MIVEC tuning - Page 2

Girlie · Jul 11, 2006, 09:07 PM

Quote:

Originally Posted by andenbre

What I have noticed is that the map goes in steps of 4.8. 1st things first are we sure that this # translates directly into degrees of advance/retard? 28 degrees seems like alot of range.

4.8steps = 1 degree

28=7 degrees

???????

7 degrees sounds about right. I am just guessing here by the way.

Girlie

JohnBradley · Jul 11, 2006, 10:26 PM

Quote:

Originally Posted by Girlie

4.8steps = 1 degree

28=7 degrees

???????

7 degrees sounds about right. I am just guessing here by the way.

Girlie

You are also incorrect (28.8 / 4.8 is not 7...its 6). It is directly translatable to dgrees. There is something on the order of 40* total adjustability in the MIVEC similar to the 40* that subaru AVCS has. I have heard directly from Mitsu techs the number is closer to 50* but I am not sure what you would gain and what load/knock/tuning error or whatever would need that much.

Keep in mind that the intake cam starts off life retarded in comparison to the 8 for better cold start up emissions. Ever notice how there isnt any EGR system on a IX?

EFIxMR · Jul 11, 2006, 10:57 PM

I just finished tuning our evo ix RS and the final numbers were 305 wtq 299.5 whp on a mustang dyno.

Will post results tomorrow when i get a scanner. Tuning Mivec is really tough.

andenbre · Jul 11, 2006, 11:53 PM

thank you girlie and john. that makes alot more sense to me.
this will be another entry in my notes

JohnBradley · Jul 12, 2006, 12:42 AM

Quote:

Originally Posted by EFIxMR

Will post results tomorrow when i get a scanner. Tuning Mivec is really tough.

How so? It seemed straight forward to me, but then again I was only tuning 5500+.

jcsbanks · Jul 12, 2006, 12:57 AM

John, how much have you added up top? Willing to post the map? I tried the stock IX RS map that was posted and it felt a little perkier but it was cool last night.

dudical26 · Jul 12, 2006, 07:03 AM

Does any one know of any other tech articles that discuss the advantages of advancing and retarding cam timing?

jcsbanks · Jul 12, 2006, 07:45 AM

The JDM RS MIVEC map is helping my spool up. I'm hitting 25 PSI at about 2600 RPM in top gear by going WOT at 2000 RPM.

JohnBradley · Jul 12, 2006, 10:55 AM

Its funny how no matter what size motor, or how many cylinders, some things are constants. I have been building engines for 16 years and tuning EFI for 6, and it all comes back to common sense sometimes. Retarded cam at high RPM=The Loss.

EFIxMR · Jul 12, 2006, 12:18 PM

I tried the JDM mivec settings your guys posted up and unfortunately it loss power on the dyno. of course YRMV, but in my honest opinion the only way to tune MIVEC is on a chassis dyno.

JohnBradley · Jul 12, 2006, 12:21 PM

I am going a limb and thinking that you lost power as in peak. What was the area under the curve like though? No need to divulge specific tuning obviously, but losing peak for a little more across the board isnt a bad sacrifice.

jcsbanks · Jul 12, 2006, 02:21 PM

Thanks John.

What I propose to do is to do runs through 4th gear on the same straight, flat section of road on the same day with three different VVT maps. Then I will take the acceleration in RPM/sec at 500 RPM intervals and plot the graphs over each other. Then I will pick the timing that gives the best acceleration in each zone. This has worked well before to determine the best boost curve. Poor man's dyno, or realistic road based loading? (we don't have real time adjustment, and I don't like doing zones by locking the dyno speed and testing for maximum torque in each zone, I think it makes it flat on the road).

JohnBradley · Jul 12, 2006, 03:40 PM

+1 for real world testing...as long as it safe. That isnt my current map, though the only change is the integration of JDM RS advance in the lower rpm ranges to see if I could reproduce some of your high boost/low rpm results. So far it has been pretty promising. I will post that MIVEC map up when it is "ready".

dudical26 · Jul 12, 2006, 04:55 PM

Quote:

Originally Posted by jcsbanks

Thanks John.

What I propose to do is to do runs through 4th gear on the same straight, flat section of road on the same day with three different VVT maps. Then I will take the acceleration in RPM/sec at 500 RPM intervals and plot the graphs over each other. Then I will pick the timing that gives the best acceleration in each zone. This has worked well before to determine the best boost curve. Poor man's dyno, or realistic road based loading? (we don't have real time adjustment, and I don't like doing zones by locking the dyno speed and testing for maximum torque in each zone, I think it makes it flat on the road).

Please let us know how it works out!!

jcsbanks · Jul 13, 2006, 01:31 AM

I will when the dealer fixes my alarm