scalbert

I gave up, I would of had to pay $200 for the signal conditioner, (one of our salespeople decided 24VDC means hooking it up to the wall outlet, I'm surprised he actually got that far).

Anyway, instead I did some back to back 0 - 60 runs with and without the plates. One thing I would like to point out before the numbers is the now noticeable difference in 'feel' now that the weather has gotten colder. It seems the cooler/denser air makes more of an impact on the engine.

With a 40 degree difference in temperature and without the plates, the car feel like fine below 4k but at this point it then has a significant surge once the revs move up further. I mean this surge is very noticeable. With the plates installed there is the familiar slight change in power delivery when the plates open but nothing like it is without the plates in there at all. Plus, power does seem to be up a little below this area.

I suspect they did tune it well enough that the 3800 opening point is appropriate.

And now again; don't take these numbers as absolutes. They are for run-to-run comparison. What I can say about them is that I am damn consistent. I made two runs at the same location with and without the plates all within 30 minutes of one another.

Without:
5.73
5.71

With:
5.59
5.60

So there did appear to be a 0.13 difference which really wouldn't be something you could definitely feel but noteworthy considering the car is only in this rev band for about 2 seconds.

Just a little FYI...

EricL

Hmmm....


Air density and temperature -- this is going to be interesting...


Have you noticed that the car does much better in the ¼ mile at low temps? (Better than just the increase in air-density (from the lower temps.) would suggest…)

$0.02

DtEW

Well, isn't the majority of the difference between the CL-P and the CL-S the Helmholtz supercharging apparatus, which works via an air resonance effect? It would be reasonable to suspect that colder air temps also affect the way that functions, resulting in a performance gain in addition to the simple air density effect.

frederix

Those are your 0-60 times?
I'd like to see some dynos with and without the IMRC plates.

astro

those times are consistent with cold air runs with headers...

EricL

Part of the difference is the Helmholtz resonance/supercharging. There are some other important differences between the CLP and S too.

The temp vs. air density is show in most physics and chemistry books to be a linear property. However, with at atmosphere, there are layers of air sitting on top of the air ground level (sea level) and make for a non-linear relationship. Could it also be possible that Acura optimized the resonance for lower temps?

There are also some issues concerning the knock sensors and the fuel-air mapping, lower octane requirements at lower temps, etc, etc; I'm not sure about this, but the car seems to exceed expectations when using "standard" temp vs. air density equations to compute 1/4 mile time, etc.

So, take your guess...

Standard Atmosphere air density vs. pressure graph (it is non-linear as shown)



(The Viper people also noticed some of this, but…)

Viper HP vs. temp etc (interesting): http://www.viperclub.org/faq/techtemp.html

HP with temp for Viper:


HP with alt. for Viper:

JRock

So he did better WITH the plates intact, right?

EricL

Yes, it seems that syncivic (Doug) gave us some good info *and* Steve did a nice job confirming it

astro

I will still do the dyno run with them off when I get my car back, what is the thing you needed to buy steve? why do you need it?

Eric, those graphs of the Vipers are crazy...I have gtech'd my CL'S many times and always got runs of 5.3 to 5.6 but I never considered it to be anywhere near accurate...I live up north where the air is almost always cold so I guess I have been lucky that way :o)

I can't believe up to 100HP difference with the Vipers..I wonder what our car would sway from...I'll make sure to do some sub zero dyno runs and then some in the summer with the same circumstance except for temp and huimidity...

scalbert

There are other differences such as compression and the cams, but the dual stage intake is part of it. The main thing I was trying to determine is not if there was a power loss below 3800 revs but how significant it was. Considering that we have an automatic with a stall speed at about 2k revs, you don't spend much time during acceleration under the threshold.

It was just something I was curious about and easy enough to play around with.

scalbert

I had a Frequency/Voltage conditioner, 0 - 500Hz In, 0 - 10VDC Out. The portable DAQ equipment only takes voltage inputs so I was going to tap one of the ignition signals and convert to voltage and then to RPM. With the conditioner (which is also an optical isolator) I could monitor RPM and set triggers in some simple software. This way I could have ran at the same spot from 2k revs to 4k revs and timed it with and without the plates. This would have been a reliable test of the differences but without that module I wasn't going to tap anything.

scalbert

It seems like the Vipers are following the 2% rule-of-thumb (maybe a little more) for temperature change, 1% - 2% change in HP with a 10 degree change in temperature.

Most NA cars are typically closer to 1% - 1.5% and Turbo cars are 2% and sometimes a little higher. It seems these Vipers are closer to 2%. I would expect out cars to fall into the 1.5% range.

scalbert

It definitely seems like there this car doesn't follow the typical curve. Whether Acura tuned for it or it is just a simple, 'wow, look what happens with this design' we probably won't find that answer.

Concerning ignition mapping, I am curious as to if Acura is using ignition triming and if so, how advanced do they go?? If they allow for significant advance increase when no knock is detected over time; then it is feasible for this car to get noticeably more power when it gets colder.

Many manufacturers now use ignition trimming instead of just set tables and KR values. There is no reason why Acura wouldn't be doing the same.

typeR

this is why I've reduced my opperating temperatures..it seems this car loves lots of air and coold temps...also scalbert...perhaps you said it already i didnt read all the posts in this topic...it sounds to me like what you were "feeling" was more a product of the reduced power brought on by not having the IMRC plate installed at the point when the plate would have opened back to full power...with possiblly a slight increase there from the reduced restriction...