perf-list-digest Friday, July 17 1998 Volume 01 : Number 031



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Ford Truck Enthusiasts - Performance
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In this issue:

Re: FTE Perf - Cylinder Head Intake Ports/Runners
RE: FTE Perf - Cylinder Head Intake Ports/Runners
RE: FTE Perf - Cylinder Head Intake Ports/Runners
Re: FTE Perf - Cylinder Head Intake Ports/Runners
FTE Perf - Re: Cylinder Head Intake Ports/Runners
RE: FTE Perf - Cylinder Head Intake Ports/Runners
Re: FTE Perf - Cylinder Head Intake Ports/Runners
FTE Perf - Headwork
RE: FTE Perf - Headwork
Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners
Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners
Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners
RE: FTE Perf - (Fwd) Re: 460 builds

=======================================================================

----------------------------------------------------------------------

Date: Thu, 16 Jul 1998 13:43:32 +0000
From: "Gary, 78 BBB"
Subject: Re: FTE Perf - Cylinder Head Intake Ports/Runners

> From: "George"
> Subject: Re: FTE Perf - Cylinder Head Intake Ports/Runners
> Date: Thu, 16 Jul 1998 09:18:30 -0700

> Someone noted that the fuel/air is 'mixed' in the manifold phlegm.
> If this is true, then further turbulence wouldn't be required and
> smooth runners would speed mixture delivery?

I think we're all kind of guessing here George based on things we've
encountered in life and our own mental powers but that makes sense to
me. What I've learned about my 460 at least is it likes warm air
intake at cruise and it likes the hot air crossover. If you use the
valley pan to keep hot oil off the manifold the cross over doesn't
affect the mixture that much IMHO but the atomization you get from
the hot spot is very valuable and offsets any gains a cold manifold
would give you, especially when you consider it's already heated by
the water passages anyway so it's not really cold in the first place.
With a warm manifold there should be very little fall out regardless
so a smooth runner might be an advantage even in a street engine.

Sleddog has other priorities than most of us with his race truck. We
want "some" performance but we want some economy too and you can't
tune for both if you don't compromise one or the other. I think a
335 series engine with no cross over might need more roughness than
the 385 series since it has no coolant passages and would tend to run
colder but again I'm just guessing :-)

Some say when the mixture turns a corner it "centrifuges" some fuel
out of the mix but I'm not really sure on that either since most
manifold designers go to a lot of trouble to keep the bends out of
them just for that reason. When you factor in the "boundary" layer
which acts as an insulator between the rough or smooth wall and the
air column you have to wonder just how much the roughness affects teh
flow anyway right? Really I would think the factor to consider is
the interior surface area per runner which is what really generates
the friction etc. which is what the single plane manifolds are all
about.


78 F-150, 2wd, 460, C-6, 235's
78 Bronco 351M, Np 435, Np 205, 33's
78 Lincoln Town Car, 460, C-6, 19.5' long!
9000#, in ground vehicle lift, Woooo Hooo!

- -- Gary --
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------------------------------

Date: Thu, 16 Jul 1998 14:07:04 -0400
From: Sleddog
Subject: RE: FTE Perf - Cylinder Head Intake Ports/Runners

friction, compressive propertires, thermal properties as heat is added to
the flow, and all kinds of stuff i can't remember from my fluid dynamics
classes. fuel going around a corner means you have to take the fuels
ability to stay suspended into account, but just air can take a tighter
corner. in this case not a matter of restriction, but rather fuel
suspension.

for the golf ball, thru a "wet" medium it MAY react totally different than
in atmospheric air. a golf ball may not fly too well thru clouds. i am
not sure on this, but dimples give lift. in a different medium (like fuel)
it may not as the compressive properties are different. BTW, i don't play
golf but i have seen practice balls with lumps, istead of dimples.

sleddog

- ----------
From: George[SMTP:maga55 ix.netcom.com]
Sent: Thursday, July 16, 1998 12:05 PM
To: perf-list ford-trucks.com
Subject: Re: FTE Perf - Cylinder Head Intake Ports/Runners

Friction differences?

George Miller

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------------------------------

Date: Thu, 16 Jul 1998 14:34:48 -0400
From: Sleddog
Subject: RE: FTE Perf - Cylinder Head Intake Ports/Runners

i have to differ. single planes are about plenum volume, tuning the length
of the runners and therefore tuning the intake pulses. friction is not a
concern when considering a single or dual plane intake. it is the common
plenum, increased plenum volume, increased runner size and dcecreased
length (usually) and ability to suck from all four bbls of the carb. my
intake flows within 2% of each runner. pretty damn good and a stock p-o-s
would never do that. heck, helf the runners are 2 inches longer than the
other half. but each cross section is different and the plenum is, shall
we say, highly modified? but i still wish i had more plenum volume.

about corners. a tall port will flow better wet around a corner than a
short and wide port of equal cross section.

as for friction, square ports are almost always better at max flow than
oval ports, yet have more surface area increase than cross sectional
increase. just food for thought.

sleddog
- ----------
From: Gary, 78 BBB[SMTP:gpeters3 ford.com]
Sent: Thursday, July 16, 1998 9:43 AM
To: perf-list ford-trucks.com
Subject: Re: FTE Perf - Cylinder Head Intake Ports/Runners

Really I would think the factor to consider is
the interior surface area per runner which is what really generates
the friction etc. which is what the single plane manifolds are all
about.


78 F-150, 2wd, 460, C-6, 235's
78 Bronco 351M, Np 435, Np 205, 33's
78 Lincoln Town Car, 460, C-6, 19.5' long!
9000#, in ground vehicle lift, Woooo Hooo!

- -- Gary --
== FTE: Uns*bscribe and posting info www.ford-trucks.com/faq.html




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------------------------------

Date: Thu, 16 Jul 1998 12:11:21 -0700
From: "George"
Subject: Re: FTE Perf - Cylinder Head Intake Ports/Runners

> Someone noted that the fuel/air is 'mixed' in the manifold phlegm.
> If this is true, then further turbulence wouldn't be required and
> smooth runners would speed mixture delivery?

I think we're all kind of guessing here George based on things we've
encountered in life and our own mental powers but that makes sense to
me. What I've learned about my 460 at least is it likes warm air
intake at cruise and it likes the hot air crossover. If you use the
valley pan to keep hot oil off the manifold the cross over doesn't
affect the mixture that much IMHO but the atomization you get from
the hot spot is very valuable and offsets any gains a cold manifold
would give you, especially when you consider it's already heated by
the water passages anyway so it's not really cold in the first place.
With a warm manifold there should be very little fall out regardless
so a smooth runner might be an advantage even in a street engine.

Sleddog has other priorities than most of us with his race truck. We
want "some" performance but we want some economy too and you can't
tune for both if you don't compromise one or the other. I think a
335 series engine with no cross over might need more roughness than
the 385 series since it has no coolant passages and would tend to run
colder but again I'm just guessing :-)

My 460 averages 7mpg no matter what, so economy really isn't an issue.
I'm after the power, both on the the lower torque side and higher rpms. At
this point in the thread, I think 'rough' applies to low rpms and 'smooth
to the higher end. What is that ideal inside runner surface.

Some say when the mixture turns a corner it "centrifuges" some fuel
out of the mix but I'm not really sure on that either since most
manifold designers go to a lot of trouble to keep the bends out of
them just for that reason. When you factor in the "boundary" layer
which acts as an insulator between the rough or smooth wall and the
air column you have to wonder just how much the roughness affects teh
flow anyway right? Really I would think the factor to consider is
the interior surface area per runner which is what really generates
the friction etc. which is what the single plane manifolds are all
about.


I sometimes wonder if it was wise for me to venture beyond 'buy parts,
balance, assemble, check tolerances, assemble and run". Ah well, guess it's
that thinking that cost me the expensive divorces and selling speed
equipment at half what I paid for it. I ran a Victor Jr. manifold with the
CJ heads and can tell you it wasn't nearly as responsive at low rpms as the
dual plane. Most of the NASCAR manifolds, high rpms, are poised to almost
dump the mixture straight down into the heads. I also used the regular
Edelbrock Performer before going to the RPM. The RPM runnuers are a
considerable amount higher than the regular performer but both are dual
plane manifolds. The rpm rating for the Edelbrock RPM is higher (also starts
higher) than the regular Performer. I couldn't tell any difference between
the two in actual operation.

George Miller


- -- Gary --
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------------------------------

Date: Thu, 16 Jul 1998 14:54:07 -0500
From: lordjanusz juno.com (Paul M Radecki)
Subject: FTE Perf - Re: Cylinder Head Intake Ports/Runners

>> I've heard pros and cons about smoothing the intake port/runner
>> inside surfaces. Some say don't as the rough surface provides
>> turbulence that creates a better air/fuel mixture for combustion
>> purposes. Others say smooth is better for faster delivery. Both
>> sound reasonable but I'm not sure which is valid. Maybe both with
>> lots of variables?. I'd appreciate any comments.
>
>I've often thought of this myself. Theoretically the rough surface
>keeps the otherwise still air layer at the surface moving so droplets
>get re-mixed into the air stream to keep it stable but in reality you
>can only get so much fuel in that stagnant air layer so once it's
>saturated no more can drop out right?
>
>I'm thinking for low rpm, stop and go driving the rough surface might
>give better economy and better throttle response but for performance
>purposes I would guess the smoother the better. The manifold plenum
>is really where all the mixing work takes place anyway and as long as
>you have a hot spot and some roughness there I would think the
>runners and ports would work better smooth?
>
The mixing takes place in the plenum, but the fuel must remain in
suspension until burned. As you noted, a slightly rough surface promotes
turbulence along the walls and helps to keep the fuel from pooling. Key:
SLIGHTLY rough, like from a grindstone, not raw casting rough nor mirror
polished. A small, localized amount of turbulence along the wall will
not impede overall flow appreciably. Remember, airflow through your
intake manifold is stop-and-go anyway as the valves open and close; it's
not real smooth to begin with. This turbulence is only critical down
near the ports where puddles can run down into the combustion chamber.

On the exhaust side, and in the chamber itself, a mirror polish is good.
Swirl-polished valves also help. Much of the (often astounding) power
made by motorcycle engines comes from micromanagement of the airflow
through the heads, but since few normal humans have extensive R&D
facilities handy, Valley Head Service of Northridge, CA (as quoted by Hot
Rod magazine) suggests grinding 1 inch deep into the ports with a stone
or cartridge roll, then polishing the exhaust side (only) with a flapper
bit. Removing sharp edges inside the chamber helps prevent hot spots
that can lead to detonation. Use a set of junk valves to protect the
valve seats while you polish, and don't forget to do the piston tops,
too. Some heads can be helped by more extensive grinding, but you MUST
know EXACTLY what you are doing or you WILL screw it up.

Hope this helps. I have a background in Physics and many back issues of
"C#evy Craft" and other car mags. lordjanusz

'94 F150 (300ci) '73 F100 (360ci) '97 Saturn (SWMBO's car)

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------------------------------

Date: Thu, 16 Jul 1998 15:10:05 -0500
From: ballingr ldd.net (William L Ballinger)
Subject: RE: FTE Perf - Cylinder Head Intake Ports/Runners

I'd like to take this thread back a step, just in case anyone doesn't
know the principles involved, and why rough inlet surfaces/turbulence is
a performance issue.

Suspension is an air-fuel mixture of the proper ratio that is to be
ingested by an engine. Air-velocity is what keeps fuel droplets from
joining together and eventually dropping out of suspension.

A large volume tract will obiously flow more air than a smaller one, but
will have less velocity, and have poorer atomiziation qualities at lower
air-speeds than a smaller volume one. Turbulence can be used to certain
degree as a substitute for velocity, keeping the low-speed
characteristics of the smaller tract and gain the flow capacity of the
larger one.

The reason for rough inlet surfaces is to disturb the syncronicity of
the flow pulse, creating turbulence. Turbulence changes the barometric
pressure and pulse amplitude inside the tract, causing the mixture to
"run in place." This gives the illusion of higher velocity, even though
it's not increasing the over all flow-volume, by fooling the mixture
into thinking it's moving faster.

One caveat is that turbulence at maximum air speeds will cause a
restriction of air flow. You can use turbulence to tune a larger-slower
tract to run better at low speed, and take advantage of it's high speed
capabilities, with a slight theoretical sacrifice of top speed flow.


- --
Come on over to my Back Porch
http://www.ford-trucks.com//lc/lc.php?action=do&link=http://www.ldd.net/scribers/ballingr
Ballinger
ballingr ldd.net
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------------------------------

Date: Thu, 16 Jul 1998 14:14:01 -0700
From: sdelanty sonic.net
Subject: Re: FTE Perf - Cylinder Head Intake Ports/Runners

>Someone noted that the fuel/air is 'mixed' in the manifold phlegm. If this
>is true, then further turbulence wouldn't be required and smooth runners
>would speed mixture delivery?
>
>George Miller

Manifold phlegm? Is that something the motor coughs up when it backfires
thru the carb? (-:

Steve
Homepage: http://www.ford-trucks.com//lc/lc.php?action=do&link=http://www.sonic.net/~sdelanty

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------------------------------

Date: Thu, 16 Jul 1998 16:31:11 -0700
From: "Darryl A. Regan"
Subject: FTE Perf - Headwork

I was just talking to the machine shop and the guy was talking about doing a
radius cut?? Says they do three angle valve jobs as part of a standard rebuild
but a radius cut is where you would rally see some gains. Anyone have any
idea what this is and does?? He is going to show me when I drop the heads
off. Thanks.


dar6 jps.net
78 Bronco Ranger XLT (460 powered) Hurry up guys!!:-)
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------------------------------

Date: Thu, 16 Jul 1998 19:50:55 -0400
From: Sleddog
Subject: RE: FTE Perf - Headwork

simply, radiusing is better for full flow than 3 angle valve job. the seat
is angled, but above and below are angled. a little better than a 5 or 7
angle valve job.

sleddog

- ----------
From: Darryl A. Regan[SMTP:dar6 jps.net]
Sent: Thursday, July 16, 1998 7:31 PM
To: perf-list ford-trucks.com
Subject: FTE Perf - Headwork

I was just talking to the machine shop and the guy was talking about
doing a
radius cut?? Says they do three angle valve jobs as part of a standard
rebuild
but a radius cut is where you would rally see some gains. Anyone have any
idea what this is and does?? He is going to show me when I drop the heads
off. Thanks.


dar6 jps.net
78 Bronco Ranger XLT (460 powered) Hurry up guys!!:-)
== FTE: Uns*bscribe and posting info www.ford-trucks.com/faq.html




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------------------------------

Date: Thu, 16 Jul 1998 19:17:10 -0700
From: "George"
Subject: Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners

I guess one of the local machine shops here that's known for specializing in
head work (non-Ford) must have read that article or, judging by his age and
experience, the owner found out on his own. That description is almost
identical to what he recommended to me for 385 series cast iron heads. He
wants $350 to do a set of heads in that fashion; not including grinding the
seats and installing bronze valve guides. And that quote was after I'd
cleaned up the combustion chambers. Ford wasn't real careful about how they
machined their rough production castings and it takes a lot to polish the
chambers and then go back and match the cc's. Shop rates here average about
$45/hr for custom work. Sound about right to those of you who have had this
work done? Costwise, I'll be all-in to the set for about the cost of one SVO
alum head and you can't get them with the small runners.

George Miller

>> I've heard pros and cons about smoothing the intake port/runner
>> inside surfaces. Some say don't as the rough surface provides
>> turbulence that creates a better air/fuel mixture for combustion
>> purposes. Others say smooth is better for faster delivery. Both
>> sound reasonable but I'm not sure which is valid. Maybe both with
>> lots of variables?. I'd appreciate any comments.
>
>I've often thought of this myself. Theoretically the rough surface
>keeps the otherwise still air layer at the surface moving so droplets
>get re-mixed into the air stream to keep it stable but in reality you
>can only get so much fuel in that stagnant air layer so once it's
>saturated no more can drop out right?
>
>I'm thinking for low rpm, stop and go driving the rough surface might
>give better economy and better throttle response but for performance
>purposes I would guess the smoother the better. The manifold plenum
>is really where all the mixing work takes place anyway and as long as
>you have a hot spot and some roughness there I would think the
>runners and ports would work better smooth?
>
The mixing takes place in the plenum, but the fuel must remain in
suspension until burned. As you noted, a slightly rough surface promotes
turbulence along the walls and helps to keep the fuel from pooling. Key:
SLIGHTLY rough, like from a grindstone, not raw casting rough nor mirror
polished. A small, localized amount of turbulence along the wall will
not impede overall flow appreciably. Remember, airflow through your
intake manifold is stop-and-go anyway as the valves open and close; it's
not real smooth to begin with. This turbulence is only critical down
near the ports where puddles can run down into the combustion chamber.

On the exhaust side, and in the chamber itself, a mirror polish is good.
Swirl-polished valves also help. Much of the (often astounding) power
made by motorcycle engines comes from micromanagement of the airflow
through the heads, but since few normal humans have extensive R&D
facilities handy, Valley Head Service of Northridge, CA (as quoted by Hot
Rod magazine) suggests grinding 1 inch deep into the ports with a stone
or cartridge roll, then polishing the exhaust side (only) with a flapper
bit. Removing sharp edges inside the chamber helps prevent hot spots
that can lead to detonation. Use a set of junk valves to protect the
valve seats while you polish, and don't forget to do the piston tops,
too. Some heads can be helped by more extensive grinding, but you MUST
know EXACTLY what you are doing or you WILL screw it up.

Hope this helps. I have a background in Physics and many back issues of
"C#evy Craft" and other car mags. lordjanusz

'94 F150 (300ci) '73 F100 (360ci) '97 Saturn (SWMBO's car)




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------------------------------

Date: Thu, 16 Jul 1998 20:19:19 -0700
From: "Darryl A. Regan"
Subject: Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners

From: "George"
To:
Subject: Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners
Date sent: Thu, 16 Jul 1998 19:17:10 -0700
Send reply to: perf-list ford-trucks.com

> I guess one of the local machine shops here that's known for specializing in
> head work (non-Ford) must have read that article or, judging by his age and
> experience, the owner found out on his own. That description is almost
> identical to what he recommended to me for 385 series cast iron heads. He
> wants $350 to do a set of heads in that fashion; not including grinding the
> seats and installing bronze valve guides.

uhh the machine shop I am dealing with wants close to $700!! Says they do
more 385 series stuff then anyone in the area. That is including guides and
hardened seats.


dar6 jps.net
78 Bronco Ranger XLT (460 powered) Hurry up guys!!:-)
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------------------------------

Date: Thu, 16 Jul 1998 20:36:04 -0700
From: "George"
Subject: Re: FTE Perf - Re: Cylinder Head Intake Ports/Runners

That doesn't sound bad including installing hardened seats. I haven't looked
at just that cost, did he break it down?

> I guess one of the local machine shops here that's known for specializing
in
> head work (non-Ford) must have read that article or, judging by his age
and
> experience, the owner found out on his own. That description is almost
> identical to what he recommended to me for 385 series cast iron heads. He
> wants $350 to do a set of heads in that fashion; not including grinding
the
> seats and installing bronze valve guides.

uhh the machine shop I am dealing with wants close to $700!! Says they do
more 385 series stuff then anyone in the area. That is including guides and
hardened seats.


dar6 jps.net
78 Bronco Ranger XLT (460 powered) Hurry up guys!!:-)
== FTE: Uns*bscribe and posting info www.ford-trucks.com/faq.html


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------------------------------

Date: Thu, 16 Jul 1998 23:17:58 -0700
From: "Darryl A. Regan"
Subject: RE: FTE Perf - (Fwd) Re: 460 builds

From: Sleddog
To: "'perf-list ford-trucks.com'"
Subject: RE: FTE Perf - (Fwd) Re: 460 builds
Date sent: Thu, 16 Jul 1998 10:58:51 -0400
Send reply to: perf-list ford-trucks.com

> i'd say 430-450 is reasonable. a little bigger cam and a solid 460-470....

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