Contour Enthusiasts Group Archives Forums Modifications Duratec Performance IMRC Opening Point

there is alot more error (human) to be had at the track then on the dyno... i trust dyno finds over track results any day... if you know how to use a dyno plot (and other features of the dynojet software) you can find the information they provide invaluable... while a simple timeslip can be very misleading and uninformative... no calibration, and plenty of room for human error. i am sorry, i don't agree with you on that at all... not to say that you can't learn something from the track, it is just not nearly as accurate as a dyno can be (for the average to better then average driver).

Rara-

So you don't think something like a custom advance curve and A/F tuning on a modded car will alter the optimum IMRC opening point then?

What about the many different lower intake diameters used? Still no change?

Fair enough... (still going to test it of course )

What are your thoughts on total removal of the secondaries then? Only 3L or Forced Induction or not at all?

Neither will significantly alter the flow volume and flow characteristics, so no, I don't think either will make changing the IMRC opening a worthwile mod.


What many different intake diameters? A change large enough to do more than slightly change the intake flow characteristics might make it worth while, but a change like that would likely only be made w/ other significant changes that warrant the larger runners (ie larger valves, ports, etc.) and hence the need to revisit the IMRC controls.


Ok. I'm all for additional testing. Just make sure your tests are not compromised by uncomparable methods etc. as so many of the "rags" tend to do on their comparison tests.



On a street driven car, I would say do not remove them (with a few exceptions) A street 2.5L SVT w/ heavy breathing mods (full, well designed exhaust, oversized TB, intake tract, etc.) can get away w/ it, though the results will be less than optimal (gr8ride's car is a great example of this, his car has some top end gains associated w/ these mods, though I really think he has lost some of his tq in the low and mid ranges. I will admit though,, his car w/ removed secondaries runs better than I expected.)
Similar thoughts apply to a 3L setup, unless it is heavily modified, and maximum peak hp is desired, rather than maximum area under the curve.
Forced induction, I think (though I have not tested this) could benefit from removed secondaries, (turbocharged engines prolly more so than S/C) more than other applications.

The stock duratec lower, the early SVT, the late SVT/3L, an enlarged late SVT/3L...

That's 4 different sizes currently available. All significantly effect airflow into the engine respectively.



Would all be same day dyno testing. That would be a fairly accurate static test (I.E. not real world)

But like I said. I like them pinned the best & that's not even getting the high rpm benefits... We be nice if the dyno says the same as the real world does...

Bret,

I believe that your thinking and mine is closer than you may realize. After all the science (and the more the better), there is still an art to tuning. You should absolutely believe the testing results and use it in determining where you want to go, but in the final analysis, nothing beats empirical data.

Uhh, I don't have an SVT and my secondaries open at 3400 every single time I'm at WOT.

(Well, when they open at all)

-Chris

I finally got the dyno scanned and saved. I don't have a server to post it on. Does anyone have a place they can put it so everyone can see these findings? Thanks!

On my 2000 Cougar my secondaries do NOT open up at 3500... more like 3100 or 3200... Now I also have the SVT lower IM... so could it be I also have code in my PCM to make the secondaries open up later... would this mean that I have some of the SVT program in my car already?

i'll agree to that.

Just to let you know that I posted dyno graphs in the "Dyno" section.