interference v. non-interference
Thread Starter
Pole Position
Joined: Dec 2004
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interference v. non-interference
what, if any, are the advantages to the consumer in building anything other than a non-interference engine? why did lexus go from non-interference to interference engines?
Lexus Test Driver
Joined: Nov 2005
Posts: 1,209
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From: IL
A quick google search found me this site:
http://www.leemyles.com/articles/int...ing-belts.html
In a nutshell:
http://www.leemyles.com/articles/int...ing-belts.html
In a nutshell:
Valves open further in an interference engine and project further into the combustion chamber than in a 'free-running' engine. This allows outside air at atmospheric pressure flow faster into the combustion chamber through the larger valve opening. The engine can therefore inhale more air, be a little smaller, and still create as much power while reducing its manufactured cost and also guaranteeing future repair business for its dealer.
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Lexus Champion
Joined: Feb 2007
Posts: 2,489
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From: Lou-Evil KY
the increase in compression also has much to do with it. the pistons in the interference engines are larger at the top, more like a dome, to ikncrease the comp. this is actually why the valves would hit in the lexus.
timing chains are also not maintenance free. they will stretch over time, causing loss of cam timing (power/efficiency). also, the chains have to be designed with tensioners and guides, wihc are usually made out of plastic on any modern engine. this plastic wears out over time causing noise, chain slack and even "catastrophic engine failure".
timing chains are also not maintenance free. they will stretch over time, causing loss of cam timing (power/efficiency). also, the chains have to be designed with tensioners and guides, wihc are usually made out of plastic on any modern engine. this plastic wears out over time causing noise, chain slack and even "catastrophic engine failure".
the increase in compression also has much to do with it. the pistons in the interference engines are larger at the top, more like a dome, to ikncrease the comp. this is actually why the valves would hit in the lexus.
timing chains are also not maintenance free. they will stretch over time, causing loss of cam timing (power/efficiency). also, the chains have to be designed with tensioners and guides, wihc are usually made out of plastic on any modern engine. this plastic wears out over time causing noise, chain slack and even "catastrophic engine failure".
timing chains are also not maintenance free. they will stretch over time, causing loss of cam timing (power/efficiency). also, the chains have to be designed with tensioners and guides, wihc are usually made out of plastic on any modern engine. this plastic wears out over time causing noise, chain slack and even "catastrophic engine failure".
Also, how does the use of a chain enable the VVTi feature? And what did Toyota/Lexus do for VVTi? I know that Ferrari uses a slanted camshaft which is able to move laterally to alter the lift, but I don't suppose Toyota did that too?
Lexus Champion
Joined: Feb 2007
Posts: 2,489
Likes: 4
From: Lou-Evil KY
vvti came out in 98 i believe. they still using timing belts though. vvti is enabled by the use of adjustable cam sprockets and hydraulic solenoids activated by the ecu. at the required time, the ecu sends a signla to the solenoids, which then use oil pressure to move the cam sprocket which then changes cam and thereby valve timing.
this is independent of the use of a timing belt or chain. other mfrs. use a chain and still enable variable valve timing through the same type of system.
this is independent of the use of a timing belt or chain. other mfrs. use a chain and still enable variable valve timing through the same type of system.