[Humbug]

and I thought it was supposed to be a secret.

it will definetly ride different... you will always try to keep the boost on to have a good response on corner exits. it might be an idea to tune up an anti lag system.

but its getting more and more complex... you might as well convert it to efi to aloow tunability... otherwise its just going to be rough and not many options.

 

[Humbug]

i would also definetly use a Dan Culkin valve on the manifold also.

 

[Humbug]

It'll come down to whether or not the power offset will balance out the weight increase. Or fit better suspension.. but at that point you get dangerously close to having to ask yourself why bother with a cbr250 since there's so little cbr250 left!

ofcourse it will... suspension will be the last thing to worry about. i doubt the change in cg would be significant enough to worry about.

if you ask that question... you may as well turbo an r1. then we are back at square one.

just tune it up... do some tests and mod some more there is alot that can be done.

 

[Humbug]

-1 to the antilag, assuming stud would rather not be replacing his turbo well, probably at all, anti lag is probably not a good option.

then stud needs to make the desicion of what the life expectancy of this thing is going to be. i rekon the engine will lunch itself well befor the turbo is 1/10 through its life span. he needs to work out how much boost he wants also.

i think the purpose of the turbo mod is to max everything at the cost of everything else. so trying to make it reliable is kind of defeating the purpose.

its all up to stud at the end of the day.[hr]

You're taking the piss aren't you? Please tell me you are!

rofl is all i will say

but in all seriousness... i think suspension should be sorted out after he works out what he is doing with the engine...

one problem at a time, yeah

 

[Humbug]

so tell me what suspension has to do with the turbo? the cg and total weight will change slightly acceleration characteristics will change... but to a lesser extent of a change of rider maybe.

i dont see how you can tune suspension to the bike before you put the turbo on... and at any rate... the turbo is already on... i wouldn't think he is going to remake the exhaust manifold to change cg etc etc?

 

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also I noticed there is no coatings on the pistons and reduced material thickness... so beware of high temps when tuning this thing... or just get forgies made from JE in the states.

something like this would be what you should need.

 

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And Humbug... tyres are the limitation, so throwing up the extreme basics of centripital motion sort of undermines your point, because higher corner speed needs higher lateral acceleration... lateral acceleration is analogous to tyre grip, so either 250's/125's have better tyres than MotoGP bikes or alternately you're missing something... read up on grip circles.

ok, going back to the basics. the formula for centripital force dictates that with the same friction co-efficient, turning radius etc etc... that the velocity of the body will always stay the same regardless of its mass... as centripital force is directly proportional to that mass...

Fc=umg and Fc=mv^2/r

so having said that... a big bike will have the same mid corner speed as a small bike... There is no way I can believe that.

The only difference is that the bigger bikes tyres need to absorb more heat by means of bigger tyres. but that has nothing to do with friction as far as I am aware.

 

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Richo, I'm not sure if you're having trouble following, or just trolling.

Fine, I'll spell it out really painfully simply.

Drew: If a motoGP bike chose to run the 250gp line, could it maintain a superior velocity through every point of the turn?

i have a feeling the 250 bikes stop faster than the motogps... but accelerate slower.

over all, i think you spend more time in your lap accelerating than you do decelerating... thus why the motoGPs have faster lap times...

but I have no idea why they wouldn't have the same corner speeds between the two.

 

[Humbug]

You didn't google grip circles did you?


Richo;- As per the above all bikes will run something between a semicircle line and a parabolic line, a parabolic line gives you a lower mid corner speed and a higher entry and exit speed, whereas a semicircle line giives you a higher mid corner speed. The problem is though that you have to have enough power to accelerate to the capability of the tyre to effectively run a parabolic line, so a bigger bike can and a smaller bike can't...

i did but it was full of crappity crap, so I went to my text books.

key word being circles... the only reason why a parabolic arc would have slower mid corner speeds is due to a smaller turning radius at the centre... so my formula is still correct.

the mid corner speed, regardless of the size of the bike is dictated by the line taken.

having said that, the line is dictated by the amount of power the bike can produce asuming same breaking rate. utilising engine power to stress the tires and accelerate at the same time... where a small engine power cant do that, so it uses centripital force to stress the tires; thus a different line is taken.

does that sound about right?

so in studs case... he is going to make his corners more parabolic shaped to utilise the turbo more i presume.

 

[Humbug]

To put it another way though, strapping 40 kilos of ballast to my R6 won't affect the speeds at which I can turn without the tyres letting go?

it wont (according to the maths) effect the coefficient of friction and the centripital force and friction force balance each other out.

you will find that your tires will get hotter and wear faster due to sliding friction.

i also presume you would have to re~calibrate your suspension.

you acceleration and deceleration rates would obviosuly become lower from the balast.

just realised, if a bike wieghed infinity... when you ride... the world would move underneath you lol... but the earth is pretty heavy wieght to move.

 

[Humbug]

dont forget that the friction force stopping the bike from sliding comes from two things. the friction factor (mew) and the downward force of the faces in contact. (Ff=mgU)

the reason why it is the same is because the downward force is the same mass used to derive centripital force... because it is pushing harder on the ground so to speak... so there is more friction. thats is why downforce aids traction (but also increases drag)

in a perfect world... we would have life sized slot car racing... but that would just be stupid in a cool kind of way

 

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i think breaking traction to make a turn sharper than its allowable turning circle would be quicker... but i guess it comes down to how fast you can change directions, regain traction and take off again. it makes me wonder why i don't see sliding in gymkhana :S

 

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Hey stud

what are you doing about crank-case pressures when rolling on and off boost?

 

[Humbug]

lol at 12.7 sec on the 400m

no way thats 105hp at the wheel... thats ob-surd on so many levels

 

[Humbug]

If I'm getting a reading of 2 (air speed measurement) at one carby shouldn't I be getting at least 4 times that at the turbo?

If you connect the turbo to charge the inlet, you should get more exhaust to spool the turbo more... so you should get higher flows when the intake is charged. what you need is higher exhaust pressures to get that turbo under load to get that flow rate up on the intake side.

But if you are getting atleast 2x... thats a good sign I think.

well, it made sence when I was writing it

Wait...

i i need to know where on the turbo you are taking the reading... is it the intake side of the turbo or the discharge end of the turbo?

You should get a higher air speed on the inlet to the turbo being a lower air pressure. it will ofcourse be slower on the discharge as the air density is increased. Thats not factoring things like acceleration of the gas to the diameter of the intake and discharge pipes... depending on the diameter of your flow meter... if it much the same to the intake/discharge there shouldn't be much difference... but if it is smaller you will find that you will get slightly more air speed on the intake as the pressure is lower than atmos and the discharge will be slightly slower but with a higher pressure... if you still want more accuracy, you could factor in manifold vacume by dividing air speed by how many bar you are under atmos... but idle it should be pretty damn close to atmos, but it depends on your meter.

but you need to fully load the turbo to find out its max mass flow rate and compare that with the natural asperated values... that should give you a max boost (in a perfect world) but it will probably be abit less.

I suppose if you wanted to know roughly what air speeds you should get... you could multiply how many bar you expect (max guess) to your air speed value... thats just treating as a liniar relationship... if you wanna be super acurate, you can refer to the turbo pump curve.

what you need to measure is mass flow rate... some how...

 

[Humbug]

I was just wondering...

How did you blow the head gasket? Isn't it brand spanking new?

Perhaps it was blown when dcotton had the turbo connected...

You might not be getting enough squeezing pressure on the head gasket to cope with higher cylinder pressures.

Might need stronger bolts to reduce their stretch... but you can only go as tight as the block internal threads/bolt spacing’s will allow.

It could be an issue in the long run.

 

[Humbug]

Anyone know the where abouts of this thing?

http://www.boostcruising.com/forums/index.php?showtopic=467235

 

[Humbug]

damn it you guys... i had high hopes T_T

 

[Humbug]

I dont think he's touched it since... doesn't mean it cant be done

 

[Humbug]

That was ment to be a sarcastic stab not a tantrum.
The rpm isn't the biggest issue inline 4 250cc attttt 20k. A setup small enough I have not seen. I heard rumor of a crf250 efi'd cbr.

how does a crf efi system work on a cbr up to 20krpm? it redlines at 13500rpm