kg/h = CFM = x HP???

[911st]

How many kg/h dose is take to support 300hp?

I need this in kg/h please.

This is way out of my knowledge and pay grade.

Thank you if you can get me close please.

[Hugh R]

I'm guessing no one understands your question. 1 HP=33,000 foot-pounds/minute. Are you asking how much air:gas is needed for 300 HP?

You might find a start in these articles in the Tech Info Center of Pelican parts

http://www.pelicanparts.com/techarticles/mult_gas_and_oil/mult_gas_faq1.htm

[911st]

Please?

Or how may normally aspirated HP can a MAF that flows to 800 kg/h support?

Or, how many for 300 hp?

[slodave]

You should really search the site. This has all been covered ad nauseum. You are not going to get to 300HP without some serious $$ and some serious engine tweaks.

My 84 puts out about 224 at the crank, this is with a SW chip, Dansk premuffler and stock muffler. A sport muffler will get me a few more HP, MAF a little more, but I will never see 300HP. This is a US spec engine.

[911st]

Thanks guys

I am not trying to build a 300hp motor. I am trying to size a MAF sensor. I do not know if 800 kg/f capacity sensor is good for 100hp, 600hp, or???

I used to know how many CFM was needed per 100hp. I do not have a clue what kg/h is. I suspect it is a metric version of CFM.

Dose anyone know about how many kg/h it takes to support every 100hp?

[Won]

I don't think you can directly relate HP to CFM. The engine size and compression ratio and peak RPM at which the peak HP occurs are a few things I can think of that would change the CFM requirement for "300" HP.

I found this online, I don't know what kind of calculation it does but it will at least give you some number: http://www.bgsoflex.com/flowcalc1.html

From http://www.samracing.com/CHP-July-06_page7.html:

CFM vs. Horsepower

For most street/strip and mild race motors that generate up to 1.7 hp per cubic inch, improvements in air flow translate directly into increases in horsepower. However, at anything beyond that level of specific output, the flow bench is no longer the Holy Grail of predicting power. "Once you hit 2 hp per cubic inch, things start getting crazy," says Judson. "Take a Pro Stock engine, for instance, that puts out right about 2.7 hp per cube. On a motor like that, it’s a given that you have a serious cylinder head that can fill a cylinder quite well. So when the exhaust valve opens, residual pressure reaching hundreds of psi escapes out of the cylinder. The velocity of the exhaust coming out the head is a bazillion times higher than what can be replicated on a flow bench." To put it succinctly, experts can find no correlation between airflow and power on the exhaust side beyond 2 hp per cubic inch. "There are things going on at that power level in a motor we just don’t understand. You can have one head that’s down 50 cfm to another head on the exhaust side that makes just as much power. Don’t get me wrong, the flow bench has contributed more to horsepower than any other part or tool in the last 30–40 years, but after a certain point flow numbers don’t mean squat."

[CruiseControl]

I understand that you are trying to determine a MAF device nominated as 800kG/hr, as to what size engine would it suit.

In rather round numbers, at 1 bar pressure (sea level) dry air has a density of 1.19 gms per litre at 25degC, the 800kG / hour you nominate would (max out ) on a 4 stroke 3.2 litre engine at 7000rpm - (subject to numerous induction factors).

or 800kG per hr / 1.19 = 672,269 litres per hour = 11,204 litres per minute = 395cu feet per minute

(also for your info at 0degC, dry air, density is 1.293gms/litre)

As for the HP many more variables to consider.
Trust this gives you a guide.

Paul

[RoninLB]

common knowledge is that cfm is determined by cylinder size and rpm.

The formulas for this determines the venturi size in carbs discussed around here. Bosch has a formula that's posted and I posted another one I found used by a HP book writer and dyno man. These also posted somewhere in carb threads. Then there are tuners that increase the venturi another 2 mm over text.

The idea is that an oversized venturi will slow air velocity and lower combustion EGT. Like it or not heat is power.

so maybe you can connect the dots?

party hearty

[psalt]

How many kg/h dose is take to support 300hp?

You can estimate hp from air flow, but you need BSFC to get an accurate result. In an engine, you also need to know VE, but you can ignore this for measured air mass through a meter.

Output is directly related to the amount of fuel burnt. The amount of fuel burnt is directly related to the amount of air available. In your case, convert the 800 k/hr into lbs/hr (X2.2)=1760 lbs/hr air. Peak output AFR is around 13:1, so divide 1760/13=135 lb/hr of fuel. Now you need BSFC (brake specific fuel consumption) which can vary from 0.45 to .060 depending on engine, (something like a 911 with large open chambers is higher than a 4 valve pent roof). Using 0.50 lb/hr (1/2 lbs/hr/hp) as a rule of thumb, 800k/hr air can make 270 hp. At 0.45 lb/hr (not a 911) you get 300 hp.

You can also use the 1/2 lb/hr per hp BSFC to estimate hp, just add up the lb/hr of the fuel injectors, say 6X24 lbs injector=144 lbs/hr X2 = 288hp. So, a six with 24 lbs/hr injectors, will make less than 288 hp.

[WERK I]

Originally Posted by psalt

How many kg/h dose is take to support 300hp?

You can estimate hp from air flow, but you need BSFC to get an accurate result. In an engine, you also need to know VE, but you can ignore this for measured air mass through a meter.

Output is directly related to the amount of fuel burnt. The amount of fuel burnt is directly related to the amount of air available. In your case, convert the 800 k/hr into lbs/hr (X2.2)=1760 lbs/hr air. Peak output AFR is around 13:1, so divide 1760/13=135 lb/hr of fuel. Now you need BSFC (brake specific fuel consumption) which can vary from 0.45 to .060 depending on engine, (something like a 911 with large open chambers is higher than a 4 valve pent roof). Using 0.50 lb/hr (1/2 lbs/hr/hp) as a rule of thumb, 800k/hr air can make 270 hp. At 0.45 lb/hr (not a 911) you get 300 hp.

You can also use the 1/2 lb/hr per hp BSFC to estimate hp, just add up the lb/hr of the fuel injectors, say 6X24 lbs injector=144 lbs/hr X2 = 288hp. So, a six with 24 lbs/hr injectors, will make less than 288 hp.

Very good, Paul! :thumbs up:

[911st]

Well done. Thank you, thank you!