Mappers ... serious question trying to understand bhp per...
#1
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Mappers ... serious question trying to understand bhp per...
Ok guys i am trying to understand this thing (bhp per injector)
we have 1.5 bar of boost
we have 4.0 bar fuel press on idle
4.0 bar on greens = 493 cc/min
so on WOT (Wide Open Throttle) you have(need) 4.0 + 1.5 = 5.5 bar fuel press
5.5 bar of fuel press on greens = 390 cc/min (2.5 bar) + 427 cc/min(3.0 bar) (given by matts figures)
= 817 cc/min
now convert cc/min to lbs/hr
817 / 10.5 = 77.80 lbs/hr
now i want to calculate the bhp per injector
inj. size (lbs/hr) * 0.8 (80% ducty cycle) / 0.6 (.60 lbs (turbo charged)) = bhp per injector
77.80 * .8 / .6 = 103.73 per injector
all 4 injectors 103.73 * 4 = 414.92 bhp
now is this correct? (i think not but where did i fooked up?)
and is there a way how you can calculate which plug gap u need?
thanks!
we have 1.5 bar of boost
we have 4.0 bar fuel press on idle
4.0 bar on greens = 493 cc/min
so on WOT (Wide Open Throttle) you have(need) 4.0 + 1.5 = 5.5 bar fuel press
5.5 bar of fuel press on greens = 390 cc/min (2.5 bar) + 427 cc/min(3.0 bar) (given by matts figures)
= 817 cc/min
now convert cc/min to lbs/hr
817 / 10.5 = 77.80 lbs/hr
now i want to calculate the bhp per injector
inj. size (lbs/hr) * 0.8 (80% ducty cycle) / 0.6 (.60 lbs (turbo charged)) = bhp per injector
77.80 * .8 / .6 = 103.73 per injector
all 4 injectors 103.73 * 4 = 414.92 bhp
now is this correct? (i think not but where did i fooked up?)
and is there a way how you can calculate which plug gap u need?
thanks!
#4
Too many posts.. I need a life!!
Originally Posted by Stu @ M Developments
Rene,
where did i fooked up?
where did i fooked up?
You will always only have 4.0 bar fuel pressure. I'll tell ya seeing as Stu won't
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#9
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Originally Posted by Hooligan
4 bar ABSOLUTE pressure
pluggap depends on boost, plugs, coil etc.
oh, and haircolor
Come and pick up that radiator and give me back my cd's...
pluggap depends on boost, plugs, coil etc.
oh, and haircolor
Come and pick up that radiator and give me back my cd's...
u got the rad then ?
will soon come up your way then we can have a nice chat
btw any figures so i could calculate the plug gap?
#11
Well you should set it up at absolute pressure i.e. sans vacuum...
You don't calculate the plug gap as far as I know: you just ask a tuner and go by that! At a guess I'd say 0.6 will do nicely!
You don't calculate the plug gap as far as I know: you just ask a tuner and go by that! At a guess I'd say 0.6 will do nicely!
#12
Too many posts.. I need a life!!
Originally Posted by Rene
you mean the fuel press you set on idle wont get any higher then that?
HTH
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thanks hooligan and guinnless for explaining that so it should always be setup on ABSOLUTE press (not that i was doing otherwise i do what ive been told to do just want to understand it )
thanks!
thanks!
#17
Too many posts.. I need a life!!
Originally Posted by Stu @ M Developments
Wahay stevie..
I reckon that answer puts you in the most knowledgable 3% of users on here...
I reckon that answer puts you in the most knowledgable 3% of users on here...
I know for a FACT that most tuners in the uk dont know that M8, hence i thought id wait around and see who said what
Oh well.. You blew that plan to fook
Oh well.. You blew that plan to fook
Thanks Stu
#18
Norris Motorsport
Yes as Stu rightly pointed out its amazing that many folk dont realise why we use a rising rate fuel pressure regulator!
Put simply any liguid or gas will always flow from a region of high pressure to a region of lower pressure until the pressure is equalised.
If we set our fuel pressure to 4bar at atmosperic pressure then we have an effective 3 bar fuel pressure above atmospheric. For every 1 bar boost we add, we must increase the fuel pressure by the same amount in order to keep the 3 bar differential pressure.
Failure to do this will result in a diminishing injector flow rate as we increase boost!
Put simply any liguid or gas will always flow from a region of high pressure to a region of lower pressure until the pressure is equalised.
If we set our fuel pressure to 4bar at atmosperic pressure then we have an effective 3 bar fuel pressure above atmospheric. For every 1 bar boost we add, we must increase the fuel pressure by the same amount in order to keep the 3 bar differential pressure.
Failure to do this will result in a diminishing injector flow rate as we increase boost!
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Originally Posted by Karl
Yes as Stu rightly pointed out its amazing that many folk dont realise why we use a rising rate fuel pressure regulator!
Put simply any liguid or gas will always flow from a region of high pressure to a region of lower pressure until the pressure is equalised.
If we set our fuel pressure to 4bar at atmosperic pressure then we have an effective 3 bar fuel pressure above atmospheric. For every 1 bar boost we add, we must increase the fuel pressure by the same amount in order to keep the 3 bar differential pressure.
Failure to do this will result in a diminishing injector flow rate as we increase boost!
Put simply any liguid or gas will always flow from a region of high pressure to a region of lower pressure until the pressure is equalised.
If we set our fuel pressure to 4bar at atmosperic pressure then we have an effective 3 bar fuel pressure above atmospheric. For every 1 bar boost we add, we must increase the fuel pressure by the same amount in order to keep the 3 bar differential pressure.
Failure to do this will result in a diminishing injector flow rate as we increase boost!
#21
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Originally Posted by Stu @ M Developments
84 views... at least 70 of em resulted in a loud "Ehhh? " i reckon..
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Originally Posted by Stu @ M Developments
84 views... at least 70 of em resulted in a loud "Ehhh? " i reckon..
Is good info tho
Ben
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ok i got this stuff in my calculation you do a x 0.8 (80% duty cycle) then the end result = 250.4 bhp on all four injectors
100% duty cycle = 313 bhp
guess that's it then ?
100% duty cycle = 313 bhp
guess that's it then ?
#31
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thanks stu
but i think ill see if hooligan can explain it to me in dutch
cause with a BSFC of 0.75 i would need to flow 620 cc/min to get a 315 bhp (is that correct?)
but i think ill see if hooligan can explain it to me in dutch
cause with a BSFC of 0.75 i would need to flow 620 cc/min to get a 315 bhp (is that correct?)
#35
Don't bother understanding Rene: pay Stu or Tony to understand and use your time to better effect i.e. learn how to fuckin drive properly to save me having to wait on you after every corner on the ring next year!
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Originally Posted by Stu @ M Developments
The point being, a small adjustment of the BSFC figure results in a large eror in injector choice..
How do you know the BSFC of the YB?
How do you know the BSFC of the YB?
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Originally Posted by Hooligan
Don't bother understanding Rene: pay Stu or Tony to understand and use your time to better effect i.e. learn how to fuckin drive properly to save me having to wait on you after every corner on the ring next year!
where can i get a decent FP gauge hooligan like marijns's one? cause i am fed of telling that not having any time to setup me car
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cool happen to have a welder by any chance ? i've got a lambda sensor wich still needs to be fitted
thought that what i replied was a std rule ?
thought that what i replied was a std rule ?