Striker223

Stall speed of the torque converter, when fully stopped and engine at idle or below that speed you have an incomplete viscous coupling of the converter outer housing and inner. This is what allows your engine to not stall out like a manual car when you slow down, the engine is free to move the outer section (that is bolted to the flexplate) but the inner section that is linked to the input shaft of the trans and also in turn the wheels is allowed to be stationary since the fluid is just forced through the two halves.

It's literally a fluid turbine with a stator and impeller and the blade angle etc determines at what rpm the fluid can no longer flow "easily" between the two and at this "stall" point the rotational speed differences will become nearly zero. When you first start moving any speed difference between the input side (engine) and the wheels side actually results in an amplification of input TQ just like a gear set would. It's obviously not near 100% efficient like a gearset is but better converters do provide up to 2-3x the force at maximum rpm differential between sizes.

As the sides speed up this speed difference and thus the multiplication reduces to essentially zero and the converter is thus "stalled", this is generally set to occur at lower rpm's on more high TQ engines and higher rpm on low TQ engines. Reason being is a small engine actually really needs the "gearing" boost from the converter vs a large one doesn't really and the sooner you reach stall the better, for several reasons.

Any speed below stall is quite ineffective from an efficiency standpoint because you are literally using fluid to move something around. Think turning a large plate on a stick with your hand directly vs with water in a bowl on top that you run your hand through quickly.....that generates a hell of a lot of heat too and beats the hell out of trans fluid. Modern transmissions are designed to actually fully lock up solid just like manual trans do once you get to higher gears and or lower loads. Stuff like my ZF8s lockup as soon as you are over stall and act like a manual trans 2-8th gears and part of 1st so that you get the maximum amount of power down and shift speed.

Stall speed can be tested by being in drive, standing in the brakes, and bringing RPM up as high as it will allow. When it stops climbing and you feel "tension" in the driveline that's stall, if you are tuned you can then floor it while snapping off the brake to launch. For drag racing you want a stall that matches TQ peak, so if peak TQ starts at 3k you get a 2800 stall converter etc.....if you intend to also street drive then spec a "tight" converter so you have a more direct fluid connection below stall so you don't have a delayed or CVT like feeling when starting out. Once in lockup it doesn't matter

Striker223

It's probably anywhere from 20-40 TQ from 2000-3800 rpm due to having to pull timing. Again it doesn't show as much in HP since up top there is less chance for detonation so there is less relative pull up top.

A software reconfiguration on my NA W12 engine gave me 48 more WHP and 38 more TQ......so yeah they totally could have and likely did alter the tune for more of the luxury midrange TQ wave in the LX.

Turbo engines can see +100/100 EASILY with just software changes IF you give them fuel to sustain the timing and boost spec. Put the wrong fuel in and the power is gone and you are left riding knock sensors. Happened to me one time in my LS430, a station claimed 93 and it was actually 87 and I felt it instantly and the ECU codes for it immediately since I was tuned

BayeauxLex

I get it. It’s onIy 2hp. I can’t explain why we run 93 in the LX, we just do and always have.

If a car stalls next to you at the red light, you’re in a race!! If @AMIRZA786 BMW friend stalls (brake boost) next to him at a light or from a roll, Amira is about to lose.🤣

Do not stall up a hybrid. I think they are slower off the line when you try to stall up. Just mash the gas like you would in an EV.

SW17LS

It’s not just 2 HP like Striker said it pulls the timing and that impacts the whole torque curve.

The point is the hypocrisy of saying that you don’t care about fuel cost but then you do. Most consumers feel the same way you do, which is why they buy 4cyl Camrys and not 6 Cyl, why they don’t buy 2.0T Accords. Why they buy 4 cyl Mercedes E Classes and GLEs.

That’s why all these technologies that you deride exist, to try and improve fuel economy to lower fuel costs which is what consumers want, including you.

As for STSs and SLSs, Northstar STSs were 300 hp not 295, and the SLS also required premium fuel.

Yes I do, the motor is designed to run on either fuel but it will deliver better performance with 91+, that’s why Lexus recommends 91+ for the luxury consumer and 87 for the Toyota consumer. I would want that additional performance vs the fuel savings. Running 87 will not hurt your LX.

Hence my ES, same thing. The engine will run on 87 with reduced performance. In 2011 they reduced the performance figures and started recommending 87, I continued to run 93 in my 2010.

Striker223

Yeah I'm not sure why they do that? I think it may be software restrictions or something or just because most are CVT they just can't...

AJT123

Whoa whoa whoa, do not call me a hypocrite. Saving $20 a tank to not get 2hp is different than me complaining about taking an Accord that did 0-60 in 5.4 seconds and stuffing a whole entire engine, hybrid at that, and adding about two seconds to said 0-60 time. Torque curve is fine as you can see in the video. Surely you can see the difference, let's chill with the name calling.

All that crap doesn't work, the 2022 Denali gets 11-12MPG. That's my issue I'm talking about. I don't want a hybrid or electric car. You don't care about gas mileage either or you wouldn't have disabled the start/stop....right? I mean you want to save every drop you can, right?

The first ones were 295hp. And you completely are missing my point. These Northstars are a perfect example of what I'm talking about, again you would be correct if we were talking about those. Not talking about what kind of gas those take, that's not germane to this. For the record though the later Northstars did take regular.

Well, they didn't.

SW17LS

Saying that something is hypocritical is not name calling. Fuel cost savings matter to most consumers, including you. There is nothing wrong with that, just own it.

Between the two of us you care more about fuel savings than I do with is kinda funny lol

I disable the start stop because I don’t care about fuel costs. I would run the specified fuel because I don’t care about fuel cost.

The reason start stop exists is because most people DO care. Yes they do work, they save a little fuel and that’s the point.

It’s a completely different analogy. Those were also low compression V8s that likely would run fine on 87. Would you have run 87 in them?

Unless you designed the car you have no basis from which to say that. Lexus says for best performance you should run 91+, they know way more about the car than you do so I would listen to them if I owned the car.

BayeauxLex

@AJT123 is saying in a 5-6k brick he’s not going to notice 2hp so running premium is negligible. With that being said, I’m not switching to 87 in our LX. I don’t drive the LX enough to “feel the difference” if that’s even possible. Will it shift better? That’s up to the person driving it. Will the average person notice it, probably not?

And he’s also right it’s been beaten to death, 87 vs 93 in LX and tundra. Majority runs 87. Does it make it right? No. Let’s get another opinion. @JDR76 What grade fuel do you run in your Tundra, loaded and unloaded and how does it perform in your opinion?

SW17LS

The difference is probably negligible I agree, but I would still run the specified fuel to get the performance the vehicle was intended to give me. That’s more important to me than the fuel cost, the fuel cost is more important to him than the performance. That’s fine…he should just own that he does in fact care about fuel cost.

AJT123

No they don't or I wouldn't have all these V8s. I told you I feel like a sucker WASTING money, not spending it. I spent $6700 extra for the most powerful engine available for our boat. Nothing on this board is going to convince me I need to put premium in my LX, so everyone can think I'm wrong lol. But still, show me documented proof of any engine trouble in an LX from regular fuel.

I don't care about fuel cost like I said, I mean sure I wish gas was cheaper but we're headed there. You don't agree, so you don't understand when I say I feel like a sucker wasting money on expensive fuel my truck doesn't need.

You disabled it because it's god-awful first. But I'm on your side here, I hate start/stop.

Start stop saves about 5-8%. And they can keep it.

No it isn't. It's an example of two engines that are actually technically different for a seat of the pants difference actually that was felt. SLS was more for low end torque, STS was more for high hp. They both were potent engines though, until 80k haha when they'd blow.

Striker223

Engines don't produce HP, they generate TQ and the amount of TQ (force) they make at a given Rpm (Speed) is what determines output. An engines peak output is the TQ peak, if you pull timing it effects first and foremost TQ and does so primarily at lower RPM where detonation has more literal time to occur and higher relative load.

Aka a timing pull hurts the actual thing the engine actually generates and does so where it matters most, the reason the HP difference is only 2 is because the heads and cam setup in the 5.7 is already running out of airflow at that RPM as can be seen in the dyno chart as the TQ falling off RAPIDLY. Aka the engine is not flowing enough to compress to the point TQ production is high, the increased RPM though naturally means it's applying this smaller force more quickly and thus power still tends to go up past 5252 RPM but it's physically impossible for an NA engine to have more TQ than HP past that RPM.

Put a better way.....to actually see what the 87 is taking from you stop the dyno run at 4800 and compare HP there instead of 5700 where the engine is not making good force regardless of fuel used. To make continued good power at high rpm you need to flow a hell of a lot more air and have large ports and that's counter to the goal in a truck.

Ever wonder why the LS460 has more hp than you? It flows better up top and can actually sustain the force levels at HIGHER rpm than you can. Aka the little 4.6 is literally more powerful than a 5.7 past 4800 and has more TQ up top. Same reason my W12 smacks around my turbo car on stage 1, the turbos run out of flow right when the 12 reaches intake runner resonance and sustains it 1400 rpm further than the turbo engine could on stock hardware.

Just trust me on this lol! I designed an engine so I had to learn how all these rules work

SW17LS

Not going to keep going around and around about this but If you didn’t care about fuel costs you wouldn’t be concerned about an extra $20 a tank. You clearly do care.

Not caring means you don’t even think about what you spend on fuel. You just buy the right and best fuel. Everybody who cares about the cost of fuel is concerned about wasting money. Difference is what one person sees as a waste someone else doesn’t. I don’t see spending $20 more a tank to get the best performance however slight a waste

I saw something @bitkahuna posted a ways up about going to Costco to save on fuel in a $150k car, I don’t do that. I only run Shell when I can help it. I just try and fill up on Tuesdays when premium is .20 off lol

geko29

If you only ever drove at redline, peak horsepower might be an important metric. Because you don't, I agree with you that it doesn't matter, especially given the small difference.

But what does matter that you don't acknowledge is that the torque curve on the way from idle to redline are dramatically different, and the LX has significantly more total area under its curve than the LC has under its curve. That's usable real-world power and improved everyday drivability that doesn't show up on a stats sheet.

To use an extreme example, my former daily makes less than 250 peak hp, even with its stage 1 tune. Not a lot by today's standards. But the area under its torque curve is MASSIVE, which in normal driving means little tiny squeezes of the throttle result in instant seat-squishing response.

Striker223

*buys fuel from the shell and ONLY the shell* Haha, yeah I have no idea what this concern for fuel costs thing is......

I still hate my Jeep sometimes. 12.2 average is just actual comedy level bad but at least it's spec is 85 octane so I can use literally anything I want. The other suv is far better at 17.6.

I've actually inadvertently been saving a hell of a lot of fuel costs by daily driving the W12 to work instead of the Jeep as well. The other Audi is going stage 4 and E85 (40 really....) soon so it will probably fall to the mid teens, e85 just sucks power density wise. Oh and 700+ whp will demand to be utilized I'm sure

Striker223

Yep, totally different type of 250 hp vs something like a ES V6