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This is more like it

magnuman said:
Zilla,
I agree with most of the things you have said, and it is lots of good info. Thanks. I love all this great discussion. I feel that DCX has left the wide open throttle (WOT) mixture a little on the rich side (11-12:1) to preclude any potential engine damage. Almost everyone on the "other" forums that has dyno'ed their LX Hemi's has come up with a rich reading at WOT. When at WOT the fuel management system is in the "open loop" mode and the oxygen sensors are not monitoring the mixture. DCX probably gets away with this because it is at WOT and not at cruise, when fuel management is in "closed loop" mode and mixture is maintained at 14.7:1 by the PCM with input from the oxygen sensors. I don't know of any state that does emission testing at WOT. I think most test under idle and cruise conditions, and would not catch this. I have built a WOT mixture control rheostat that theoretically will richen the mixture, hopefully to 12.8-13.5:1 which is where maximum performance is achieved. I based my assumptions on the shop manual's vague statements that the mixture is always programmed for 14.7:1 under all conditions. After seeing others' dyno results I may have to modify this setup to lean the mixture out to get the desired results, if this is true. I am thinking of buying an onboard exhaust gas analyzer to verify this before messing with it anymore. As far as the CAI goes, I am sure there is some improvement with most descent ones. I personally built my own. It is a double wall, double insulated intake that maintains the stock filter to plenum length and utilizes the stock air box, K and N drop-in filter and one additional 3 inch cold air duct into the airbox from just behind the grill. My intake air at cruise on the highway runs at ambient, and in town, 0-8 degrees above ambient. The reason I maintained stock filter to plenum length is because of an article in Poplular Hot Rodding Magazine. I will quote the part that sold me: "The system has a tuned length from the filter to the plenum and from here each port runner to valve is a tuned length. Computer modeling and dyno testing has allowed the ports, plenum and filter-to-plenum runner length and diameter/volume to be sized near optimally for a wide power band consistent with street performance needs." I've also enclosed a thread from "maneval69" off another forum that shows the HP/Torque difference between stock and with NO filter, which demonstrates there is room for improvement (almost 20 HP) and the rich condition I was talking about at WOT. "Here are the dyno results for my stock RT. 2500 miles on the car.
I did 4 pulls all with the #17 fuse pulled and the car in 3rd gear.
The first 2 where as I pulled it in the shop with all stock equipment in place.
the best of the first 2
SAE Max Power 278.1 @ 5100
SAE Max torque 318.2 @between 4000 and 4400(it's not marked on my sheet)

For runs 3&4 I unhooked the intake from the air box and left the hose unfiltered.
ready for this!
SAE Max Power 296.5 @ 5200
SAE Max torque 327.9 @between 4000 and 4400(it's not marked on my sheet)

It would appear that a free flowing intake is well worth it.
My brother dynoed his ls1 right after I got through. He gained only 5 horsepower by opening his air box to eliminate the filter. His does have the ram-air box though.

Air- fuel ratio
Mine read 11.7 to 12 from 4100 through 5200 rpm on all runs. That means there is power to be made by leaning the mixture (programmer)


One more thing -This motor sounded awesome with the intake elbow unhooked from the airbox!"
Thanks Magnuman your input is definitely most valuable. This information what I and probably others- needed to get closer to a fuller appreciation of what is actually happening. The significantly rich at at WOT brings us closer to the truth. We are in absolute agreement on reducing the WOT richness to optimize the mixture for maximum power. Please keep us informed with full details, of any success with optimizing this - definitely worth a new thread.

For me your statement by Vizard in bold re retaining the tuned lengths that the have been computer modelled and dyno tested is one of the most important. Based on what you have posted I (and probably others) would like more specifics on your own CIA system that adds to Chrysler's work on the intake. If you have time: a brief materials list especially the double walled, double insulated intake, a few pictures, and your installation comments would earn you much forum kudos.

The dyno figures you posted clearly show peak power benefits of a free flowing intake - do your have figures for, or can you post the comparative curves showing the full rev range?

We are clearly on the same wavelength here - thanks again

Zilla :)
 

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I asked this before in a different thread and it went unanswered. Not trying to be a smartass here at all. The computer has to compensate for air volume changes in some way, otherwise we would constantly be seeing lean rich conditions. I read the previous posts about the calculations being "preprogrammed" within certain parameters etc... okay, makes sense, BUT. There is a huge difference in air between me driving in the mtns at 10,000 feet at 90 degrees and driving at sea level at 30 degrees, everyone can agree on this I'm sure. Obviously the computer will make up for the difference in air volume. Now what I want to know is this. Why won't a CAI make the computer think it's closer to the sea level/cold temperature area even though I may be driving at 80 degrees and 5,000 feet? Since it is getting more air, and it will compensate for it, won't that equal more power?

On a side note, I got into a little arguement with a local speed shop about the C, we were talking mods and I told him that people were saying a CAI has no effect because of the speed density system. He said that is absolutely WRONG. It will compensate for the extra air and add fuel because it will see a lean ratio at the O2 sensor. He says the O2 will actually make up for quite a bit. He has turbocharged cars with a speed density system (Honda I think he said) and the computer added the fuel to make up for it.... Not my words, his, and he has made HUGE power on numerous types of cars so I respect his opinions.

Also, if the ECU is uncrackable, and the SD system won't make up for extra air, how the heck are they supercharging the motor???

Enough questions....
Thanks!
 

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Good points, PE. Of course the ECU adjusts the air fuel ratio all the time. It just has outer limits.

Case in point: this past winter, I opened up the breathing on my stock air box by drilling a series of 1" holes through the base. We had some really cold days - down to -30 Celcius. The car was definitely much quicker with the cold air and the better breathing, according to my SOTP meter.

There has been some very good info presented in this thread. I am not disputing the presentations. Just pointing out that:

  1. The Hemi is a 4 cycle internal combustion engine that demands big quantities of air coming in at mid-range and above.
  2. The factory tuning is not optimized for performance.
  3. A good CAI will give noticable gains to a stock 5.7 Hemi
 

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Pwdr Extreme said:
I asked this before in a different thread and it went unanswered. Not trying to be a smartass here at all. The computer has to compensate for air volume changes in some way, otherwise we would constantly be seeing lean rich conditions.
There's a difference between air volume and air density. The cars computer adjusts fuel based on both of these, but "performance" potential depends entirely on air density to burn fuel not overall volume.

I read the previous posts about the calculations being "preprogrammed" within certain parameters etc... okay, makes sense, BUT.
This has to do with the fuel maps preprogrammed into the cars computer at Open loop, or WOT (Wide Open Throttle) conditions.

Closed Loop -- ECU is adjusting fuel delivery based on O2 sensor conditions.

Open Loop -- ECU is delivering fuel based on TPS (Throttle Position Sensor) and predetermined fuel maps (Basically a database on how to control the injectors and at what RPM)

There is a huge difference in air between me driving in the mtns at 10,000 feet at 90 degrees and driving at sea level at 30 degrees, everyone can agree on this I'm sure. Obviously the computer will make up for the difference in air volume.
Yes, huge difference, but the AF ratio will be adjusted at cruise, or part throttle based on air density readings from the O2 sensors for the leaner air. Like I said previously, at WOT the car will go in open loop mode and deliver fuel based on the preprogrammed maps, not from the sensors. In higher altitudes cars don't perform as well as in lower altitudes due to the air quality. (This is why superchargers, or turbos are great for high altitudes, not for delivering more mass air, but more O2 molecules. To put it in perspective, a car in Colorado will need 10psi of boost to burn as much fuel as a car in Florida does with 8psi of boost.

Now what I want to know is this. Why won't a CAI make the computer think it's closer to the sea level/cold temperature area even though I may be driving at 80 degrees and 5,000 feet? Since it is getting more air, and it will compensate for it, won't that equal more power?
Again, It depends what you're talking about. Part throttle closed loop operation, or WOT open loop.

SD FI systems adjust fuel delivery with manifold pressure and Air inlet temperature. Depending where the IAT (Inlet air temp) sensor is located (close to the manifold probably) the air temperature difference in a CAI vs. Stock intake will be barely noticeable for the computer to make adjustments to fuel at part throttle or cruise. The only thing I think it will do at this point is give a little better gas mileage. Afterall, you don't care about power cruising down the street.

Now, as for making power at WOT the only way to do it is feed colder air into the engine with a CAI and adjust the preprogrammed fuel maps.

However,

I commented before that the CAI could work based on how rich the computer tells the car to run at WOT. For example, if the car runs at 11.5:1 AFR (Air Fuel Ratio--Air:Fuel), but would make more power at 12.0:1, adding a CAI would make the air dense and effect the power output, but this has nothing to do with the computer adjusting, it's kind of like adding leaner jets to a carbuerator. (Keep in mind, you make more power burning all the fuel delivered, that's why a leaner or higher AFR is desired....So long as the car doesn't detonate.

On a side note, I got into a little arguement with a local speed shop about the C, we were talking mods and I told him that people were saying a CAI has no effect because of the speed density system. He said that is absolutely WRONG. It will compensate for the extra air and add fuel because it will see a lean ratio at the O2 sensor. He says the O2 will actually make up for quite a bit. He has turbocharged cars with a speed density system (Honda I think he said) and the computer added the fuel to make up for it.... Not my words, his, and he has made HUGE power on numerous types of cars so I respect his opinions.
Obviously this would be true in a boosted application with A WIDEBAND O2 SENSOR! Our C's don't have them. :p They have narrowband sensors and ARE NOT used in WOT. He should know this and obviously overlooked it. He needs to get off the Honda crack. :D j/k (Essentially what a wideband O2 can do is measure rich conditions like 11.5:1 AFR and adjust the computer at WOT. Stock Narrowband ones can only measure around 14.7:1. This is only for cruising and to run lean to meet emission requirements. Like I said before, at WOT the car runs considerably richer and it's physically impossible for the O2 sensors get any readings and tell the computer to adjust the fuel.

Also, if the ECU is uncrackable, and the SD system won't make up for extra air, how the heck are they supercharging the motor???
About the ECU being uncrackable.....NOTHING is uncrackable....just give it time. :D

As far as your supercharging question. Without programming the computer they can do it one of two ways.

They can have a secondary computer that senses boost (manifold pressure) and dumps more fuel into the manifold using auxiliary fuel injectors, (sort of like a separate fuel line for a wet nitrous system. When the solenoids open to dump n20 in, it also dumps more fuel in.

The other way is with an FMU (Fuel Management Unit) essentially what this does is sense boost and restrict the fuel return line to the gas tank. This causes the fuel pump, possible 2 fuel pumps, to spike the fuel rail pressure from 40-45psi up to 60-90psi which "tricks" the injectors into squirting more fuel. This way is dangerous because you can lock up the injectors depending on what kind they are with too much fuel pressure, lean out the motor, and BOOM!....Not to mention the FMU just failing all together and leaning the motor out.

I hope this helps and sorry if I put some of you to sleep. :D
 

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I just ordered the volant intake and I have an Escort GT2 Timer and will do some before and afters with it...
 

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Just chiming back in on this as many of my "pro" comments were used in Zilla's post - just want to keep them in context.

In stock form, the HEMI in these cars sounds like...well, it sure doesn't sound like it has a HEMI! No where have I said it adds hp - and my observations on throttle response and pulling a little bit harder are just that...observations, with no proof to back them up. I didn't put the Borla/Volant combo on my car to add hp - I added it to make my car SOUND better than the whisper quiet stock setup!! The C is my daily driver - have I noticed some improvements? yes. Do I have a dyno sheet? no, don't care if I have 15 extra hp, it's not why I did it. Would I buy or recommend the Borla/Volant combo? Absolutely!

Again, I didn't buy these mods for the hp, I did them for sound! If it's hp you are looking for - then get dyno sheets to prove they work if that's what you want, but for the nominal gains (if any), I don't care if there is any more power.
But I've said it before and I'll say it again. At 340hp, this car is a big animal, now, it sounds like one too!!! And for that, the mods have been worth every penny I've spent.

*I will be running the 1/4 soon with it and it will be fun to see what my times are. :D
 

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vvv90 Okay, that info makes more sense out of it thanks!!!! One thing that still confuses me a little bit is WOT differences between high altitude hot ambient and low altitude cold ambient. If the computer is not using the O2 to adjust, wouldn't there be a big enough difference in the air to cause a lean/rich condition with the varrying altitude/temperature?

The next time I run into the speed shop guy, I'm going to mention what you've said, I'm interested to hear his comments ;)

Thanks again!
 

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will the increase in air and temperature of the air now coming in thru the volant system, thus affecting the air/fuel mixture (and with computer not adjusting for it), affect the engine adversely in any way, short or long term?...thx for all input.
 

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Pwdr Extreme said:
vvv90 Okay, that info makes more sense out of it thanks!!!! One thing that still confuses me a little bit is WOT differences between high altitude hot ambient and low altitude cold ambient. If the computer is not using the O2 to adjust, wouldn't there be a big enough difference in the air to cause a lean/rich condition with the varrying altitude/temperature?
Though there will be differences in lean/rich conditions at WOT for the same car at different altitudes, it's probably not enough to either ping or blow black smoke out of the tail pipe. Probably just a difference of 11.0-12.5:1. Afterall, cars aren't tested for emissions at WOT, just under moderate load and cruise where the O2 sensors can do their job.

Also who knows??? with todays advanced SMPI systems, there could be a "learn" factor for air density from the O2's that could affect the fuel maps.

Afterall, I'm not a engineer.....but I did stay at a Holiday Inn Express last night.

Personally, I think ALL cars should come with a wideband O2 sensor. We'd get optimal power under any driving condition.

The next time I run into the speed shop guy, I'm going to mention what you've said, I'm interested to hear his comments ;)

Thanks again!
Do that...He's probably just so used to boosted applications with 2 or 3 bar MAP sensors and aftermarket EFI closed loop systems he overlooked it.

To be frank, this is EFI basics. He SHOULD know this if he's tuning EFI cars.

http://www.autoshop101.com/forms/h58.pdf
 

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HEMISKI said:
will the increase in air and temperature of the air now coming in thru the volant system, thus affecting the air/fuel mixture (and with computer not adjusting for it), affect the engine adversely in any way, short or long term?...thx for all input.
None whatsoever.

The computer will adjust under cruise and part throttle.
 

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To me, if it makes no negative effect on my speeds, and sounds better, with a possiblity of an added 0.5-1.0MPG, it'd be worth it to me.

And I'm not as concerened about dyno charts as I am my 0-60 speeds or 1/4 mile speeds with a simple upgrade like this.. I'm kinda curious to see what happens!!

Anyone know if they have 10 people yet?
 

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Sounds like they are close to 20 people for the 2nd GP! Hmmm....I wonder how active the Volant/CAI threads will be after all of those new installs!!!!!!!!
 

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Under cruise conditions the Manifold Air Pressure sensor (MAP) acts like a barometer, and sends this info. to the Power Control Module (PCM), which in turn adjusts injector pulse width to maintain the 14.7:1 air-fuel mixture. This is the main input that controls mixture at different altitudes. The Intake Air Temperature sensor (IAT) provides input for changes in temperature. It's really a pretty complex, yet neat setup, but would be better if it were a Mass Air system. The limits of our Speed Density system are mainly the pre-programmed limits/ranges of the PCM. These limits/ranges are designed to accomodate nearly all environmental conditions we are likely to encounter. To indicate the complexity at cruise, for instance...the PCM adjusts mixture by using inputs from MAP sensor, RPM sensor, IAT sensor, engine coolant temperature, camshaft position, knock sensor, throttle position, 02 sensors, air conditioning switch position, battery voltage, and vehicle speed. At Wide Open Throttle (WOT) inputs used ar IAT sensor, engine coolant temp., RPM, knock sensor, MAP sensor, and throttle position. The fuel injection system also has built in pre-programmed short and long term fuel correction (adaptive memory) routines that are triggered anytime mixture reaches a predetermined "switch" point. The adaptive memory is a whole different bucket of worms though. My head hurts! Guess we've pretty much beat this to death.
With regard to Cold Air Intakes (CAI's), the main approach I used is that the cooler air (denser) in, the better for performance and gas mileage. Really though, at this point I am more interested in the gas mileage. This is why my home built CAI utilizes an additional air inlet from behind the grill to the airbox (in addition to the stock "eardrum" inlet in the fenderwell), a double insulated stock airbox, a K and N drop-in filter, and a double wall, double insulated intake tube from filter to plenum. I don't know if this, by itself, works, but I do know that with this and my other minor mods., my in-town and highway mileage has increased significantly. I now get 15-18.4 mpg in town/rural, and 27.5-28.3 mpg on the highway between 60-70 mph. I have recently changed to synthetic oil and will be taking 600 plus mile trip next week. It will include mountain, flat land, and rolling hills. I hope to do even better now. For those who doubt, a true COLD AIR kit...not drawing heated underhood air is a good investment IMO. If anyone is interested on how I did mine, I'll start another thread that specifically addresses my CAI. Let me know.
 

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New thread

magnuman said:
If anyone is interested on how I did mine, I'll start another thread that specifically addresses my CAI. Let me know.
Yes :)

Zilla
 

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Jet Performance Chips

What about Jet Performance Stage II Chips? Don't they reprogram the computer specifically to allow for max performance using open "Borla" type exhaust and CAI's? And removing the rev limiter? <evil grin>

Remember - there are no such things as supid questions....only stupid people!

Bob
 

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BobCav said:
What about Jet Performance Stage II Chips? Don't they reprogram the computer specifically to allow for max performance using open "Borla" type exhaust and CAI's? And removing the rev limiter? <evil grin>

Remember - there are no such things as supid questions....only stupid people!

Bob
Yes they do reprogram the standard fuel maps on a car and adjust for mixture and spark advance giving maximum performance. However, I've never been a fan of those aftermarket computers. The best thing to do is do all the mods you plan on doing, like CAI, Headers, Rockers, new intake manifold, whatever, and wait for the ECU to be cracked and take it to a dyno. If they get a large volume of people just like the LS1 tuners see, they won't be much more expensive.

But that's just my opinion, prices and results based on my suggestions will vary.
 
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