turbocharger supercharger

[shinyribs]

...sneaky devil.How many times have you wrecked the trials bike so far?That thing would be a death sentence in my hands

[TOOLS1]

Still on two wheels Did order a new counter-shaft sprocket, for it, and going to move the foot pegs down, and back as per the advice of other owners. I am also going to make the foot pegs larger, and shorten the break pedal. Need to hurry up, and get this done. There is going to be a vintage trials in Wichita in 4 weeks.
TOOLS

[shinyribs]

you have issues

[TOOLS1]

Yea! Not enough time
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[ksharp]

you know what i might get you to do that indeed, tomorrow is my friday and ima map some stuff off and ill shoot you a message

[samir_nayanajaad]

Man shiny I hope your still hanging around this forum in a few years time cuz now im seriously thinking of doing this with my bike.  My original plans were to rebuild the engine later and just focus on getting it running and ride-able now so you stick around so I can pick your brain; Deal?

While Im here wanted to run some numbers by you that you mentioned. You said that stock CR with 8-10 psi boost was doable.  Found a handy calculator on the net and this is what it had to say,

You are running 10 PSI of boost at an altitude of 2000 feet. Your motor's static compression is 9 :1. At this boost level and altitude your effective compression ratio is 14.72 :1, and without altitude correction your compression ratio would be 15.12 :1

Link to calculator

Will that seriously run on premium or is that calculator off??

[shinyribs]

You may be 100% right with those numbers,Samir. I have never boosted a bike of any sort. My only experience with forced induction has been on big block chevys and that one 5.0 ford we tinkered with.The rule of thumb on auto engines is 9-10 comp ratio + 10lb boost+93 octane = will live all day.Might not work out the same on such a smaller displacement engine.I want to study up on that some more.Generally when going for bigger boost numbers(on autos)you would go with a 7:1 ratio.That will allow up to 15-17 lb boost on pump gas...MAX!
  Another thing needed to accurately judge eff. comp.ratio is to know the volume output of the blower.

 For example,we ran a 486 cu. in. BBC with 12:1 static comp. with a 250 B&M Megablower and got 18:1 effective comp.   That blower produced 250 cfm of air per revolution.
   We then took that exact same motor,installed an 8-71 GMC style blower and got the same eff. comp. ratio,but turned the blower alot slower and ran much faster.The 8-71 produces about 600-650 cfm per revolution.
  By turning the bigger blower slower,but still producing the same/more cfm of air per rev.,we eliminated excess pulsations in the intake tract,less heat generated by not compressing the air as hard,and loss parasitic drag by turning lower blower rpms. At the track the car went from 5.20's to 4.80's with ONLY a blower change.It equates to roughly a 300-350 hp increase by using a more efficient setup,even though boost was exactly the same.
  It is impossible to estimate effective compression without talking to the blower or turbo manufacturer themselves.We talked to B&M when we used their blower ,and Littlefield when we used their 8-71.They had to know cubic inch,elevation(like you said),intended rpm of engine and intended rpm of the blower to calculate it.I would have a hard time trusting any chart to figure those numbers without all the info being factored in.But that is strictly opinion on my part.I will not preach opinion as fact.
  There are so many factors that affect effective compression other than boost or piston design.Camshaft profile is the biggest one.The more duration the cam has,the more cylinder pressure it will bleed off at lower rpm operation.That is why you see race cars,with their monster cams,running huge compression ratios.Its not so much that it actually produces more power(very little really.roughly 3% increase per point of compression)but that it helps restore lost bottom end torque due to a very inefficient camshaft profile.
  Again,i know nothing of the cams on these bikes,but i would assume they have a rather tight cam profile.I assume this due to the good bottom end torque they produce and the good fuel mileage they achieve.
 I'm not leaving until they make me.Hope to see you around,too.Ride safe!BTW,picking my brain is about as effective as picking your nose...alot of stuff in there,but most likely worthless

[ksharp]

ight ight from what im  getting here do i need to run pressure lines from the inlet side of the to the diapram to push against the modified pressure inside the carbs therefor acting normally, or do i run the pitot to the float bowls for added fuel under boost ?

[ksharp]

ok no thats not my question i know i have to presureize the top of my diaphrams with a pitot, but if im pressureizing my float bowls why do i need a fuel pressure regulator if my fule pump is on a higher psi then my max boost, will that just cause the carbs to run rich ?

[samir_nayanajaad]

EDIT: after writing this I thought maybe a picture would help out. No comments on the art work, I have a day job that I'm sticking with.

Man shiny i think im starting to get this stuff, not too hard.  Let me take a swing at ksharps question. Ksharp, take this with a gran of salt as you know I am no expert here but I think I get the basics at least.

If your fuel pump runs higher psi than your max boost with no regulator it will run rich at idle/lower rpms, like you said.  More or less you want your A/F ratio to remain steady throughout the RPM range and with boosting PSI always increases with RPM so your fuel pressure needs to change with boost.  Even though you are pressurizing the float bowls at low rpm you fuel will overcome it too easily with out a regulator.

To make it simple just think of how a standard carb would act if the gas tank was 10 feet above the carbs. The gas has a longer way to fall so its tendency to flow is much higher(or potential energy is higher) so when it starts to flow it really wants to get moving. That's of course a dramatization of whats happening but still same concept. (I think)

[ksharp]

got ya but u would also have to pressurize the top of the diaphram in a cv carb or else the needle would just stay open would it not, and also i figure out i need a fuel pressure regulator which will add a bit more complexity to this fuel system

[samir_nayanajaad]

From reading stuff it seems like it is recommended but in just thinking about it I would just drill a hole in the bottom of the throttle valve or something. I would think that would be enough to equalize the pressure (maybe a little less psi than your boost) to the point it wouldn't override the throttle spring.  

I don't know what kind of carbs you have, I only understand the round top ones that I have been cleaning on the past month (done now btw shiny and tools thanks for the help).

[shinyribs]

Samir nailed it.When the boost changes the fuel pressure HAS TO also.It has to be done just to keep the float bowls full.If you run too much fuel pressure it will not make the bike run rich,it will flood the bowls.It will just over power the float/needle and seat.You cannot force feed fuel through a carburetor.Whether you are using forced induction or not,the fuel is always DRAWN into the engine by vacuum.You may not be able to read it on a gauge,or even record it,but there is always vacuum,whether naturally aspirated or not..Remember when we were talking about pressure differential? A larger jet is less restrictive and will "allow" more fuel to enter an engine,but it will not "push" more fuel in.Same thing with fuel pressure.You only need enough pressure to fill the bowls completely to the point where the float will cut the needle off.Naturally aspirated,these bikes rely on gravity and the float and needles are calibrated accordingly.When you pressurize the float bowl that Honda intended to have "zero" pressure in it,you have to adjust accordingly.There is no one pressure that will work with all boost levels,thus dictating the need for a boost referenced fuel pressure regulator,and of course an electric fuel pump to supply that pressure.

[samir_nayanajaad]

Ok the way you explain it makes more sense. At least I got parts of that right.

Also I have been thinking about this shiny, to make a roundtop carb suitable for boost all you need is the boost running to the over flow on the bottom of the float.  That slot that is cut in the throttle valve for alignment would leak enough past as to not have to worry about it pushing open the valve.  No need to even drill a hole like I suggested earlier.  Am I thinking through this correctly?

Then after that we just need a fuel pump, regulator, good ignition that we can retard at higher rpms(dyna is cable of this right).

Man this has given me a whole new world to think about where I want to take my bike.

[Piute]

Pressure 101 (required course)

[ksharp]

ight another question why do i have to run another line form the fpr to the tank ?

[shinyribs]

Ksharp,some fuel pumps will not deadhead,meaning that they require a bypass back to the tank.

Now remember,i am talking about experience i had done myself with cars.I have never turbo'd a bike.

Most pumps that require a bypass line is due to the fact that they are massive electrical motors and they use the circulating fuel to help cool the motor of the pump.Like i said earlier,last fuel pump like this i used was rated for 1,000+hp so it generated some heat!Some of them do it simply for quieter operation.Some guys swear by using bypass systems for more consistent fuel pressure.That is probably true,but since i use mine for 5 or 6 seconds at a time under WOT,never really had a problem with that.I havent done any research on bike specific parts.Just going strictly off old drag racing experience with bbc's only.well and one sbf.

  The last blower motor i had that was gas did not have a return line.One inlet in,two outlets out(for that particular setup)and one line to sense boost.Thats it.

   Samir,i wish i could tell you everything you need to know.I would,if i could.I have never even ridden my bike yet,let alone turbo'd one!This is all talk from a car guy.You do need to pressure balance to fuel bowls,yes.I dont see any reason why using the over flow vents should not work.
   As far as the slides go,i don't know.I would have to sit down a look at a carb better to know if it was needed or not.From the sound of you talking about the alignment slot,i think you are ahead of me at this point.That sounds reasonable to me,but depending on how small the slot is,it may not provide the volume of air needed to do the job.I cant really say yay or nay on that.
  I know what you mean about getting your brain going.Ksharp is gonna be responsible for alot of money spent around here!!

[shinyribs]

I posted this separately to make sure it got noticed
 Disclaimer:   All previous info was from the archives of a rusty brain.I have not ran a blown'turbo'd car in over 3 years.
  I was wrong on one thing!!!  Looked back thru my notebook at some tuning notes and saw the old fuel pressure tune.We were NOT running an additional 7 lbs of fuel pressure over boost. We were running a base of 7 lbs f.p. and adding 1lb of f.p. per each 1lb of boost.
  Sorry,thats my bad...all on me.I apologize for the mixup

[ksharp]

the third line would be to elimanite pressure drop at launch and prevents carb flooding by bypassing the excess to the tank

[ksharp]

because for blow thgrough u need a fuel regulator that has a boost refrence, now all i need to do is figure out a blow off valve so i done fuck the turbo for snapping the throttle close seeing is how it will still be the daily driver