Side by side acceleration & braking test

  • Thread starter sucahyo
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Tire effect on weight transfer
http://www.stoptech.com/tech_info/wp_rearbrake_upgrades.shtml
Finally, under an OEM bias condition, the rear brakes only contribute about 15-20% of all the braking force the vehicle generates, and when you install sticky tires you actually DECREASE the amount of work they need to do. Why? Because at the higher deceleration levels afforded by race tires, there is more weight transfer taking place, reducing the normal force on the rear tires and increasing it on the front (remember F=µN from above?). If anything, we now want to decrease the rear effectiveness. Ironic once again.
Click to expand...
So the rear should have more smoke on super soft than on simulation tire......
White OZ rim: simulation tire.
Black Dunlop rim: supersoft tire.


Make sense, the white do not have tire smoking at all.

More recent test on BMW 328Ci:
White: hard slick
Red : super soft slick



The smoke on red comes earlier.
 
Nice work Sucahyo 👍 i'll use your tactic, of defining same buttons for different controllers in epsxe, to test some identical cars, like some Mugen/non-Mugen models. :rolleyes:

However i think you shouldn't generalize so much in your conclusions...
For example, i did the ride height acceleration test, and i got better acceleration with lower ride height...

I used Tom's T020 on Red Rock with manual gears, and starting in 1st gear i would get better acceleration with higher ride heght, but that's because the car with lower ride height was having more wheelspin. Starting in 4th gear and accelerating only after the "start" appears on screens (meaning low rpms), i had no wheelspin and in this situation the car with lower ride height had a very small advantage (aerodynamics reasons maybe).

So , what would happen if i had more downforce and/or traction controller when i was starting in 1st gear?
My point is, there's always more than one factor affecting the tests and a change in one of them might give you different results...

Also, the type of car (FR, FF, 4WD, MR) is one factor that might have influence in some tests...
 
MacRoadster
However i think you shouldn't generalize so much in your conclusions...
For example, i did the ride height acceleration test, and i got better acceleration with lower ride height...
Click to expand...
oops, maybe you're right :). I should test more car.............
BTW, do you know any car that can use racing brake and smoking rear tire when using super soft tire? Or any car that don't smoke when using racing break and super soft tire?
I want to test weight transfer effect when using different brake, but finding rear bias car is hard, 10 car I test so far is not rear bias............
 
Damper vs Spring, reducing weight transfer
Rodney Arndt
File is in this url.
The most important thing to remember regarding shocks, is that the stiffer the shock, the less grip it will have at the corner or end of the chassis.
Shocks do NOT control the amount of weight transfer in a corner. They will however control how quickly the weight is transferred.
Click to expand...

Damper brake test
White rims (top) : 1/1 1/1 damper
Black rims (bottom) : 10/10 10/10 damper
all : 2.0/2.0 spring rate, 135/135 ride height



Black which using higher damper setting is slower on acceleration.
The braking distance seems the same, and the smoking speed is the same. So damper do not affect weight transfer. Or maybe a little, because it seems the black smoke little less than white.

Spring brake test
White rims (top) : 2.0/2.0 spring rate
Black rims (bottom) : 10.0/10.0 spring rate
all : 1/1 1/1 damper, 135/135 ride height

Lets ignore that black is faster. Black tire doesn't smoke at all. Meaning the spring rate manage to reduce the weight transfer, make the rear wheel has more weight and reducing slip.

Conclusion:
Make sense, damper do not seems to effect weight transfer, spring do. But if you think this comparison is not fair enough, I can test it with other value. I open to sugestion.
 
Stock vs Racing part II, reduced smoking
I am not satisfy with previous comparison that resulting in a lot of smoking when braking. So, to minimize the smoke on default front bias S15, I use 1/24 brake bias controller, 2.0/2.0 spring rate, and 130/130 ride height.
Red using racing brake, blue using normal brake.




Red have faster breaking even on high speed braking.
The last image show that using racing brake have effect on weight transfer.
 
Ride height effect on FF car acceleration
Following MacRoadster advice, I test the spring rate effect on acceleration on Civic Type R.
Yellow using 135/135 ride height, black using 89/89 ride height, both using 20.0/20.0 spring rate, 24/24 BBC.



Black is faster, so using low ride height on FF can make the car faster. I think this is caused by weight transfer. Using low ride height, the weight transfer is less, so the front wheel that move the car has more traction, which make it has better acceleration.

To test this conclusion I did a Spring rate test.
Yellow using 20.0/20.0 spring rate, black using 2.0/2.0 spring rate, both using 135/135 ride height,24/24 BBC.



It is clear that yellow has faster acceleration.
This is almost the same from FR car result. Although in Silvia spring rate acceleration differences is lower than ride height acceleration differences , where as in Civic spring rate acceleration differences is higher than ride height acceleration differences.
I think this means that high spring rate provide better acceleration on both car, maybe cause by better grip, but I'm not sure. The reduced acceleration on FR maybe caused by the weight transfer that make the rear wheel has less traction.

So, weight transfer have effect on both acceleration and braking.


Additional test
Drag vs low ride height acceleration
Yellow : 89/135 ride height
Black : 89/89 ride height



From previous test low ride height is faster, but in this test we see that using drag height can give faster time, the acceleration differences seems bigger on high speed. I think this caused by added downforce on the car making the tire have better traction. In silvia test drag setting also give faster acceleration.
If it is true that drag setting give more downforce, then using drag ride height will also increase our cornering speed.
 
sucahyo
BTW, do you know any car that can use racing brake and smoking rear tire when using super soft tire?
Click to expand...
I usually use racing brakes and super soft tires in all cars, and i always give my FF cars some oversteering when braking (using high rear brake settings, harder rear suspension and no/low rear wing). So i guess all of them can smoke... :rolleyes:

sucahyo
Spring
White rims (top) : 2.0/2.0 spring rate
Black rims (bottom) : 10.0/10.0 spring rate
all : 1/1 1/1 damper, 135/135 ride height

Lets ignore that black is faster. Black tire doesn't smoke at all. Meaning the spring rate manage to reduce the weight transfer, make the rear wheel has more weight and reducing slip.
Click to expand...
I'm not sure about this one...
Usually an harder suspension makes a car to easily loose it's grip, since it puts more pressure on the tires, and quickly becoming more than the tires can handle...
With softer suspension there will be an higher difference between front/rear heights when you accelerate, since the softer rear springs will compress more, lowering it. So the car's weight should move more to the rear...

In any test you do when you see one car loosing grip, try to use full downforce on both cars and limit their power, in a way that none of them looses their grip. Because, for example, stronger brakes are good as they help you brake, but if too strong you'll lock the tires and... that's bad. What i mean is, if you get bad results in one way it doesn't really mean it's bad, you might just be going too far...
 
MacRoadster
I usually use racing brakes and super soft tires in all cars, and i always give my FF cars some oversteering when braking (using high rear brake settings, harder rear suspension and no/low rear wing). So i guess all of them can smoke... :rolleyes:
Click to expand...
Yes, but they smoke the front tire or give no smoke on 1/24 BBC, at least on civic type r, altezza 280T, integra and primera. I still can't find car that can make rear tire smoke as much as mine R32.5 on 1/24 BBC.

MacRoadster
I'm not sure about this one...
Usually an harder suspension makes a car to easily loose it's grip, since it puts more pressure on the tires, and quickly becoming more than the tires can handle...
With softer suspension there will be an higher difference between front/rear heights when you accelerate, since the softer rear springs will compress more, lowering it. So the car's weight should move more to the rear...
Click to expand...
I forget to write that that is a braking test, not acceleration test. For many test I reverse the car to make better speed. I start from low rpm. I release the throttle momentarily before pressing the brake.
If the road is smooth, I think the spring will act as weight transfer balance. So, when braking the weight transfer will be decide by spring rate value. The tire looses grip when braking when the weight on that tire is not enough or the brake is too strong or the tire grip is not enough.
Because the mine r32.5 is rear bias, we need to make the weight transfer as low as possible, make the rear weight more when braking. Also we need to make the rear brake as weak as possible (although the test is using 1/24 to show a lot of smoking). This test is using super soft tire, so this provide maximum grip available.

About spring rate, it seems that even though using high spring rate reduce the weight transfer, making the rear have less traction than using low spring rate, the grip provide by high spring rate manage to overcome that.
MacRoadster
In any test you do when you see one car loosing grip, try to use full downforce on both cars and limit their power, in a way that none of them looses their grip. Because, for example, stronger brakes are good as they help you brake, but if too strong you'll lock the tires and... that's bad. What i mean is, if you get bad results in one way it doesn't really mean it's bad, you might just be going too far...
Click to expand...
I test the car using no weight mods so both car have same downforce. For that testing I specifically made the rear to smoke by using harder rear brake, 1/24 BBC, to see the weight transfer easier. If the rear do not smoking, I don't know how to see the weight transfer effect. Checking the front tire smoke is difficult because using 24/1 is not enough to make the front smoking, maybe 50/1 can make i smoke, but I too lazy to hybrid it..............

In acceleration test I don't see any smoke, so I assume it don't loose grip.
For braking, if your wheel is locked, you can try to change the brake bias to the wheel that is not locked. If both locked at the same time (jaguar xjr), we should reduce both. On most car (the car that I test is about 20) we can use 24/1 or 24/24 or 1/24 without making the tire smoking above 10kmph, the key is to use proper brake bias.
If you are not using super soft, I think you should not worry about wheel locking. Simulation tire can't give smoking on these test. I still can't smoke it yet.
 
Brake bias effect
I keep mentioning that Mine R32.5 has rear bias and Silvia S15 has front bias, but I never do braking test that comparing the proper bias performance. So this is it.

Mine Skyline R32.5
White rim (top) : 1/24
Black rim (bottom): 24/1





So, even with rear tire not smoking, black have the worst braking.

Silvia Aero
Red (top) : 1/24
Blue (bottom) : 24/1




Blue start to smoke even from 170kmph, and the braking is worst.

So, tire smoking is a good bias indicator, but should not be use to judge the braking performance. Coincindentally, lower front always give better time on both front and rear bias, with using front bias BBC to front bias car making about the same braking differences with using front bias BBC to rear bias car.
No conclusion yet...........
 
sucahyo
I forget to write that that is a braking test, not acceleration test.
Click to expand...
Ahh... ok it makes sense now :) I was thinking on acceleration :P

I just did some tests with FF cars, and yes rear tires are hard to smoke on a straight brake. They usually smoke easily with me, but that's on normal driving where i'm still braking when i start cornering.

But if you want an FF car that smokes rear wheels, try Tom's T111. I just made it's rear wheels to smoke with 16/14 brakes and super soft tires, but i had to use gearbox to help braking. This way more weight is transfered to the front making the rear to loose grip.

sucahyo
I keep mentioning that Mine R32.5 has rear bias and Silvia S15 has front bias
Click to expand...
What you mean by that? You can adjust it with the brake balance controller...
 
liam2maps
Boy has this got everyone talking.
Click to expand...

Yeah, no kidding. A couple weeks ago it seems Sucahyo didn't know a thing about brakes, in our setup thread he often didn't even bother to tune them! I oughta start taking notes on all this. Most of the time when i brake during my sim races, i'm going by intuition, but I never bothered to do a study on all the different settings.
 
Last edited:
MacRoadster
But if you want an FF car that smokes rear wheels, try Tom's T111. I just made it's rear wheels to smoke with 16/14 brakes and super soft tires, but i had to use gearbox to help braking. This way more weight is transfered to the front making the rear to loose grip.

What you mean by that? You can adjust it with the brake balance controller...
Click to expand...
Thanks, I'll try Tom's T111.

I mean that when using the same BBC setting the Mine R32.5 will smoke the rear tire more than Silvia. Or Silvia smoke the front tire more than Mine R32.5. By smoking I assume the brake force is bigger on that wheel.
Front bias means that the front brake force is bigger than the rear.
So, rear tire smoking = rear bias, front tire smoking = front bias.
example: using 1/24 BBC should give the car more rear tire smoking, using 24/1 BBC should give the car more front tire smoking.
This is what happen when we use 1/24 BBC on silvia and 24/1 BBC on Mine R32.5.


Silvia still smoke the front tire although the BBC set to extreme rear. And the Mine R32.5 don't smoke at all even when using extreme front BBC. So this means, the bias of the car in GT2 is not the same. Using the same brake bias controller value will not give the same brake bias.

Parnelli Bone
Yeah, no kidding. A couple weeks ago it seems Sucahyo didn't know a thing about brakes, in our setup thread he often didn't even bother to tune them!
Click to expand...
This forum improve me a lot :).
 
Stock vs racing brake on different tire
I finally got rear bias car (thanks MacRoadster :) ), so I can continue with stock vs racing brake.
White rims (top) : racing brake.
Black rims (bottom) : normal brake.
Both car using 2.0/2.0 spring rate, 125/125 ride height, and 1/24 BBC to make the rear tire smoke more.

Braking on super soft tire




White has better braking.

Braking on sports tire




I am confuse with the tire smoking image, second run gives the same smoking on black, no smoking on white. White has better braking.

Braking on normal tire



White has better braking.

Braking on simulation tire



The difference is unnoticable.

Conclusion:
Racing brake have better stopping power than normal brake. The difference is more noticable on sticky tire.
The weight transfer when using different brake is unnoticable, except for sports tire anomally.
 
sucahyo
I mean that when using the same BBC setting the Mine R32.5 will smoke the rear tire more than Silvia. Or Silvia smoke the front tire more than Mine R32.5. By smoking I assume the brake force is bigger on that wheel.
Click to expand...
I see... that's an interesting observation, but you're forgetting something...

That might mean they have a different weight distribution. A car with a weight distribution of 40/60 (rear/front) should lock rear wheels easier than a car with 55/45, assuming they have same tires, wheels, brakes, total weight, etc...

Wheel size and other factors that affect braking, might also explain that difference between Skyline and Silvia.
 
MacRoadster
I see... that's an interesting observation, but you're forgetting something...

That might mean they have a different weight distribution. A car with a weight distribution of 40/60 (rear/front) should lock rear wheels easier than a car with 55/45, assuming they have same tires, wheels, brakes, total weight, etc...

Wheel size and other factors that affect braking, might also explain that difference between Skyline and Silvia.
Click to expand...
you're right :).
 
Extreme toe effect on turning
By using PEC I can set extreme value for toe. With this I hope we can understand toe effect better.


Front toe effect
Red = -6.35
Blue = +6.30

Red response the steering first, but only for a moment, after that blue turning faster than red.

Red = 0.00
Blue = +6.30

This show how toe will restrict your high speed turning ability.

Rear toe effect
Red = -6.35
Blue = +6.30

Red turning faster, notice the speed, red is sliding the rear, blue doesn't have as much decelleration. rear toe out will make the tail slide easily, rear toe in will make the car turn happy.

Red = -6.35
Blue = 0.00

the turning speed deceleration on red compared to neutral toe.

I will add normal toe effect later
 
RouteUK
Dont red cars go faster anyway? thats what i heard from my mum.....
Click to expand...

No that's not true. That's another Gran Turismo myth along with the theory that car washing will make your car faster/make it sell for more money. There is no hidden drag strip or milk truck, either.
 
I didn't know about the hidden milk truck myth, shame i would of stoped living to unlock it. Of i trot to the GT5 "cars they should put in section"
 
Another huge myth was started at Granturismoforum.com a couple months after GT2 came out--this loser was sayin if you fill your garage with all black cars without duplicating any of them, the game would reward you with “the hidden McLaren”. So some people actually tried it--they bought 100 black cars and nothing happend. Turns out the guy who started the rumor later fessed up and apologized. He was doing some sort of experiment.

Anyways, there is no Mclaren in GT2. Big rumor dispelled.
 
TCSC effect on acceleration and braking
Originally I just want to test the TCSC effect on acceleration, but during testing I found out that TCSC have greater effect on braking!

Yellow Civic : 254 TCSC
Black Civic : 1 TCSC
Both using super soft tire, race brake, 24/24 BBC




Red Silvia : 254 TCSC
Blue Silvia : 1 TCSC
Both using super soft tire, race brake, 24/24 BBC




Blue Supra : 254 TCSC
Yellow Supra : 1 TCSC
Both stock, normal tire




Blue Supra : 51 TCSC
Yellow Supra : 1 TCSC
Both using super soft tire, race brake, 24/24 BBC




Blue Supra : 26 TCSC
Yellow Supra : 1 TCSC
Both using super soft tire, race brake, 24/24 BBC






Conclusion
Using TCSC too much can make the acceleration suffer. But right value will make the car faster. This is same with the TCSC description


Even if not mentioned in the description, using TCSC improve braking, by using the right value you can significantly increase your braking distance.
TCSC can improve acceleration, but the greatest effect is on braking!
 
CVT vs 5 speed transmission on Honda Logo TS
When I try to race using stock Honda Logo TS just for fun in sunday club Highspeed ring, I got surprised by its ability to keep up with Silvia R Spec, and Honda Type R. So, I place it head to head with other Honda logo with superclose transmission upgrade too see what make it fast:

Black (top) : superclose 5 speed transmission
Red (bottom) : stock 2 speed transmission




The CVT Logo have more acceleration than 5 speed logo on launching. But after reaching highspeed the 5 speed catch up. I thinking this is because the rpm on CVT is not on peak hp rpm.

So, I test again using more powered Logo: stage 2 turbo, racing muffler, super soft tire, racing flywheel, and triple clutch.
Black (top) : superclose 5 speed transmission
Red (bottom) : stock 2 speed transmission




This time the CVT win in all speed acceleration, on launching even with less acceleration advantage, the CVT logo still have more acceleration. On high speed when the 5 speed changing gear the CVT will create more distance.

Racing both car in short seattle result in CVT wins.


So, CVT is faster.
Too bad there are no other more powerfull CVT in GT2, and I don't know how to hybrid CVT to other car................
 
Yeah, that's real interesting. My guess would be that the CVT would have better top-end but worse acceleration. And my guess would be wrong.
 
It seems CVT is banned from racing because it is too fast (some say it is 2 second faster lap in william renault F1) and very uninvolving.........
 
NA vs Turbo, race test
Interested with thread in GT4 section Stage 5 (original) turbo Vs Natural Aspiration Vs Supercharging, tested!, I decided to do the same. So:

Takumi(NA Trueno) vs Wataru (Turbo Levin) :)


Trueno : Stage 2 NA


Levin : Stage 1 Turbo + port grinding


Both car have 164 hp, custom suspension racing flywheel, carbon shaft, custom gear, triple clutch, super soft tire.

The race is a close one. In grindelwald NA trueno wins. It seems bigger tourqe in turbo do not help acceleration.



Lotus Elise
Blue : NA


Red : Turbo


Same, blue always win in grindelwald in either start on 1st position or 2nd position even with +3hp for red.


No conclusion, turbo is cheaper and can get more power. In a same car, a fully tuned turbo will beat fully tuned NA in many cases. But if you want to enter the car in a restricted hp race, using NA is best for overtaking.
 
sucahyo
NA vs Turbo, race test
Interested with thread in GT4 section Stage 5 (original) turbo Vs Natural Aspiration Vs Supercharging, tested!, I decided to do the same. So:

Takumi(NA Trueno) vs Wataru (Turbo Levin) :)


Trueno : Stage 2 NA


Levin : Stage 1 Turbo + port grinding


Both car have 164 hp, custom suspension racing flywheel, carbon shaft, custom gear, triple clutch, super soft tire.

The race is a close one. In grindelwald NA trueno wins. It seems bigger tourqe in turbo do not help acceleration.

Same, blue always win in grindelwald in either start on 1st position or 2nd position even with +3hp for red.

No conclusion, turbo is cheaper and can get more power. In a same car, a fully tuned turbo will beat fully tuned NA in many cases. But if you want to enter the car in a restricted hp race, using NA is best for overtaking.
Click to expand...

Torque has little function during actual races. Torque only gets you going...horsepower is what keeps you going. Torque only comes into play when you're accelerating from a dead stop and sometimes it helps you get out of those tight corners quicker....this is why muscle cars do better on smaller tracks in Expert Generator races than they do on longer tracks against the Skylines and RX-7's.
 
I can explain traction control vs electronic stability control and turbo vs supercharger but remember I suck at explaining. I can give it a go though.

I'll explain Turbo vs supercharger vs NA first though ok.
 
Turbo first.

-- Turbo
Turbo is NOT a rocket or a jet type of booster thing. No. What it is, or what I was told ages ago is that it's a simple thing that forces more air into the engine or intake or whatever. Remember engine needs fuel, spark and air to work. The most important thing to do when working with a turbo is not intercooler but actually ECU.

What you are doing is trying to force more air into the intake or engine etc. Now if you force more air into the engine you will need more petrol and possibly a better cleaner spark. For example we know fire(explosions, engine explosions) need a flame(spark), fuel(petrol) and air(air). So what you do to one side you must do to the other side too

See you have to get the perfect mixture.

RICH: Too much fuel and you don't get full power PLUS you are wasting fuel.
LEAN: Too little fuel and you don't get full power either. Engine may fail to detonate.

Both wreck the engines. You can rich it slightly for more power but after that there is a curve. When you see racing cars driving around they often have a switch called fuel mixture. It has a number and it has a preprogrammed function. A driver can choose to rich the mixture SLIGHTLY and get SLIGHTLY more power or may lean the engine and get a little less engine and last longer without a pitstop. Riching and leaning decrease engine life in a race too because the engine is NOT at peak. Riching may have the engine working too hard to burn the fuel. Leaning might have too much air and not enough fuel.

It's a fine line. ALWAYS REMEMBER the ECU is the MOST important thing with the turbocharger. People always forget it. When you get a turbo charger installed a good installer will fix the ECU for you. Garrett Turbo does that. Best turbo chargers I know of. They power the Ford World Rally Championship focus as well as other motorsport. They also are very popular in road cars 300ZX.

Now that I stressed the ECU part I'll do a small teeny bit on the intercooler. Basically cool air in the engine is better than hotter air. When the turbo charger forces more air into the engine (think of it as a small fan blowing air) if it spins too hard it might produce more heat than power. You'd want to cool that wouldn't you? Hence the intercooler. Intercoolers main job though is too cool everything down, not just intake air for turbo.

--- Common mistakes made by losers
1// Saying a turbocharger is the best thing ever invented. Definately not true. It's a double edged sword that is very picky on which car it will work on.
2// Price matters. No, installer matters. Yes the price does come into it but go to a proper professional and an actual company who specialise in turbo chargers. Garrett rules for turbo chargers. Can't go wrong with a T3.
3// Installer doesn't ask for ECU -or- ECU isn't sent to be recalibrated. You NEED more fuel in there otherwise your engine will either screw up and not detonated correctly OR just simply the car will suck.
4// Kids just install a bolt on turbo for a car that simply can't handle it. Not all pistons and cams can handle it. Check the difference between a Nissan 300 ZX '88 turbo and non turbo. Different cams.
5// Not thinking about turbo lag. It takes a while go a turbo to kick in. So accleration often suffers, not just that BUT you have to maintain it more often. Not just that but even a smart ECU can't spit more fuel into the engine when it's needed and less when it's not needed.
6// Running a turbo too hard. Breaks the engine and produces more heat than actual power.
7// People are unrealistic and often blow engines.

I'm going to go back to drinking now. Someone save this but give credit where needed.
 
Nice ecplanation, I don't know that too rich or too lean can damage the engine.........
so, can we use turbo to increase milage ?
 

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