Hey guys,

Just got my cosworth cams installed, and the car runs pretty crappy on my stock cams maps. I am running a GST base tune tweaked for larger injectors and using E-85.

I know for idle / cruise I need to dial out some of the overlap in the MIVEC maps. Is that alone enough for me to do a long road trip to take the car to be tuned? My current MIVEC settings are the ones from the GST base map.

Thanks for any help,

Keith

 

Yea you are going to have to dial the mivec settings way back. The cosworth cams for sure drive and idle a bit crappy compared to the smoothness of the kelfords.

Are you running cams on the stock RA turbo??

- Bryan

 

Yup, stock turbo. I want to see how far the stock turbo can be pushed. 12.90 so far, aiming for low 12's to high 11's after getting tuned and putting on the 16" volk racing wheels and drag radials.

Do you think the MIVEC settings from the stock tune would help enough, or should I dial them back even further?

Later,

Keith

 

For me (Dom 2.0 + Cos cams), I don't go beyond +25 or so on intake and I gradually decrease to +10 by 6500 RPM or so. As for exhaust, I'm pretty much 0 throughout the entire WOT range.

Also as a side note, there isn't much you can do for the idle mivec area since +10 is minimum for intake and 0 is minimum for exhaust. It should already be set like that for any tune you come across any ways. Just increase the idle/cruise timing, raise your idle, and adjust your fuel trims as needed to take care of the idle/cruise.

 

Well, the car is drivable now! I haven't played with ignition timing or fuel tune yet. What I did so far was to take the bone stock USDM Ralliart MIVEC map, and pull out 5 deg of advance on the intake and 5 deg or retard on the exhaust. This gets rid of 10 deg of overlap in the cruise / low boost areas of the map. The stock USDM maps don't have any adjustments for high boost operation unlike the JDM maps, and for now I will leave them like that.

I still get a slight bit of hesitation in the lower gears when going WOT, probably from running a bit lean more than anything else. I am definitely running leaner in the upper RPM's.

The stock Ralliart turbo on stock cams was only able to hold about 16.5 psi at 6500 RPM in 4th gear. With the cosworth cams I am holding 19.0 psi at the same RPM point in 4th gear!!!

Another thing I noticed, at 80 mph, even on almost dead flat ground I am building just a bit of boost. It may have been a VERY gentle up hill slope, but on the stock cams with JDM MIVEC maps I never built any boost in that situation.

In short, I am really starting to like these cams

Keith

PS: I don't have the idle RPM defined in my maps, so I can't bump it up... can anyone help out with that one?

 

53600010 ?

 

55590006

The stock rom is available as a zip file here:

http://norcalmotorsports.org/users/b...M_55590006.zip

Thanks,

Keith

 

I would have thought that with cams the engines ability to breath would increase making it harder to maintain boost with the same wgdc. Please correct me if I'm wrong.

 

It probably has more to do with running the stock ROM MIVEC tables in that RPM range than it has to do with the cams themselves. The JDM MIVEC maps have a crap load of overlap in the upper RPM as compared to the USDM MIVEC maps. That extra overlap on the JDM MIVEC maps probably leads to more power even at a lower boost pressure... but they are also meant for a car with a larger turbo (EVO X turbo vs Ralliart turbo) I hope David is willing to play with the MIVEC maps when he does the tuning.

Later,

Keith

 

You're forgetting the fact that since there is more intake, the exhaust pressure also rises which results in higher boost.


This is physically impossible, as I stated before the minimum mivec for intake is +10* and 0* for exhaust. Since most tunes (stock Ralliart, JDM, GST, gunzo, etc.) idle at those mivec settings you cannot decrease any more overlap since they are already at minimum. Even if you set the numbers to be lower in ECUFlash, the actual will only be 10* intake and 0* exhaust. Try logging actual mivec and you'll see what I'm talking about.

 

I think he means that he pulled 10* of overlap out. Meaning that he went from say 20* of overlap to 10* of overlap (just an example, not sure of the exact numbers).

 

understatement!

 

Right, I'm sure that is what he meant but since the stock tune he uses is already at minimum overlap during idle, I was telling him that he can not decrease any more than what it already was.

 

I think he is talking about the cruise area of the map.

 

You're right, I dunno why I was so stuck on idling portion