note: 4.09 in A4 is too low for stock rev limited and motor. This was only a test.


I set up a little race between an A4 and M6 vette with some slight mods.
Both have 4.09 gears and sticky tires (zero spin). Both cars were launched hard. The A4 had a 3000 RPM stall and the M6 was dumped at 5500 RPM. The M6 had an "average" driver in it (tenth of a second between shifts).



Results: The M6 jumps out because of using the engine/flywheel inertia to help get the car moving, but, because the tires hooked so well, even with 4.09's the RPMs dropped to 2300 RPM. This gave the A4 (stalling at 3000 RPM) time to make up the difference and drive by while the M6 shifts.

You can see the M6 matching the A4's speed in 3rd gear vs 3rd gear. This is were the 6-speed's advantage shines, but it wasn't enough.

60 foot times:

M6: 1.75s
A4: 1.79s

1/8 times:
M6: 8.19s
A4: 8.13s

1/4 times:
M6: 12.94s @ 104.19
A4: 12.84s @ 105.15

It would be a closer race if the M6 spun a little to keep the revs up and had a better driver. I think the A4 deserves some more respect. (curse those stock 2.59 gears) :eek:

:cheers:





[Modified by Red94Vette, 9:56 AM 6/8/2002]

 

Go A4!! :D

This program of yours is awesome! :yesnod:


[Modified by vettes rule, 11:37 PM 6/7/2002]

 

Why did you say curse those 2.59 gears?

That's what I have and it sounds like you are saying they have potential in drag racing. :eek:

 

This program was years and years an years in the making! I started making simple formula equations when I was 14 y/o. Then when I learned physics in college I started re-thinking my sim.

You see, here is the deal. When a programmer tries to make a simulation of something he doesn't know a lot about, the program's interface is good but the results suck and are in a form you can't use.

When a drag racer tries to make a program his programming skills sucks, the results are better but the user interface blows.

If you get someone that is an experienced drag racer, has an engineering degree, and can do some creative programming, then you get a great product.

The secret is in breaking everything down into it's raw elements. There's no trick equations in my program. Everything is physically sound (using laws of motion, physics, etc.) All the parts are modeled with inerta.

Here is one cool part about this program. The engine, drivetrain (including wheels), and car can all be at different speeds at the same time.

Example: You could be launching the car at 5500 RPM. The clutch starts to grab and pulls the engine down. Meanwhile, the drivetrain & wheels starts to accelerate. And if there is tirespin the rear wheels will spin faster than what the car is moving.

Usually the engine will drag down til it reaches the drivetrain speed and then when traction is greater than engine output the tires will slow down and match the speed of the car. All this happens in my progam.

Nothing but the best.

:cool:

 

Why did you say curse those 2.59 gears?
That's what I have and it sounds like you are saying they have potential in drag racing.

No, no. Both cars have 4.09s. I was cursing GM for 2.59s stock. With some good gears an A4 would be deadly from a stop.

Here is a run A4 vs A4. One has 4.09s the other 2.59s



60'
2.59 gears: 2.07
4.09 gears: 1.79

1/4:
2.59 gears: 13.27 @ 103.88
4.09 gears: 12.84 @ 105.15

.43 seconds faster (4+ car lengths)

:cuss

That's why.


(notice the speed gap on the two cars.. the 2.59s are closing it up but it is still slower, this means the 2.59's had a little more acceleration on the top end. This is why people talk about high gears pulling better on the big end. In this case the 2.59s were so far behind it didn't matter)




[Modified by Red94Vette, 11:16 PM 6/7/2002]

 

Thanks. :D I thought I could actually get away with a high stall converter and keep my gears stock.

That program looks awesome. :cheers:

 

You can get away with a high stall and 2.59s. Let me run a sim for you A4 vs A4 2.59 vs 2.59s stall vs stock stall.

Hold on.

 

Ok, both A4 2.59s. One has a 2000 stall the other 3000 stall. My torque curves start at 2000 RPM so I have no way to lower the stall below 2000 so you might see a little more gain than this.



60'
2000 stall: 2.17
3000 stall: 2.07

1/4:
2000 stall: 13.43 @ 103.77
3000 stall: 13.27 @ 103.88

Looks like about a .16 second gain with a good stall and 2.59s. That's a car and a half gain with an almost stock motor.

:cheers:





[Modified by Red94Vette, 12:03 AM 6/8/2002]

 

:D That's awesome. Thanks for running that for me. :cheers:

 

4.09s and a 3.06 first gear is pretty steep though. First gear would go by in a flash and probably with tire spin in a realistic setting. Remember, this was with 13" slicks and VHT track bite (no spinning) :yesnod:

 

I think I will try one more test of "3000 stall 2.59" vs a "3000 stall 4.09" A4 setup. This time though, it will be from a rolling start.

Results soon to follow...

 

Now this is classic. This is a 30 MPH rolling start. The 4.09 is too low of a gear for 1st so he is in the bottom of 2nd. The underdog 2.59s start at the top of 1st gear.

2.59s (orange) 4.09 (blue)



This shows why if you have better gearing than the other guy, try and get a race from a stop. A roll-on has some bad match-ups where you can get screwed like the 4.09s did here.

2.59's take the win!

:lol: :yesnod:


I already knew this, my friend has an A4 with 2.59s and from a 30MPH roll he is deadly. :cuss


[Modified by Red94Vette, 12:53 AM 6/8/2002]

 

Lots of folks are talking bout going up to 3:54 gears in the A4s. Could you please run a test of a stock A4 w/2:59's vs an A4 w/3:54's? I know you said you can't go below 2000 stall, but I think stock is 1800 anyways, right?

 

sure... i can probably set it to 1800 if I change the 2000 to 1800 and type in an "estimated" torque at that RPM. I will give it a shot.




[Modified by Red94Vette, 7:53 AM 6/8/2002]

 

Run: 3.54 vs 2.59s (1800 stall)

Great Weather Conditions: high 60's, 29.92 in Hg, 50% RH
Stock motors but with bolt-ons. I say that because dyno2000 (I use the torque curves from that program) assumes your motor has no restrictions besides the T/B and exhaust. So, this is K&N, aftermarket exhaust, perfect tune, etc.

After I perfect my drag racing proggie I will venture over to horsepower and tq sims. I have already done some work in this area and I know how to go about it.



Look at the RPM difference at the end, 3.54s are above 5000 and 2.59's are below 4000 RPM.

4.09s would be too low in an A4 with stock rev limiter and stock form, that's why 3.54's make nice gears for the A4.

:smash:




[Modified by Red94Vette, 9:45 AM 6/8/2002]

 

Here is a 4.09 with stock rev limiter. (not good)



Take notice on how the rev limiter is modeled, just like the real deal. There is a fuel cutoff and fuel resume RPM programmed in. :jester


[Modified by Red94Vette, 10:07 AM 6/8/2002]