Does port matching the intake manifold to the heads really add power? This assumes of course that the manifold ports are smaller than the head ports to begin with. And I don't mean gasket matching, I mean actually transfering the head port to the manifold and making the manifold match.
Any dyno experience one way or the other?
My guy says it doesn't matter.
thanks!
Ron

I used the gasket when I matched mine,they matched great on the heads,but were off on the intake manifold.Don't know if it helped any but the manifold was off to much for me.

Originally posted by Ron454:
Does port matching the intake manifold to the heads really add power? This assumes of course that the manifold ports are smaller than the head ports to begin with. And I don't mean gasket matching, I mean actually transfering the head port to the manifold and making the manifold match.
Any dyno experience one way or the other?
My guy says it doesn't matter.
thanks!
Ron I agree with your guy,,, within reason :D

And I also agree matching it to the gasket is a horrible idea unless the gasket happens to fit the head.
If the fit is close I have seen no gain but it looks impressive,,,,
If you are talking an eighth inch or more, especially at the top I would match it as air simply does not normally like abrupt changes.

Good, thanks Mike.
This will save me a lot of time.
It's actually nos something that can be done unless the engine is assembled anyway........and mine isn't yet!
Ron

Ron,

Ironically, we ran into a similiar situation with an Edel Performer2-0 on a 396 motor. The car was together with the out of the box 2-0 and driven for a while. We later changed the 2-0 out for another identical 2-0 that was port matched. There was a significant difference in performance. However, on the 2-0 there was a large port mismatch on both sides. One side the top of the manifold runner was too low (1/8" or more) and the other side the bottum of the runer was too high (again about 1/8" plus)- the mismatch may have even been 3/16"+. As side note, GM sells there alum manifolds in as-cast and CNC versions. I think the question is - how bad is the mismatch and how anal are you in making it right?

We port matched the intake on my 540 during assembly. Actually easy to do on a Super Victor using a small mirror. We got better initial port matchup by swapping the Dart heads side for side. :confused:

Originally the Super Victor,when first released had large exits to the heads but apparently they felt a need to reduce that dimension so guys could taylor them to their heads.The difference was enough on Bills motor to justify removing the filler they cast in to the runner exits and some epoxy was used to improve radius transition at some locations.......does all this help? probably! graemlins/thumbsup.gif

You will not notice it in seat-of-the-pants acceleration, but maybe a couple of HP on the dyno at best. Been there, done that. It looks cool, but it is pretty tough to match the head and manifold precisely when you put it together.

not so tough when the plenum is as large as a super victor and with layout fluid and a scribe with a small mirror it can be done quite easily.......just a matter of all the small details adding up......how thorough do you want to be? ;)

Waste of time IMHO..show me a timeslip documenting the difference.

like I said ,how thorough do you want to be?.......the effort is minimal,really, to do the work .......I am quite sure that if you had the opportunity to see the situation above you would see the point

Originally posted by mr 4 speed:
Waste of time IMHO..show me a timeslip documenting the difference. Chris...
Better than that.
In Joe's case, I can show you the video...

http://www.chevelles.com/video/nova.wmv

Remember...this is a 355 cu, 5 speed with NO adders. All motor in a 3000 lb package. :cool:

by the way,mr 4 speed,so far wasting time on my project has produced a 9.85@136.10 with my no nos. 355 graemlins/thumbsup.gif

man...thats one sweet Nova

Makes you wonder about port matching when the L78 intake works so well on oval port heads.

This may be as delicate as the oval vs rec port debate. I would tend to think the impact of port matching an intake may have a greater impact as the level of performnce progresses. It also may be dependant on the how bad the mismatch is to start with. It is also feesible that a high velocity intake port (oval) may actually pull enough so as to reduce the impact of a mismatch, whereas a rec port design has such lower velocity that the incoming charge benefits from a smoother flow. Can't say I've ever seen this done, but can you flow a cylinder head with an intake bolted up?

Originally posted by GRN69CHV:
This may be as delicate as the oval vs rec port debate. I would tend to think the impact of port matching an intake may have a greater impact as the level of performnce progresses. It also may be dependant on the how bad the mismatch is to start with. It is also feesible that a high velocity intake port (oval) may actually pull enough so as to reduce the impact of a mismatch, whereas a rec port design has such lower velocity that the incoming charge benefits from a smoother flow. Can't say I've ever seen this done, but can you flow a cylinder head with an intake bolted up? That's the BEST way to flow a cylinder head.

Originally posted by GRN69CHV:
...Can't say I've ever seen this done, but can you flow a cylinder head with an intake bolted up? This is the only way to tell if you're leaving hp on the table. If the flow with the intake bolted up does not decrease the flow thru the head, don't worry about modifications to the intake. If the flow with the intake bolted up is less than the flow thru the bare head, do whatever is necessary (port match or full porting)to remove the restriction in the intake. For example, our out-of-the-box Dart Wilson intake restricted our out-of-the-box AFR 220 "competition ready" heads by about 30 cfm... that's approximately 65 hp in our application. After fully porting the intake, we gained the 30 cfm back (plus a couple).

If the flow with the intake bolted up is less than the flow thru the bare head, do whatever is necessary (port match or full porting)to remove the restriction in the intake. In a street application, I would think that the intake would ALWAYS reduce flow when compared to a bare head, by virtue of increased port length.

It would seem to me that you would have to greatly increase manifold port size and give up velocity to see the manifold restriction drop to nothing. I am not sure that trading velocity for flow is necessarily a good thing, as I suspect it would have a negative impact on mixture quality in a wet flow system.

Am I wrong? :confused:

Originally posted by novadude:
</font><blockquote>quote:</font><hr />If the flow with the intake bolted up is less than the flow thru the bare head, do whatever is necessary (port match or full porting)to remove the restriction in the intake. In a street application, I would think that the intake would ALWAYS reduce flow when compared to a bare head, by virtue of increased port length.

It would seem to me that you would have to greatly increase manifold port size and give up velocity to see the manifold restriction drop to nothing. I am not sure that trading velocity for flow is necessarily a good thing, as I suspect it would have a negative impact on mixture quality in a wet flow system.

Am I wrong? :confused: </font>[/QUOTE]=
Kind of depends on what you are doing with the engine.
You will normally not have to make the intake much if any bigger in cross-section than the head.
You don't want to make a sewer pipe out of the head or intake but you also don't want to give up 65HP in a performance deal either.
Why would you go out & buy 2000+ dollars worth of heads, brag to all your buddies about your head flow & then bolt something on them that takes away 10% of that flow??
If it is a street deal & you have heads that flow substantially less then say Rogers heads above then a decent intake is not going to be much of a restriction.
And you may find,,, assuming you have the budget to do so that the intake in question can be smaller in some areas with no loss in flow ;)

But as I posted earlier, air simply does not like abrupt changes in area especially wet flow air so if there is much of a difference at the point in question it should be matched.

And to be clear, when I posted earlier:
"If the fit is close I have seen no gain but it looks impressive,,,,"
I could not measure any difference before & after with a Vic Jr on the dyno but the intake also was a reasonably good match to start with in this case, definitely less than an eighth inch.

I was thinking of long runner intakes (blame that TPI intake discussion), and maybe even dual planes (maybe not?) :confused: . Assuming a constant port cross section, I'd think that all those bends and port length are bound to have a negative impact on the overall flow of the system.

I guess I can believe that a short runner single plane with a good entry angle to the head will not hurt flow very much. A short straight section of port probably doesn't make a huge difference, since the bowl area is the largest restriction in this case.

What about manifolds that twist and turn (dual planes and TPI type stuff)?

I am very interested in this as well. My ported Vic Jr. has ports that are larger than my AFR 315's by about an eighth of an inch, only on the bottom of the ports. Is this hurting my performance? I just assumed most of this post relates to the intake ports being smaller than the head ports. My motor is making 625 hp.(engine dyno)

Originally posted by 69ttop502:
I am very interested in this as well. My ported Vic Jr. has ports that are larger than my AFR 315's by about an eighth of an inch, only on the bottom of the ports. Is this hurting my performance? I just assumed most of this post relates to the intake ports being smaller than the head ports. My motor is making 625 hp.(engine dyno) If you gotta have a mismatch yours is in the
best place :D
I would prefer to never have a step of any size where the head is smaller than the intake.
My preference would be to fill the bottom of the intake.
You can do it with epoxy if it is the right stuff.
We use a product called Splash Zone A788 Epoxy as do all the head porters I know.