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Old 09-24-2013, 10:15 AM   #1
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1 3/4 primary long-tubes too much for stock 5.0??

I'm wanting to do some mods to my stang NOW, and long-tubes are usually my first upgrade to any v8 I get my hands on. It looks like BBK and MAC, both offer long-tubes in 1 5/8" and 1 3/4" primary diameters. I plan on eventually having a stout 331, or maybe a 347 stroker making a touch more than 400hp with either a blower or nitrous, and guessing the 1 3/4" headers would suit that best? If so, will the large tubes hurt my bone stock motor's power in the mean-time?

Also, would anyone out there prefer one over the other as far as header companies are concerned. I've owned 2 sets of BBK long-tubes so far, 1 set with 1 5/8" primaries on a 97 2v gt with nitrous, and another set on my 04 cobra that were also 1 5/8", which leads me to question the need for 1 3/4" headers on a motor with less power anyways??? Both sets of bbk's worked well with no leaks using the ball / socket connection to the mid-pipe.
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Old 09-24-2013, 04:06 PM   #2
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I did 1-5/8" longtubes, with 7# of S-trim and that made 495rwhp.


[SPAM: for sale now too (going 351W block)]
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Old 09-24-2013, 05:30 PM   #3
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Old 09-24-2013, 05:43 PM   #4
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I did 1-5/8" longtubes, with 7# of S-trim and that made 495rwhp.


[SPAM: for sale now too (going 351W block)]
Inch and 5/8 it is! thanks. Just read here that a lot of people using 1 3/4?
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Old 09-24-2013, 06:08 PM   #5
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Inch and 5/8 it is! thanks. Just read here that a lot of people using 1 3/4?
Posts like that are not very helpful. Who says he wouldn't have made 525hp with 1.75"?? Maybe 1.75" headers would have made 496hp? Who knows. Make a combo, and design everything together.
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Old 09-24-2013, 06:43 PM   #6
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Just knowing it made good power with relatively small primaries sounds good to me, Cheaper / easier fitment.
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Old 09-24-2013, 07:05 PM   #7
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go 1 3/4" ceramic coated. You'll need it later and prob not gonna lose that much as it sits.

I went 1 3/4" & 3" all the way out and didnt look back. Gt40 heads with a 316. Maybe TFS TW later on....the exhaust will be ready
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Old 09-24-2013, 08:55 PM   #8
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go 1 3/4" ceramic coated. You'll need it later and prob not gonna lose that much as it sits.

I went 1 3/4" & 3" all the way out and didnt look back. Gt40 heads with a 316. Maybe TFS TW later on....the exhaust will be ready
Good point, plenty of room to grow.
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Old 09-24-2013, 09:03 PM   #9
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1 3/4 will offer room to grow not power can't be made with 1 5/8. The 1 3/4 MACS I had were pinched off so much at the head they might of well of been 1 5/8. The
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Old 09-24-2013, 09:04 PM   #10
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I wonder what the 1 3/4 headers would do to the powerband of a stock 5.0...

I'd play it safe and just get some bbk 1 5/8.
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Old 09-24-2013, 09:49 PM   #11
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I won't comment on header sizes but I will add that the fit, finish and overall visual quality of BBK headers is WAY nicer than any MAC header I've ever seen. MAC uses thinner gauge steel and also uses individual flanges on the primary tubes which, if you ever remove them to work on the engine, can make re-installation a real pain in the butt.

Every set of BBK long tubes I have installed fall right into place, no drama. The only negative aspect of them is that the size of the collector ball socket flange necks down to about 2" and does hinder flow. A few minutes with a die grinder and a rotary file bit to open the holes up to a full 2.5" and problem solved.
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Old 09-24-2013, 10:47 PM   #12
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Great info guys, thanks. I might just continue with my good luck with BBK's for sure then.
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Old 09-25-2013, 02:02 PM   #13
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I would go with the 1 3/4" BBKs I have had both 1 5/8" and 1 3/4" BBKs on foxbodys and the 1 3/4" are MUCH MUCH easier to install than the 1 5/8"ers.

Those headers on the Pic above that Ed posted look like either 1 3/4" or 1 7/8"ers.
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Old 09-25-2013, 02:08 PM   #14
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Quote:
Originally Posted by jeffskar View Post
... I plan on eventually having a stout 331, or maybe a 347 stroker making a touch more than 400hp with either a blower or nitrous...
... which leads me to question the need for 1 3/4" headers on a motor with less power anyways??? Both sets of bbk's worked well with no leaks using the ball / socket connection to the mid-pipe.

Sounds like he wants about 400+hp.
Sounds like he likes the ball/scoket.

Thus my suggestion for midrange 1-5/8", and NOT the room to grow 500+hp on 1-3/4".
(unlike the 2.0" primaries on the 427cid blown, that I am currently building)
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Old 09-25-2013, 02:25 PM   #15
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Quote:
Originally Posted by jeffskar View Post
I plan on eventually having a stout 331, or maybe a 347 stroker making a touch more than 400hp with either a blower or nitrous, and guessing the 1 3/4" headers would suit that best? If so, will the large tubes hurt my bone stock motor's power in the mean-time?.
You don't need a 331/347 to do that, and no those will not hurt your power now.
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Old 09-25-2013, 02:57 PM   #16
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Keep in mind that exhaust size and tuning makes a lot more difference in a high specific output naturally aspirated engine than it does with the same engine under boost.

Naturally aspirated you are relying on the exhaust to help scavenge and any back pressure will have a large effect on power. With positive intake pressure, you are literally pushing the exhaust and some of your boost out the exhaust... so really as long as it is not overly restrictive to the point where it can't handle the exhaust flow, the effects of exhaust on a mildly boosted car are often not comparable.

For example, look at the exhaust manifolds on terminator motors... doesn't stop them from making huge numbers.

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Old 09-25-2013, 03:21 PM   #17
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Originally Posted by Ed Curtis View Post




Stock 5.0 Ed, stock.
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Old 09-25-2013, 03:34 PM   #18
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Here is a test on a basically stock engine. The shorty headers are def. better on a stock engine, and you'll prob. lose quite a bit with long tubes based off what that test shows. (if you go with 1-3/4") Of course once you change heads down the road those test results will be different.

Short & Long-Tube Headers Test - 5.0 Mustang & Super Fords Magazine

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Old 09-25-2013, 03:45 PM   #19
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If the motor is truly bone stock, the 1 3/4 headers and assumed suitably flow capable exhaust system are going to be too large (for the engine combination in that state). They are not too big because of any relationship to the stock 5.0, or any sort of hp capability; I dont subscribe to that thinking, its all about valve events, flows, crosssections, rpm, and displaced cylinder volume.

They are too big because the valve events are just not right to effectively use that much flow capability and cross-sectional area on the exhaust side. the exhaust lobe positioning is too early, even with the cam installed at the typical 115/115 positioning, its just not good.

Retarding it seems to be a possible avenue, but it will kill the intake side even more. Retarding it is not going to be productive unless you were to go up to some huge rocker (like 1.8 or something). The motor will respond favorably to a lot more inlet valve activity, then delay, and possibly shorten, the exhaust activity (narrower LSA) and things will begin to turn around pretty nicely.

As it sits, the exhaust activity is just way too early. The cylinder pressure is lower, the motor will be a little sluggish and just not provide a good mid range response, and it will likely hamper the upper end as well. You will also notice that this scenario is the typical report experienced when too large of exhaust is added. the difference is I provided some reasoning, and its not really the exhaust's fault, its the overall combination.

If the intent is to assemble for future growth (and there is no harm in that), then atleast make some changes so the larger exhaust doesn't hurt it too bad. I assume the intent is not to open up the motor, or spend money on cams. So at least try to recoupe some of the relationship by adding 1.7 rockers on the intake side only. (possibly borrow from a friend). Also on the exhaust side, leave current the exhaust system in place. Install the 1 3/4 headers but let the collector neck down (albeit smoothly) to your current exhaust system. these sort of items will enable the early exhaust to be absorbed a little better.

Then later on when changes are made, you can do the rest of the exhaust, for example.

A lot could be said for a huge headed 5.0 Ford motor, with stock hyd roller cam, and a seriously flow capable exhaust. they can be quite impressive.

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Old 09-25-2013, 06:16 PM   #20
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I did 1-5/8" longtubes, with 7# of S-trim and that made 495rwhp.


[SPAM: for sale now too (going 351W block)]
That's quite a sweet lookin bullet there!!
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Old 09-26-2013, 12:18 AM   #21
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Those headers on the Pic above that Ed posted look like either 1 3/4" or 1 7/8"ers.
1-7/8"
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Old 09-26-2013, 08:11 AM   #22
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Posts like that are not very helpful. Who says he wouldn't have made 525hp with 1.75"?? Maybe 1.75" headers would have made 496hp? Who knows. Make a combo, and design everything together.
INdeed, been saying that for years.

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Just knowing it made good power with relatively small primaries sounds good to me, Cheaper / easier fitment.
That supercharger on that might have had something to do with it, moreso than the headers.
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Old 09-26-2013, 03:42 PM   #23
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As it sits, the exhaust activity is just way too early. The cylinder pressure is lower, the motor will be a little sluggish and just not provide a good mid range response, and it will likely hamper the upper end as well. You will also notice that this scenario is the typical report experienced when too large of exhaust is added. the difference is I provided some reasoning, and its not really the exhaust's fault, its the overall combination.
Whatever Buddy. Everybody "knows" that the reason you lose the low to mid torque with a big exhaust is because you don't have back-pressure!

In seriousness thanks for your informative posts lately.
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Old 09-26-2013, 08:18 PM   #24
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A lot could be said for a huge headed 5.0 Ford motor, with stock hyd roller cam, and a seriously flow capable exhaust. they can be quite impressive.
Mine does allright in my heavy turd, for what it is.
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