what is dual vtec engagement?

[zerosilver19]

found an ecu for my jdm gsr motor that is a 95 that i'm building to go in to my 99 civic ex and the ecu is a chiped ecu by mugen it says, it lists that it has dual vtec engagement at 4600rpm and 5800rpm. What does that mean i know vtec engagement in the 5k rpm range is good but whats does it mean when it lists it has dual engagement at those rpm levels? thanks. by building i men i just bought the long block for 1800 and puttin in itr tranny, and upgrading swap parts for a turbo down the road.

[scallywag]

The gsr motor has 2 stage vtec. One stage kicks in at 4600, and the other at 5800. The first one you really feel as much as the 2nd, that one packs more punch!

[zerosilver19]

thats kick ass

[jcrx]

Originally Posted by scallywag

The gsr motor has 2 stage vtec. One stage kicks in at 4600, and the other at 5800. The first one you really feel as much as the 2nd, that one packs more punch!

Shut the hell up.

The GSR has a Intake Air Bypass system, which is a secondary set if butterfly valves in the intake manifold that open at a set rpm to aid in high rpm flow, it doesn't have two stage vtec.

[scallywag]

damn dude, you don't have to be such a dick! Then why does a vtec controller have 2 stages to set? Or are you just setting when the secondary set of butterfly valves open on the second one? The only reason I thought that is because a thread a while back said that the gsr is a 2 stage vtec, no one seemed to argue so I figured it was true, and since you can feel it twice when you are driving I figued it was true! non the less, you don't have to be an asshole to correct someone!

[jcrx]

I wasn't being an asshole, if you'd like, I can be.

The reason vtec ontrollers have two setting is for low to high lobe and back from hi to lo. For instance on the VAFC you can set lo->Hi at 5800, and hi->lo at 5200, so that in between shifts it's easier to stay in vtec.

[scallywag]

I see, thanks for clearing that up.

[SiGNAL748]

Prelude VTEC's also have an IAB

[jcrx]

Yip.

[SiGNAL748]

http://www.92lude.com/flapper_valve_mod.htm

Theres actually a mod to keep them open all the time.

As to why you'd do it, i'm not sure. To me, you'd seemingly lose power if you did it.

That article says you'd gain power sooner, but i'm hesitant to believe that until i see some dyno charts.

[jcrx]

You suffer some low end torque by leaving the valves open.

[SiGNAL748]

But, do you think the high end gains are worth the doing the mod and losing the low end?

The process looks like a hassle.

[jcrx]

IMO no, you can gain a little top end many different ways other than that, but it is a free mod, so people will do it.

[colin161822]

actually there is a 3 stage vtec, pick up a hyper rev and read for yourself.

but what that ecu is doing is wanting to opening the butterflys in the manifold to help with low end torque and high end flow. long runners are better for bottom end power and short for high end power. thats why a stock b20 mani is so long. and a type r is so short.

[jcrx]

No one is talking about the three stage vtec from the 96-00 Civic D15Bs.