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| Air in fuel engine dynamics question http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=60667 |
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| Author: | lgoodbar [ Fri May 13, 2011 11:32 am ] |
| Post subject: | Air in fuel engine dynamics question |
As we all know, the Jeep loses power when air is mixed with the fuel. The engine can rev to 2,500 RPM with no acceleration. Does anyone know what is going on inside the engine when this happens? If air is in the fuel, why doesn't the engine stall? Is it due to low pressure combustion creating low pressure exhaust, nullifying the turbo? One of my friends thinks the engine should stall when the Jeep loses power like this. --Loyd |
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| Author: | warp2diesel [ Fri May 13, 2011 8:35 pm ] |
| Post subject: | Re: Air in fuel engine dynamics question |
A very small amount of air in the fuel system delays the timing and reduces the quantity of fuel injected causing less than ideal running. More than a very small amount of air in the fuel system will cause crappy running because the fuel is not injecting properly, too late and not enough. Too much air in the fuel system will make it so the engine does not run at all, because of no fuel. To put this into perspective, lets say you are going 70 MPH at 2000 RPMs and getting 30 MPG. 2000RPM X 60 min= 12,000 rev/hour. Since the engine is 4 cycle the injectors will each fire 6,000 times every hour. 70MPH/30MPG=2.33 gal per hour. 2.33/(6,000 X 4) = 0.000097 gallons every time each injector fires when going 70 MPH at 30 MPG, that is a very small quantity of fuel and a bubble that small can cause a miss, more bubbles or bigger bubbles can cause more misses or no running at all. Fix the air leak and install a lift pump and the problem will go away. |
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| Author: | dkenny [ Sat May 14, 2011 5:19 pm ] |
| Post subject: | Re: Air in fuel engine dynamics question |
good answer. if any fuel make it into the combustion chamber..it'll burn..if there is enough air..not enough air..black smoke look at warp's number for the amount for fuel..what if 25% of that was air..yep 25% less power..this is a tiny fraction of the air already in the chamber..so the air isn't the problem its the missing fuel! if too much is missing..it will stall and died..How much load is applied to the engine. if you're try to haul a 5,000 lb trailer you have a vastly different fuel requirement that try to run at idle(noload). the dynamics of a diesel are different that a gasser..if a gasser is starved of fuel it stalls/dies..what about too much fuel?..yep the same.. feed a hot gasser water instead of gasoline? it dies..a diesel?? only after the heat cannot make enough steam to keep it running.. -dkenny |
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