Dyno Numbers

[Stonehorsw]

Originally Posted by ZDan

I am not buying those curves showing 188hp vs. 140hp as the actual delta between 1st gen and 2nd gen, it's gonna be more like +20% rather than +34%.

1/4-mile speeds are a good indicator of horsepower, particularly between similar cars (and gen 1 & gen 2 are largely the same car).
2013 BRZ and 2017 BRZ both tested 95mph in the 1/4 by Car and Driver, and they tested the 2022 at 101mph. !/4-mile speed scales with the cube of power, so the actual power increase should be about (101/95)^3 = 1.20X (1.21x accounting for +30 lb. weight gain)

My stock '17 dyno'd 179hp at the wheels on Dynojet, I expect the 2022 to put up 215hp. A big increase and more than rated power would suggest, but +34%? No... If it really made that much more, it would be trapping ~105mph.

That makes sense. The baseline car may have lost some power in their testing, which would bring the delta to a higher level. This is not knocking on DT, as they are very professional.

A 20% increase is better than what i was expecting anyways, and keeps my hopes high for a 240whp level with E85/header, granted that fueling system can handle that.

[ZDan]

Originally Posted by Stonehorsw

That makes sense. The baseline car may have lost some power in their testing, which would bring the delta to a higher level. This is not knocking on DT, as they are very professional.

A 20% increase is better than what i was expecting anyways, and keeps my hopes high for a 240whp level with E85/header, granted that fueling system can handle that.

Yeah, 100% agree, +20% is great and more than expected. I was predicting 98/99mph in the 1/4 based on 228hp, to see 14.0 at 101mph is a HUGE improvement over 14.8 at 95mph, that's a big increase in performance

[OkieSnuffBox]

Originally Posted by Stonehorsw

That makes sense. The baseline car may have lost some power in their testing, which would bring the delta to a higher level. This is not knocking on DT, as they are very professional.

A 20% increase is better than what i was expecting anyways, and keeps my hopes high for a 240whp level with E85/header, granted that fueling system can handle that.

Unless they've made big changes to the fuel system (which I doubt) it handles nearly 300whp stock, so I wouldn't be worried about that.

[soilent]

Originally Posted by ZDan

I am not buying those curves showing 188hp vs. 140hp as the actual delta between 1st gen and 2nd gen, it's gonna be more like +20% rather than +34%.

1/4-mile speeds are a good indicator of horsepower, particularly between similar cars (and gen 1 & gen 2 are largely the same car).
2013 BRZ and 2017 BRZ both tested 95mph in the 1/4 by Car and Driver, and they tested the 2022 at 101mph. !/4-mile speed scales with the cube of power, so the actual power increase should be about (101/95)^3 = 1.20X (1.21x accounting for +30 lb. weight gain)

My stock '17 dyno'd 179hp at the wheels on Dynojet, I expect the 2022 to put up 215hp. A big increase and more than rated power would suggest, but +34%? No... If it really made that much more, it would be trapping ~105mph.

Originally Posted by ZDan

Yeah, 100% agree, +20% is great and more than expected. I was predicting 98/99mph in the 1/4 based on 228hp, to see 14.0 at 101mph is a HUGE improvement over 14.8 at 95mph, that's a big increase in performance

So one thing I noticed is they haven't advertised the drag coefficient of the new car. At least not that I've seen personally. Is it possible that the new car has a good bit more drag and thus is causing it to be slower in 1/4 mile times? Not mention there's more external factors to 1/4 runs like driver, weather conditions, surface conditions, etc. to affect the time vs a pretty controlled environment like a dyno shop.

At least so far, we've seen several dynos that suggest the delta is higher than expected when it comes to power. I think your math is correct, but is it possible there are other factors you're not accounting for that skew the numbers a bit? Not saying you're wrong, I just want to get down to the bottom of this, because I too am a bit skeptical about the dyno readings we have thus far. Although, they do seem to be piling up in the favor of power than we thought.

[ZDan]

Originally Posted by soilent

So one thing I noticed is they haven't advertised the drag coefficient of the new car. At least not that I've seen personally. Is it possible that the new car has a good bit more drag and thus is causing it to be slower in 1/4 mile times?

That's a big no. For one thing, drag is gonna be really close, and for another, it's just not a big factor in 1/4-mile trap speed (within reason of course!).
When I was doing performance modeling of my V8 RX7 for a Texas Mile run, I was surprised at how little trap speed was affected by drag coefficient. Even over a standing mile, at 185mph, power/weight is *everything* and aero drag isn't as big a player as you might think. FWIW I predicted 184 mph and hit 184.8mph

Not mention there's more external factors to 1/4 runs like driver, weather conditions, surface conditions, etc. to affect the time vs a pretty controlled environment like a dyno shop.

Car and Driver testing is probably about as consistent a barometer as you could ask for. And trap speeds are way more reliable than ET for judging a car's actual power, not nearly as variable with the launch.

At least so far, we've seen several dynos that suggest the delta is higher than expected when it comes to power. I think your math is correct, but is it possible there are other factors you're not accounting for that skew the numbers a bit?

Yes, of course, but if anything, the new car's much better midrange probably means that I'm more likely overestimating its *peak* power a bit.

Not saying you're wrong, I just want to get down to the bottom of this, because I too am a bit skeptical about the dyno readings we have thus far. Although, they do seem to be piling up in the favor of power than we thought.

It definitely seems like a bigger jump than 205hp to 228hp... Considering same peak power rpm at 7000, it makes sense to me that the 20% jump from 2.0 to 2.4 should result in about 20% more peak power, which is what the C and D trap speeds suggest. Still 2x the bump than what we were expecting! But +34%? No way.

[nikitopo]

Not sure why you mix and match 1/4 mile times with peak power numbers. In such timings it is torque that matters the most and not peak power. Same about comparing on a dyno a 2015 (pre-facelift) car with new car. It is known that pre-facelift cars had a poor tune from factory and it was fixed a bit with the +'17 manual transmission cars. But still a 140whp result on a dyno for the old car is very shitty. The only thing I can imagine about the new one and the 228 hp catalog number is that ignition timing is less aggressive or D-4S is used more optimal and thus it is not that sensitive to fuel quality issues. Therefore the much better dyno numbers comparing to old car. Maybe in regions that you have shitty fuel the new one will be a much better option.

[Blighty]

Originally Posted by ZDan

I am not buying those curves showing 188hp vs. 140hp as the actual delta between 1st gen and 2nd gen, it's gonna be more like +20% rather than +34%.

1/4-mile speeds are a good indicator of horsepower, particularly between similar cars (and gen 1 & gen 2 are largely the same car).
2013 BRZ and 2017 BRZ both tested 95mph in the 1/4 by Car and Driver, and they tested the 2022 at 101mph. !/4-mile speed scales with the cube of power, so the actual power increase should be about (101/95)^3 = 1.20X (1.21x accounting for +30 lb. weight gain)

My stock '17 dyno'd 179hp at the wheels on Dynojet, I expect the 2022 to put up 215hp. A big increase and more than rated power would suggest, but +34%? No... If it really made that much more, it would be trapping ~105mph.

Hmm. We have an even smaller sample of 1/4 mile times than dyno charts.

I think if you don't trust dyno's yet, then we can't trust 1/4 mile yet either. Wind, launch, gear change - all vary.

What we do know is its all pointing in the right direction.

Edit: For example, theC&D 2016 FR-S was 1/4 @ 93mph, suddenly its 28% better. Another C&D had it at 94mph, and yet another at 95. Most recorded forum posts put them in the 89-91mph stock.

1/4 mile, unless its on the same night with perfect execution both times you are looking at small factors that blow out the results.

I look forward to many cars dynos, and hope some owners get a chance to dyno back to back.

[Stonehorsw]

Copied from a post from William Knose on Facebook. Again, 50 hp increase.
I will wait until I get more pumped up, but seems like car is doing very well.

[ZDan]

Originally Posted by nikitopo

Not sure why you mix and match 1/4 mile times with peak power numbers.

I'm matching 1/4-mile trap speeds with peak power numbers. Not times. Why? because 1/4-mile trap speed strongly correlates with (cube root of) power/weight.

In such timings it is torque that matters the most and not peak power.

No, power is what matters. Torque, by itself, tells you NOTHING. Torque doesn't tell you the whole story. Power does. If you know a car's power and weight, you can pretty well tell what it will do in the 1/4. If you only know torque and weight, you really have no idea...

Maybe in regions that you have shitty fuel the new one will be a much better option.

Maybe. For sure the new car makes significantly more power, on the order of +20%. But definitely not 34% more...

[ZDan]

Originally Posted by Blighty

Hmm. We have an even smaller sample of 1/4 mile times than dyno charts.
I think if you don't trust dyno's yet, then we can't trust 1/4 mile yet either. Wind, launch, gear change - all vary.

I trust dynos when I know all the parameters.
But when posted dyno plots tell me a "header and a tune" will get me +30hp, I'm callin' B.S. on that...
1/4-mile trap speeds are *waay* more trustworthy. Even allowing for wind, launch, gear changes, etc.

NA engines are pretty simple. Displacement pretty much dictates torque, and torque and rpm pretty much dictates power. There is no way +20% more displacement is making +34% more power in a very similar engine at the same 7000rpm peak. It's just not happening.

Edit: For example, theC&D 2016 FR-S was 1/4 @ 93mph, suddenly its 28% better.

??? What you mean "28% better?"

Another C&D had it at 94mph, and yet another at 95. Most recorded forum posts put them in the 89-91mph stock.
1/4 mile, unless its on the same night with perfect execution both times you are looking at small factors that blow out the results.

With C&D you're getting consistent test methodology, and they also adjust for atmospheric conditions to represent sea-level pressure at 60F. 93mph-95mph or 94 +/-1mph isn't too unreasonable.

I look forward to many cars dynos, and hope some owners get a chance to dyno back to back.

I do too. But I definitely trust C&D's 101mph trap speed (and 95mph for the gen1) more than I trust dyno plots showing the FA24 making +34% more power, that just doesn't add up.

[Yoshoobaroo]

I’m assuming @DeliciousTuning is at least a bit surprised with the massive delta between the 2 cars. Maybe this will lead them to either a problem with their ZN6/ZC6 car, or maybe find something they overlooked. I agree it’s very unlikely this delta is representative of the real life difference. It’s possible I guess, but it just doesn’t add up.

[alphasaur]

.8 seconds and 6mph in the 1/4 is closer to a 50hp gain than 23 IMO

[Baldeagle]

Originally Posted by ZDan

I trust dynos when I know all the parameters.
But when posted dyno plots tell me a "header and a tune" will get me +30hp, I'm callin' B.S. on that...
1/4-mile trap speeds are *waay* more trustworthy. Even allowing for wind, launch, gear changes, etc.

NA engines are pretty simple. Displacement pretty much dictates torque, and torque and rpm pretty much dictates power. There is no way +20% more displacement is making +34% more power in a very similar engine at the same 7000rpm peak. It's just not happening.

??? What you mean "28% better?"


With C&D you're getting consistent test methodology, and they also adjust for atmospheric conditions to represent sea-level pressure at 60F. 93mph-95mph or 94 +/-1mph isn't too unreasonable.


I do too. But I definitely trust C&D's 101mph trap speed (and 95mph for the gen1) more than I trust dyno plots showing the FA24 making +34% more power, that just doesn't add up.

I also think quarter mile trap speed is the best gauge for actual road power. Given a 20% increase in displacement, a 20% increase in power seems extremely reasonable. There are a number of online calculators that estimate qtr-mile speed based on a car’s weight and power. Here is one:

https://www.ajdesigner.com/fl_horsep...trap_speed.php

It uses this formula:

HP = Weight *(Velocity/234)³

• For a car that weighs 2,900 pounds to trap at 95 mph, it requires 194.2 hp.

• For a car that weighs 2,915 pounds to trap at 101 mph, it requires 234.4 hp

That difference is exactly 20.6%.

Another variable in this equation is gearing. The 2022 accomplished 101 mph with a 4.1 final gear versus a 4.3 final gear for the 2017 BRZ. That equates to 4.8% less torque multiplication and implies slightly more than a 20% power increase for the 2022 BRZ.

I’ll be very curious to see future road tests.

[ZDan]

Originally Posted by Baldeagle

Another variable in this equation is gearing. The 2022 accomplished 101 mph with a 4.1 final gear versus a 4.3 final gear for the 2017 BRZ. That equates to 4.8% less torque multiplication and implies slightly more than a 20% power increase for the 2022 BRZ.
.

Nah, gearing (within reason!) doesn't affect trap speed much. 2013 BRZ did 95mph in the 1/4 with 4.1 diff, 2017 BRZ (with 5 more hp) also did 95mph with 4.3 diff, got there one tenth quicker... Trap speed is (pretty much) power/weight. Small advantage of 4.3 gearing at most speeds is negated by having to upshift sooner resulting in a huge disadvantage at some speeds.