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Hi Folks,
While I haven?t posted a lot on this project lately, the project has not been back burnered. In fact I have some new info to share.
Let me first start by saying, I had my Jeep on the dyno yesterday. This was an ?On the House? run to read and record peak Horse Power and Torque measurement prior to the ?tuning adventure? I am about to begin.
Here are the results.
Please note, I have done no tuning what so ever other then to increase the spark gap by 0.010-inch. (I will explain this action in a few minutes.) Other then the spark gap these are the results I received with a straight ?Bolt-On of the Avenger Super Charger?, right out of the box.
Peak Horse Power at the Wheels
Stock Engine = 124.3 HP at 4500 RPM
Super Charged = 187.7 HP at 4550 RPM
Net Gain = 63.4 HP
Net Gain as a Percent = 51%
Peak Torque at the Wheels
Stock Engine = 163.2 ft-lbs at 3000 RPM
Super Charged = 249.7 ft-lbs at 2750 RPM
Net Gain = 86.5 ft-lbs
Net Gain as a Percent = 53%
That said let me tell you what else has been happening here.
I had the opportunity to spend two full days with my Jeep over at my friends shop in Speedway, IN.
Joe runs an engine dyno tuning shop up in Speedway. (I think it has something to do with some racing that goes on up there.) His shop has 6-chassie Dyno?s and 6-engine stand dyno?s.
Unfortunately given the time of year this is, each was fully rented out in 24 hours blocks of time.
But we did some work, some testing and I did get an education.
Here is some of what I learned. Perhaps it may be helpful to others who have super charged their Jeeps.
Where I Started At
(Please Note: I had not yet run my super charged Jeep on the dyno when I went up there.)
I could not be more pleased with the performance of my Avenger Super Charger.
Having done super charger installations on other vehicles over the years I kinda knew what to expect. Most of what I was expecting, as far as additional tuning needs goes, I didn?t see a big need for.
Performance, based on the seat of my paints was and is indeed remarkable.
After re-flashing the PCM twice, and driving my TJ for a bit more then 1,600 miles the only down side I have found is an ever so slight ?Ping? which occurs between 1,800 and 2,200 RPM coming off a steady throttle.
Others here and via email have shared a similar problem, only much more severe then I was experiencing.
In my case this was hardly noticeable, again happening only when trying to accelerate lightly.
I called Joe and he told me drive it up there and he?d take a look at it.
First thing he did was take it for a five-mile test drive around the track. His diagnosis; ?Spark Timing most likely too far advanced.?
After letting the engine cool off we pulled the spark plugs. They read fine.
Joe disappeared for a few minutes behind one of the many privacy curtains in the building and came out with a micro fiber optical camera! (his place not only looks like a hospital ward with all the privacy curtains, but he has hospital type tools as well.)
Each cylinder was inspected using this tool. WOW! You can see everything inside, just as if the head was off.
There was NO Carbon Buildup at all, not on the heads, piston tops or the valves.
This procedure was done to insure the knock was not caused by pre-detonation, due to carbon build-up in my 85K plus mile engine.
As I said, no carbon build-up at all!
Joe had me re-gap the plugs another 0.010-inch. So I took them to 0.045-inch and put them back in.
After hooking up a data recording computer and taking out the extra O2 Sensor I installed in favor of a Wideband Lamda Sensor I took it out for a 15-mile test drive on the street
Guess what?
No Spark Knock, none at all!
I mean completely gone!
Back at the shop I asked Joe what happened?
He told me we ?retarded the timing?, across the board, by about 1.2 Degrees by increasing the spark gap by 0.010-inch to 0.045-inch.
My Continuing Education
I was telling Joe about others with the same super charger kit having very sever spark knock and that I wanted to try and understand why.
He had me pull my Stock Air Box, which was connected, to the Snorkel, and install a K&N free flow filter under the hood. Then I took it for a test drive recording all sensor data along the way.
I didn?t make the entire 15-mile drive. I couldn?t.
I thought the engine was going to break! The spark knock was horrific! It was so severe, it sounded like a bucket of bolts rattling around under the hood. A power reduction was clearly noticeable, even by the seat of my pants.
I felt like if I continued on with this I was going to break things so I limped back to the shop after about 10 miles.
When I told Joe what happened he gave me his typical smart reply. ?I Know?.
We pulled the data monitor he showed me what was happening.
The Intake Air Temperatures with the K&N filter sucking hot air from under the hood were a minimum of 55 and a maximum of 73 degrees F hotter, then the Intake Air Temperature coming through the Snorkel.
Here?s the explanation, as I understand it.
Warmer air is Thinner. Thinner air weighs less. Air that weights less requires less fuel, and More Spark Advance. (TO A POINT!)
Colder air is Thicker. Thicker air Weights More. Air that Weights More Requires More Fuel, and LESS Spark Advance. (TO A POINT
There is however more to it then Air Density and the correct A/F Ratio. Specifically the A/F Volume.
For example, 1 Ounce of Fuel and 14.7 Ounces of Air will give you an A/F ratio of 14.7
Also, 1 Pound of Fuel and 14.7 Pounds of Air will also give you an A/F Ratio of 14.7
But these two, identical A/F Ratios are not the same, by Volume!
Put too little A/F mix, by Volume in the cylinders, with timing too far advanced and you will get Spark Knock. (Joe says so anyway and I am willing to go with it till I know something otherwise.)
After looking at the recorded data, WITH the Snorkel, it appears Timing Advance was a hair more then it should be, at certain RPMS and Boost pressures.
Joe tells me that this is occurring at the point where vacuum is lost and pressure from the blower is just beginning to build. This is the transition from normally aspirated engine to a pressure operated one. This is also the transition from ?Cloosed Loop? to ?Open Loop? mode.
Why is this happening?
Well, as I understand it, based on Joe?s explanations, the combination of MAP sensor signal (which is only capable of measuring 1 bar, or one atmosphere) and IAT sensor signal are unable to provide the correct inputs to the ?Perfect Gas Law? to calculate Timing, and to a lesser degree on my engine fuel mapping.
The problem is greatly amplified when the intake air temperatures increase, as evident in the use of the free flow K&N filter and sucking in under hood hot air. Ignition Timing is just Too Far Advanced for this air temperature/density.
I asked Joe why, with the exception of the slight spark knock, it worked so well with the Snorkel.
He told me with the cold air coming through the Snorkel it was close, but it wasn?t right on the money.
Looking at the actual Air / Fuel ratio?s as read and recorded using the wideband O2 Sensor, it was easy to see there was plenty of fuel available from these 26 pound injectors. But just like with the Timing, the A/F Ratio is close, but not perfectly mapped.
At times, under high boost, the A/F ration was as Low as 11.9, which to me means the 26-pound injectors are quite capable of flowing the needed extra fuel for the blower. As I had suspected, almost across the board my installation was and is running RICH, with or without boost pressure.
The Ratio UNDER BOOST was in a range of 12.0 to 12.9 A/F Ratio, 95% of the time.
The Ration WITH NO BOOST was typically 13.0 to 14.2 A/F Ration.
As you can see both are generally ?Rich? mixtures.
The only time it runs lean is when going from transition, from normally aspirated to pressure mode, when that slight throttle increase induces the ?ping?. (closed to Open Loop transition.)
Joe disappeared behind a few more curtains and came out with a ?black box?. After connecting all the sensor up to my Jeep I took it for another test-drive with the K&N filter still in place.
WOW!!!!
The difference was amazing! Not only was there Absolutely NO SPARK KNOCK, but there was a remarkable performance improvement!.
I have to have one of these black boxes! (Well I thought I did till I found out the price!)
This ?Black Box? that Joe hooked up was a special type of Piggyback Computer that managed and monitored timing based on individual cylinder spark knock and the A/F ration for each cylinder using a knock sensor for each cylinder. Timing is advanced or retarded based on actually knock and controlled on a cylinder-by-cylinder basis.
It also had a 3 Bar MAP Sensor and required the Wideband O2 Sensor.
But for $3,800 I think I can live without it. Joe agrees.
As big a difference as there was in performance in my putting the Avenger Supercharger on my stock engine, there was an almost equally big difference (seat of the paint measured) with this ?Black Box? on the engine. Across the board, all RPM ranges, boost or no boost, my engine hummed like it never has before.
Being I have no intention of spending that kind of money Joe gave me his advice as to what I should do; Call ?Split Second? and purchase a custom built Fuel / Timing Calibrator Piggyback Computer.
(Please note I had already received this exact same advice from a gentleman named Hugh who has also done this Avenger Super Charger installation on a 4.0L Jeep. He was extremely pleased with the results he received.).
The FTC1-019 is a custom built Fuel Management and Timing Management computer that piggy backs onto the stock PCM. It come with it?s own 2.5 Bar MAP sensor and enable total management of the Fuel mapping tables (in Open Loop Mode) and Ignition Retard mapping tables across the RPM/Boost range
The FTC1-019 gets wired up to the crank and camshaft sensors, as well as the upstream O2 sensor and a few other things. Then you simply plug your laptop into it via a serial cable and begin to tune TWO, 3D mapping tables, one for Fuel vs. Boost Vs RPM, and another for Timing, vs. Boost vs. RPM.
As you tune these parameters you record them into the FTC1 as often as you would like by writing to the EPROM in the box.
When testing the results of your tuning effort the FTC1 records all sensor signal data in both data table and graphic overlay format to be downloaded and viewed on the laptop.
Taking the advice of both Joe and Hugh I order an FTC1-019 Timing/Fuel Controller from Split Second built to my Jeep?s 4.0L specs, injector size and boost pressure. It arrived last evening and I will be playing with it this weekend. The unit I ordered has an optional ESC control unit that allows me to force the Jeep PCM out of ?Closed Loop? engine management mode, whenever the Boost Pressure exceeds 1 PSI. (The transition window into Boost pressure from vacuum pressure.)
This is to ensure I can feed the engine a steady diet of fuel and timing both for performance, engine longevity and yes for emission purposes as well. (This is important to me.)
Joe?s Comments
It isn?t every day I get to pick the brain of someone as knowledgably about these issues as my friend Joe. In truth I doubt there are very many people in the world who are as knowledgeable or experienced in engine tuning of this kind.
Here are some notes I?d like to share regarding Joe?s opinion and comments of how MY Avenger Super Charger installation performs and what might be done to make performance and timing issues go away.
+++++26# injectors are more then enough if the Timing and Fuel Mapping are tuned.
+++++Fuel mapping, given the Stock PCM and the Stock 1Bar MAP sensor perform remarkably well. Not Ideal or perfect, but very operational and safe if you can retard the timing a few degrees.
+++++Ignition timing needs to be managed better. Ignition timing is too far advance across much of the boost / rpm range . This is a particular problem when migrating from no boost to a boost condition in the engine.
+++++In addition to the ?Spilt Second? solution for both Fuel and Timing mapping, there are other ways to manage the Ignition Timing available from MSD. Mallory, Accell, and a few other Ignition Management manufacturers. He didn?t get specific to models but a quick look through the Summit and Jeg?s catalogs and you can find them. I did.
+++++Anything that can be done to cool the intake air, upstream of the blower, such as a snorkel will greatly improve performance, have a positive effect on spark knock, and help to ensure engine longevity.
+++++Piggyback computers such as the Split Second? unit are by far the best solution to gain optimum performance and protection of the engine. Anyone reasonably skilled (me) should be able to get 90 to 95% of all available performance out of the engine in their driveway in one good day of tuning, The remaining 5 to 10% would require a dyno to help extract.
+++++Basic Super Charger Starting Points for my 4.0L Jeep engine.
Coldest intake air possible
Advance Ignition Timing to the point of spark knock. Then Retard Ignition Timing by 1.5 to 2 degrees across the board. This should generate maximum power without breaking things. This should be done at all RPM and Boost Levels
Target Air Fuel Ratio?s as follows:
No Boost = 14.7 to 14.0
0.1 to 2.0 psi = 13.5 to 12.7
2.1 to 4.0 psi = 12.7 to 12.5
4.1 psi and up = 12.4 to 12.2
That?s all I have right now folks. Daylight is burning here so I am going to go get another cup of coffee and install the Split Second FTC1 and see how this things works.
I will post more when I have something of any perceived value to share.
Have a great day.
Frank
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