Contour Enthusiasts Group Archives Forums Modifications Duratec Performance IMRC Opening Point

Did you look over your cube to find that out?

Stock opening for an SVT is around 3400-3500rpm at WOT. It can be significantly higher at part throttle.

Non-SVT's open around 3800-4000rpm at WOT

Superchips programs their chips to open around 3200 rpm.

No. (that's why I'm interested in his & A/F data would be great!)

I just have airflow data (and other laptop data), butt-dyno, and my G-tech guesstimator currently. Now I know flowing more air by itself does not guarentee more power, but that would by taken care of with the S-AFC tuning.

I had planned to have dyno proof by now, but that is indefinitely on hold at the moment... No matter what the results I will report them...

If you know why they were set at 3400 & 3800 rpm respectively, let us know please...

I know that the driveability on a stock engine would be compromised with a lower IMRC point. Also emissions do rise.
The info I got about Ford's thinking was from Superchips; so lumped together with the 2 previous listed you can take it as you like...

Most of the info I get is from my own car (imagine that) so others mileage may vary, contents may settle, no return to sender.
After all I'm modding my car - not anyone elses...

BTW - I still like them pinned the best... Go figure...

if you don't have data to support your side, why do you rip on NYnicksSVT for not having posted his yet? Hello, pot, this is kettle . . .

The primary concern when the IMRC open points were calibrated, was to maintain the maximum area under the tq curve, and minimizing the tq drop-off in the curve. This was at the personal direction of the head of SVT Engineering (then called SVE) John Coletti, and was concurred by the calibration engineers.

The transition from only primary runners to both sets of runners can be greatly smoothed out by altering the open points of the IMRC, but a large amount of the area under the tq curve is lost, though peak #'s are not significantly altered.

Right now, I won't waste my time arguing specific #'s for the opening points, because, I am going from memory on the numbers, rather than having any actual calibration data in front of me.

Amen brother Rara. I'll post the graph next week and this discussion will be over. I hope my scanner can handle an 8.5x11" paper. Once I scan it, is there anyone who has a server on which I can post it? Thanks!

To answer the other question, I actually did 13 pulls. I wanted to check some intake mods and optimize my car. In the process, the tuner suggested finding the optimal point to try and make up the loss at 3500rpm. We tried and determined it was already optimal. Now my car runs with good spark advance and a consistent A/F ratio of 13. Total cost for the dyno tune was $400. Good mod for me since I was running A/F ratio of about 8...Yikes!

Didn't know my side NEEDED to be supported for him to support his side...

He started making these claims. I asked for proof. Let me know what's wrong with that Kettle... :rolleyes:

I have tested MY car. I know what works on MY car so far... Like I said prevously - I'm not modding OTHER peoples cars now am I...

...should I even bring up where is your proof either one of us is wrong...

well, NYnicks' results obviously coincide w/ SVT's findings.

He stated what he had found in his testing, then you ripped him up for not having his dyno scans, then turned around and stated what you had found/done on your car without providing a shred of evidence, not even a promise of dyno sheets to come. basically the exact same thing he did, only worse.

I never stated that either one was right or wrong, I posted what the guy who calibrated the freaking car told me.

I ripped him (after a few nice posts with no success) for his broad assessment that changing the IMRC point was bad for every Duratec; without proof.

All inclusive statements are 99.9% incorrect...

Well, given what I know of the Duratec, and what has been told me by the SVE calibrator(s) about them, and in particular, and knowing that NYnicksSVT has dyno data to support his findings, I will tend to beleive that it is better 99.9% of the time to leave the IMRC points where they are. This would apply to all stock, or near-stock Duratec's. The only exceptions would be, engines that aren't functioning correctly in the first place, or heavily modified engines, ie forced induction and/or serious engine modification like head work, 3L etc.

Just a quick comment on dyno's. You don't race on a dyno, you race on a track. The dyno can be a fabulous tool in helping find what works, but in the final analysis, racing is more art than science and it is the art of tuning to the application that makes the difference.

This is great stuff on the secondary openings. I suspect that it would be hard to improve on the factory settings unless large modifications were made. I suspect that the openings would be sensitive to things that alter breathing significantly. A hotter cam may benefit from raising the openings, more displacement may need more air at lower speeds, large increases in port size or shape may also make a difference. I also suspect that port length is critical to this design.