I guess it would be helpful to know if the Evo motor has an "interference" design or "non-intereference" design. This refers to the valve to piston clearance (as controlled via cams) you know valve timing right? I am not real knowledgable on cams and timing but I know on some cars they say that timing belt maintenance is critical because if the belt breaks timing control is lost and you can have valve and piston collision obviously doing major damage and costing lots o' money. In a non interference design this is not possible due to having clearance even if piston at tdc and valve fully extended into chamber.

If the Evo is non-interference design then theoretically you could never advance timing too much becasue valve travel would be limited by spring compression right?
Does anyone know if/how this is applicable to an Evo engine?

 

The Evo engine is an interference motor. The timing belt goes and you're lucky if you don't walk away without the motor blowing.

 

Negative on changing the RPM scaling in the boost maps. Changing it to get control at 8K was more proof of concept than anything else.

Also anyone asking about over advancing Cossies and causing valve to piston contact please refer to this quote:

 

I have been playing around with the mivec maps (fq360) and have increased the rows from 4500 to 5000 rpm to value 24 and have increased 5500 rpm value to 19. Now, the low down does not feel 'as' mental as before during spool-up but at around 5000 rpm the engine does seem to come more alive?

I have rounded the numbers at 6500 rpm to smooth the map out.

My question is, would increasing (retarding inlet cam?) the numbers at 5000 rpm cause any side-effect of the low down mivec-control ie. spool-up?

Also, at 5000 rpm the engine is more 'alive', you can feel this. This reminds me of the Honda V-Tec engines, is the Mivec pretty much the same?

And finally, I think the mivec is boost related, any more info on this?

Cheers!

 

Adjusting the high RPM values shouldn't affect the lower ones.

The MIVEC system could be compared to VTEC, bit it is not the same. VTEC is more of an "on/off" switch for the cam timing (the lobes might actually be different on the VTEC side), where MIVEC on our Evos is continuously variable. MIVEC is more like having adjustable cam gears that you can change on-the-fly.

MIVEC is related to boost. I don't think changes in the MIVEC map will allow for more or less boost, but you can use it to aid in spool up by increasing the values in the spool up range.

Hope that helps (and also that I'm not completely wrong).

 

MIVEC is nothing like VTEC. VTEC used two different cam profiles on each cam. MIVEC cams only have one profile.

MIVEC give use the ability to change the cam timing of the intake cam, which is the same thing the "I" in "I-vtec" did on the K series engine.

 

Anyone running a mivec map they care to share using 91 octane and boosting around 20-22psi?

 

I was going to leave comment on this thread that I think the gains that some see with a little inlet cam advance up top depend on how much top end boost you run. I've always pushed the top end boost quite hard on my turbo with standard actuator but AVC-R on 90% duty cycle with 10% meth in the tank to support, and it does gain power. It may gain even more with the actuator tightened which I'll do soon when the O2 housing is changed. However, I don't see reductions in the time taken to go from 5000-6000 or 6000-7000 RPM with more inlet cam advance. I wonder if because I push the boost that the point where the exhaust manifold pressure exceeds the inlet manifold pressure is at lower RPM, and therefore I don't gain from more overlap up top. It might make sense to have say 4.8 degrees in the eg the 6500 RPM area at say 200-220 load, but 0 at 240-260 load for example?

 

I see what you are saying JC, and then just let it interpolate advance between the load cells?

FWIW I found a 2mph difference in 2 back to back 1/4 mile passes with advance versus no advance. This was between 0* and the 9* I am currently running because of the 280 exhaust (S1's still arent in) cam. This was at 23psi at redline on the Green, which might skew the results somewhat compared to what you are talking about with a stocker. Even on stock cams I usually run 6-7* with what appear to be favorable results.

JB

 

I'm running up to 26 PSI at 6000 RPM, 23 at 6500 and 20 at 7000 on the stocker, so the little thing is being worked hard, but it takes timing and it seems to make power even without meth, although even driving hard my inlet manifold temps never went over 104F today which is a 66F day, which I don't think is bad. If anything at speed the charge temps really drop. I can see how running lower boost or running a more efficient turbo would allow benefit from more overlap, but even with the meth I can't make the overlap work up there for me and it encourages detonation.

 

If anyone has access to a dyno I will gladly put my mivec map up (or JC) in order to see any difference in advance?

 

^

Use DataLogLab's dynograph feature.. it works pretty well at comparing one tune to another

 

interesting, on my ix w/ 272 mivec cossies on both the stock turbo and a 20g-9, i saw no discernable difference on the dyno advancing the intake past 5500rpms...

 

On the dyno, I have found that advancing the mivec past 6k will bring the peak hp up sooner and stay flatter but not actually increase peak numbers, this might be worth a 2mph difference in the 1/4 mile that John has been seeing. Same amount of peak horsepower, but for a longer duration.

Depends on the car and mods as well, some cars and mod combos, it isn't as 'effective'.

 

On the 05 Evo I used to:

1. Set the boost
2. Tune the AFR
3. Tune the timing
4. Go back and fine tune AFR

On the 9 @ what point do you tune the mivec map?