General Supercharger Thread

I was very surprised. I was guessing 1-1.5psi

 

Awesome!!!

 

sea level with 76 and 650. my shit rips. still think it would be better with 1000 inj, dw340 pump, and 70 pulley.... but that's just me

 

I run 60# injectors on my twin turbo LS6 and still have room as well as a 255LPH fuel pump so I feel this would have to allow for some safety being that it is 65# injectors and 340LPH fuel pump the Whipple kit should be good for pretty high boost levels. I think I will aim for 10-12psi, I will not be WOT very often or for very long periods of time.

 

For reference I’m at 80% and I’m running 750cc and a 450 pump.. you’ll find out soon enough. One down at 8psi was close to 80 on my the old man’s Whipple at 1k above sea level

 

Yup the Dyno will clarify things for me I just don’t want to buy or “borrow” more pulleys than I need.

 

Lol you’re telling me

 

Nice what sizes are those? For sale?

 

I think I can make out most of the sizes but those look to be the -5 pulleys and I was told by Whipple I needed the -4s

 

The 3.3 size was 8 psi for me. And yea it’s available

 

Running the 2.0 on the tvs1900, 750's, 450 fuel pump and it goes...do the 70! Haha

 

I'm thinking about it!! I just am not sure how 'far' I want to take this.
It drives great as-is and fits my needs (probably more than I need but that's subjective...)
I just think an extra 50whp would be nice lol
My biggest hesitation, to be honest, is the injectors. Would love a nice plug n play option for 1000's but as I understand it that is not on the table.

 

I currently have a 2.3 press on. I have Snivs 2.2 but getting the press on off is a PITA. I'm running the DW 340LPH @ 55lbs on 5-0 650s, pretty sure @snivilous said I'm under 70% injector duty but I may be mistaken. Considering I have seen near 12lbs on the 2.3 I'm hesitant to do the 2.2 but most likely will someday when I finally put the Mishimoto radiator I have had for OVER a year in.

ALso, post O2s are on the way, be here tomorrow.

 

Yes sir

 

Do it!!!

 

Going from the 2.2 to the 2.0 netted a solid 2psi increase. @snivilous pulley table is spot on. I'm at sea level...

 

@snivilous is still tweaking my tune but I am at 96% IDC on a stock Maggie 1900 setup and stock engine. I always like to learn so I looked up IDC since I am pretty much maxed out. I found an interesting read, here it is. It's long but informative.

Here I will attempt to dispel some widely advertised misconceptions about what Injector Duty Cycle (IDC) is. It is a subject that many people get wrong and even many professionals seem to miss the point as well.

It is a widely believed notion that IDC is a state of operation which dictates how long the injector is open and that an IDC of 100% would result in a statically open injector. Meaning it would simply remain open all the time until IDC's fall below 100%. This suggests that the supplied voltage is constant. This could be because people are confusing "duty cycle" in terms of how the injectors are being tested with "injector duty cycle" in terms of being a state of engine operation
With this belief, this would suggest that IDC has control of the injector and dictates when it should open and close which conflicts directly with the very idea of what the IPW(injector pulse width) is and does when in fact IDC is only a final calculated result of its environment. The first thing to consider is that the IPW is the only thing which defines when an injector is opened and how long it remains open, and the violation occurs when suggesting the injector remains open all the time which would result in an infinite IPW. Which is absurd. An injector that is static will be flowing during all four strokes of the engine cycle. IDC, simply put, is the result of various conditions... not the influence on those conditions.

The ECU derives it's IPW based on displacement, flow, air/fuel concentration, VE, load, RPM and other compensations. If your injectors are not big enough for the application, and the conditions are right, the IPW will actually be longer than the time it takes the piston to complete one stroke. The less you can decrease that time the better (to a point).

This is where the concept of duty cycle comes into play. To put it as simply as I can, IDC is how much of the intake stroke the injector is firing and is represented in % of intake stroke. The IPW is how long the injector is actually open and is represented in milliseconds. So if your intake stroke lasts for 20ms and your IPW is 22ms, then your resulting IDC will be 110%
To explain this, imagine the piston beginning it's intake stroke. The ecu commands the injector to open. When the piston gets half way down the cylinder, the ECU commands the injector to close. The resulting IDC would be 50% or half the intake stroke. If the piston makes it to the bottom of the intake stroke and the ECU commands the injector to close then, the resulting IDC would be 100% or all of the intake stroke.

In a situation where the injectors are not big enough for the application, the ECU will command the injectors to come on at the beginning of the intake stroke but not command it to close until some time after the piston has begun its compression stroke. So lets say your IDC's are 115%. What this means is that the ECU has defined an IPW that will last 100% of the intake stroke and 15% of the compression stroke for a total of 115%.

It is widely recommended that you keep your IDC below 90% in worst case scenarios. It is important to know that if your IDC's are good today they may not be tomorrow. This could be because of changing conditions due to environment or fuel. For instance if your IDC's are 95% today at 7000ft above sea level, and you take a trip to sea level, your IDC's will be well in the red. The same thing could occur between summer and winter weather and different grades of fuel.
Some reasons to track your IDC's are...

1. Excessive IDC's can result in very inconsistent AFR's or a leaning out condition. Because the ECU is commanding an IPW to be greater than the intake stroke time, the engine may not get all the fuel it needs because the valve will be closing while the piston begins it's compression stroke and the injector is now firing on a closed valve. This could also result in pooling of fuel at the intake valve resulting in unatomized fuel entering the cylinder upon the next intake stroke.

2. The lower you can get your IDC the better the intake charge has a chance to mix resulting in very consistent AFR's and smooth operation.

Now with that said, you don't want your IDC or IPW to be to small either. Too large an injector could result in IPW's being so short in time that the injector doesn't have time enough to start flowing fuel resulting in choppy idle and inconsistent fuel trims during lower RPM operations.

 

it would be nice if our Scangauges/whatever could monitor this....the scangauge said he could build the formula, but he did not know the variables...

 

Good info. Why we try not to stray above 80%. Can start getting inconsistent spray patterns and can vary the amount of fuel delivered.

 

I was lean on the stock set up too. I had to go to a 450 pump, I went to a 2.3 pulley and had to get a complete fuel system with 750cc injectors. I'm now running a 2.0 @snivilous pulley and had to bump it up to the 1000cc injectors.

 

I haven't checked this last tune tweak, but I know I am running rich right now. My AFR right now is 9.8 - 10.4. Letting the current tune settle in to get another data log and go from there.

 

My original tune was at 87% IDC, not bad. But it's gone up to what it is now. Haven't done a current log but I know I am rich from the readings on my AFR gauge. We will see what it settles in to and see if injectors and/or fuel pump is in the future plans.

 

Any way to add or link this to the OP?

 

I'm around 10.8 down to 9.8 afr, ocassional dip and rise. It will settle in at 10.5 which is where I want to be in moderate boost.

 

rpm / 2 * pulsewidth / 1000 / 60 = rpm * pulsewidth / 120000

Engine rpm divide by 2 to get the revolutions that the intake stroke is on, multiply that by pulsewidth and you end up with total injector open time in a minute (intake strokes per minute * pulsewidth). But that's being measured in milliseconds, so divide by 1000 to get it into seconds. You now have calculate total injector open time in seconds, over a minute span. Divide by 60 seconds (since rpm is in minutes so need to convert back to minutes) then to get the percentage of injector open time. Which just ends up simplifying down to RPM * PW / 120,000

And double checking that in HPT:



6000rpm * 15.6ms / 120000 = 78%

 

@ScanGauge


James,

can this be programmed into the SG3?

 

Is that a window option we can see while logging? Id like to see what mine is

 

Sniv can send you the channels he monitors and you just load it in

 

I just emailed you the datalogging files I use. If you don't want to use them that's fine, just search Injector Duty Cycle which is under the Math tab and plot that:

 

The more useful way imo is to plot it on the spreadsheet, then you don't have to sift through the log finding the peak on the line graph. The spreadsheet will just show you the max value from the whole log. This is how I set it up: