EXHAUST SYSTEM DESIGN

[OB_DAVE]

HAVE ANY OF THE EXH. MANUFACTURES TRIED TO BUILD A TRUE 4-1 INSTEAD OF THE POPULAR 4-2-1 WHICH IS GEARED MORE TOWARD A SUPERBIKE FOR MID RANGE TORQUE TO HELP EXIT CORNERS.IT SEEMS THAT WHEN ALL OUT HP IS NEEDED SUCH AS IN DRAG RACING,MOST RACERS USE THE 4-1 SYSTEM FOR THE TOP END POWER THAT THEY BUILD.THE HAYABUSA HAS PLENTY OF MID RANGE TORQUE BUT I WANT MORE ON TOP END. DAVE.

 

[OB_cbxchris]

I think yosh has a cyclone which is just a plain old 4 into1...I may be wrong on this...anyone else?

 

[OB_Yngve]

I know one guy in Sweden who made one true 4-1 by himself. After porting his head it upped his RWHP to 177 from a low 155.

 

[Frank Adams]

yngve, that guy should have gained more than 22+ hp....thats not good...

 

[Guest]

TOJ

How did you determine that the Bus engine eats 225 cfm (106,188 cc's). What RPM ?

We are having a debate in the General Forum about the utility of ram-air. see "Best Ramair System".

[This message has been edited by Lyle (edited 11 August 1999).]

 

[OB_TOJ]

I´m the guy with a one-off real 4-1, the problem with making the 4-1 is space, if you are going for a street system there are limits with the lenght of the headers, therefore my exhaust is a compromise between space and power. The problem with a ported head is that the improvment shows at higher lift and the busa camshafts are really tame with little lift and short duration:8.5mm at intake and 7.2mm at exhaust(a stock head flows 225cfm at 10mm lift with 28" test pressure).
The 22rwhp is okay if you consider the facts that i havn´t got a PC 2 or a Yoshi fuelbox so I know there are couple more ponies when I got the fuel right.

 

[Frank Adams]

man you sure are missing out on something..i think i'd be making a call you'll be glad you did...i'd like to talk to you more but i'm runnin short on time here today. gotta go i'll catch up with you later.

 

[OB_TOJ]

No I havn´t changed camshafts yet, but I will as soon there is some for sale so if anybody knows if there is any on the market
I would like to know, because it´s winter here soon and it´s time to split the busa engine again.

 

[OB_TOJ]

The 225cfm was measured in a Superflow SF 600
flowbench with the cyl. head separate.
By the way I´m into 180´s rwhp now, and there is still more to come because I picked up my PC 2 today.

 

[OB_Bob]

Frank--your bike is almost ready---what will your heads flow? Was is necesary to port/polish the heads for more flow to achieve the hp target your after?
What is your hp target?
Bob

 

[OB_Bob]

TOJ
Will you change cams, or have you already?
The PC II will help you greatly I believe. I wil be time consuming however.
Has anyone else flow benched the heads of the BUS?
If so, what were the numbers?

Bob

[This message has been edited by Bob (edited 12 August 1999).]

 

[OB_Yngve]

This is a message for the swedish guy only...
sorry to keep U all out
Hei Thomas....
Jeg kommer ned til Piteå denne helgen( 27-29 Aug ) for dragracing ( hvis det blir fint veder) Da kan vi diskutere litt Hayabusa over en øl eller to ( eller flere )

 

[OB_TOJ]

To Yngve: Tjena jag kommer också att försöka ta mej till Piteå om vädret är bra där- så vi syns där isåfall