I've read somewhere that the current generation Fit engine has a much higher VTEC RPM kick-in than the previous fit. The new one is somewhere between 4500 and 5000 RPM, right? So, if you're driving in an MPG-maximizing way (paying attention to the gauge), wouldn't you potentially go a LONG time (months) without ever activating VTEC once?

And - if so, does anything in the valve/cam area suffer from lack of use? I'm imagining things gunking because they never engage and stuff like that.

And obviously I obsess about my new car...

 

Once you've broken in the engine, don't be afraid to push it once in a while.

Maybe it's just a placebo effect, but sometimes it looks like the engine runs a little smoother/more efficient after a bit of aggressive revving. (Based on the instant mpg readout)

At the very least its a lot of fun!

 

all the parts for Vtec get "washed" with oil from splash. EXCEPT the Vtec engagement solenoid. Kick the Fit in the butt every once in awhile so VTEC engages and you will be fine.

 

How long is the break-in period? I'm ready to rev it up! @ 5k miles now...

 

5k miles is way past break in - rev away!

 

like mentioned....the oil gets over all your valve train components regardless of how often you mash the pedal. Theres alot of preasure slushing that oil around.

 

The Fit has a sad VTEC, its nothing like the older Honda's Ive been in. Hell even my old 2002 Honda VFR800 had VTEC and when it switches on, you better hang on cause you can feel and hear the strong power surge. My friends 98' GSR and 00' Si both surges hard under VTEC. I cant even tell where VTEC begins and or ends on the Fit lol. Its probably cause its a under powered 1.5 SOHC and not a DOHC.

 

I can feel exactly when vtec kicks in. Which is a problem in my book.

Honda designed vtec initially for gas mileage. the idea of 2 or more intake cam profiles means there will be more then one peak engine efficiency mark. (I didnt say power)

If you feel vtec, the crossover point is one of two things
A) set too high
B) Honda decided to help the car out and put a MUCH larger profile on the upper.

If its (A) lowering it would improve efficiency and mid-range power
If its (B) enjoy it, Honda put it high enough the normal driver wont use it much, but if you need passing power, dropping a gear makes it a fun experience!

 

googled it...
VTEC was initially designed to increase the power output of an engine to 100 HP/litre or more while maintaining practicality for use in mass production vehicles. Some later variations of the system were designed solely to provide improvements in fuel efficiency.
Japan levies a tax based on engine displacement, and Japanese auto manufacturers have correspondingly focused their R&D efforts toward improving the performance of smaller engine designs through means other than displacement increases. One method for increasing performance into a static displacement includes forced induction, as with models such as the Toyota Supra and Nissan 300ZX which used turbocharger applications and the Toyota MR2 which used a supercharger for some model years. Another approach is the rotary engine used in the Mazda RX-7 and RX-8. A third option is to change the cam timing profile, of which Honda VTEC was the first successful commercial design for altering the profile in real-time.
The VTEC system provides the engine with multiple camshaft profiles optimized for both low and high RPM operations. In basic form, the single cam profile of a conventional engine is replaced with two profiles: one optimized for low-RPM stability and fuel efficiency, and the other designed to maximize high-RPM power output

 

That is grabbed from wikipedia and lists ZERO references or citations, as stated by wikipedia

Vtec was first COMMERCIALLY used in a car in the 80s, the first motor using it being a dual cam

This is coming from HONDAs own site.



The improvement to efficiency directly relates to engine power when used with a small displacement motor (these are my words)

http://world.honda.com/history/chall...e/text/01.html

 

Have you read the whole story? VTEC was never designed just for gas mileage. The goal originally was 100hp/L. Thats why the first cars with VTEC (Integra, CRX, Civic Si, NSX, Prelude) were all performance models. No one says VTEC just kicked in yo im getting better mpgs. Low profile is for torque/efficiency and the high is for HP good mpgs is mostly a byproduct of a small NA engine running at a low rpm.

 

The improved gasmileage comes from the low cam profiles. Not during the vtec switchover.


The smaller profile lower makes it possible for more air velocity at a lower rpm.

More velocity means better atomization and torque.


SO yes, honda did it so they could combine a gasmileage motor with a performance one.

This is why all my old d16 vtec motors ALL got 40mpg+ off vtec. and still went one to create over 100whp even in factory trim and tune.

Of course, Honda made such a large move to fuel efficiency that once you are able to tune the older D and B motors, they got both power and fuel mileage increased since they dogged the tune so much for supreme reliability

 

lol ok ok...what im saying is you dont have to design a 1.5L engine to be efficient. A small displacement motor is gonna be efficient in almost all cases. Kajitani wanted to push the envelope and add power to an already efficient engine by designing a valve train with a high rev range (8000rpm +) and high duration cams that didn't sacrifice what Honda already had (efficiency). That power + efficiency in a light body will of course give you a 1.6L thats capable of 40mpg+. The I-VTEC system that we use combines that with VTC which allows the timing to be changed variably. The L15A7 in our fits runs super retarded even though its a 10.4:1 compression ratio. I suspect this has more to do with it being tuned to run on low octane gas though

 

That is my theory also. (compression and timing)

Honda wanted a peppy efficient motor that could withstand the abuse of neglect.

This motor is afterall, wanted by the SCCA for racing.

I bet with several degrees of timing, some creative machinging to fix the "cast header collector" crap and some very good tweaking of the tune this motor could easily surpass the 140hp crank number.


My old d15b7 that was factory rated at 102 crank hp made over 120whp with just a d16a6 cam, adjustable cam gear, nice header, and an intakemanifold I had made that mimics the ol integra type r manny (B18C5). That tune was not very conservative though. It needed you to be on your A game with the ignition and fueling

EDIT and a heavy head shaving to increase compression to around 11:1

 

I thougt T1r already had a header/downpipe to kinda alleviate the problem. There is no fixing it if its cast into the engine block. Cant wait for Hondata to finish with our Flashpro. Everyone is gonna advance the shit out of their motor to take advantage of 91+ octane gas.

 

Just put in some new slugs versus shaving the head, what I would do anyways, for me it's not really worth it to just gain .6:1 compression, especially since the engine will already be apart. 12.5:1 slugs do exist for the L15A. The head also needs a bit of caressing as well and a new cam would always be welcomed, but not getting around the manifold design. J's has already reached 150ps (maybe even closer to 160ps now with more tuning and addition of a cam on their dynapack) on a L15A here, with mild head work, 12:5:1 pistons, exhaust components, intake components and ECU flash; a customer's car that easily walks by my Fit on circuit when we have played. Granted his is even lighter weight than mine with a carbon roof panel and Lexan windows all around minus the front windscreen, but the extra power is the big contributor.

Austinite, VTEC is activated at 5400 on the newer model L15A. And as stated already, that VTEC kick you felt is actually a bad thing, huge loss in power and then a sudden spike. This was remedied on the K series where there was a very linear power delivery, only by sound did you know VTEC was activated, same as with this tiny L15A or you can install an LED to indicate when VTEC engages. The previous Fit VTEC was just actually just activating all 16 valves. It was a true economy type of VTEC.