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Author Topic: RWHP Formula .  (Read 3030 times)

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Offline Greg H

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RWHP Formula .
« on: April 28, 2013, 02:06:21 am »
We're moving house at the moment  , and I've been digging out some old mags etc whilst sorting out stuff for the tip . I mentioned somewhere on a previous post that back in the day I used to calculate the rwhp of bikes that I raced over the quarter , using a formula . Well here it is , I'm not sure if the details will be legible though  :D :D

 
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Offline johno

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Re: RWHP Formula .
« Reply #1 on: April 28, 2013, 03:31:33 am »
Gregory, your teasing me, yeh small.............is it outright top speed or quarter?
Whats the bottom line for your proposed motor, be interested to know :)
johno
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Offline Greg H

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Re: RWHP Formula .
« Reply #2 on: April 28, 2013, 01:03:02 pm »
Well , I think I'll mark that down as a failure  ;D, Maybe I'll be able to scan the article and hopefully make it more legible  ::).
johno , it'll be quarters ;) . I can just about justify the time and expense I'm devoting to my sohc Honda drag bike build , but I just can't get excited over a sohc Honda top speed bike . I guess that running the Busa has spoilt me . It hasn't always been easy , and it certainly aint been cheap , but it has been fun,and as safe as it is possible to be whilst going really fast on two wheels.
Although I havn't finalised the exact spec of the motor yet, I can say  that the Honda will be running a N/A Gas powered drag motor.And that I plan on using the strongest internal components (built utilising the latest materials), that I can get my hands on .I also intend on using some new components, which will allow me to succesfully replicate the exterior look of a period ( mid seventies) P/Stock drag bike motor ;). There are certainly some components currently available out there that  fit the bill , such as the RC replica blocks which APE do, and the latest Keihin CR carbs for example .
Regards Greg "H".   
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Offline joe p

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Re: RWHP Formula .
« Reply #3 on: April 29, 2013, 02:44:21 am »
Yeah, you gotta love the new stuff out there. I have a friend that has a ZX14 with a turbo on it, he drives it to work and back all the time. And then this weekend he went to the track and he ran 8 second passes in the quarter mile! But as far as the SOHC 750's go, I think there are more parts for them now than there were 20 years ago. Just love them 70's P/Stock drag bike.
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Offline Sam Green Racing

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Re: RWHP Formula .
« Reply #4 on: April 29, 2013, 03:23:45 am »
Quote from: Greg H on April 28, 2013, 01:03:02 pm
but I just can't get excited over a sohc Honda top speed bike .
Regards Greg "H".

Don't let member Dodger hear you say that Greg.  ;D ;D ;D ;D ;D

http://forums.sohc4.net/index.php?topic=96337.0

Sam. ;)

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Offline cb650

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Re: RWHP Formula .
« Reply #5 on: April 29, 2013, 06:09:02 am »
There used to be one online years ago.  Only needed 1/4 mile time and weight.  Didnt account for wind resistance.
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Offline Sam Green Racing

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Re: RWHP Formula .
« Reply #6 on: April 29, 2013, 06:30:19 am »
They work in theory but you can't gaurantee them when you put it in practice.

Sam. ;)
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Offline Greg H

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Re: RWHP Formula .
« Reply #7 on: April 29, 2013, 12:26:09 pm »
Quote from: Sam Green Racing on April 29, 2013, 03:23:45 am
Quote from: Greg H on April 28, 2013, 01:03:02 pm
but I just can't get excited over a sohc Honda top speed bike .
Regards Greg "H".

Don't let member Dodger hear you say that Greg.  ;D ;D ;D ;D ;D

I did have a go at building a Honda sohc top speed bike once . I'd been inspired by watching Mel Nolan on his turbo bike at Elvington . I raked out a stock frame , sawed off the top fame rails knocked up a small fuel tank and fitted a dustbin fairing at the front and a steamlined tail piece at the back, the seat consisted of a flat piece of ally turned up at the end . With the 970 motor fitted it cracked 170 a couple of times , it was good fun back then, but doing it again just doesnt float my boat I'm afraid . 

http://forums.sohc4.net/index.php?topic=96337.0

Sam. ;)
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Offline Sam Green Racing

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Re: RWHP Formula .
« Reply #8 on: April 29, 2013, 01:26:54 pm »
170 is not to be sniffed at young Greg 8) 8) 8) 8) 8) 8) 8) I'm sure with some major weight loss one could push 190 all motor. ;)

Sam. ;)
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C95 sprint bike.
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Offline NitroHunter

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Re: RWHP Formula .
« Reply #9 on: May 01, 2013, 11:55:17 am »
Quote from: cb650 on April 29, 2013, 06:09:02 am
There used to be one online years ago.  Only needed 1/4 mile time and weight.  Didnt account for wind resistance.

MPH needs to be factored in, not just ET alone.  There can be lots of reasons for slow ET's, like tire spin, turbo lag  ::)  missed shifts, ect. but with minimal factoring for fairings, gearing and horse power determine top end (1/4 mile) trap speed. 
My over-turboed stock bore 736 wouldn't get out of it's own way until 3rd gear... then would come on like gang busters, running 143 mph.  8)
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Offline cb650

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Re: RWHP Formula .
« Reply #10 on: May 01, 2013, 03:04:48 pm »
Ok I did state didnt account for wind resistance.  Wheel spin should be a no brainer.
(I know it killed my times but the bike did better like that so that proves I dont know what I'm talking about)   Also if you make a few runs unless you a complete idiot youll use your best time not the one you missed shifts on.
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Offline johno

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Re: RWHP Formula .
« Reply #11 on: May 02, 2013, 02:06:38 am »
Hi Gregoreeeeee, hope your thawing out OK.   My son is off next week on his grow up backpacking trip around Europe for 4 months .   He was worrying about the weather but I said the girls might like a cuddle to warm up.
I was reading your 170mph stuff, thats serious speed man !
After reading some landspeed forums I had just made up my own formula for top speed then you come along and blow it away...............possibly..... ;D

The theory was  :o   100hp equates to 150mph..............200 hp equates to 200 mph

So the record I'm looking at is 150mph........so 100hp for the 750 engine( one can only hope I know)
If you had a SOHC 1,000 that run 170 according to my theory you would have had to have around 140 to 150hp,
did you ever have it on a dyno ? to see what you had ?
cheers Johno
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Offline Greg H

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Re: RWHP Formula .
« Reply #12 on: May 04, 2013, 01:38:05 am »
Hi johno ,It's been a long winter , but the weather has recently taken a turn for the better over here ;) , so it's time to get things done , it's surprising how a bit of sunshine makes all the difference   ;D ;D
To be honest if I was to build a  top speed bike now ,I'd spend the majority of my time and resources on getting the lowest CD figure possible , the power output of whichever power unit I decided on using would be well down my list of priorities .Streamlining, ie free horspower is definately the way to go  ;D.
Regarding the power output of my 970 motor  ,  I think I calculated that it made 85/90 hp back then, but I may have been way off with that figure ::). To be honest I've never thought that the speeds we acheived on that bike were anything special, after all Percy Tait hit 167 on his works Triumph triple at Elvington, and they made ONLY ;D 85 hp , and that was without the benefit of a dustbin fairing etc  ;).
Regarding your formula , well ,  where you calculate that a bike needs 200 (I'm assuming here that you mean rwhp) to hit 200mph, I've found is correct for any of the current crop of fast road bikes such as Busa's Z14s etc .However, I'm sure that if someone spent as much time/money on improving the streamlining on any of those bikes, ( rather than just constantly trying to up the rwhp without paying any serious attention to improving the aeros), they could achieve 200mph with less power,and just leave their motor stock ::) .


Regards Greg "H".


   
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Offline johno

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Re: RWHP Formula .
« Reply #13 on: May 04, 2013, 03:57:08 am »


I totally agree with the aero versus HP stuff.    Its been keeping me busy trying to deal with it. ::)

The white dirt and high temp really knocks the ol top speed around.

Point in question ! Ol Percy Tait triple with around 85hp timed at 167mph where as the John Davey trident above , lookin good soundin good ...... best run 119mph  this year at Lake gairdner.
cheers Johno
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Offline johno

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Re: RWHP Formula .
« Reply #14 on: May 04, 2013, 04:06:44 am »
Im glad we raised the issue of triumphs...............notice the leaks dripping on the plate.  nothings changed since 1973 ;D ;D ;D
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Offline Sam Green Racing

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Re: RWHP Formula .
« Reply #15 on: May 04, 2013, 04:31:26 am »
 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
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C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Greg H

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Re: RWHP Formula .
« Reply #16 on: May 04, 2013, 12:57:37 pm »
Thats a good looking Trident johno  8). I take it that it runs in a class where streamlining isn't allowed . Regarding Percy Tait, I believe that on the day he ran those speeds it was cold and icy ,so he had to ride the wheels off that bike to run that fast ,  he was a works rider after all, so I guess he wasn't lacking in the b---s dept ;D ;D.

 
 
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