R18 non-si VTEC explained

[Nix]

I sort of explained this in a different thread but this may get more attention from people looking for answers.

The full tech article:

http://asia.vtec.net/Engines/RiVTEC/index.html


In short the iVTEC on the r18 is for fuel economy not power. Over 3k rpm and you are out of "VTEC" range and into a normal cam profile. It makes the car feel like it has more power but it is not the same as the VTEC on the Si. There is only one cam so having it operate in two different ways is pretty impressive.

Spirited driving means you are never in VTEC with an r18. It's very different since VTEC on most Hondas ALWAYS comes "on" at a set RPM. With iVTEC throttle/driving conditions have to be in set parameters for the ECU to activate VTEC mode - for fuel economy.



Under normal driving conditions, the R18A runs on its normal set of cam-lobes which in a completely reversed role, Honda calls the 'hot-cams'. So VTEC-off on the R18A means it can be considered to be running high cams. When the right conditions are acheived for fuel economy, VTEC engages the 2nd set, the 'low' or 'economy' cams. Thus VTEC-on on the R18A means it is running low cams. More importantly is VTEC engages the low-cams only if the right conditions for fuel economy are acheived. If they are never acheived, like when we are driving aggressively for the whole trip for e.g., VTEC will never open on the R18A.

 

[Ron Flood]

that makes no sense at all ....

 

[Bulkybear]

Basically vtec is a variable cam timing system. On the Si you have the normal cam profile and at around 5k rpms it engages the high performance cam profile. On a non Si model vtec is used for fuel economy and not performance. Under light driving your car will engage vtec, switching to a fuel economy cam profile. When you get more aggressive it switches off the vtec, entering you into a normal cam profile (because the non Si versions have no performance cams). The reason lobes were mentioned is because the vtec system is largely mechanical. There are actually 2 sets of lobes on each camshaft. Non Si gets fuel saver and normal lobes. Si gets normal and performance lobes. View: https://www.youtube.com/watch?v=AcT_ZyY3F0k&feature=youtube_gdata_player

 

[Ron Flood]

my vtec sucks.... fuel saver??? hahaha ya right, then how come i get worse mileage than my 2001 without vtec and its sticker says it gets 2 mpg better...? hahaha all car manufacturers are big fat liars when it come to mileage, hyundai being the worst... hahaha but thanks Bulkybear for clearing things up for me, makes sense to me now... vtec can be used for different applications essentially.... im not complaining about my mileage on my civic tho, im just saying.... but riddle me this... a 7thgen comes with a single cam vtec head and makes 12 more hp than its non-vtec counterpart....

 

[Bulkybear]

If the 7th gen was the ep3 I remember reading that the Si in those years was hated due to the lack of actual vtec and low performance. Other than that idk. And I'd be willing to bet your gas mileage would be affected by your altitude if you live that close to Alaska but I could be wrong. Your vtec doesn't suck, I bet you don't spend as much in gas as I do

 

[Ron Flood]

funny story Bulkybear, i looked it up... all to do with the series.... K series gives more valves at higher RPMs and a R series disables cylinders at lower RPMs... so it sounds like im a 3 cylinder... lol

 

[Ron Flood]

If the 7th gen was the ep3 I remember reading that the Si in those years was hated due to the lack of actual vtec and low performance. Other than that idk. And I'd be willing to bet your gas mileage would be affected by your altitude if you live that close to Alaska but I could be wrong. Your vtec doesn't suck, I bet you don't spend as much in gas as I do

hehehe i spent less on fuel than i do on insurance.... and i get a 46% discount.... same altitude.. right next to the ocean.... my tired old 2001 still gets better mileage than my new 2012 is all i kno.... i still have both cars..... lol, ill drive my 2001 til the wheels fall off then ill buy another one and use my 2012 as a work car...

 

[Ron Flood]

R-series

[edit]​

i-VTEC with Variable Cylinder Management (VCM)

In 2003, Honda introduced an i-VTEC V6 (an update of the J-series) that includes Honda's cylinder deactivation technology which closes the valves on one bank of (3) cylinders during light load and low speed (below 80 km/h (50 mph)) operation. According to Honda, "VCM technology works on the principle that a vehicle only requires a fraction of its power output at cruising speeds. The system electronically deactivates cylinders to reduce fuel consumption. The engine is able to run on 3, 4, or all 6 cylinders based on the power requirement. Essentially getting the best of both worlds. V6 power when accelerating or climbing, as well as the efficiency of a smaller engine when cruising." The technology was originally introduced to the US on the 2005 Honda Odyssey minivan, and can now be found on the Honda Accord Hybrid, the 2006 Honda Pilot, and the 2008 Honda Accord. Example: EPA estimates for the 2011 (271 hp SOHC 3.5L) V6 Accord are 24 mpg combined vs. 27 in the two 4-cylinder-equipped models.
i-VTEC VCM was also used in 1.3L 4-cylinder engines used in Honda Civic Hybrid.

 

[Bulkybear]

Yeah some have cyl/valve deactivation. I'm not a fan of Honda suv's though.

 

[Bulkybear]

And btw our civics don't have the vcm part. So the only thing that's changed is the valves lift and duration. They are not enabled or disabled.

 

[Ron Flood]

imma calll the 1800 number to my dealer this week and talk to the head mechanic.. and pick his brain.... lol

 

[Monk]

imma call the 1800 number to my dealer this week and talk to the head mechanic.. and pick his brain.... lol

Did you read the"LINK" from the 1st post? It's a very well written explanation.(long, but it's about "your" car!!!! (mine too).

 

[Ron Flood]

Did you read the"LINK" from the 1st post? It's a very well written explanation.(long, but it's about "your" car!!!! (mine too).

call it wat u want... but i get it now.... it still changes between cam lobes, not how many RPMs compared to the SI's VTEC(but it still kinda does).. there are 2 exhaust and 1 intake that are fixed valves with essentially your cars computer switches back and forth between 2 intake valves(one for high output and another one for fuel economy) but still.. i bet the honda mechanic couldnt explain it to me.... but i still say its not a true VTEC.... hondas full of it.... duping unsuspecting customer like me.... lol

 

[Monk]

call it Wat u want... but i get it now.... it still changes between cam lobes, not how many RPMs compared to the SI VTEC(but it still kinda does).. there are 2 exhaust and 1 intake that are fixed valves with essentially your cars computer switches back and forth between 2 intake valves(one for high output and another one for fuel economy) but still.. i bet the honda mechanic couldn't explain it to me.... but i still say its not a true VTEC.... hondas full of it.... duping unsuspecting customer like me.... lol

It's kind of like when they*(all car/truck manufactures*) started taking/marketing everything with the word sport somewhere in the name.......... a little history.... sports cars were things like MG , Triumph , ..... even a Jag wasn't considered a sports car, it was a Grand touring.

But Vtec is really a Honda trademark that's using their method of valve control, even though it can accomplish different things. I have a VFR Vtec MC that runs on 2 valves per cylinder until reaching 6,700 rpm then all 4 valves per cylinder kick in.

 

[Ron Flood]

thats sooooo true Monk.. its a sad truth tho.... but under the same driving conditions my 7th gen still gets better mileage than my 9th gen which is rated 2mpg better... lol and neither got any better mileage after break in.... but my 9th does have more grunt forsure!

 

[Nix]

We had the same thing with our accords. Mileage stayed the same but hp/performance numbers were quite a bit higher despite the sticker touting "better" mileage. I guess technically more hp for the same mpg is better.

Also the design of the car can have a lot to do with it. Our old 2001 accord was very angular, like the stealth fighter jets (I know thats a huuuge jump but, angular design-ish ness), and it got great mid 30's mileage. Newer 2005 accord was very rounded and the mileage was not any better if not a little worse.

Also - airbags and safety systems. The newer cars have loads more and it weighs A LOT!

Old accord: 2 bags. One for me, one for you, right in the face!
New accord: 6! Face, sides, curtains, seats,.......and so on.

Im sure its the same with the civics. Larger, heavier cars now than they once were.

 

[Ron Flood]

hehehehe lighter(thinner) steel and also thin plastic interior. i could go on and on Nix .... as could you also bro. the R18 has alot more lower grunt than my D17. top end they feel the same.. but i still remember the day i de-catted my 7th, replaced it with a 4-1 header and a 2" N1 exhaust... made a HUGE difference! so its not really apples to apples right now... and i will honestly never ever de-cat my 9th, maybe a hi-flow if the aftermarket ever makes one.... which i doubt, because if they were going to, there would already be one out... funny thing too my 9th really isnt any larger then my 7th side by side, just shaped alot differently....

 

[samRai]

I don't think Honda will use the iVtec just to save gas. I finally found the Ivtec power in 9th civic R18z1 in Manual transmission. Try to Push your r18, rev it high at econ mode. But remember the gas pedal is wire by wire. You have to feel the gas and watch your RPM. It took me 11 months to know my Car and I felt the iVtec in a long and wide road without pressure... No cops and No other Vehicles. The R18 sohc is so underrated. I'm planing to do a video. When I got a chance.

 

[Bulkybear]

I don't think Honda will use the iVtec just to save gas. I finally found the Ivtec power in 9th civic R18z1 in Manual transmission. Try to Push your r18, rev it high at econ mode. But remember the gas pedal is wire by wire. You have to feel the gas and watch your RPM. It took me 11 months to know my Car and I felt the iVtec in a long and wide road without pressure... No cops and No other Vehicles. The R18 sohc is so underrated. I'm planing to do a video. When I got a chance.

If you go back and read through this thread we've explained how I-VTEC works on the r18. It's not speculation lol. You have a fuel saver cam profile and normal cam profile. Vtec activates when you are easy on the car cruising, kicking in the fuel saver cam profile. When you floor it or downshift, or even mat the throttle a little vtec disengages, activating the normal cam profile. I'm not sure but I've also read that the econ mode doesn't affect the first or last 25% of the pedal. And I know if you run ac you can feel it cycle on and off. So what you're feeling is either vtec disengaging, econ mode deactivating because your floored, or the ac cycled off or a combination of the 3 (considering there are no mechanical issues with your car that would keep it from running normally when cruising).

 

[Nix]

Single cam with two cam profiles on it. Once you get it above a certain RPM, 3500 I believe, it changes to the "normal" cam profile and you can feel the power increase. Also as RPMs go up the HP increases as well. The R18 does have a better torque curve than the Si but generates less HP. Again, the R18 in cars that are better suited by low RPM torque for highway cruising and just moving around town not high RPM sports car action.

It is completely different from the Si and the K series that has two cams and completely changes which one is operating at the VTEC crossover.

I do like my R18 and I haven't really felt underpowered except occasionally when trying to merge in a short distance. I can definitely get the car moving fast enough to get a really bad ticket with ease.


Horsepower is a function of torque.

HP=(RPM * T) / 5252

HP at a given RPM depends on how much TQ there is. Hence, higher RPM = More HP.

Max TQ I think is around 128ft/lb. So HP = (3500x128) / 5252

HP is around 85 at 3500 and by the time you are up to 4500 you are making a beastly 109HP!!!!

Again TQ also changes but say it stayed even at 128 from 0-7000. Max TQ is 128@4300 RPM.


Stock dyno readings from 8th gen R18's, manual trans numbers, were almost always maxing out in the 109 to 115hp range. AT THE WHEELS. Any automatic will be slightly less.