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The official crazy ideas on how to build horsepower thread

11K views 59 replies 21 participants last post by  JAWS 
#1 ·
So I posted this question on another thread earlier, but thought I would start a thread of its own. I intend this to be a thread where people who are thinking outside "the box"( I prefer WAY outside the box) to come and talk/ask about it. Maybe it will take off maybe it won't, and maybe the mods will kill it. We will see.
In my youth I drag raced motorcycles ( Suzuki) with a couple of brothers who were very intelligent and willing to try anything to go fast. In the end we went fast as most, but really didn't discover anything except what Vance and Hines already knew. So I know a little about making internal combustion engines go fast, but wouldn't call myself steeped in it or anything.
The other day I was riding my F/I tuned sportster home from work and considering the best way to get more out of it. A stock F/I sporty has 79 horsepower at redline. The dyno sheet on mine says it hits 80 horse at 2000rpm and carries it to the same redline. And it feels like it. But I would like it to either have a higher redlineor make more horses, or both. So as I was considering bigger cams, valves and Pistons , I thought of Elffors blown 45 build. And thought every blower runs off the output of the motor, what if you spun it off the output shaft of the tranny?
Of course metering the fuel on this ever changing blower ratio would be a problem, and maybe keeping the hearings in the blower shafts. But wow, if you could over come that , you would have one hell of a LSR bike!
Anyway if you have a crazy idea or some input on mine, fire away.
And I know the bike I talked about isn't JJ compliant,( I have two that are) it just happened to be the one I know the numbers on and I was on when I first started thinking about this stuff. Let the games begin.
 
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#40 ·
I know nothing about oil mist. I was thinking about oil itself on the flywheels, flywheel scrapers ect. Dick O' Brian said something to the effect that the XR's you could see would actually start to visually slow down on the straight aways, after they stood up from the corner, as oil started to rope up on the flywheels.
 
#42 ·
in 1995 to 1998 we went buell road racing in CCS its North east club racing - had that issue show up right away as the buell is in fact still a sporty - but we were allowed computer technology so with that we seen the speeds drop off in all the left turns as well as the straights -

5 speed sporty has doorway in the cases to the right side between the cams so we welded them up closed - the thought was the excess oil from the cam cover was spilling into the lower unit causing a rope effect

then we had an oil pump made with 2 extra circuits one would be for an extra oil pan intake, the 5 speed has and one for the cam cover that we designed a pick up for it so it did not lean out the oil pumps regular intake

S&S - made me a special stroke flywheels and diameter was around 3-5/8 and then had to buy 25 crank pin nuts as the timing of the nut to the pins
torque to the location of the flat on the nut And that had to ground @ 45* so the rear rod could pass by in the circle - the crank pin was also hollow to reduce weight jims made them < that dick would not sell one to me but i ended up getting two with help - we then used S&S special rod length for greater dwell time at TDC - OEM rods 6.96 length < i believe thats correct - S&S rod length 7.113 - then went to air cooled cylinders 3-7/8 bore nikasil plated with NOS pistons needed solid tops and removed .087 from the tops co compensate for the rod length -

Note buells engine location sets the bikes suspension location so using exact bolt up had to stay in place and all its dimensions height and length could not be altered in any way

the problem road racing was the bike RPM legs 7200 was max beyond usable piston speed in the iron cylinders as its 56 thousand feet per second death come at that point internally - and we needed 8600 RPMS to compete at PRO level

the final year at the nationals in 1998 at Mid Ohio we went 159.7 on that straight away
 

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#43 ·
thank you for that explanation. I have never thought about a hollow crank pin. With the hollow crank pin, is the oiling to the rods the same with the bigger cavity, and is it hollow all the way thru? I would appreciate it if you could give a few more details about the crank pin. Thanks!
 
#44 ·
Pin is hollow, not to tight press fit in the wheels so you can true it up.

Once done, you press an alloy plug in each end, these are tight fit that forces the pin in the wheels.

You drill/tap them in the middle to screw an extractor in them to remove them, so new plugs everytime you split the crank...

Patrick
 
#46 ·
Another thing I have thought about was the wrist pin bushing changed to a roller bearing like I have seen on some 2 strokes? I know this is not really outside the box like some of the other things mentioned here. I have never seen it done to an old Harley or indian,
 
#47 ·
The straight XR pin is huge in diameter... Uses the same roller set as the big 54R rods for KR and XLR... It is designed to be hollow. And the flywheels are forged steel to take the strain of a 5 or 6 thou interference fit...

I personnally wouldn't attempt to hollow a std taper pin... Unless you drastically want to reduce rotary weights...

Patrick
 
#48 ·
we used Carbon coated titanium pins that were .087 wall straight through and only 2 inches long held by clips not buttons - 1/3 the weight of a normal race pin

the photo is the 5 speed sporty hollow crank pin

the other is a 1933 to 53 Indian chief crank pin

the 45 and the indian does not have enough room for a real effect BUT the sporty / 45 flywheels that use sporty rods maybe - one could say the difference in rod weight takes too much away - even tho the sporty rods are tough -- unless you use the titanium rods but at 2000 a set it makes the thing pricey
 

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#49 ·
A guy brought in a reed body for a two stroke the other day and wanted me to mill a .250" spacer to sit between it and the motor. Claimed it would give the bike more low end torque.
This got me thinking about something I think about occasionally. The question is, will intake runner length make that dramatic a change in HP? I know it increases the air speed and is supposed to more efficiently fill the chamber. But wouldn't this depend a great deal on cam timing? Wouldn't you need a large overlap? Or would you benefit some no matter what? And then I keep thinking about building a downdraft intake for a Harley . Would it be worth the effort? Any thoughts are appreciated.
 
#50 ·
if runner length did not matter the 2 / 4s tunnel ram would never been invented

its all in the pistons dwell time / pro stock NHRA uses a short honda length rod in a 500 cube engine - idea is to snap the piston off the deck to gain a big gulp on the intake port at the begining of valve opening - yet pro stock / fuel harleys use way over stroke very long piston dwell time so to squeeze every ounce of power out of every fuel charge both work for completely different reasons
 
#51 ·
So, you want to get crazy with the horsepower ideas...

First, think about how the MoPar corp's engineers found that intake tuning was a function of manifold length, and, the speed of sound...

...then look at what a manifold with runners and a plenum looks like... Now, look at what it looks like with a carb bolted on it...

...now, go look at 4th and 6th order bandpass loudspeaker enclosures...

The bandpass box can actually put out more dB over a narrow band than the speaker in a regular enclosure can.

There are a lot of factors (speaker cone area, speaker compliance, port length, port diameter, plenum volume, etc.) that influence how much of a boost there is, and over what frequency range.

It's made me wonder if there isn't a small gain to be had by looking at an intake from a sonic/accoustic point of view, as well as a flow/volume/velocity/fuel droplet view.

Hey, this is the crazy idea thread...

-Bill
 
#52 ·
Bill, I think you are on to something there, if you look at modern intakes compared to the older style and compare the hp and mileage they are getting out of these smaller motors.

S&S made a video a while ago now promoting their slip on mufflers and were talking about the same thing only on the exhaust side, it was an "aw ha" moment for me.
 
#54 ·
Here ya go KC,
http://www.sscycle.com/media/instructional-videos/

Back in the day they would say ya need back pressure on the exhaust which I knew was bull shit but, I never had a better answer until I watched this video, he explained it pretty damn well and with the dyno to back it up.

Now, if ya take that to the next step like Bill did, if it happens on the exhaust side, why wouldn't it happen on the intake side?
 
#57 ·
Not sure how an exhaust augmenter would help in our application ( I guess I'm not crazy enough to see it). I'm still thinking of the downdraft intake on a Harley. You all spoke of Mopar intake runners, I remember they had some cast intakes that looked like spider legs and were open around them. I guess to let air pass around them and help keep them cool. Also they seemed to be tuned in length. But back to the augmenter idea. Would a double Venturi in a velocity stack before the carb throat create even more air flow than a plain velocity stack? Feeling a little insane and out of the box right now

Of course the needed length of the double Venturi may be to long to be usable?
 
#59 ·
These intakes?



Chrysler "long rams" - gave a super kick between 2500-3000 RPM. Same motor with 1X4BBL actually made a couple more HP up top, but the torque peak hit way harder with long rams, and at a lower speed.

Since they put the carbs pretty much over the exhaust, I don't know how cool that intake charge actually was...

Have seen helmholtz resonators in the piping between throttle body & air filter... didn't ever think of it being able to "spring" some extra air into an engine; just thought of it as a noise reduction thing. Live and learn.
 

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#58 ·
A tuned exhaust sytem is strangled by a neglected intake. Intake runner length as well as airbox volume needs to be addressed. The teardrop S&S is nice at WFO high rpm but a tuned helmholz resonator will benefit everything else done in the name of power.

See here,here and here for some background. If you're building something pretty this may not be for you. But if you want the most out of the engine read on.
 
#60 ·
In high school a buddy and I put those on his 440 in his 4x4 ramcharger. We for kicks, put a boost gauge in to see what happened. We were also running this on a 13:1 motor on propane. We called it the BBQ.


Incidentally, he also had tuned exhaust.
 
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