hi everyone,
I have done some home work regarding the SOI this is the calculator I use to keep me in the ballpark, it takes into account the injector size and calculates based on target AFR the load and required IPW and Injection duration and adds to it the overall timing to give you a picture of when to start injection.
This is what I really use to check if my injectors will be up to the task or not.
this is how it looks like after putting the data back into the table.
Last edited by jarrah; 09-27-2015 at 05:57 AM.
I haven't looked at the spreadsheet yet, but how does the response/pedal feel with an SOI chart like that? I tried a similar looking curve and it felt like it hurt part throttle power/response, like too much injection time in certain areas deadens the snappiness or hurts combustion, I don't know.
Higgs did u get the chance to open the file and have a look at it i will try tomorrow those values on the dyno
I did download it but I need to get a log and input some values still....didn't get the car out this weekend. Maybe I will just use my truck.
I know this is an old thread. I was running through old threads and decided to try this SOI curve. It makes logical sense.
On a 2015 GMC 5.3L It caused KR on a tune that was running without any KR. Changed to this curve and at Part throttle medium to heavy load (Heavy tip in 1600 to 2000 RPM) It created some big -8 deg knock retard. It still makes sense however. I am trying it again tuning out the KR by DECREASING some of the Injector advance in that area. This curve added about 20 deg avg in there. It looks like that's to much down low at part throttle med load. Setting the cruise at 50 mph causes immediate KR for a second, then OK.
mod11.hplmod11.hpl
Anyone else try this curve/spread sheet? It looks like a real good start with a little tweaking. A dyno would really do the job here. Did anyone get a chance to see it on a dyno?
Last edited by Robert C Morgillo; 09-18-2017 at 10:20 AM. Reason: spelling
It advances the injection timing and makes things lazy NA doing it this way due to improper atomization - Would maybe be decent with a blower, but even then not sure?
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
From what I have seen jarrah has been super helpful on the math/chart stuff. I see he says that he uses that system to see if injectors will be big enough for certain applications...but with everything I have read on SOI from GHuggins greater fuel economy is usually gained on the GEN5 by retarding slightly from stock. I would love to take one my client's GEN5 6.2 Denalis for a few days of experimenting...but I don't see it happening in the near future so I'll just keep begging for more info.
GHuggins etc... Where do we start with the SOI stuff? Backing it up on cruise conditions, Id assume advancing it under high load conditions like blower cars etc but what kind of ballparks? Have yet to do much DI stuff, just a little diesel tinkering but its been forever messing with that even
Factory Stock 97 SS M6 13.51 @ 104.3 mph
Stock Longblock LS1 w/ 233/238 P.S.I. Cam
10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago
'99 TA trunk mounted 76mm 6 Liter
9.0s in '09 @ 153 MPH
Turbo 5.3 Volvo 740 Wagon
32psi and still winding out 5th on the highway somewhere
To me it appears to be sensitive. The DI does not have much time to deliver. That seems to be becoming apparent. GHuggins and the rest with dyno time on DI gas motors, have a lot of knowledge here. This is definitely a "try it and see" area on these DI gas engines. Under multiple load and cruise conditions, it seems to vary a lot. I think in a diesel you just pour in as much as you can! The difference here is at 5500 RPM the injectors have less than half the time, and a more volatile fuel. One things for sure, when I change it, it makes noticeable changes. Not at all like a port injected gas motor, where you can make bigger changes with less effect.
There is a small area where the injectors seem to be timed to correlate with the EGR effect of the VVT however.
Last edited by Robert C Morgillo; 09-19-2017 at 01:59 PM.
Yeah. I think you are right on. As SOI is soooo related to camshaft timing....if you reduce or remove the "EGR effect" from the cam timing tables (way more cylinder pressure), SOI and the "variable cam" spark tables may have to reflect that to some extent. I don't see an injector timing table directly related to cam timing but more loosely as the SOI table is built on expectations about ignition and cam timing. I still think that it will prove to be worth it to reduce the EGR effect in the mid throttle regions (maybe .40 cyl airmass and up, more like the low or mid baro cam table) giving much better response and reduced need for gear changes during medium throttle transitions BUT keeping the reduction in pumping losses/economy in very light throttle situations. I have done this on several 6.2s without SOI adjustments and been very happy....but am sure that with proper SOI tuning the improvements will be even better. I am looking forward to see where this is going....
As the camshaft retards, spark lead is advanced (through the VVT modifier table) and injection timing is also advanced (in the SOI base table).
I would think advancing injection while retarding valve events would be the opposite of what you would want to do, but if advancing the spark lead to counteract torque losses from cam retard requires more injection time, I guess that's how GM wanted to do it. Maybe there is enough EGR effect at that RPM to pull fuel sprayed with an open exhaust valve back into the cylinder.....
I am trying this curve now. I applied Ghuggins suggestions and gave it a roll. Exactly what you expected IARLLC.
Capture.JPG
This POI is a global reduction from stock. The area in the EGR zone is "normalized". It is then smoothed from about .44 g Cylinder air mass and up the RPM scale. I found that I had to dial back ignition timing (which was aggressive) from 1200 - 2000 rpm Med To High Load (.44 to .68 Cyl g), as much as 5 deg in some areas to eliminate KR. The interesting thing is the vehicle response. Part throttle Fuel consumption seems to be unaffected with the ignition timing reduction. I think this reflects the increased cylinder pressure in the EGR zone. Top end full load needed no changes. The vehicle runs well after timing changes with no surging or, recognizable issues. Throttle response and the ability to hold in gear under loading is apparent. There is definitely something here to look at. This is an open, long tube header vehicle. The VVT is altered to remove all EGR effect. I think this needs to be factored in. I do not believe the results will be the same on a full exhaust application. A dyno is required now to see if there was any real numbers that can be looked at. Seat of the pants and logs are just a hypothesis at this point.
These Gen V motors make you want to run in modified classes! It looks like you can tune the heck out of these baby's! If we had the budget......
Last edited by Robert C Morgillo; 09-20-2017 at 07:49 AM.
VVT mod tables are 0. I globally reduced injection time a small amount. I over laid the VVT chart and the SOI chart. I tried to "normalize" it in that small EGR area. Then smoothed out the 2000rpm and up. It behaves just like in the 1980's where when you blocked off the EGR valve you introduced spark knock at part throttle tip in. And just like way back then, throttle response seemed to improve once the ignition timing was modified to eliminate KR.Originally Posted by Higgs Boson
Good book
Here is a good read on GDI. Automotive Spark-Ignited Direct-Injection Gasoline Engines A very expensive book!
Interesting. Especially the "oil dilution" that can occur with various SOI events.
A good excerpt here...
https://books.google.com/books?id=j8...timing&f=false
Robert
Have you read that book? I found your link to it earlier and I am still hesitating on adding to cart. That excerpt makes perfect sense, it may be time to adapt a GEN4 EOI calculator?
No, I have only read the excerpt that the link leads to. I also have it in the cart but, the price! Wow. It is directly what we are doing. A good engineering book on applied DI Gas Engines. If anyone buy's it, maybe they will let us know if it is worth that price.
I may have to pay a little more to play, I'm this deep may as well go a little further. I have my head wrapped around what is going on. Just missing some critical data to make it that more clear.
If I due some drunk amazon priming ill share what I can.
Thank You
This is an awesome thread that I'm going to bump. Maybe there's a newer, more relevant thread somewhere about this topic?
I have altered my VVT tables and aggressively blended out the EGR effect from .48g airmass up and pretty much eliminated any retard below the same airmass above 2600 RPM. I'm curious how I should adjust SOI in those load ranges that I added cam advance back in.
Also, side note, anyone know what happened to GHuggins?
I don't know but if GHuggins would write a book on SOI (for GEN5s I'd buy it.)
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