 a technical discussion, engine efficiency |
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| r_towle |
 Aug 15 2005, 08:27 PM
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Custom Member  Group: Members Posts: 24,705 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States 
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so, I have been thinking (not always a good thing)
If an engine is basically an air pump, and the objective is to make it as close to 100 percent efficient, why is the exhaust valve so much smaller than the intake valve? Forget emmisions, forget fuel delivery, just want to understand why this is so...it is so on most engines... Rich |
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| Jake Raby |
Aug 19 2005, 10:20 AM
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Engine Surgeon Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Engines are most efficient @ peak torque.... Thats the point where the most power is being made with the least amount of work or fuel. This can be clearly seen by measuring BSFC on the dyno. Keep in mind this is at WOT- part throttle conditions can vary peak torque due to manifold pressure and load. |
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Posts in this topic
r_towle a technical discussion Aug 15 2005, 08:27 PM
michel richard Cause on the exaust stroke there's a hard pist... Aug 15 2005, 08:49 PM r_towle I thought that there is a vacuum sucking the mixtu... Aug 15 2005, 09:29 PM Jake Raby ......... Because that about 20% of the air fuel m... Aug 15 2005, 09:38 PM r_towle thanx for that reply Jake...as always you get to t... Aug 15 2005, 09:40 PM Jake Raby Rich,
The summary I made was very general... With... Aug 15 2005, 09:43 PM messix the exhaust is at very high pressure after ignitio... Aug 15 2005, 10:06 PM lapuwali If you look at typical cam timings, the exhaust va... Aug 15 2005, 11:15 PM Brett W There is no vaccum in the cylinder. Nothing sucks... Aug 16 2005, 12:22 AM messix i guess that vacuum assist power brakes don't ... Aug 16 2005, 12:30 AM r_towle So, taking this knowledge, how can we apply it to ... Aug 16 2005, 12:24 PM lapuwali The cam in the stock engine was chosen more for em... Aug 16 2005, 12:46 PM Sammy Brett nailed it, there really isn't such thing... Aug 16 2005, 04:30 PM lapuwali IMHO, Brett didn't "nail" anything. Both of y... Aug 16 2005, 05:20 PM lapuwali Easy. Explain the technical terms first in layman... Aug 16 2005, 06:41 PM r_towle <... Aug 18 2005, 01:11 PM Jaiden Follow this link it will give you all the calculat... Aug 18 2005, 01:32 PM Mueller 
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