I have been contemplating two concepts that have appeared in searching about mivec.

Modify for more advance. Then time the mivec gear retarded to some degree

I don't know if this works because I haven't tested it. But it seems to be one of those case by case scenarios as to whether it is effective or not.

Has anyone modified their mivec gear on a stock bottom end. What cams etc?

What cams need more lsa up top? I have s2 cams and I'm looking deeper than bolt ons for better power under the curve.

 

So all your map plots will be X degrees over what your actually advancing, resulting in targets under X becoming a retard.

Unfortunately I don't have any answers for you but I am intrigued and subbed for the discussion.

 

https://www.evolutionm.net/forums/ev...-cam-gear.html

Basis for modifying

There's a thread on high boost in which db tests fp cams and Robert from fp emphasizes top end cam retarding more than stock.

It was the quick and dirty mivec testing.

One run at full advance one run at full retard (lol) .

 

What you're taking about is basically what 2.4l engines have to do to time correctly. English racing will modify your mivec gear if you need it done.

 

I know this, I linked and posted in the thread in reference.

I'm not looking for someone to mod for me.

Interested in how much more lobe separation is meaningful

 

I haven't come up with anymore negative lsa being needed. However is any more than the 28.8 crank degrees currently useful? If we use all of the standard amount in aggressive set ups then I would think so.

Information deriving from "mivec tuning "

I did a solid rereading of that tonight

 

i think less overlap is profitable when emap exceeds imap. if your running in that realm, your plan makes sense. have you considered first messing with exhaust cam gear timing, or have you already tried that?

 

No, Infact I don't intend to push things out of the efficiency that much. Rereading the mivec threads made me realize that there is plenty of intake cam retard available stock.

I would still be very curious as to what more mivec could do in transitional and torque phases, seeing how some maps use the max, would more be beneficial.

I am starting to understands cam talk a little better after siphoning the 2006-2007 era of mivec discussion.

Exhaust gear may be advantageous but I'm currently thinking that my stock turbine hta 71 would be the narrowest point in any quest for top end gains exhaust wise. . But for 100 bucks probably well worth it..

I'm shopping for a mivec gear now.

After the clutch gets installed I would like to do a few static mivec advance tests including that of which isn't possible on stock un cut gear.

It's rather discussion less territory and I hope to discuss it with those who have, and maybe will I suppose?

 

it seems that you started the thread with the notion of wanting more available retard. did i misread? also, how much boost are you pushing at peak power?

 

That quickly changed with a solid understanding of the actual relationship if the intake cam position.

If more lsa was needed I would say that's still my intent .. How would I find out if that's needed?

I don't want to trade off low for top and top for low. If I were to gain at around then.. Ill do what it takes

Modified mivec has a few directions you could go, I just assume at this point we include the advance only option aswell.

But you are 100 percent correct with my starting intentions.

 

I'd say that midrange stands to gain the most from more intake cam advance because at lower rpms, there's more time to fill the cylinders so early opening is less important. As long as emap stays below imap, more intake cam advance would seem to be more and more beneficial as rpms climb.

 

My 71 can run around 20-21comfortable at peak hp and 28 easily peak torque. 400/400 + vd/dj.. I'm probably going to run much more conservative - and efficient when I start up for the spring. Theory has been above me and you cleared a lot up with top end emap ratio vs overlap. Leaving more cam advance still to be tested in the midrange.

 

A little disclaimer so I won't get flamed:
This post has absolutely no intellectual value and should only be used for entertainment purposes.

 

Modifying the cam gear only adds advance unless you set the cam gear off a tooth to use the extra advance to maintain 28* or so peak advance and then have the difference available for retard up top. I havent run more than -3.5* on most cam profiles.

This is also a closed loop system on the stock ECU so the map is still the map, you dont have to add number in your head to know where you are. It is what you make it unless it is physically impossible to get there (i.e 45* when the max would be 38* on a 4G63).

Since the stock range is -1.2 to +28.8* I would say that for the most part modding it is unneeded unless you were looking for more down low.

 

So the first part is what I originally intended. Retard gear use mod to gain back .

I was trying to see if on 93oct my s2's would warrant more lsa. Glancing at your older mivec map I am using from the thread I kinda answered that myself with the level of advance you ran out top .

Moving forward, gains are gains if modding the gear alone could get me low/mid id be willing to try. I see everyone peaks at 28 seeing if we could get more would we be able to use it effectively?( again on a standard 4g63 2.0)