To my understanding VTech kicks in at 4800RPMs on our 3rd Gens. Is their a way to make VTech activate sooner, like 4000RPMS? something we can buy to tune this?

 

i heard ppl using vtec controllers but then again there is really no point unless your heavily modded and then doing a tune. search the forum and you'll find all the answers.


just my

 

yeah it's possible, but from what i can remember - a lot of members discouraged it - something about it not being "optimal"..........aka it's most effective where it's set, as is.

 

ummm its V-Tec, not Vtech... just correcting u b4 sum1 throws flames at u

 

They measure in GHZ not RPM

 

LOL oops sorryi bet 7 times out of 10 ppl mispell it!!

 

lmao!!!

 

in the OWNER MANUAL is a complete explanation of vtec and when and how it works.
Pretty trick system that relies on oil pressure changes to operate!

 

Hmmm... I will have to look that up.

 

Our camshaft lobes are otimized for low RPM operation, i.e. maximum torque off the line and good emmissions and fuel economy. At the factory computed changeover RPM it will go to the bigger cam for deep breathing resulting in maximum horsepower. However there is no bigger cam, it's just an extra lobe next to the intake lobe on the cam in use all the time, we call it "VTEC". The big lobe being egg shaped is cut to allow in not only more air, it holds the intake valve open for a longer period of time as well. To this deep breathing the computer adds fuel and the power we want is produced.
So while that vtec kick might be desireable sooner, the rpms aren't there to utilize it. Looked at another way, a big cam deep breathing engine can barly idle, but produces huge power at high rpm's. A normal cam engine idles great but runs out of breath past 5000 rpm's. Vtec cures both challenges.

 

No thier not maximed for low torque of line, wow

 

here we go

 

Another flamewar is gunn happen take cover

 

so yes or no they are maximized for low end torque off the line?

 

thank you for some useful information, that does help in my understanding of it

 

I only want to lower my Vtec engagement by a few hundred RPM's,, from 4800 to around 4200 rpms, and i beleive this device will do it for me.

http://www.autocarparts.com/part/1581/0/



For me, Vtec engages way too late for my taste, when i want that extra "umpfh" of boost it seems like it engages at 4800 rpms then a second later your almost at redline,, it's almost useless for power activating that late. just my thoughts on it

 

Base 3G TL VTEC kick-in: 4700rpm.
3G Type-S TL VTEC kick-in: 4950rpm.

 

The idea behind identifying proper VTEC engagement is to minimize that "umpfh". If you feel a sudden boost in power then it's not efficiently climbing through the powerband. The idea behind VTEC is to maintain a constant powerband. Lowering the VTEC engagement point may offset the powerband. If you really want to learn about VTEC, check out websites like honda-tech.com. Experts who drive B16 (Civic SI) or B18C1 (Integra GS-R) know the feeling of VTEC the most since it's so much more apparent on those motors. Well, not everyone but you'll find lots of information about VTEC there.

 

I have never have felt that umph of boost. It feels the same as going threw the whole rpm powerband, 1,2,3,4,5,6 all feels the same.

 

the vtec kick is less noticeable on the tl

 

It turns out that there is significant relationship between the way the lobes are
ground on the camshaft and the way the engine performs in different rpm(rotations per minute) ranges. To understand why this is the case, imagine that we are running an engine extremely slowly -- at just 10 or 20 rpm, so it takes the piston seconds to complete a cycle. It would be impossible to actually run a normal engine this slowly, but imagine that we could. We would want to grind the camshaft so that, just as the piston starts moving downward in the intake stroke, the intake valve would open. The intake valve would close right as the piston bottoms out. Then the exhaust valve would open right as the piston bottoms out at the end of the combustion stroke and would close as the piston completes the exhaust stroke. That would work great for the engine as long as it ran at this very slow speed.
When you increase the rpm, however, this configuration for the camshaft does not work well. If the engine is running at 4,000 rpm, the valves are opening and closing 2,000 times every minute, or thirty to fourty times every second. When the intake valve opens right at the top of the intake stroke, it turns out that the piston has a lot of trouble getting the air moving into the cylinder in the short time available (a fraction of a second). Therefore, at higher rpm ranges you want the intake valve to open prior to the intake stroke -- actually back in the exhaust stroke -- so that by the time the piston starts moving downward in the intake stroke, the valve is open and air moves freely into the cylinder during the entire intake stroke. This is something of a simplification, but you get the idea. For maximum engine performance at low engine speeds, the valves need to open and close differently than they do at higher engine speeds. If you put in a good low-speed camshaft, it hurts the engine's performance at high speeds, and if you put in a good high-speed camshaft it hurts the engine's performance at low speeds (and in extreme cases can make it very hard to start the engine!).
VTEC (which stands for Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts. As the engine moves into different rpm ranges, the engine's computer can activate alternate lobes on the camshaft and change the cam's timing. In this way, the engine gets the best features of low-speed and high-speed camshafts in the same engine. Several of the links below go into the actual mechanics of the VTEC system if you are interested.
Several engine manufacturers are experimenting with systems that would allow infinite variability in valve timing. For example, imagine that each valve had a solenoid on it that could open and close the valve under computer control rather than relying on a camshaft. With this type of system, you would get maximum engine performance at every rpm range. Something to look forward to in the future...
­

 

look into the apexi afc neo if you want to "control" vtec engagement

 

You haven't figured out how to get VTEC to engage yet? Maybe you should start a "How Do I Get VTEC To Engage" thread in Problems & Fixes.

 

The problem is if it goes to the big intake lobe too soon, power will fall off momentarily until the rpms get back up.

 

On our SOHC motors, vtec is only applied on the intake valve, not both valves. That's why it's more noticable on the DOHC 4 cylinders.

 

you could buy a UR lightweight crankshaft pulley- dropping 6 pounds off the crankshaft pulley weight(of 8 total!) will get the engine TO vtec faster-

quicker revving engine, so you feel the power more, is the end result
see Unorthordox Racing for more details and hp/torque charts

 

that sounds like something to look into, sounds much less complicated than changing the Vtec engagment.

 

How do you buy a Honda/Acura product and still don't know how one of the biggest trademarks of the car is spelled, works, or altered?

 

Your Signature:


Either this is a funny little underhanded jab ( :lol: )

OR

You just owned yourself.

 

The entire signature of "mods" is a jab. Thanks, come again.

 

The BMW DOHC 6 cylinder has a system on both intake & exhaust that provides the same function using a different technology.

 

A lot of cars have variable valve timing...

 

The main difference is BMW does not use a throttle plate to regulate the engine speed but uses the valve timing & lift instead.

 

I'm an idiot.


V V V V

 

How it works....use your search....

https://acurazine.com/forums/3g-tl-2004-2008-93/vtec-explained-what-3g-garage-l136-589631/


I will have Ron fix the pic links for you guys....

 

 

 

I guess there flat out wasn't enough room in the cam area to do vtec on the intake and exhaust lobes on the SOHC motors.

I didn't realize BMW had this technology available yet. I remember years ago when they were working on it. So, no throttlebody, throttle is determined solely by valve lift and duration? Did they end up going with a solenoid style valve? How's the durability and what models is it offered on?

 

Looks like they figured out how to get VTEC on Intake and Exhaust with a SOHC on the 4G 3.7L:


http://www.hondanews.com/categories/733/releases/4679

 

Valvetronic is BMW's trade name for a variable valve timing system on a single (intake) cam. It was introduced in 2001 on the 318I & is used on all the engines except some of the M series.

Double-VANOS (double-variable camshaft control) is the BMW trade name for valve timing on both the intake and exhaust camshafts.

It uses an extra set of rocker arms, called intermediate arms (lift scaler), positioned between the valve stem and the camshaft. These intermediate arms are able to pivot on a central point, by means of an extra, electronically actuated camshaft.

I don't know when it was introduced on the 6 cylinder but my 2004 330Ci has it. 60,000 miles & no problems with it