HiPo manifolds Vs headers - MustangForums.com

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Old 05-10-2011, 12:44 AM   #2
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if you look in any classic mustang catalogs you will see that the Hi-Po exhaust manifolds require different H pipe or for you to cut and reweld yours

as far as performance gains, that depends, what is behind it, if it dwindles down to a single exhaust than even keeping the stock exhaust manifold but going to true dual exhaust would have been better

a better example would be these Hi-Po manifolds with a true dual exhaust, assuming that's what you are going for than the gains will still be minimal unless you do something to the intake side, what carb / intake manifold are you running, 2 barrel or 4 barrel, how healthy is your engine, good compression, is it an AC car, if it is an AC car I bet deleting the AC unit would yield as much horse power as this exhaust setup

in other words don't expect much

what's better these manifolds or headers, well wars have probably been fought over that one, depends who you ask, headers supposedly dissipate heat better and with proper porting and polishing can flow really well, on the other hand some favor the long tube headers (both require different H pipes than the stock)

which ever you go, remember that it's only part of the horse power puzzle and you need to think of the system as a whole

I beg you to dyno the car the way it is now, and then put on the new exhaust and dyno it again, post both results and become our hero, lol, and settle this debate once and for all
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Old 05-10-2011, 01:51 AM   #3
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A set of good tri y headers will out flow them its one of the mods shelby did to the 289 to get the power up on it.
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Old 05-10-2011, 07:15 AM   #4
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1. can i install these with relative ease

2. can i install them without bending/cutting the stock exhaust.
Yep. You'll need the HP H-pipe, of course.

3. is the installation comparable to that of tri-y headers?
No. Well, not that different in normal driving.

4. from a performance gain to cost ratio which is better?
Cost is roughly the same, a bit more for the tri-y's than manifolds.

5. what kind of improvement can i expect?
Slight, either way.

if there is a relatively small change in power from hipo manifold to headers which is easier to install?
The manifolds are WAY easier to install.

I switched from long-tube headers to HP manifolds years ago, after dealing with the heat, noise, etc. of headers. Never been sorry.

If you don't do this to your heads, you're wasting your time and money installing manifolds or tri-y's:

289/302 Cylinder Head Port Matching

If you do that to your heads, you'll probably get more power even with stock "logs" than you would with headers.

Last edited by 2+2GT; 05-10-2011 at 07:17 AM.
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Old 05-10-2011, 11:43 AM   #5
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To me the hardest part of the swap is removing the old manifolds and exhaust..After that you are bolting on new parts with fresh bolts and clean threads...I installed a set of Tri-ys on a 66 coupe and they bolted in very easily..I would say not any more difficult than the stock manifolds and by FAR the easiest set of headers I have installed..Having said that I did run into some minor clearance issues with the clutch linkage and bellhousing...If you have an automatic you probably won't have any issues...The headers will breathe much better than the manifolds..
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Old 05-10-2011, 01:41 PM   #7
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its not hard to pull the heads...you can have both sides off in about an hour or less....
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Old 05-10-2011, 04:29 PM   #8
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Originally Posted by MustangFTW View Post
Is it possible to do the port matching with everything assembled? if not how hard is it to remove the heads and then port match them? (im sorry if im asking stupid question, this is my first time doing anything like this.)
You could probably do it on an assembled engine, if it was on an engine stand.

If the engine is in a car, they'll have to come off. Could easily be done start to finish on a Saturday if you had everything you needed before starting.

Afterward, going out to cruise night, it'll feel like you upgraded the cam.
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Old 05-10-2011, 06:24 PM   #10
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Hmmm… I have to guess you don't have the factory service manual.

Remove the distributor (a nice digital photo will help you get it back with the rotor in the same place)
Remove the exhaust manifolds
Remove the intake manifold
Remove the pushrods (I place them in 16 holes in a wood block, so they go back where they were)
Remove the heads

Do yourself a HUGE favor and get the manual, though.
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1965, c9oz6250c, exhaust, ford, header, headers, hipo, horsepower, install, manifold, manifolds, mustang, po, tri, triy

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