LX 570 Harrop Supercharger Stage 1 and 2 Impressions
- Thread starter boringdriver
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Jason Andrews
Modaholic
Stage 1 w/no tune the stock injectors are okay, but maxing out duty cycle. Once stage 1 is tuned it needs TRD injectors and I see a lot of Tundra guys reporting it hitting max duty cycle hence warranting even larger 650cc+ injectors even at stage 1 w/a tune.
My tuner has not experienced maxing the TRD injectors on stage 1 tune from what I gathered. My speculation is that the elevation in Denver and less available air means it needs less fuel. At my home elevation I'm probably lucky to make 3.5lbs but when I go to sea level I want to make sure I have enough fueling to keep the AFR in the low 10's at WOT. A wideband AFR gauge is my next mod.
Many of the Tundra forum guys mention that even the Magnuson tune that comes with the new TVS2650 can run lean and it's better to get a custom tune by someone who knows their stuff.
I guess if the stock injectors are almost maxed at 7 psi boost and then a tuner tells you a larger injector is maxed out at the same boost…something doesn’t make sense. Either the Harrop setup is way too lean or the tuner setup is a tad rich. More than a tad..Stage one tuner doesn’t increase air mass flow correct?
Jason Andrews
Modaholic
I am by no means a professional or claim to know much other than what I've seen documented by others who are much smarter than me. The "tuners" I was referring to that said they are maxing injectors are guys who feel comfortable enough to tune their own trucks and they post their data. Many others chimed in that they agreed they had experienced the same. It's a 500 page thread now so it's a lot of info.
Most anyone would be concerned an un-tuned forced induction install could be too lean. I keep seeing that everyone wants their air fuel ratio in the 9.9-10.5 range when going WOT because it needs the extra fuel to keep the ring landings cool. So yeah to be safe you want it rich as ****. The OEM sensors cannot log anything <12 so with apps like OBD Fusion etc so you can't get a reading in a range where you need to know unless you install a standalone wide band air fuel gauge to monitor it. This way you can know you are in a safe zone when you want to stand on the skinny pedal.
Moby
GOLD Star
There may also be a question of whether the stock or modified fuel pressure regulator is being used. If a tuner has you revert back to a stock FPR than you are going to need bigger injectors. OR the top end fueling of a stock stage 1 even with the modified FPR really isn't sufficient. Without a wideband as Jason notes it's impossible to tell. I'm currently looking for a fabricator to install O2 bungs on my downpipes. I could do this myself but I'm still in the process of moving and don't have my TIG machine at my new place yet.
Edit: On my 2FE with a Split Second programmable MAF conversion I ran an Innovate wideband and the comfort that it provided was well worth it.
Edit: On my 2FE with a Split Second programmable MAF conversion I ran an Innovate wideband and the comfort that it provided was well worth it.
Check out the Holley clamp on O2 bung setup. I used this on an EFI conversion for 74 Lincoln.
There is “safe” and then there is excessive. My TIO540 dumps in 38 GPH at takeoff power to make 300hp and will happily run at 180HP for 7 hours at a time at13 GPH. But that is an air cooled turbo 9 liter 6 cylinder engine- very low perimeter to volume ratio for cooling. Not like a compact 5.7L 8 with water cooling.
I dont think my Ecoboost was running 9.9-10.5 even making 14+ Psi lol.
And I know the 5.0L Coyote guys with Whipples are in the 11's generally and I think those kits run 10-11 psi.
9.9-10.5 seems insane on a lower boost application at 7 psi.
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Jason Andrews
Modaholic
I think 11's are probably fine for a general stage 1 with a tune; provided everything else is stock.
Yes, the stock pulley on the Harrop and Maggy 2650 are generally good for about 7psi at sea level. Deviating from stock for additional mods like intake, throttle body, exhaust (headers) can decrease the boost numbers seen.
The 9.9-10.5 AFR I mentioned was what I thought everyone was shooting for when venturing beyond stock stage 1 tune. Whether that is a smaller pulley or the above mentioned mods or both. There are guys who are really pushing the limits getting into 12psi with consistent 10-11psi on stock block and internals.
Yes, the stock pulley on the Harrop and Maggy 2650 are generally good for about 7psi at sea level. Deviating from stock for additional mods like intake, throttle body, exhaust (headers) can decrease the boost numbers seen.
The 9.9-10.5 AFR I mentioned was what I thought everyone was shooting for when venturing beyond stock stage 1 tune. Whether that is a smaller pulley or the above mentioned mods or both. There are guys who are really pushing the limits getting into 12psi with consistent 10-11psi on stock block and internals.
A few thoughts
- Hot start will need tuning for new injectors. Either scaling or adjustment as the atomization, flow pattern, and different pulse width will change what the engine wants to start. It's a matter of finding the right hot start tables to adjust.
- Injectors need to be sized for worst case, and not nominal. It's going to be that cold day at sea level when running out of injector leads to a not so good time.
- Target lamba (A/F ratio) at WOT depends on timing, extended loads, and margin. Don't tune just for max power but sustainment and safety of max power. If one is just doing mild freeway pulls is one thing, but for continuous high speed or towing type use, it's important to have enough fuel for sustainable combustion temps and power.
- Hot start will need tuning for new injectors. Either scaling or adjustment as the atomization, flow pattern, and different pulse width will change what the engine wants to start. It's a matter of finding the right hot start tables to adjust.
- Injectors need to be sized for worst case, and not nominal. It's going to be that cold day at sea level when running out of injector leads to a not so good time.
- Target lamba (A/F ratio) at WOT depends on timing, extended loads, and margin. Don't tune just for max power but sustainment and safety of max power. If one is just doing mild freeway pulls is one thing, but for continuous high speed or towing type use, it's important to have enough fuel for sustainable combustion temps and power.
Problem is, unless they shut off Knock Feedback and KCLV, the PCM is going to chase after the peak timing all the time. Or they will have to limit the spark tables at high air loads so that KCLV isnt able to push so hard but that will result in the KCLV advancing after a hard pull.
But turning those off would be a bad idea because they also function to retard timing if needed.
Also, i would hope that if someone is towing they are not pulling 7% grades at 12 psi at 2000 rpm and are letting the engine rev a bit but who knows.
Moby
GOLD Star
Forgive my ignorance, but what is "KCLV"?
cmon, you didn’t know that it means knock correction learn value?! 
New one to me as well…
New one to me as well…
Knock Correction Learned Value. Its basically a long term average timing "trim." Knock Feedback operates in real time and adjusts the timing on the fly, and if Knock Feedback is advancing or retarding timing consistently, it will drag KCLV with it to try and keep Knock Feedback close to the zero point.
So, based on feedback from the knock sensors, the PCM is always trying to adjust timing to maximize output for both economy and power. This is why running higher octane fuel actually can make a difference on these motors, they are not stupid and they will take advantage of the higher octane.
I'd be curious what peoples KCLV is on a stage 1 Harrop truck with 91 octane. On my stock 2018, I sit at a KCLV of around 18 when I run 91 and am towing.
Jason Andrews
Modaholic
IIRC my KCLV on my '18 LX was 18.3 according to OBD Fusion when I ran it for a year without a tune. After a tune, bigger injectors, 1 step colder plugs it still reads the same.
LTFT used to be +-10% now they run +-20%
Moby
GOLD Star
Interesting that the learned value didn't change. From reading the General Supercharger Thread on Tundras.com it seems like there is a lot of timing pull back untuned. I would have expected a tune to reduce that at least some by scaling back on timing.
Timing tables function based on air load and rpm. Whether the truck has a blower on it or not does not change how much air the engine needs to move the truck down the freeway and around town so, realistically, the truck is operating like normal 99% of the time until you actually use the supercharger.
Just because it has a supercharger does not mean the engine is taking 7 psi of boost just cruising down the road. Because of that, the timing should remain similar to stock unless you are always flooring it everywhere. The KCLV probably wont react to one quick pull for a few seconds over the course of a 30 minute drive.
The stock timing tables, at least on my 2018, go up to an air load of 1.1. At 7 psi you would be an air load of <1.5(lower because the engine is not 100% volumetric efficiency. For example, my F150 Ecoboost needed to run like 9-10 psi of boost to arrive at an air load of 1.5). I dont know what the PCM does beyond an air load of 1.1. It might just stay at the timing for 1.1 or it might interpolate out to 1.5.
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Unless an engine is operated at high loads/boost, one may never see the results in KCLV. It may also not be a single value, rather multiple value across the map.
I don't see that as a problem. It's correlated and A/F and timing ultimately are tied at the hip and work together. Lean A/F targets at high volumetric efficiencies and high loads results in lots of heat. Without enough cooling (and octane to your later point), ignition will have back-off to prevent uncontrolled pre-ignition and engine destroying detonation.
Maybe what your getting at is that these basic setups are riding the knock sensor which I agree is bad form. It may work but overtime, and over transient conditions, it can bite.
I don't see that as a problem. It's correlated and A/F and timing ultimately are tied at the hip and work together. Lean A/F targets at high volumetric efficiencies and high loads results in lots of heat. Without enough cooling (and octane to your later point), ignition will have back-off to prevent uncontrolled pre-ignition and engine destroying detonation.
Maybe what your getting at is that these basic setups are riding the knock sensor which I agree is bad form. It may work but overtime, and over transient conditions, it can bite.
Yeah thats what I mean. Regardless of how much a tuner might retard the timing tables I think KCLV and KF will try to advance it until it(the PCM) is happy again.
I know people that turned off Ford’s version of KCLV on their Ecoboosts because it annoyed them if it didn’t just peg all the time and max out, but I don’t think they fundamentally understood how it functioned or that if they got a bad batch gas or something, they had no safety net.
bjowett
Supporting Vendor
Here is what happens to 3UR FE pistons when things go wrong under boost.
