shovelhead drag pipes
Robert Sommer
or just make it louder?
notbob
Robert Sommer wrote:
>
> Will drag pipes increase the performance on a shovelhead
> or just make it louder?
They will increase performance IF the bike is tuned to take advantage.
You will need to make appropriate adjustments to air intake and fuel
mixture, also.
nb
Joe Mama
> Will drag pipes increase the performance on a shovelhead
> or just make it louder?
You will lose distinct low-midrange torque, but you will be able to wind the
heck out the engine to significant RPM's through the gears. You will
probably notice some high end improvement, but for maximum performance,
the pipes should be dyno tuned and cut to match your particular motor. My
understanding and experience tells me that the typical length for early OHV
engines is about 42" - 45", though some people may disagree with this..
-jm
1968 XLCH
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Roger Mauck
Joe Mama wrote:
S&S says approx 30". I say throw the drag pipes in the trash and get a good
set of hi po mufflers. You torque curve will love you for it. I've never seen
drag pipes for sale any longer than 40 inches anywhere. Also never, ever put 2
inch drag pipes on an 80 inch Shovel your performance and ability to tune it go
right out the window.
Roger
Joe Mama
> S&S says approx 30".
They must be referring to all-out drag racing, though I cannot even envision
this, since there would almost zero back pressure, which would completely
destroy the low end off-the-line torque needed for the track. I would think
that running straights at 45 inches would be beneficial for the added bit of
extra back pressure you would get out of it..
> I say throw the drag pipes in the trash and get a good set of hi po mufflers.
> You torque curve will love you for it.
There are a lot of mufflers which claim to provide good results, but i've
never seen any dyno stats where anyone used the same engine to test
several different exhausts systems for comparison. Out here in the SF
Bay Area Thunderheaders are the big rage, but I don't like them..
> I've never seen drag pipes for sale any longer than 40 inches anywhere.
I never bothered to measure them, but back in the 60's we used to
run home-brew straights which we had made at a muffler shop to fit
our machines the way that we liked. I preferred over-the-transmission
kicker cover and down, but some guys liked to go over and straight
back or even under it. What I liked about straights was that you
could wind the heck out of the motor through the gears and with my
28 tooth tranny sprocket almost never hit red line all the way..
The word was that optimum length was approximately 42 inches, but I
think that the variable was 40-45, which I ran at about 45 inches. To
be honest with you, I ran at the drags once and progressively cut my
pipes down about an inch at a time to about 40 inches in between
each run and didn't notice one bit of change in my ET. I've got a
binary somewhere in my files taken after the race. I'll post it in abpmh..
> Also never, ever put 2 inch drag pipes on an 80 inch Shovel your
> performance and ability to tune it go right out the window.
Absolutely, though the advantage of 2" pipes is that it would be more
practical to run a more efficient baffle than with the 1-3/4" pipes..
Roger Mauck
Joe Mama wrote:
> On Sun, 19 Aug 2001 17:48:52 -0400, Roger Mauck <rma...@adelphia.net> wrote:
>
> > S&S says approx 30".
>
> They must be referring to all-out drag racing, though I cannot even envision
> this, since there would almost zero back pressure, which would completely
> destroy the low end off-the-line torque needed for the track. I would think
> that running straights at 45 inches would be beneficial for the added bit of
> extra back pressure you would get out of it..
They were referring to the length that makes the best power.
>
>
> > I say throw the drag pipes in the trash and get a good set of hi po mufflers.
> > You torque curve will love you for it.
>
> There are a lot of mufflers which claim to provide good results, but i've
> never seen any dyno stats where anyone used the same engine to test
> several different exhausts systems for comparison. Out here in the SF
> Bay Area Thunderheaders are the big rage, but I don't like them..
Almost any muffler would be better than drag pipes especially for the "low end
off-the-line torque" you speak of. Most mufflers require tweaking the baffles to
get a good balance of torque and power. My ol' stroked Shovel made more power and
torque with mufflers in place of the drag pipes. The mufflers were opened up pretty
much internally.
>
>
> > I've never seen drag pipes for sale any longer than 40 inches anywhere.
>
> I never bothered to measure them, but back in the 60's we used to
> run home-brew straights which we had made at a muffler shop to fit
> our machines the way that we liked. I preferred over-the-transmission
> kicker cover and down, but some guys liked to go over and straight
> back or even under it. What I liked about straights was that you
> could wind the heck out of the motor through the gears and with my
> 28 tooth tranny sprocket almost never hit red line all the way..
I don't get the reference to a 28 tooth tranny sprocket on a Shovel. Please
explain.
>
>
> The word was that optimum length was approximately 42 inches, but I
> think that the variable was 40-45, which I ran at about 45 inches. To
> be honest with you, I ran at the drags once and progressively cut my
> pipes down about an inch at a time to about 40 inches in between
> each run and didn't notice one bit of change in my ET. I've got a
> binary somewhere in my files taken after the race. I'll post it in abpmh..
>
probably because you were never in a rpm range where you could use the extra
length.
>
> > Also never, ever put 2 inch drag pipes on an 80 inch Shovel your
> > performance and ability to tune it go right out the window.
>
> Absolutely, though the advantage of 2" pipes is that it would be more
> practical to run a more efficient baffle than with the 1-3/4" pipes..
>
Baffles, not in my drags, never! As a side note a friend of mine is experiencing
some medical problems. He hasn't been able to ride his bike for a while. The other
day when I got home from work it was sitting on my porch. He called me and said he
couldn't ride it and it seemed such a waste to let it sit. So he brought it over
with insurance and new tags and said to ride it like it's my own. He said he
couldn't sell it and I'm the only one he'd trust with it. After riding my '01 RK
his ol' Shovel feels like an absolute monster. It's loud too. Drag pipes and all.
After riding my bike with it's supper quiet exhaust system his bike sounds fuckin'
brutal. I almost makes me paranoid to ride it. Oh yeah and with the S&S E, hi comp
pistons, ported heads and Crane cam it feels like it would easily kick my new bikes
ass. O'course it might just be the drag pipes.
Roger
Joe Mama
>> They must be referring to all-out drag racing, though I cannot even envision
>> this, since there would almost zero back pressure, which would completely
>> destroy the low end off-the-line torque needed for the track. I would think
>> that running straights at 45 inches would be beneficial for the added bit of
>> extra back pressure you would get out of it..
> They were referring to the length that makes the best power.
Thirty inches does not conform to my understanding of "best power."
>> There are a lot of mufflers which claim to provide good results, but i've
>> never seen any dyno stats where anyone used the same engine to test
>> several different exhausts systems for comparison. Out here in the SF
>> Bay Area Thunderheaders are the big rage, but I don't like them..
> Almost any muffler would be better than drag pipes especially for the "low end
> off-the-line torque" you speak of. Most mufflers require tweaking the baffles to
> get a good balance of torque and power. My ol' stroked Shovel made more power and
> torque with mufflers in place of the drag pipes. The mufflers were opened up pretty
> much internally.
If you'll look at the "image07.jpg" that I posted on abpmh, the stock XL
mufflers were punched by taking the block out the main throat with an
old fork tube. It was still almost as quiet, yet minimised the restriction
to where I noticed an all around increase in power, and it wound out
in first and second gear rather than torquing up really fast and tight..
>> What I liked about straights was that you
>> could wind the heck out of the motor through the gears and with my
>> 28 tooth tranny sprocket almost never hit red line all the way..
> I don't get the reference to a 28 tooth tranny sprocket on a Shovel. Please
> explain.
It doesn't matter what you put it on. Stock four speed cs tranny sprockets
are 22 tooth, but in my opinion are street ratio and not suited for the hwy.
Most guys ran 23-25, but I ran an old VL 28 tooth which gave me low RPM
cruising on the road, better gas mileage, and the ability to wind the motor
all the way out to the max through each gear without really red-lining..
It was a gas at the drags when I could have gone across the finish line in
third gear and probably still took it. I paired off with one braggart who
kept mouthing about how he could beat me, and cleaned his clock so bad
that I shut down early and coasted across the finish line in fourth to take
the race with him still behind me..
I raced a guy one time and paced him in second gear until he was tached
out in fourth, and waved bye-bye to him as I shifted into third and left him
like he was standing still. Gearing and knowing when to shift is a crucial
part of the performance criteria..
>> The word was that optimum length was approximately 42 inches, but I
>> think that the variable was 40-45, which I ran at about 45 inches. To
>> be honest with you, I ran at the drags once and progressively cut my
>> pipes down about an inch at a time to about 40 inches in between
>> each run and didn't notice one bit of change in my ET. I've got a
>> binary somewhere in my files taken after the race. I'll post it in abpmh..
> probably because you were never in a rpm range where you could use the
> extra length.
This doesn't make sense. How can a motor run in a drag race and not get
into a usable RPM range? Why not just run straight out of the exhaust port?
The binaries are posted in abpmh..
>> Absolutely, though the advantage of 2" pipes is that it would be more
>> practical to run a more efficient baffle than with the 1-3/4" pipes..
> Baffles, not in my drags, never!
I like the looks of drag pipes, in particular the XLR style, but i'm not
gonna run them and take a chance of getting citations, especially in
the State of California where they won't "fix-it" on exhaust violations
any more. I would want to run baffles, but there aren't any efficient
units which balance performance with noise attenuation, and in this
application the 2" straights would have a definite advantage..
> As a side note a friend of mine is experiencing
> some medical problems. He hasn't been able to ride his bike for a while. The other
> day when I got home from work it was sitting on my porch. He called me and said he
> couldn't ride it and it seemed such a waste to let it sit. So he brought it over
> with insurance and new tags and said to ride it like it's my own. He said he
> couldn't sell it and I'm the only one he'd trust with it. After riding my '01 RK
> his ol' Shovel feels like an absolute monster. It's loud too. Drag pipes and all.
> After riding my bike with it's supper quiet exhaust system his bike sounds fuckin'
> brutal. I almost makes me paranoid to ride it. Oh yeah and with the S&S E, hi comp
> pistons, ported heads and Crane cam it feels like it would easily kick my new bikes
> ass.
> O'course it might just be the drag pipes.
And you ain't never gonna convince me that you really believe this.. ;-)
BUDJOSEPH
>From: Roger Mauck
>As a side note a friend of mine is experiencing some medical problems. He
hasn't been able to ride his bike for a while. The other day when I got home
from work it was sitting on my porch. He called me and said he couldn't ride it
and it seemed such a waste to let it sit. So he brought it
>over >with insurance and new tags and said to ride it like it's my own. He
said he
>couldn't sell it and I'm the only one he'd trust with it.>>>
Man, that says it all right there...
Ride Safe,
Bud