Quote:
Originally Posted by freebeard
|
Intake (Air)
volume is around 1/4 of exhaust gas volume IIRC and that's all
due to the much
higher temperature of the exhaust gas.
IMHO,
if you do NOT have a Tuned Length 'Banana Branch'
Exhaust; cooling the exhaust gasses means way less gas volume 'trying to escape' and THAT means less energy wasted by the engine having to 'push' it out.
ie: Heads (with built in manifolds) that cool the exhaust to the cooling system see this benefit.
I recall reading about some race class where you had to use the stock engine manifold and exhaust.
Someone enclosed the stock manifold in a water jacket, cooled by the stock (upgraded?) cooling system and saw something like 10 to 15 extra kw from doing so!
There is said to be a noticeable decrease in exhaust noise too, all else being equal.
ie: I don't think integrating
un-optimized manifold systems into the head is worth the weight savings..?
But
they do
benefit from the extra cooling vs a std,
un-cooled, un-tuned-lenghth manifold.
(I did a quick search for:
Exhaust; cooling the exhaust gasses means way less gas volume 'trying to escape' and THAT means less energy wasted by the engine having to 'push' it out
This is what Google AI has to say (with links):
AI Overview
Yes, cooling exhaust gases reduces their volume and, therefore, the amount of energy needed to expel them, potentially improving engine efficiency.
Here's a more detailed explanation:
Cooling and Volume:
When gases cool, they contract, meaning they occupy less space. This is a fundamental principle of thermodynamics.
Reduced Energy Requirement:
An engine expels exhaust gases by creating a pressure difference between the cylinder and the exhaust system. If the exhaust gases are cooler and thus less voluminous, the engine doesn't need to work as hard to push them out, reducing energy waste.
Exhaust Gas Recirculation (EGR):
Some engines use cooled exhaust gas recirculation (EGR) to reduce NOx emissions and improve fuel efficiency. By recirculating a portion of the exhaust gases back into the intake, the combustion temperature is lowered, which in turn reduces NOx formation.
Waste Heat Recovery:
Cooling exhaust gases can also allow for waste heat recovery. The heat energy in the exhaust can be used to heat the engine coolant, warm the cabin, or generate electricity, further improving overall efficiency.
Exhaust System Design:
The exhaust system plays a crucial role in managing the flow of exhaust gases and ensuring efficient removal. It includes components like the exhaust manifold, catalytic converter, muffler, and tailpipe, all designed to optimize gas flow and reduce backpressure.
ie: There is a lot to be said for a (finned?) copper pipe exhaust, from the
Pressure Wave Termination Box back. IMHO
(NB that the various attempts at a a Pressure Wave Termination Box that come up in the above links have 'Got it wrong' IMHO:
The last 'Into 1' pipe length is also important in 'sucking' exhaust out of the engine and has been skipped (Pre BWTB) in all those V8 examples...)
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