HSTuners - View Single Post - LS/VTEC...what is it? Please explain to me.

nonovurbizniz · 04-17-2004, 01:30 PM

VTEC has NO effect on boost other than benificial ones...

It opens the valves higher... that lets more air in... whether it's by vacum or forced in...

The problem with vtec engines and boost is their stock cam timing... lots of them have over lap... a point where the exhaust valve is still open a little as the intake valve is opening... this in an NA block helps suck air into the cyl... in a boosted car it allows power to escape... All you really need to do to boost vtec efficiently is to either get a cam (in the case of a SOHC) made for boost or time the DOHC's properly...

Other than that variable valve lift is the most ideal scenario for boost... it allows the engine to make power before boost by not opening the valves too much... and to let the power in once you're in the upper rpms making boost...

Also depending on where the turbo spools you may want to change the normal vtec event... if it spools high you may leave it the same or raise it a touch... if it spools fast then you may want it to engage early to take advantage of the extra air available.

ON TOPIC...

I know a kid who's built SEVERAL VERY succesful ls/vtec engines... he's also built turbo ls's... He thinks that they both have their up and down sides.. but says there is NOTHING inherently wrong with doing an ls/vtec... it's just a matter of execution... if you build it properly it will last just as long as any other motor... they're problem proned becuase they're generally done by in-experienced dudes trying something out.

04-17-2004, 01:30 PM	#20
nonovurbizniz Registered User Join Date: Jul 2002 Location: ECUSA Age: 48 Posts: 2,693	VTEC has NO effect on boost other than benificial ones... It opens the valves higher... that lets more air in... whether it's by vacum or forced in... The problem with vtec engines and boost is their stock cam timing... lots of them have over lap... a point where the exhaust valve is still open a little as the intake valve is opening... this in an NA block helps suck air into the cyl... in a boosted car it allows power to escape... All you really need to do to boost vtec efficiently is to either get a cam (in the case of a SOHC) made for boost or time the DOHC's properly... Other than that variable valve lift is the most ideal scenario for boost... it allows the engine to make power before boost by not opening the valves too much... and to let the power in once you're in the upper rpms making boost... Also depending on where the turbo spools you may want to change the normal vtec event... if it spools high you may leave it the same or raise it a touch... if it spools fast then you may want it to engage early to take advantage of the extra air available. ON TOPIC... I know a kid who's built SEVERAL VERY succesful ls/vtec engines... he's also built turbo ls's... He thinks that they both have their up and down sides.. but says there is NOTHING inherently wrong with doing an ls/vtec... it's just a matter of execution... if you build it properly it will last just as long as any other motor... they're problem proned becuase they're generally done by in-experienced dudes trying something out. __________________ I am an A$$hole... take anything I say to heart at YOUR OWN RISK...