boosted

charlie31603 · Post by **charlie31603** » Fri May 27, 2005 4:29 pm

So the BSFC has nothing to do with the how much the fuel pump flows or what the injectors flow, correct. It just determens what a tipycal(sp?) motor would consume, right. So it takes a turbo motor .55 or .60 lb/hr for the motor to make that one horespower. So to make my motor to have 400 hp. It would need 68.75 or 75 lb/hr at 43.5 psi. So I would just get the 75 lb/hr to make it on the safe side. Now. I know my car is not going to make that much power right now. So is that big of an injector going to effect my drivabilty. Thanks!! Adam

AmericanFrog · Post by **AmericanFrog** » Wed Jun 01, 2005 10:44 pm

Ummm, hate to be a pain, but isn't 1 bar = 1 barometic pressure, or 14.7 PSI or 100 kpa, at sea level (HS physics class comming back to me)

1 bar = 1 atm = 14.7 psi = 100 kpa = 760 torr (mm of hg) = 29.92" of hg

I think that's right

don't wantany error in any's calcuations that are that large (these numbers are not exact, but iirc, all of those are within 1.5%)

Devilman · Post by **Devilman** » Fri Jun 03, 2005 3:32 pm

Sorry to hijack slightly, but Im wondering, does RPM have any relation to BSFC?

surely an engine developing 300bhp @ 12000rpm would be using a lot more fuel than a motor developing 300BHP @ 6000rpm? or doesnt it work like that?

Just trying to get a feel for when I setup my Gixxer Turbo.

Thx.

renns · Post by **renns** » Fri Jun 03, 2005 3:39 pm

AmericanFrog wrote:Ummm, hate to be a pain, but isn't 1 bar = 1 barometic pressure, or 14.7 PSI or 100 kpa, at sea level (HS physics class comming back to me)

1 bar = 1 atm = 14.7 psi = 100 kpa = 760 torr (mm of hg) = 29.92" of hg

I think that's right

1 atm = 14.696 psi, which is 101.325 kPa. 1 bar is exactly 100 kPa (which converts to 14.5 psi), a bit less than the 'std' atmosphere. Hence the slight discrepancy between 14.5 psi and 14.7 psi numbers.

If really bored, go here: http://www.engineeringtoolbox.com/pressure-21_587.html

Roger.

CivicMike · Post by **CivicMike** » Sat Apr 15, 2006 5:52 am

Devilman wrote:Sorry to hijack slightly, but Im wondering, does RPM have any relation to BSFC?

surely an engine developing 300bhp @ 12000rpm would be using a lot more fuel than a motor developing 300BHP @ 6000rpm? or doesnt it work like that?

Just trying to get a feel for when I setup my Gixxer Turbo.

Thx.

I don't believe so, maybe you would use a bit more fuel because of your tune but theoretically you are using the same amount of gasoline to make 300 HP at ANY RPM. (since the fuel is providing the power)

whittlebeast · Post by **whittlebeast** » Sat Apr 15, 2006 6:28 am

These sheets ignore lots of thing like injector opening time, squirts per engine cycles, 2 stroke / 4 stroke and RPM. Lots of other info on this sheet.

Try http://www.ncs-stl.com/fuel/ReqInjectors03.xls

AW

Uncle Bob · Post by **Uncle Bob** » Sat Apr 15, 2006 7:39 pm

Devilman wrote:Sorry to hijack slightly, but Im wondering, does RPM have any relation to BSFC?

surely an engine developing 300bhp @ 12000rpm would be using a lot more fuel than a motor developing 300BHP @ 6000rpm? or doesnt it work like that?

Just trying to get a feel for when I setup my Gixxer Turbo.

Thx.

work is work. HP is HP. Your two example are too generic to answer them in detail, but in general, 2 EFFICIENT engines will have the same BSFC's for both your examples. The question is, are they both efficient?

There is a lot of factors in BSFC, and its hard to quantify without measuring it for real. The main thing to keep in mind is, its moreso a tool for getting in the ball park for your application, and its definitely better to overdo it than under do it!

But if you want more detailed info on injector sizing for a giving motorcycle size, the turbo'd busa boards would be the best resource for that, assuming you can get HP, injector size and pulse widths at peak output from members.....might be a challenge.