What's the point in having TVIS???

Post by **dr.occa** » Fri Oct 31, 2008 9:40 am

the idea is developing a primary-> secondary hand off for power/trq at lower rpms threw to mids where then "secondaries" open up for the "hand off" so to speak. just like carburetors. it's what is known as the venturi affect.

to see an illustration of this same technique working in action see the colt cams thread w/ accompanying dyno sheets that NonStopTuning had tested and published their findings.

links:

86garage thread
... New CAMS being tested by NST ... Update ...

Club4ag thread
NonStopTuning Testing With Colt Cams Tri Flow Cams

the design of the cams open the valves in SUCCESSION rather than simultaneously to create the proper trq & hp. this "swirl" that is generated is part of the VENTURI affect. the tri-flow design (along with your TVIS and Honda's early secondary butterfly plates technology) was inspired by how carburetors are setup: primary chamber (aka idle circuit) and secondary chamber (aka main circuit).

inducing good VENTURI flow is the N/A tuner's specialty in gaining hp/trq "naturally". this natural phenomena occurrence can be seen in your typical vacuum cleaner. it's the transfer of air/fluid from an area of high pressure (typically the environment outside of your engine) to an area of low pressure (created in your combustion chamber as the piston travels on the downward stroke right before the compression stroke).

TVIS works similarly to how you would swap ends on your vacuum cleaner. you would first want to promote good initial air flow threw a narrower opening so you would use the knife shaped attachment. let's say your vacuum cleaner is the type that can pick up speed (most vacuum cleaners don't though). well your bottleneck is the narrow attachment. since you've already gotten you vacuum cleaner going at a good velocity and need it to continue on picking up speed it's time to increase the opening, so it's time to move to a larger attachment while the vacuum cleaner is going so as not to lose the velocity you currently have. fortunately, the attachment you have has an adjustable opening. let's say to widen the attachment's opening all you have to do is twist it. now the openings wider and you noticed the vacuum cleaner just picked up in "rpms" and you're shirt suddenly just got suctioned off of you due to the increase of pwr your vacuum cleaner just experienced.

this is just to illustrate the idea behind your TVIS and other similar designs found in other engines.

MadeInThe80s · Post by **MadeInThe80s** » Thu Jun 25, 2009 3:31 pm

The Integra GSR (B18C) use the same type of system in their intake plenums as well. A dual throttle type setup for lower/higher RPMs.

mbehrens · Post by **mbehrens** » Thu Jun 25, 2009 3:51 pm

ford also has a simaler system in the split port intakes on there umm escorts lol... sorry had to add my two sense

Post by **dr.occa** » Fri Jun 26, 2009 7:23 am

since we're back on the subject:

Honda's F22A/B SOHC series engines also employed a dual runner intake controlled by a vacuum operated solenoid. instead of being side by side the secondary runners ran underneath the primaries.

mooreofit · Post by **mooreofit** » Sun Jul 05, 2009 8:50 am

audi has some really cool intake that have adjustble plenums and runners.

ga_goosh · Post by **ga_goosh** » Mon Jul 06, 2009 2:06 pm

isnt there a certain sized cam that is best to use without tvis? dont know what size it is but i have read that some where

landslideATX · Post by **landslideATX** » Sat Nov 14, 2009 1:11 pm

can the butterflies be taken off of the tivis for more power/torque? like with a 240?

Post by **dr.occa** » Sat Nov 14, 2009 2:33 pm

landslideATX wrote:can the butterflies be taken off of the tivis for more power/torque? like with a 240?

more torque by widening intake runners?

no.

loss of low to mid range torque when opening intake ports. potential of more power in higher rpms.