn't want them all to be the same.

 

[TorRed]

My first choice is what I have on hand, if anything. Then manifolds if you can find them and if they aren’t 1200-1400 dollars. So mostly if I’m in a time punch I buy headers…. Begrudgingly

I have both actually, probably keep the manifolds with the car if I go headers, if I go manifolds I'll be selling a new pair of Doug's 1 3/4".

 

[T Brashears]

Headers,because I wanted all I could get out of my 383,and because I wanted to have to make **** fit and buy a new starter and….
Workin on my trans isn’t the worst,buddies 67 coronet with a 440 is misery working on tranny linkage.

 

[moparedtn]

This question has been beaten nearly to death, both here and elsewhere out there honestly.
Heck, even Nick's garage has done entire episodes directly comparing the two on the same near-stock
engines back to back.

The simple consensus is - if the engine is anywhere near stock (or even mildly modified), on the street
the manifolds simply do not give up enough HP to make headers worth the aggravation and expense.
Yes, headers do contribute a little to the sound of the exhaust as well, but not enough for most to even
detect honestly...

That said, Fred has some of those big tube goofy Hedmans on him that I got with him 13+ years ago
that refuse to rot so I can make the case to replace them.
I despise the dang things honestly (along with the 3" dual exhaust all the way out the back); the whole
exhaust is overkill for what is only about a 425-450hp engine on a good day and makes any sort of work
around the car a colassal pain in the *** - not to mention, the exhaust bakes my wife and I like taters on
a typical summertime drive to boot.

If I raced Fred - if he had the cajones to warrant them - I'd be fine with headers.
I don't - HE doesn't - so I'm not.

 

[furious70]

Headers, always unless it's a stocker you're flipping.
Plenty of other Dyno tests from other sources like engine masters that prove they work.
The old resto to rad 383 and 440 magazine articles also showed they worked with the stock cam and heads

 

[Orig69]

I opened up the ports on my original exhaust manifolds to the same size as the exhaust ports on the heads for a smooth transition.

My M1 dual plane (stealth) intake manifold also looks original.

 

[Cojohnso1]

For a street cruiser? Manifolds. You're really not going to get that much of a boost with headers on a stock/near stock 383. HP Manifolds flow pretty good. Max Wedge Manifolds will all but match header performance on street builds.

That's how good Mopar Manifold design and flow numbers produce. Race builds are a different story of course.

 

[TorRed]

Heck, even Nick's garage has done entire episodes directly comparing the two on the same near-stock
engines back to back.

I've watched those episodes a couple of times. The most recent one was the 70 Roadrunner convertible's 383/432 stroker that they tested with both and decided to stay with exhaust manifolds. That has me thinking I might go a similar or even same route. It was interesting that when he road tested the car he didn't seem all that enthused about how fast it went and was mostly impressed with the 'sticky' tires. He even investigated whether the 6BBL was opening all the way up (maybe a result of the exhaust manifolds?), and they were. I'm wondering if I went with 440Source Stealth heads vs his mostly stock 906/452(?) heads would it make keeping the exhaust manifolds even worse or still be a positive addition?

Thanks,
Jim

 

[fesser]

When I got my convertible It needed a new exhaust. I knew I wanted to order exhaust from TTI but had a hard time deciding to order with headers or keep the HP manifolds. I kept the HP manifolds. Main reason was my other two cars have headers, so I didn't want them all to be the same.

I recently confirmed with TTI, that (at least for my 68 Coronet) if you want to switch to their headers from Stock manifolds with down pipes, the starting point of the rest of the exhaust (near the bellhousing) is in the same location so it shouldn't require modification. What I mean is, the main body of their kits are the same whether you intend to run headers or cast manifolds with downpipes. In my case I don't have to change anything from the area of the bellhousing back when switching from 440 HP manifolds (on a 440) and downpipes, to a 400 with their long tube headers.

 

[70bigblockdodge]

Headers, headers, headers, manifolds suck and HPs are too much money. Headers work all the time. If your peak torque is at 3200 rpm it is still going to be close just more of it. Fuel mileage increase for those that actually knock out more than a couple thousand miles a year.
Never seen a dyno sheet or a time slip that was worse with headers.

 

[33 IMP]

Has anybody asked if you HAVE manifolds?
If you have manifolds run em. If you DONT?
Headers, all the way. Prices asked for hp manifolds are nuts.

 

[moparedtn]

I've watched those episodes a couple of times. The most recent one was the 70 Roadrunner convertible's 383/432 stroker that they tested with both and decided to stay with exhaust manifolds. That has me thinking I might go a similar or even same route. It was interesting that when he road tested the car he didn't seem all that enthused about how fast it went and was mostly impressed with the 'sticky' tires. He even investigated whether the 6BBL was opening all the way up (maybe a result of the exhaust manifolds?), and they were. I'm wondering if I went with 440Source Stealth heads vs his mostly stock 906/452(?) heads would it make keeping the exhaust manifolds even worse or still be a positive addition?

Thanks,
Jim

I reckon you could always call them and ask, eh? I bet they have some data on it.

 

[33 IMP]

I've watched those episodes a couple of times. The most recent one was the 70 Roadrunner convertible's 383/432 stroker that they tested with both and decided to stay with exhaust manifolds. That has me thinking I might go a similar or even same route. It was interesting that when he road tested the car he didn't seem all that enthused about how fast it went and was mostly impressed with the 'sticky' tires. He even investigated whether the 6BBL was opening all the way up (maybe a result of the exhaust manifolds?), and they were. I'm wondering if I went with 440Source Stealth heads vs his mostly stock 906/452(?) heads would it make keeping the exhaust manifolds even worse or still be a positive addition?

Thanks,
Jim

If the idea of improved head swap is to improve airflow thru the motor, using a stock style intake and exhaust manifolds will be two corks for airflow, making the head swap appear ineffectual, and a waste of money.
If I was doing a head swap for more power, I'd make sure I had a good intake, carb and headers, first!
Any of the four, by itself, won't mean much. Including headers.

 

[TorRed]

Has anybody asked if you HAVE manifolds?
If you have manifolds run em. If you DONT?
Headers, all the way. Prices asked for hp manifolds are nuts.

Hi 33 Imp, thank you for asking and yes I do have a gorgeous pair of exhaust manifolds to put on, almost zero pitting, basically look new in their fresh paint. I've also bought a new set of Doug's 1 3/4" headers, but as my plans evolve to lower HP, lower stress on the motor, more stock looking, the last few HP/TQ numbers aren't as important to me, a more balanced motor is. Thanks, Jim

 

[33 IMP]

Hi 33 Imp, thank you for asking and yes I do have a gorgeous pair of exhaust manifolds to put on, almost zero pitting, basically look new in their fresh paint. I've also bought a new set of Doug's 1 3/4" headers, but as my plans evolve to lower HP, lower stress on the motor, more stock looking, the last few HP/TQ numbers aren't as important to me, a more balanced motor is. Thanks, Jim

Okay, in my opinion, you answered your own question
For your stated desires and direction, 100% the manifolds.

 

[TorRed]

If the idea of improved head swap is to improve airflow thru the motor, using a stock style intake and exhaust manifolds will be two corks for airflow, making the head swap appear ineffectual, and a waste of money.
If I was doing a head swap for more power, I'd make sure I had a good intake, carb and headers, first!
Any of the four, by itself, won't mean much. Including headers.

I just rewatched Nick's Garage test of a slightly warmed over 383 (slightly hotter cam, true 9.4/1 compression, Ede Performer intake, bowl blended heads) on that motor headers added a whopping 19 HP & 18 TQ peaking at 402 HP & 422 TQ. Manifolds were 383 HP & 404 ft/lb of TQ. Not zero difference, but not a whole lot either. I could probably get over 400 HP if I had the heads worked on, ran a little more cam and upped the compression to 9.6-9.8 to 1. 400+ HP out of a stock appearing 383 sounds pretty sweet!

 

[TorRed]

If the idea of improved head swap is to improve airflow thru the motor, using a stock style intake and exhaust manifolds will be two corks for airflow, making the head swap appear ineffectual, and a waste of money.
If I was doing a head swap for more power, I'd make sure I had a good intake, carb and headers, first!
Any of the four, by itself, won't mean much. Including headers.

And I totally agree which is why I'm thinking if I incrementally improve the heads, cam, compression and intake

I reckon you could always call them and ask, eh? I bet they have some data on it.

So I just asked Lunati's tech line about my cam with a stock stroke 383 and they said as long as I have at least 9.5 to 1 compression or more (I'm thinking more like 9.8 or 10 to 1 if I go custom pistons) my cam will work fine. So a plan is taking shape.

Thanks,
Jim

 

[PurpleBeeper]

I haven’t run stock manifolds since the 80’s