Quick rule of thumb for some of you who may not know. Tuners and engine builders have been using this little trick for years. For every 1 #/min of airflow, you will be at approximately 10 crank horse power. Most people use a range of 8-12 crank horsepower per pound a minute of air. I like to use 10 hp and it usually works out very well. For example, when the truck was completely stock, it made 37#/min of airflow peak, which is roughly 370 crank. Very close to what Ford rated these trucks at. Take out 18% for drivetrain loss (give or take) and you end up around 303 hp at the wheels. This is about what my truck made when it was bone stock. Neat!
Airflow is a great way to estimate horsepower numbers. Of course, this is not perfect. Airflow does not account for increased spark advance or different fuels that allow for even more aggressive spark. It can be used as an effective ballpark.
We are going to take a quick look at boost on the last runs in histogram form, just to see what we were getting on the new turbos vs the stock ones.
Stock Turbos on SCT 93 Preloaded Tune: Load vs RPM vs Boost
Full-Race / BorgWarner OEM+ Turbos on SCT 93 Preloaded Tune: Load vs RPM vs Boost
Overall, not much different again. I would call it a wash. There a few points that the stock turbos made more boost, and a few where the opposite is true.
My original intention at this point was to compare the original BoostKing Custom tune with the stock turbos, to the Full-Race / BorgWarner OEM+ Turbos on the same tune. When I got to this point in my testing, I decided that the old custom tune would not be safe for me to run. I made a test hit and torque hit over 570 ft/lbs. Not exactly what I’m looking for and honestly a little scary as I was not trying to blow the motor. Too much airflow down low can cause fuel starvation issues, and even with my +35% HPFP I did not want to chance it or get into that territory.
Remember, my old daily driver custom tune would spike around 21-22psi early on with the stock turbos, but fall to 17 and hold about 15-16 psi to redline. I never really liked that 22psi spike but I never worried about it too much because on the street when I would go WOT, I would ensure my RPM’s were above 3000 before laying rubber.
Admittedly, before these turbos were installed, I had intentions of putting my truck on the dyno to work on that spike and a few other things. Time and other priorities here at work made that very difficult to find time. I knew how to drive the tune to mitigate the risk.
With these new turbos, that 22 psi spike became a much larger concern for me, so I decided to just start the complete custom tuning process for the Full-Race / BorgWarner OEM+ Turbos at this point. My goal with these turbos is to control the initial boost spike and maintain a meatier power band up top.
Moving on, let’s take a look at where my truck ended up at and start reviewing the data from the final tune file.
As you can see, the final numbers on 93 pump for my truck came out at 448 whp/510 wtq. Let’s compare that back to the old daily driver custom tune and stock tune as well.
Those are some serious gains under the curve. Power starts earlier and carries longer than the old turbos.
To recap on peak power numbers:
100% Stock Truck and Tune: 305whp/385wtq
Stock Tune with Stock Turbos + mods: 319whp/390wtq (+14hp/5tq)
SCT 93 Preload with Stock Turbos + mods: 360whp/395wtq (+55hp/10tq)
Old BoostKing Custom Tune Daily Driver + mods: 390whp/511wtq (+85hp/126tq)
Full-Race / BorgWarner OEM+ Turbos with FINAL Custom Tune: 448whp/510wtq (+143hp/125tq)
These values only represent peak gains. Just for fun, here is a chart of the truck when it was 100% stock, vs where it is today with the upgrades and tuning.
If you look at the vertical line just after 6000 rpm, you can see there is +200whp under the curve compared to a stock truck. The gains under the curve are insane. When at WOT, these trucks operate between 4500-6500 rpms between shifts give or take. You can see that with these mods and turbos you are right in the meat of the power on every shift. The stock turbos would begin to fall off hard after 5000 rpm. Not these turbos. Power all the way through.
Now we can start reviewing some data from the final Full-Race / BorgWarner OEM+ Turbos custom tune. Let’s call it BoostKing OEM+ Turbo Custom Tune.
• Boost – Now peaks around 19 psi. Average throughout pull is around 17-18.5 psi. No early spike either.
• Spark – I was able to work more spark into this tune, and on this run peaked around 14.5 with an average around 13.
• Load – Max load is 2.04.
• Air Flow – Max is around 55.7 #/min.
• Charge Temps – Peak around 104 °F at redline.
• Fueling – Starts near .82 lambda finishing around .79 lambda.
On the second screen shot above, you can see that the throttle is not open until a little before midway in the run. This is on purpose. To assist in controlling the boost spike that usually happens very early on, I employed a few tables that the PCM uses to control load targets. Using these tables correctly, I can let the PCM close the throttle to help hit the load target, and control boost until I want it.
As the RPM’s climb, I move these tables up above the load I am going to target, which lets the PCM open the throttle more. If I were to exceed the load limits of these tables, the throttle would close some. Desired TIP vs Actual Tip and other sensors would see this throttle closure and automatically reduce boost using wastegate duty cycle.
Another key factor in this calibration is how much torque you command, how you command it, and what you do with the Torque/Inverse Torque tables. Driver Demand torque is exactly as it sounds. I knew that these turbos would perform better at higher RPM’s and to take advantage of that, the torque table was modified to “fit the curve” of what I expected the power and torque delivery to do.
Here is a look at a stock Driver Demand Table:
Here is the new Driver Demand Engine table.
Many times, I’ve reviewed files to find that the tuner has raise the Driver Demand torque table to the moon. In conjunction with that, I often find many other torque limits raised to ridiculous values. Then in the same file you will usually find that the Torque/Inverse tables are left stock.
Some limits can be moved “out of the way”, however I find it a better practice to set these limits just above your targets. This allows the PCM to still work as intended and help catch unexpected conditions and scenarios that may occur.
Torque and Torque Inverse are very important tables, and understanding how they play a role in the system is important. Essentially the way this PCM works is this. The driver pushes down on the pedal, which looks up an amount of torque demand. This output torque from the Driver Demand table is used to look up the load required for those conditions in the Torque/Inverse Tables. There are 16 tables for this, and which ones are used depends on the HDFX blending as designed by the OEM logic.
The PCM looks at the active weighting factors, and goes on the Y axis of the Torque Inverse Table, which is a torque value that matches the Driver Demanded Torque. Kind of like this image:
The PCM interpolates for data between the lines. The value that it finds here in the Inverse table is the LOAD required to make that much torque at that RPM. This is all done in conjunction with constant blending between weighting factors, which also blends and modifies the VCT schedule.
Once the PCM has the Load required for the Torque requested, it converts this in to an airflow value for desired air mass and other calculations using this equation:
Airflow #/min = Engine displacement for one-cylinder (.00157 for 3.5 eco) x RPM x # of cylinders/2 x desired load (torque inverse value)
This final value is used to determine how much to open the throttle to deliver the desired torque.
I log the HDFX weighting factors, figure out which ones are used at WOT, by how much, and in what RPM ranges. For example, my truck runs like this.
WF = Weighting Factor for HDFX
WF 12 = From initial hit to 4100 rpm this is basically 100%
WF 10 = Comes in around 4100 rpm and holds to 4600 rpm. WF 12 is going away while WF 10 is coming in. WF 10 is 100% at 4800 rpm where it tapers to 70% by 5500 rpm.
WF 8 = 30% use at 5500 rpm as WF 10 tapers down, WF 8 ramps up to 80% after 5500 rpm and holds this trend till almost redline
WF 7 = Coming in strong at 6000 rpm but by then the run is almost over.
Log screen shot of this:
You can get a feel for the amount of use each Weighting Factor is doing and see how when one blends out, another is blending in. Sometimes a few are disabled. There are 16 of them, and some of them are being blended in at very small percentages. I only pay attention to the WF that has the most priority, unless it's split between 2 of them. Point is this is one of the main steps to figuring out which of the Torque Tables and Inverse will need to be adjusted in the WOT area.
Part throttle is the same, just with more factors being blended. Usually WOT only uses 3-5 factors actively at play.
After collecting that data, I know which Torque/Inverse tables to touch and when. I also know what spark tables to use for WOT because they will match.
How do I know how to modify the Torque/Inverse tables, and what load targets to hit? A little bit of math, a little bit of guessing, and a little bit of experience.
Load can be calculated based on a few simple parameters that we already have. If we know the engine displacement, RPM, and airflow, we can guestimate the load. This explanation can get lengthy so I’ll just break it down to a simple form.
The basic formula looks like this. You can complicate things if you want more accuracy by accounting for barometric pressure, humidity, and temperature adjustments. Let’s not go there for now.
Load (VE) is = (Actual Airflow / Theoretical Airflow) x 100
Theoretical Airflow is = (RPM / 2) x (Displacement / 1728)
If we take a 3.5 Liter engine, and convert that to cubic inches, we get ~214.
We can figure out the theoretical airflow as if our engine was naturally aspirated. Basically, how much air it could possibly consume based on RPM and displacement without forced induction.
Let’s figure out the theoretical airflow at 3000 rpm for our engine.
= (3000 / 2) x (214/1728)
= 1500 x 0.12384
= 185 CFM (cubic feet per minute)
We can convert CFM back to #/min as well, since that’s what we usually log. I’m just going to use a calculator I made that uses 72° F with 14.7 psi of atmosphere (sea level), and 0 boost since we are calculating this engine as if it were naturally aspirated. Most will consider those conditions “standard” so I will leave them there. I won't show this math, you can google it though.
185 CMF = 13.82 #/min
Now we can figure out the Load based on Actual Airflow. For this example, I’m just going to make something up, and say that at 3000 rpm the airflow was 26 #/min.
(Actual Airflow / Theoretical) x 100 = Load estimate
(26 / 13.82) x 100 = 188.4%
If you log load as a faction like I do, this would read 1.88 load. Essentially the engine is consuming 88% more airflow than if it was naturally aspirated.
Does your head hurt yet? Does everyone want to start tuning now? Anyone ready for another beer? Something stronger?
Moving on. As you can see, lots of math involved. I’ve created countless excel calculators to use while tuning so don’t feel pity on me, I don’t calculate this stuff by hand much anymore.
Now back to the Torque/Inverse Tables. I looked at what the stock turbos were capable of from previous logs, looked at some data I had on the Full-Race / BorgWarner OEM+ Turbos and came up with a ballpark on what I thought the load would hit with my boost targets.
Now I go in and set the torque on the Y-axis of the Torque Inverse Tables first. The torque and torque inverse tables must be inverse of each other. I made a reverse calculator to allow me to plug in the load I wanted, which would automatically calculate the complimentary Torque Table in the correct cells. To use this method, you must set the Inverse Y-axis up first. If you don’t, you’ll be off.
I modify the Y-axis to match the Driver Demanded Torque I will see in ¾ to WOT conditions. Blend all the values up and down for smooth transitions. I want to fall in to the top area of this table without running off too much. From there I modify the load values on the Inverse Table and let my calculator spit out the Torque Table. Copy and paste that into the tune and do the next table. Once I’ve done this to the relevant weighting factors, it's time to put it in the truck and see what happens.
Quick look at a set of Torque/Inverse tables that have been modified for my truck.
You may notice that the bottom half of the table is stock. This may seem strange to you, but here is my reasoning. The PCM logic is somewhat flexible. It can handle some error without you even knowing. These turbos will not flow much more at normal cruising and daily driving, the area that’s stock for the most part. They really are a baby upgrade compared to other turbos like what RBrown runs.
To prove this, I’ve been driving this tune for the past ~2000 miles. The truck drives very much like it did before the turbos. The street manners are perfect. Most people would have no idea that this truck puts out 450whp. No surging, no bucking, no stumbles. Aside from the pleasant whistle from the turbos, this truck drives like stock if not better.
A few more things about tuning these before I wrap this up. Boost control. For my truck, a Gen 1 without port injection, my largest concern is too much low-end torque, which is a result from usually too much boost. With the Full-Race / BorgWarner OEM+ Turbos, I knew they could stretch their legs up top, but I wasn’t sure how much spool up would be affected, or what people commonly call turbo lag. For my truck with my modifications, there was almost no perceivable difference in the ability to spool up and generate boost down low.
I decided that I didn’t want too much boost down low so I employed some PID controllers and a few limits down low to reduce boost. Therefore, when you look at my dyno chart, you may notice a bump around 4250 RPM. This is when I allowed more boost to come in.
You can see above where the boost comes in and only hits around 16 psi until just past 4000 rpms, where I allow it to reach 18-19 psi for the remainder of the run. This was on the dyno, and on the street it actually dropped about .5-1 psi which I’m completely fine with. It provides and almost flat 18 psi through redline, which for me is set to 6100 rpm.
Using these PID controllers, a few load limiters, I allowed the PCM to close the throttle, drop wastegate duty cycle faster and “catch” the typical boost spike you would see in may tunes. I know that instant rush of low end torque that many of us feel in our tunes feels great, but generating 480-550 wtq at 2500 rpms is very hard on the motor. I suspect that this is the reason for some engine failures on custom tunes. We know that the HPFP has trouble keeping up with the air mass down low even on stock turbos. I made sure that would not be an issue on my truck.
Speaking of Fuel Pressure, how did that work out? Here is a screen shot of just the rail pressure on my final pulls. Keep in mind I do have the upgraded 35% HPFP. No other fuel system modifications.
Hard to tell what values it's at, but peak pressure is around 2400 psi, and the lowest it hit under WOT is around 2150. 250 psi fluctuation isn’t something to worry about. This is nothing like the 6-800 psi drop I had when I tested with E85 last year. It’s not as smooth as I would have liked in that log, but I found on the street it is much more stable. I suspect on the dyno, RPM’s climb much faster and the PID controller probably need a little tweaking to make faster corrections. Since this didn’t prove to be a problem on the street, I left it alone.
Now I could go on and on about every single change I made for this set up, but let’s face it, I’d have another 50 pages and most of you would fall asleep. I am writing this originally in Word and at this point I have almost 7000 words and 30 pages. It’s time to real this thing back in and get down to the final results, opinions and feedback.
The main goal for this write up was to describe to you the tuning process, show you some real hard data on what these things do without any smoke and mirrors. I want to discuss the problems some folks had getting tunes and explain my thoughts on all of this.
I can now say with confidence that the tuning on these Full-Race / BorgWarner OEM+ Turbos is not that difficult. As a matter of fact, I put the stock tune on for 3 days, driving back and forth to work, and honestly it felt like a stock truck. It ran fine, no CEL’s or bucking and surging. Everything was fine, except my truck was slow.
Even the off the shelf SCT 93 Preload would run fine on these turbos, even though it's Torque/Inverse are not adjusted for these. The PCM will handle that.
There really is no reason that tuning should be difficult to attain on these turbos. After all these are a baby upgrade in comparison to EFRs etc. My wife has driven the truck and says she didn’t notice anything but more power. I recently took a trip to northern Alabama, 600+ miles one way. Drove it all the way there, loaded down with luggage and gear for a vacation. My wife and I shared the drive time, and it went smooth as you could want. Through the hills of the Smoky Mountains it drove up and down those hills like you would want. I have nothing but good things to say about this set up.
These turbos are essentially plug and play. If your stock turbos need replacement, you could upgrade to these without a worry. The stock tune will handle these. It also works with all existing modifications, such as ported manifolds, upgraded downpipes, SPD turbo adapters, and the list goes on. 100% OEM fitment and the quality you expect from Full-Race and BorgWarner. Full-Race supplies the hardware on these so contact them directly if you are looking to upgrade. BorgWarner will just direct you to Full-Race.
One small revelation and a little kudos to my CP-E intercooler (sorry Geoff). The drive up to Alabama was done at night, and we encountered some very heavy rain, bad traffic in Atlanta, and all sorts of mixed driving and temperature changes. After arriving, and spending a few days at the cabin, it was time to take some trash to the dump. My brother and I loaded the truck and drove to town. After dropping off the trash, I wanted to show him some power. I put my foot down and the truck misfired and stumbled. I thought to myself, oh no, something is wrong, did I mess up my tune. Long story short, I got a CEL for a cylinder 6 misfire. Thinking oh no, here I am out in the woods with limited tools, what am I going to do? After my nerves calmed a little, thinking the worst, I decided to check for moisture in my intercooler. The CP-E intercooler has two metal drain plugs, one on each side of the end tank. I pulled those out, started the truck, and about 2 cups of water came out. I suspect this is due to the 600+ mile trip where I basically ran at highway speed, through rain and temperature drops, and never went WOT the whole time. I usually go WOT a few times a week. I had never personally experienced the “water in intercooler” issue until this day. Props to CP-E for those little plugs and how easy it was to pull them out, drain the crap and get moving again. The misfire went away and she’s back to normal. That said, when I had my Full-Race intercooler, I never had those issues, probably due to the higher mounting position. My dad now has the Full-Race FMIC on his truck and towed a boat all the way up there and it went great. Charge temps in check and power all the time. He loves the Full-Race unit. So kudo’s to both intercoolers, winners in my book.
To those of you who were early adopters of these turbos and had a bad time getting a good tune, I’m sorry, sincerely. I don’t want to point fingers at anyone or get into any politics of that. Some of you may just be really picky, maybe your tuner sucked, maybe he just didn’t have experience with these and he tried. I don’t know, and it's really not for me to say. I do thank you for trying and giving your feedback. You jumped in early and might have got burned a bit. You helped push me to the point of trying this myself and doing my best to give feedback to the community. My only hope is that this helps dispel some myths about these turbos and tuning difficulties.
Dyno Video for Fun
Full-Race BorgWarner OEM+ Turbos
Datalogs and Dyno Runs to download: