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Dyno thread

36K views 157 replies 34 participants last post by  Cptnslo 
#1 ·
Sharing from Facebook, I know that she’s on here but I’m drawing a blank on her user name:

figured we could consolidate these runs and future runs.
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#2 ·
#14 ·
Some cars run closed loop at wide open, some are open loop. Not sure why some manufacturers choose to do that in the era of the wideband 02 sensor, that's above my pay grade.


I'm not a tuning expert but I've dipped my toes into it plenty of times and spoke with many tuners and tuned my own cars with a powerfc and all that shit. I think they're leaning it out when it's out of boost for throttle response/pep, since it's basically NA down low and the engine load isn't that much to risk anything. NA motors run lean pretty much all the time throughout rev range.
My guess is to also squeeze out some fuel economy.

Even NA wide open throttle AFRs are usually in the high 12s, depending on the engine.

This situation is occuring when the engine is at wide open throttle. Even if this AFR correlated inversely to boost, it would normally be in the 14s briefly. It might be 14s the instant the run starts then have a sharp drop into the 11s that mirrors boost increase.

You also can't lean burn when cruising, because that creates high NOx emissions which would not earn it federal emissions compliance.
 
#10 ·
I'm not a tuning expert but I've dipped my toes into it plenty of times and spoke with many tuners and tuned my own cars with a powerfc and all that shit. I think they're leaning it out when it's out of boost for throttle response/pep, since it's basically NA down low and the engine load isn't that much to risk anything. NA motors run lean pretty much all the time throughout rev range.
 
#13 ·
who knows the exact oem tuning strategy but you can almost bet it's related to emissions. leaner burn means less less emissions.

curious what fuel that was on. if 91, there's a good chance there was some timing being cut. 93 or some mix of e85 will usually remove most knock.
 
#20 ·
#23 · (Edited)
I just saw the article from road and track... I then searched the forums, and found this thread. The car was clearly not dyno'ed correctly (based on how he GRYaris was dyno'ed for consistent&correct numbers). They likely had a hard time getting consistent numbers. Then, finally, the car likely went into a decreased power mode, was heat soaked, and produced lower numbers than actual.

From the accelerstion tests against the CTR, I have always estimated 280whp on a dynojet vs 290whp on an fk8 and 295whp on an FL5.

We should have an entirely seperate thread on how to dyno a GRCorolla correctly, so that people can be aware. From the GR Yaris dyno tested, the way to get consistent and correct numbers is to put it on a 2 wheel, not 4 wheel dyno. There are reasons for this, which we can get into on another thread.
 
#28 ·
As you increase torque, you increase power, due to the relation of the two (hp=torque*rpm/5252). Due to the multiplication factor that RPMs give to hp, provided that torque doesn't drop off at high RPMs, the peak hp is normally above 5252, and peak torque is below 5252. A car can be tuned so that it runs a 11.5:1 AFR (air-fuel ratio) at low RPMs, and 12:1 AFR at high RPMs, or vice versa.

People tend to confuse hp and torque. Acceleration is hp to weight ratio. You want that hp to be readily available without having to drop a gear for ease of driving, and that means you want the most hp you can get at low RPMs, which is the shortened term "torque" when describing this. Torque is also a twisting force that has no time component, as hp does, is at the output of the crankshaft, and you cannot use without the hp component (i.e. wheels&tires, rpms). It's physics, and there are arguments trying to defy physics, but it's just not possible.
 
#37 ·
Ultimately the issue comes down to the AWD system detecting mismatching wheel speeds with 0 degrees of steering input and will shift power around and possibly cut spark timing or fuel to compensate. Not a big deal if you're not over driving any of the wheels as the sensors will read normal condition, all wheels are spinning at the same speed. However, once you introduce the over drive the rear wheels will spin faster than the fronts by design which begins to force the AWD computer to compensate. You don't tune on the basis of guessing what the AWD computer is doing hence disable the rear clutchpack and tune 2WD for consistency and reliability of the tunes.
 
#38 ·
TimeRacer speaketh the truth!

Consistency is the key here, and no reduced power mode is also the key.

258.6whp & 252.6whp does NOT backup the acceleration tests. I could possibly believe 275whp, but definitely not under 260whp. Should be right at 280whp, with the CTRs making 290-295whp.
 
#39 ·
Sharing from Facebook, I know that she’s on here but I’m drawing a blank on her user name:

figured we could consolidate these runs and future runs.
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You should add Limit+1's Dyno to the 1st post. Might want to mention that both tests so far were done without the car being put in dyno mode.... the 1st dyno test that actually used dyno mode, wins! Well, in my book.
 
#41 ·
Ok you can disable the clutch pack and run in 2WD to enable you to get a constant baseline for tuning which is what you want but that actually is not going to give you an accurate absolute whp power reading is it ?

Considering you put this thing on the track and 20minutes of hard driving later it goes into 2WD tells you the transmission losses are pretty high to generate that sort of heat in the front/rear clutch pack.

10% drivetrain losses for an AWD car wouldn't be out of the question so you would not expect any more that 270whp at best, if the clutch pack has to start shifting power about that's all additional losses and you would find yourself at 250-260rwhp in no time in real world driving.
 
#44 ·
Ok you can disable the clutch pack and run in 2WD to enable you to get a constant baseline for tuning which is what you want but that actually is not going to give you an accurate absolute whp power reading is it ?
Forgive me but I'm drawing a blank on what you'd actually need that for.

You might be able to calculate it though. Run it in FWD mode to find the crank HP. Run it in AWD mode and let it run down to find the drivetrain loss. Crank HP - AWD drivetrain loss = AWHP
 
#42 ·
Wow... everything you need, is here:

Please please please read. Ok, I'll summarize, but you need to read that. There is a dyno mode, and it takes a special sequence of pedal&hand brake presses to enter dyno mode.

Next, cars are underrated. Welcome to modern day sports cars. For Ex: Do you think that magically the 2020 mk5 supra rated 335hp, can make 340whp? It does... how is it possible? Is it some kind of perpetual motion machine that just keeps on creating more power, the more power it makes? Does it have negative losses on the drivetrain? Or is it underrated? IT IS UNDERRATED. wow.

Read the thread, there is much more there.
 
#43 · (Edited)
Here's another point. The 260ish rated hp GR Yaris, puts down 240whp... which would also be an argument for the GR Corolla to put down 280whp... despite what we know about it's acceleration tests from a roll against a 290whp stock fk8 CTR (with 140lbs less weight). If the GR Corolla had 250-260whp, it would be an absolute slaughter, but it's not. 3-4cars lengths difference, not 8-10car lengths. Or in bus lengths, 1 bus length, not 3 bus lengths.

The GR Corolla is also faster from a roll against an Elantra N manual with 260whp (rated 276hp)... and yet the GR Corolla weighs more(3186 vs 3262) has AWD, and... has 275whp minimum, by the results (wins by 1 car length). The GR Corolla against an Elantra N DCT with 280whp (rated 286hp) should be a dead heat, depending on the driver of the GR Corolla and how fast he can shift (3262lbs vs 3296lbs). 280whp vs 280whp. Most likely the DCT wins it.

Here's the video/roll races I'm referring to
here
 
#52 ·
If you pull the handbrake only, it doesn't disengage the rear drive system... the car would eventually break through the resistance of any braking force you give it. It's like going down the street, mashing on the gas and the brake pedal with two feet, at the same tume. All you're going to do is wear out the brakes prematurely, and if your on a 2wheel dyno, you're going to break something... the rear drive system, the dyno, the wall, the car, all of the above, etc etc. Yeah, don't do that. It's not smart enough to keep you from hurting things.
 
#48 ·
the thing here is that none of these dyno runs are being done for the purpose of tuning. they are specifically being done for likes and subscribes.

weee!!! hey!!! look at me!!! I've got the car on a dyno and it shows numbers!!! keep watching for more!!!

so yeah, perfectly whatever, post some irrelevant dyno numbers to get clicks, no big deal. at the end of the day, whether they are in a FWD only mode or not, it's just pulling a number off a computation table.

when people start tuning using a dyno to get the most power for their mods, that's when consistency matters, and the only relevance that proves is specific to that car with those mods on that day on that dyno. which at that point, it's still irrelevant.

but I guess it's fun, and it helps pass the time if you don't have your car yet, so please, continue :)
 
#49 ·
the thing here is that none of these dyno runs are being done for the purpose of tuning. they are specifically being done for likes and subscribes.

weee!!! hey!!! look at me!!! I've got the car on a dyno and it shows numbers!!! keep watching for more!!!

so yeah, perfectly whatever, post some irrelevant dyno numbers to get clicks, no big deal. at the end of the day, whether they are in a FWD only mode or not, it's just pulling a number off a computation table.

when people start tuning using a dyno to get the most power for their mods, that's when consistency matters, and the only relevance that proves is specific to that car with those mods on that day on that dyno. which at that point, it's still irrelevant.
I mean thats what I said early on, It is still useful if youre adding modifications to the car and running again on the same dyno in similar conditions to see if youre making any extra power
 
#59 ·
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