scalbert

Just for the hell of it. I was driving back from KY yesterday and was thinking about this topic.

From what we have seen on dyno plots torque starts dropping off at about 3500 revs and then climbs back up once the plates open typically not regaining until about 4000 RPM. So what happens below 3500 revs if the plates are open?? What happens between 3500 and 4000 if the plates are open?? If there is a loss of torque down low, where does it show up and where is it regained??

Obviously these questions will need to be answered on the dyno, which I plan on doing once the RES is available. Two runs normal, two runs without the plates, two runs w/ plates + RES and then two final runs w/o plates + RES. This should be interesting and fun.

But in the mean time I plan to do some quick testing by timing 3rd gear pulls from 2k revs to 4k with and without the plates on the same road. This should give and idea about the low engine speed loss if any. More on this later.

But the reason for this thought was due to the issues with faulty IMRC systems in which there is a noticeable loss of power from 3800 RPM on up. What could be done to prevent this from failing??

I also thought about instances where people have run against the CL-P where the CL-S starts pulling after the revs climb and into the IMRC open stage. According to what I could gain from the Helms manual the CL-P doesn’t have a plate system, it looks like the center area is always open as should be with the CL-S after 3800 revs. Also, Acura shows the peak torque really being in the area where the plates are open and since it starts dropping off before this and is regained after the opening event there could be more or no less torque below here.

I was also thinking about the actual instances where we are below 3500 revs. From a standing start this is very little time and, if on it, taken up quickly due to wheel spin. Our TC stall speed is at least 2k so there are just 1500 revs before the torque drops while waiting for the IMRC to open. Without the plates it would seem that there would be no drop starting at 3500 but it could also be lower at this point increasing up to where it is after the opening would have occurred.

Are the plates there for increased torque down low or are they for another aspect?? Since most of the advertised HP/Torque points are in the mid to high RPM range where the plates are already open there is a possibility that the plates are limiting torque in trade off of gas mileage. A long shot definitely but will certainly be investigated.

What I have noticed so far cannot be taken as a conclusion as hard testing would need to be done. But there is no evidence of a low end loss of torque. I launched several times last night, and not even loading the TC, and the result was significant wheel spin. I even kept it in 2nd and 3rd and accelerated from about 2k revs and the feel was no different. If there is a loss it is imperceptible. But the other area is that I don't feel that slight lull in power just before 4k revs. There might be slight benefits where we don't have to wait to regain torque, just a thought though.

This is a very loaded issue and only real testing will answer this in the end.

astro

Steve, this is something I've been tossing around with my dyno shop...I think that it will show some losses down low, but I really doubt that they will be so much as to kill the idea....

how hard is it to remove the plates? I will go to the dyno next week and try this theoy out if you or anyone can tell me how to remove the plates...

scalbert

Takes a whole 2 - 3 minutes. Just remove the engine cover and the manifold cover plate, about fourteen 10mm bolts total between the two. Then you can use a strong phillips head screw driver to remove the retaining screws on the plates, three per each of the two plates.

That is it...

JRock

I wonder how this would work in conjunction with an RES that is designed for that? (Considering the current RES is designed for the IMRC plates to be there.)

Hmmm, interesting ideas here.

scalbert

Considering that it is not relevant above 3800 revs where they would be open anyway and that it worked for the CL-P also which is always open by not having any plates, it probably doesn't affect the outcome, positive or negative, differently that what it would with the stock plenum cover plate.

But again, just an idea and it will be tested.

JZ

Finally, an interesting post! Seems like it's been a long time coming.

Props once again to Scalbert.

JRock

Now we just need someone to remove the IMRC plates, dyno, then design a RES that offers peak performance for a non-plated intake, and dyno that. Then compare that dyno with the dyno of a car with plates and regular RES.
And if the non-IMRC RES shows better gains, sell it along with a FAQ for IMRC removal!

astro

nice of you to contribute

since it's easy to do, I will dyno my car as soon s I get it back from the stereo shop...I should be able to book dyno time for Monday November 26...I will take out the blades at this time and do back to back runs and post the results...

thank you Steve for telling me how easy it is to remove them....

EricL

I found a link to some of you may find useful. According to Doug (AKA syncivic) the removal of the plate dumps HP at low RPM (most of the literature suggests this, but I defer to a past thread):

Quote from syncivic:
7. Secondary air valve worth 20HP at 6100 RPM but if pinned open will loose 10-15HP below the 3700RPM transition threshold...so don't get any bright ideas.

Here is the link (to the entire thread):


http://www.acura-cl.com/forums/showt...highlight=gain

scalbert

Astro, below is an image taken from the Helms manual showing the parts breakdown. The only thing not shown is the platic engine cover which is obvious, four 10mm bolts at each cover of the cover.

In it you can see the upper cover which exposes the IMRC plates. And I looks like my memory hasn't failed me as their are fourteen 10mm bolts in total between the engine cover and the upper cover.

Just as an addition when you get to the IMRC plate screws. Try and cool the engine first as these screws are soft. I stripped the phillips head imediately on the first one as they are tight. I then switched to a larger screwdriver and applied more pressure to get the rest out easily.

BTW, the image is large, about 1/2 Meg:

http://www.flwse.com/images/steve/En...32A2Engine.jpg

Mike

here's a smaller image guys.

scalbert

But it is certainly worthwhile to look into but I do expect that there are power losses, but not on the 10 - 15 HP level. It would be nice to see actual Dyno numbers on this, along with any other claims of HP deviation, from multiple sources. A singular source is never a good way to validate something.

But again, I don't expect to see anything other than a loss, but how much is what I am curious about.

Not directed to you Eric as you were merely relaying information, but why was HP mentioned in the low end when torque is the number that should be identified?? HP increases or decreases at this low of a rev are minimal when compared to torque values. So resolution is lost in the translation.

Let's say there is a power loss at the lower revs, say at 3k RPM and the HP lost is about 12 HP (middle of the road in the mentioned claims), this would mean that there was over 20 lb/ft lost which is significant. Drop this down to 2k RPM (the lowest useable RPM range in these cars) and this loss equates to over 30 lb/ft, highly noticeable!

I would also assume we would not see a drastic change in torque when the plates do open if there were no plates in place. As it stands right now the torque drops off quick starting at about 3500 revs and then starts increasing at about 3800 revs ending at just over 4k, this is when the plates open. If they don’t open then the torques continues to drop until just over 4k revs and then flattens at nearly 20 - 25 lb/ft lower than where it had been. If there were a drop without the plates I would expect that the level would increase at a somewhat linear rate, not spike back up. Point being, 3700 RPM is not a magic number where all flow dynamics immediately change or else there would be serious differences between the plenums of the J32A1 and the J32A2 other than the plates.

It will be interesting to see what the dyno plots look like. In fact, I don't recall seeing any plots showing anything valid fewer than 3k revs anyway. So it may not show any real difference anyway. But again, it is all for expanding the real knowledge of these engines, and fun while we are at it.

spiroh

Scalbert,

I give you tall props.

Spiro

scalbert

Just as an side, there are oiling passages leading into the plenum cover plate. What these are for I can't be completely sure but are probably for emission purposes to heat the air quicker kinda like the cooolant flow to the TB.

Not to start something but could these be blocked also as I don't recall return flow passages?? Just playin here...

EricL

Steve, I am not dissuading you from trying the test (messenger vs. message issue [as you stated]). I am just relaying previous info that "was stuck in my head". Why stuck? I am also very interested in what the actual graphs would look like.

As far as the issue of presenting the loss at low and high in HP (rather than the non-derived units) -- I don't know. Perhaps, it was 1) a mistake or 2) an intention to present unified units (apples-to-apples, oranges-to-oranges).

BTW – yes, I look at the torque curve first to see what is going on…

At this point, I am assuming that the numbers presented were valid (however, there is the issue of the velocity of air being dependent on air density and air density is dependent of temp (to some degree). So, this gets back to the whole issue of a tuned cavity and how it behaves with temperature (I believe Doug (Syncivic) had a hot and humid summer for testing (The temps on the dyno readouts seemed to convey that)

So, just to toss in more "variables", the torque gain or loss and break point in split to "full" chamber could also be affected by temperature. I would be very interested in seeing the dynos done at low and high temps. (My area of interest is piqued in this area IN ADDITION to MORE dynos with and without the plate(s))

scalbert

Ah, the wonderful part of a newer engine design. Find what does and doesn't make power. Or what looses power as the case may be...

When/If the RES comes out would be a great time for several people to make dyno runs and test this idea, (myself included). It is easy to do and wouldn't impose much on the dyno operator. But it would provide a wealth of knowledge to all of us.

IMO, Doug's dyno plot will always be made in a condition most would call summer heat and humidity regardless of the time of the year, that is south FL. Much different to S. CA. The Dade/Broward county area may not know how to vote but it is certainly one of the most consistantly warm areas of the country. (Will be down there shortly ay some of the cane fields).

Regardless of the outcome I will still find this car lacking in low end torque. Having almost slammed against some rocks yesterday on the way back from KY near Chatanooga (avoiding road work on I24) I find I hit the brakes more to avoid things than hitting the gas to move ahead. But then again, the smoothness of power delivery during acceleration is nice when in a turn.

EricL

Steve,

?? Thoughts...

1. For dyno purposes, how about some clip leads, etc to just hold the actuator on -- to keep the plates open. There is just the 2P connector -- some quick and dirty clip leads would make steady-on and steady-off testing easy for quick back-to-back dyno runs.


-???-


There are 20 other variations on that theme (including just using the actuator cable)...

Helms 11-138

scalbert

I haven't put a scope on the signal to the actuator, but initial thought would be just 12VDC switched to it. However, they could be changing to 12VAC through the IMRC control module, just a thought and easy enough to check out in the next day or two. I'll take home my Tektronix handheld scope and check the signal.

If it isn't just simply 12VDC then you could tie in a ground switch to the control input of the IMRC control module. Apparently the ODM on the PCM for this control isn't checked for ground fault so it should set a DTC.

Or else the cable would be pulled and latched open as mentioned, etc...

Since I had been driving around I opted for removal. But for a quick test it isn't needed. But it is also just about as easy as most other methods so I guess it's and individual choice.