Discussion:
74" Shovelhead Theoretical Max HP Question
(too old to reply)
matthew j henschel
2004-10-04 08:23:03 UTC
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Subject says it all... assuming, lets say no more then 10:1 compression.
How would I calculate a maximum horsepower? Or would I?

Anyone have real world numbers?

-Matt

Oh & there's a bottle of Maker's Mark in my left saddlebag if you want a
shwig.
jjs
2004-10-04 12:59:23 UTC
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Post by matthew j henschel
Subject says it all... assuming, lets say no more then 10:1 compression.
How would I calculate a maximum horsepower? Or would I?
Can't. Too many variables.
Toni Froehling
2004-10-04 14:40:09 UTC
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Post by jjs
Post by matthew j henschel
Subject says it all... assuming, lets say no more then 10:1 compression.
How would I calculate a maximum horsepower? Or would I?
Can't. Too many variables.
You can use something like the Accellerator program, but you'd need to know a
bunch more about the engine, i.e. bore, stroke, cam specs etc. You can make
some guesses when using the program, but it becomes pretty theoretical at that
point. You'll also have to face the age old dilema of how much head work
you're planning. Shovel heads are kind of a mess and unless you dual plug them
and do a fair amount to them, they limit you quite a bit. We ran one in a
drag bike and ran ten's with it, but that was with big compression and 96 cubic
inches.


Court Jester

www.CourtJesterRacing.com
Philip Nasadowski
2004-10-04 16:19:40 UTC
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Post by matthew j henschel
Anyone have real world numbers?
About .1mm by .1mm

Well, that's about how big a 74" shovel (Shovelheads forever!*) looks in
my rear view mirror after about 5 seconds.

You want big HP, go by a Twin Cam or Evo. All trying to get big HP out
of a 30 year old motor does is cost you money and give you a big pile of
busted parts.

*(In increments of 3,000 miles)
matthew j henschel
2004-10-04 23:11:20 UTC
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Post by Philip Nasadowski
Post by matthew j henschel
Anyone have real world numbers?
About .1mm by .1mm
Well, that's about how big a 74" shovel (Shovelheads forever!*) looks in
my rear view mirror after about 5 seconds.
You want big HP, go by a Twin Cam or Evo. All trying to get big HP out
of a 30 year old motor does is cost you money and give you a big pile of
busted parts.
*(In increments of 3,000 miles)
LOL! The Shovel vs Evo one is an iffy one, due to the cheesy stock cases,
but the twin cam seems like it's got some serious meat to it and could make
real horsepower.

But regardless, I don't want BIG horsepower, I'm just wondering what people
have got out of a stock 74". I'd be -real- happy if it could pull off 90hp
out of a 1200cc motor. Probably pushing the limits of reality with that
one, but it's a dream... anyone come close?

-Matt
Easy, #39
2004-10-05 11:55:22 UTC
Permalink
Post by matthew j henschel
Subject says it all... assuming, lets say no more then 10:1 compression.
How would I calculate a maximum horsepower? Or would I?
for something that old, an abacus comes to mind.

or a dyno.

--
Easy, #39
the " look at option 2" Asshole (tm)
matthew j henschel
2004-10-05 17:36:17 UTC
Permalink
Post by Easy, #39
Post by matthew j henschel
Subject says it all... assuming, lets say no more then 10:1 compression.
How would I calculate a maximum horsepower? Or would I?
for something that old, an abacus comes to mind.
or a dyno.
--
Easy, #39
the " look at option 2" Asshole (tm)
That's the best response I've heard yet, good one.

Lemme rephrase the question, "What horsepower numbers have people got out of
74 inches?"

-Matt
75FX - Chiseled Stone Wheel
Easy, #39
2004-10-08 03:06:58 UTC
Permalink
Post by matthew j henschel
Lemme rephrase the question, "What horsepower numbers have people got out of
74 inches?"
well, it all depends on how much money you throw at them. and how reliable
you want it to be.

not much of an answer, but it's the truth. too many ponies means the it
ain't gonna run as long.

like court jester said, the limitations are in the heads.

--
Easy, #39
the "how much money you got? Asshole (tm)
matthew j henschel
2004-10-10 07:13:13 UTC
Permalink
Post by matthew j henschel
Post by matthew j henschel
Lemme rephrase the question, "What horsepower numbers have people got
out of
Post by matthew j henschel
74 inches?"
well, it all depends on how much money you throw at them. and how reliable
you want it to be.
not much of an answer, but it's the truth. too many ponies means the it
ain't gonna run as long.
like court jester said, the limitations are in the heads.
--
Easy, #39
the "how much money you got? Asshole (tm)
...still trying to get this damn abacus hooked up to the rear wheel. Trick
shit, no doubt.

Any pointers on books or resources regarding head flow theory? I got no
idea of the physics of it except what old bikers tell me, half of which is
probably really good information and perhaps even wisdom. It's the sorting
it all out thing that gets trickey. Weld the ports, enlarge them, polish
them, keep em rough, etc. I gotta make it work for ME, and knowledge is
power. Input accepted.

I've lowered my sights a little. I'm shooting for 80hp outta 74 ci and less
then 10:1 compression with a fairly flat torque curve (ie not all above
4500rpm).

Meanwhile, I'll chase down reoccuring leaks and other assorted fastener
phantoms.

-Matt
Toni Froehling
2004-10-10 14:23:35 UTC
Permalink
Post by matthew j henschel
...still trying to get this damn abacus hooked up to the rear wheel. Trick
shit, no doubt.
Any pointers on books or resources regarding head flow theory? I got no
idea of the physics of it except what old bikers tell me, half of which is
probably really good information and perhaps even wisdom. It's the sorting
it all out thing that gets trickey. Weld the ports, enlarge them, polish
them, keep em rough, etc. I gotta make it work for ME, and knowledge is
power. Input accepted.
I've lowered my sights a little. I'm shooting for 80hp outta 74 ci and less
then 10:1 compression with a fairly flat torque curve (ie not all above
4500rpm).
Meanwhile, I'll chase down reoccuring leaks and other assorted fastener
phantoms.
-Matt
With those goals, I'd start by checking with a few cylinder head hotshots. The
guys who do shoveheads are getting harder to find, most being obscured by the
glut of evo and twin cam "experts". I'd call one of the older, established
high performance guys like Dan Baisley or the equivalent. I have no idea if
Dan's doing shovel stuff now, but he'd have some ideas. He's one of the more
knowledgable guys I've talked to on head flow theory. Might also call Barry
Gerolomy.

In general, without having the heads done right, you're going to have a bitch
of a time making a drivable combination. With the combustion chamber design on
a shovel motor, especially at increased compression you fight the battle of
lighting the fuel early enough to complete combustion, while at the same time
trying to avoid detonation. Dual plugging helps, but isn't the complete
answer.


Court Jester

www.CourtJesterRacing.com
MaGGie
2004-10-10 17:06:05 UTC
Permalink
Post by matthew j henschel
Any pointers on books or resources regarding head flow theory? I got no
idea of the physics of it except what old bikers tell me, half of which is
probably really good information and perhaps even wisdom. It's the sorting
it all out thing that gets trickey. Weld the ports, enlarge them, polish
them, keep em rough, etc. I gotta make it work for ME, and knowledge is
power. Input accepted.
Don't know any books specifically Matt but this article about DIY head
porting is pretty good. Most illustrations are car engines but the theory is
the same. I'm not suggesting you DIY as that can get spendy real quick if
you aren't sure what your doing wrt porting yer heads. It explains it pretty
well though.

http://www.sa-motorsports.com/diyport.shtm

http://www.nightrider.com/biketech/ is a decent resource for HD tech info
too.

HTH

MaGGie
s***@trippin.net
2004-10-10 18:01:48 UTC
Permalink
On Sun, 10 Oct 2004 03:13:13 -0400, "matthew j henschel"
<***@capaccess.org> wrote:

<schnipp>
Post by matthew j henschel
Any pointers on books or resources regarding head flow theory? I got no
idea of the physics of it except what old bikers tell me, half of which is
probably really good information and perhaps even wisdom. It's the sorting
it all out thing that gets trickey. Weld the ports, enlarge them, polish
them, keep em rough, etc. I gotta make it work for ME, and knowledge is
power. Input accepted.
Check these guys out: http://www.bcheads.com/

Snarl... the "betcha they know how" Asshole(tm)

--

Snarl AH#67, BS#37, SENS
EKIII rides with me...

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