Tolerances and fit.

A couple of questions involving aircraft engines and in particular,
the K1A5 300 HP, IO540.

I've read a lot about blueprinting, but it seems to me that
blueprinting is not the same as optimizing.

How close are the Piston sets including rings, wrist pins and rods
balanced? How close would, or could you get on a custom balance job?

How close are the combustion chambers matched for volume?

How about the cross sectional area through the intake and exhaust
ports to the valve seats? Are they matched, smooth, and optimized for
flow?

Can all, or any of these be done/improved and the engine still remain
certified?

I would think that the piston sets could be balanced and remain
certified as long as they remained within spec. OTOH I have my doubts
about smoothing ports and combustion chamber volume matching.
GAMI injectors can be used to match fuel flows. Are they considered
stock items or do they take an STC?

I doubt that much is going to change in the way of combustion
efficiency, but OTOH I'd think that a very careful balance job,
combustion chamber matching, and polishing the ports would gain some
HP and result in a much smoother running engine.

Yes, I have a K1A5 IO540 that is going to get a rebuild. I just
haven't decided which way to go.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

Roger Halstead wrote:
....
How about the cross sectional area through the intake and exhaust
ports to the valve seats? Are they matched, smooth, and optimized for
flow?

Smoothing the intake and exhaust ports is somewhat controversial. Some say

I don't know much about this, and it looks like John's answer was pretty good. I
have only one thing to add. I read somewhere, probably in a dirt bike magazine
long ago, that intakes should _not_ be highly polished. A slight texture helps
to keep fuel droplets suspended in the air, and not deposited on the walls of
the intake tract. Maybe little bumps in there are like vortex generators,
keeping the flow energized.

On Sun, 07 Sep 2003 12:57:16 -0700, terra wrote:

Roger Halstead wrote:
...
How about the cross sectional area through the intake and exhaust
ports to the valve seats? Are they matched, smooth, and optimized for
flow?

Smoothing the intake and exhaust ports is somewhat controversial. Some say

I don't know much about this, and it looks like John's answer was pretty good. I
have only one thing to add. I read somewhere, probably in a dirt bike magazine
long ago, that intakes should _not_ be highly polished. A slight texture helps
to keep fuel droplets suspended in the air, and not deposited on the walls of
the intake tract. Maybe little bumps in there are like vortex generators,
keeping the flow energized.

I used to sail a good bit, and got into the techy side of it,
measurement, handicapping, etc. It was well recognized that a super
slick hull finish was NOT good for the reasons mentioned, flow
separation. A very smooth in-line sanded finish was thought to be
best.

Maintainence of attached flow is ultra important. I would THINK that
bead blasting of intakes would offer the best finsih.

George

How about investment cast cylinders that are about 2% matched versus 14-18%
of your brand?

How about PMA pistons that are within one gram?

How about requesting a balance check when you send the crank and rods in to
Aircraft Specilaties for rework.

How about talking to knowledgeable and willing people like Monty Barrett of
Barrett Performance engines or Bill Cuningham at Powermasters?

Really, it all depends on what you want to spend for that little extra step
of labor.

Good Luck

"GeorgeB" wrote in message
...
On Sun, 07 Sep 2003 12:57:16 -0700, terra wrote:

Roger Halstead wrote:
...
How about the cross sectional area through the intake and exhaust
ports to the valve seats? Are they matched, smooth, and optimized for
flow?

Smoothing the intake and exhaust ports is somewhat controversial. Some
say

I don't know much about this, and it looks like John's answer was pretty
good. I
have only one thing to add. I read somewhere, probably in a dirt bike
magazine
long ago, that intakes should _not_ be highly polished. A slight texture
helps
to keep fuel droplets suspended in the air, and not deposited on the
walls of
the intake tract. Maybe little bumps in there are like vortex generators,
keeping the flow energized.

I used to sail a good bit, and got into the techy side of it,
measurement, handicapping, etc. It was well recognized that a super
slick hull finish was NOT good for the reasons mentioned, flow
separation. A very smooth in-line sanded finish was thought to be
best.

Maintainence of attached flow is ultra important. I would THINK that
bead blasting of intakes would offer the best finsih.

George

On Sat, 13 Sep 2003 14:24:09 GMT, "Sta 2" wrote:

How about investment cast cylinders that are about 2% matched versus 14-18%
of your brand?

How about PMA pistons that are within one gram?

How about requesting a balance check when you send the crank and rods in to
Aircraft Specilaties for rework.

How about talking to knowledgeable and willing people like Monty Barrett of
Barrett Performance engines or Bill Cuningham at Powermasters?

I received a nice, detailed e-mail from Monty with an explanation of
the work they do.


Really, it all depends on what you want to spend for that little extra step
of labor.

There is little difference in the price of a good custom overhaul and
the blueprinters. of course, YMMV depending on who does the work.


Good Luck

Thanks,

I'm working on the mount at present and will probably be sending in
the engine some time this winter, or early spring. I currently need
it for alignment.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)


"GeorgeB" wrote in message
.. .
On Sun, 07 Sep 2003 12:57:16 -0700, terra wrote:

Roger Halstead wrote:
...
How about the cross sectional area through the intake and exhaust
ports to the valve seats? Are they matched, smooth, and optimized for
flow?

Smoothing the intake and exhaust ports is somewhat controversial. Some
say

I don't know much about this, and it looks like John's answer was pretty
good. I
have only one thing to add. I read somewhere, probably in a dirt bike
magazine
long ago, that intakes should _not_ be highly polished. A slight texture
helps
to keep fuel droplets suspended in the air, and not deposited on the
walls of
the intake tract. Maybe little bumps in there are like vortex generators,
keeping the flow energized.

I used to sail a good bit, and got into the techy side of it,
measurement, handicapping, etc. It was well recognized that a super
slick hull finish was NOT good for the reasons mentioned, flow
separation. A very smooth in-line sanded finish was thought to be
best.

Maintainence of attached flow is ultra important. I would THINK that
bead blasting of intakes would offer the best finsih.

George