i-VTEC vs. BMW's stuff
 

I'm not that well educated on i-VTEC, but when I went and test drove a new 3 series the other day the guy was telling me that BMW's can vary and control more with their system(whatever it's called) than Honda can with i-VTEC. My question is what does BMW have that Hondas doesn't.

Come on guys. Help me prove this BMW salesperson wrong...I hope.

As far as I can see, Double vanos changes timing by around 12.5 degrees. and lift by .9 mm, and no change in duration.

i-Vtec in the TSX changes timing by as much as 50 degrees but I don't know the difference in lift. Since the system switches to a totally different camshaft lobe, it is also varying lift as well as increasing duration.

I'm sure we have more than a mere .9 mm lift change! Jeez, that 's less than 1 mm lift change, and NO change in duration for BMW.

I'f you're interested, I have an introduction video i made for the RSX up on google video. It has i-VTEC animations in the middle of the video. You can see it below. Just remember, I'm not an actor (or director).

http://video.google.com/videoplay?do...1&q=colin+sato

^^^Nice vid, Colin. Complete with outtakes! :D

what does VTC(denoted by the "i") do for our engines?

Nice video! Shot on location in beautiful Hawaii, it reminds me of my recent trip there.

I bet there's not many places where you can push an RSX-S with those 35 mph speed limits :)

Variable Timing Control. It is responsable for continuously varying the cam phasing (up to 50 deg). VTEC switches between two cam lobes for timing and duration.

I have an older video I made fr the TSX back in 2004, but I need to update it for the new body style.

Sadly, many things is not just right and wrong. You ought to do some research on what is "i-vtec" first. Without having some basic knowledge about the technology, you are just wasting people's time.

I have been researching constantly for the last two hours and I have only asked about the things I haven't grasped so you can keep your fucking comments to yourself busyshifter. I have what I feel is a pretty damned good idea of what i-VTEC is. I just needed some clarification. Here's what I understand to be true about i-VTEC and BMW's Double VANOS/Valvetronic.


HONDA
-DOHC denotes that the engine uses VTEC for both intake and exhaust valves (since SOHC can only use VTEC on the intake valves)
-VTEC(Variable Valve Timing and Lift Electronic Control) denotes dual cam profiles which adjust lift and opening duration of both intake and exhaust valves.
-The "i" denotes that the engine uses VTC(Variable timing control) for the intake camshaft. This controls the overlap between the intake and exhaust valves. VTC can only alter the intake camshaft.

BMW
-Double Vanos allows the engine to adjust camshaft timing for both intake and exhaust valves' overlap.
-Valvetronic allows for variable valve lift.
-BMW does not seem to have anything that controls duration of the valve opening.

It seems that Honda can adjust valve opening duration while BMW cannot. It also seems that BMW can control camshaft timing for intake and exhaust valves' overlap while Honda can only control the intake valves' camshaft timing.

So Honda covers all 3 bases(duration, lift, and timing) for intake and exhaust valves, except timing which is only covered for the intake valves.
BMW only covers two bases(lift and timing) but covers them for both intake and exhaust valves.

I think Honda has accounted for more. What's your opinion?

Stewie, You've asked a good question, and I'm not a mod here, but I will say that we don't usually conduct ourselves like that here. Your comment to busyshifter is a little out of line.

As for your assesment, yes and no:

DOHC - The base Accord and base RSX engine use a twin cam head but only have VTEC on the intake side.

VTEC - See above, there are a lot of "flavors of VTEC" and some only work in the intake valves (the non-NSX v-6's for example)

"i" in i-VTEC - Only works on the intake side, BUT, since it's working relative to the exhaust side, adjusting both is not needed. It's a relative change in overlap.

thanks for the video colin, i like the bloopers :D

Now you are talking. Gotta give it to you. Good job on getting the information together.

Well, shooting the video would have been a lot faster with out them...........

Great video,....bloopers were good. Any chance you will post a link to the TSX one, or the updated one you make for it? :wish:

Thanks for the credit busyshifter. Sorry bout the little outburst guys. Just spent a long intense two hours educating myself about VTEC. It wore me out.

Anyways someone mentioned that VTEC(changing lift and duration) doesn't happen on the exhaust valves. On this site http://auto.howstuffworks.com/framed...whatsvtec.html
they seem to think that VTEC happens on intake and exhaust valves. I think that it is the "i"(VTC) that only happens on the intake camshaft.

Is this correct information?

They seem to think on this site too that VTEC (different cam profiles) occurs on intake and exhaust valves.

http://www.honda-tech.com/zerothread?id=1137848

I like the RSX video. :thumbsup:

I finally feel that I have a strong grasp on i-VTEC. Now I understand Colin that you were talking about no VTEC on the exhaust valves for the accords and base RSX's. Disregard my last two posts trying to refute that. You are obviously a VTEC master. I sent the email to the BMW salesguy so we can see what he comes up with in response. Thanks for helping me put together a solid argument. The salesguy seemed awfully proud of his BMW Double VANOS and valvetronic...

Stewie, I think it's bbest to limit youself to exactly the car you're interested in. There are a lot of versions of VTEC and for the uninitiated it can get confusing.

For the TSX, VTC on intake only (remember it's realtive to the exhaust cam). 3 lobe VTEC on both intake and exhaust.

But, just for those interested:

The first production car with VTEC in the US was the NSX. This had the three lobe VTEC on both intake and exhaust cams.

Next came the Integra GS-R with the same valvetrain.

Then the SOHC versions started showing up in Accords (1993 ish). VTEC only on the intake side.

The 3.0 CL in 1997 debuted the all new J series V-6 with the SOHC cam intake only VTEC.

Civic HX came next with VTEC-e. An economy version that staggered the opening of the intake valves to increase swirl in the compustion chamber

i-VTEC started on the RSX in the new K seires engines. These are twin cam engines, with VTC on intake only, and VTEC on intake (base RSX) and on intake and exhaust (Type-S)

Just to clarify... Max VTC advance on the RSX is 50 degrees. The max VTC advance on the TSX is 25 degrees.

Thanks for that clarification! Ha Ha, it's still more than 12.5 deg.... ;)

Ooh, nice, thanks. Strange, I would have thought it would have been used on the Prelude first, since that was really used as a testbed for newer technology.... like the active 4-wheel "steering".

Btw, nice video! It's almost like a commercial. :D

Well it is a commercial.....for me! My biggest challange is getting clients to make arrangements with me prior to their first visit to the store. The main purpose is the put a "face" on the e-mails I send out.

Swirlie, do we really want to remember the 4WS Preludes? Not really the best example of leading edge technology? ;)

So stewie are you basing your decesion between a TSX and 3 series on which has superior variable cylinder manahement? :D

I have to say the information you provided in the video is the best I've seen from any salespeople. Most salespeople that I've encountered don't know much about the products they are selling. I hope your effort is inspirational to others. :thumbsup:

haha...

please, if possible, post his response...

Haha, maybe not. But it was the one that popped into my head when I thought about it.

Actually I went to drive the new 3 series because I love driving cars...I wouldn't trade my TSX for anything...unless I had a bunch of money come in, then I might buy a 3 series. The fact that I didn't even want to buy a 3 series is beside the point, the salesguy was rather rude and wouldn't let me rev the engine at all. Then I asked if I could roll the window down to hear the engine and he was like "why?". I responded "I want to hear the engine." He seemed to think I was mildly retarded and made some comment about it being too cold and I "should come back in the summer if I want to do something like that(critical tone)". Guy just pissed me off. Then he tried to diss i-VTEC. I'll post his email if he responds to mine.

Actually, I'b also be curious to read what you wrote him? It would help put his reply (if any) in context.

My first email to the BMW guy said this:
"I was unimpressed with your service. I expected better of BMW so I will continue looking at other dealerships."


My second email with my VTEC argument said this:
"During our test drive you mentioned that BMW's Double VANOS/valvetronic in
the 330i was better than Honda's DOHC i-VTEC in the TSX. I believe that you
may be mistaken.

HONDA
-DOHC denotes that the engine uses VTEC for both intake and exhaust valves
(since SOHC can only use VTEC on the intake valves)
-VTEC(Variable Valve Timing and Lift Electronic Control) denotes dual cam
profiles which adjust lift and opening duration of both intake and exhaust
valves.
-The "i" denotes that the engine uses VTC(Variable timing control) for the
intake camshaft. This controls the overlap between the intake and exhaust
valves (called phasing). VTC cannot alter the exhaust camshaft timing.

BMW
-Double VANOS allows the engine to adjust camshaft timing (phasing) for both
intake
and exhaust valves' overlap.
-Valvetronic allows for variable valve lift.
-BMW does not seem to have anything that controls duration of the valve
opening.

It seems that Honda can adjust valve opening duration while BMW cannot. It
also seems that BMW can control camshaft timing (phasing) for intake and
exhaust
valves' overlap while Honda can only control the intake valves' camshaft
timing (phasing).

So Honda covers all 3 bases(duration, lift, and timing) for intake and
exhaust valves, except timing which is only covered for the intake valves.
BMW only covers two bases(lift and timing) but covers them for both intake
and exhaust valves.

I think Honda has accounted for more. What's your opinion?"

It's been almost a day now so we'll see if the guy responds.

And...?

:popcorn:

I'm new here but I can't keep quite on this thread any longer.

You think the BMW dealer was rude and wouldn't let you rev the engine yet you had no intention of buying a car. I think you were actually being rude by not only wasting his time, but then being confrontational with him. How would you like to be the one buying the car after it's been beat on by someone only seeking a joyride?

For the record, I currently own a Honda Pilot, have owned 4 Accords and currently have a TSX on order. I also currently own a 2002 BMW M3 and a 1999 BMW 740iL.

I don't care what the difference is between engine designs, BMW's and Honda/Acuras are completely different cars. I love Honda for there reliability. I love Acura for there value but, and it's a big but, neither is, or ever will be, in the same league of any but the cheapest BMW's. Sorry but that's the way I see it having owned and loved both brands.

I chose the TSX as a better value then a 325i. If I were willing to spend more on this, my 4th car in the family, I would have jumped on a 330i with the performance package but now you're talking 20K more then the TSX.

I wonder how Porsche and Ferrari handle variable timing?

If you're ever in the Northeast PM me and I'll take you out and we'll rev the hell out of the M3 right up to its 333HP 8K redline. Maybe then you'll understand how different they are and that while one system might be best for a sedate and reliable family car the other is better for obtaining higher performance.

So now we're down to comparing TSX's to M3's? Sheesh. :rolleyes:

That reminds me, has anyone modded their VTC mechanism (a la Hondata's 45-degree ideas) or swapped for the 50-deg RSX mechanism? Obviously it would be someone who has done some intake- and exhaust-tract modification.

http://members.roadfly.com/jason/m3engines.htm

Every time I hear people bragging about the e46 m3's engine I love to wonder if they realize how badly those engines were originally designed. (i.e. the "Supersession of Camshaft Bearings", "Supersession of Crankshaft Parts", "Supersession of Oil Pump", "Supersession of Camshaft Drag Lever", "Supersession of Oil Pressure Switch" links)


Nothing like buying a $50,000 car only to realize that some of the most vital engine components were poorly designed and needed to be replaced before it self destructed.


And yes I realize the m3 is an incredible driving machine and as far as mixing performance and refinement one of the best on the road, but I still think it's a testament to BMWs total lack of concern when it comes to building a quality product. It's almost as if they treated the e46 M3 like it was some kind of crappy shareware that they didn't want to spend the time or money to debug so they just released it, sold a few thousand, let the poor buyers find all the bugs one by one and then pay them off with a longer warranty. "Sorry we sold you a POS, here's an extended warranty so when something else breaks on your E46 M3 Beta version 1.001a we can see where else we messed up."

My point exactly.