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95 Honda civic LX
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1 Posts
Discussion Starter #1
Got a p2j head and it has vtec-e I think, on which only 1 intake valve operates until the vtec kicks in and make it two intake valve at high rpm. yeah 16 lobes only

Question is can I just delete the vtec system and make it run 2 intake valves all the time like on those non vtec heads?
 

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95 Honda civic LX
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1 Posts
Discussion Starter #5
It won't idle worth dick either, if it does.

What is the purpose of this?

just thinking of gaining some free HP down low and just confuse why non vtec d15 engine run just fine without vtec (4 valve all the time).

Also thinking that vtec-e is just for economy
 

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Prelude, Integra DB9
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365 Posts
just thinking of gaining some free HP down low and just confuse why non vtec d15 engine run just fine without vtec (4 valve all the time).

Also thinking that vtec-e is just for economy
I thought the e stood for efficiency.

A tiny bit of reading suggests that the way the vtec-e works is to take advantage of the swirl effect you get if you speed up the intake charge (eg: reduce the cross-sectional area.) This should actually give you more torque at lower revs, compared to having all the valves fully open.

Once the engine speeds up, the flow is accelerated anyway, and bringing the second set of cams into play helps to consume all of the fuel/air mixture at the right time.

I take all this to mean that your vtec-e engine will actually be less efficient if you do what you're suggesting - and that's even if you can find an ecu that will get the best out of the change.




[Caveat: I'm a rank amateur ...]
 

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Premium Member
2005 Legacy GT
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1,754 Posts
The advantage of all VTECs is to be able to run two cam profiles. One for down low (optimizing low end torque for drivability) and one for up high (optimizing valve opening for top end power). I think VTEC-E was slightly more complicated and allowed for a third option to optimize mpg. However ... eliminating/killing VTEC kinda kills the low end (take a look at some B series engines running Toda's VTEC killers).

Also unless you plan on getting it retuned ... the ECU is not going to expect whatever is happening and it will run like ass because the fuel and timing maps will not be set up for the new configuration.

In response to why do non-vtec Ds run with out it ... it's a completely different head/cam set up. They don't have the VTEC lobes and are running a single cam profile. They were designed that way and have fuel and timing maps to match.

Take a look at a VTEC vs Non-VTEC cam and a couple of videos about how VTEC works and it will start to make sense.
 

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Registered
93 maybe 94 coupe
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289 Posts
Also 4v operation is bad for low rpm cylinder filling and therefore pressure which means less tq, which is what makes power until rpm is the bigger multiplier in the math. This is evidenced by our higher rpm efficiency peaks vs a 12 or 8 valve design.

I wouldn't expect major gains.... the intake might sound cooler though
 
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