Author Topic: Setting your trany up (Read 673 times)

SFRT - Frenchy · « **on:** June 17, 2005, 03:59:37 PM »

I'm trying to maximize acceleration in those racing video games, what should I do?

Shift at the peack HP, and set the next gear to start at peack Tq?

Chairboy · « **Reply #1 on:** June 17, 2005, 04:14:36 PM »

Gotta say... I had my misgivings when I saw the title.

In regards to the question, which games specifically? Depending on the realism, the max torque might be elsewhere, and waiting until the redline might not get you the best acceleration.

If, on the other hand, it's like 'Pole Position' by Atari from the 80s, then redline that sucka.

SFRT - Frenchy · « **Reply #2 on:** June 17, 2005, 04:17:43 PM »

Forza Motorsport for Xbox, fairly realistic. Peack HP is not the redline.

lazs2 · « **Reply #3 on:** June 18, 2005, 08:51:45 AM »

don't know about games but...

allways shift at peak hp or a little above so long as HP doesn't drop off too radicaly or you induce something like valve float.

lazs

rpm · « **Reply #4 on:** June 18, 2005, 04:58:22 PM »

It all depends on the powerband of the engine. You want to shift at the max of the powerband.

lazs2 · « **Reply #5 on:** June 19, 2005, 08:51:44 AM »

uh.. define "powerband" and "peak" for me rpm.

lazs

Skuzzy · « **Reply #6 on:** June 19, 2005, 09:08:43 AM »

It would rather depend on what type of racing. In the 1/4 mile, typcially you want to keep the engine at its peak power output for every shift.

In a road race, you want to make sure each shift does not result in a power loss when the engine shifts RPM's. In other words, you might push the RMP higher and allow the horsepower to drop off, if it means the next shift will come in at the same of higher horsepower than the last gear.

This is a way over simplistic perspective as there are hundreds of variables involved in real life. Dunt know about the game though.

moot · « **Reply #7 on:** June 19, 2005, 10:29:06 AM »

Rule of thumb I'd say is to shift as soon as there's more power in the next gear. Allowing for any additional variables like Skuzzy says, e.g. clutchtime or road slope or sideways Gs at shifttime, etc.
Simplest way is to graph power/rpm, memorize that, then draw rpm/roadspeed, and draw your ratios as you best guess they should be.

e.g. if you have an engine with a perfectly flat peak of power from 5 to 10krpm, there'd be 1st gear from 0 to 10krpm, then each consequent ratio just a tad more vertical than the previous, altogether covering the ideal low and top speed of the circuit.

Then adjust for useable grip, etc

lazs2 · « **Reply #8 on:** June 19, 2005, 10:31:36 AM »

why would you ever want to shift at a point lower than what would leave you at peak hp for the next gear? Unless we are talking about pulling trailers or trying to move a buncha crates of eggs or sumthin.

lazs

moot · « **Reply #9 on:** June 19, 2005, 10:58:44 AM »

Just estimating by instinct.
You'd want the gears to stretch from 1st to last (say 6th), with the ratios set to have as much power as possible from lowest to highest speed expected on the circuit.

I figure the best acceleration is found with the ratios yeilding the most thrust, most thrust is from most power, most power in a given time lapse is with any given ratio that sits with the most surface between it and the power curve above it.

This is where I imagine an ideal ratio should be if the gearbox is linear and sequential.

Skuzzy · « **Reply #10 on:** June 19, 2005, 11:05:00 AM »

Yep, looks about right for a wide ratio tranny, and assuming the ratios are the same increment from shift to shift.

moot · « **Reply #11 on:** June 19, 2005, 11:09:29 AM »

I see what you're saying lazs, I guess it depends how much you want to squeeze the ratios together.

All things being equal, with a 4-ratio gearbox on a stretched out track, you'd have long ratios and be forced to land the next gear before peak power, like the third pic above, but on a short track with a 6-gear, you'd be able to squeeze em together enough to shift at the moment that lands you on the next gear's peak.

Not sure which is right. Instinctively it still makes more sense to me that the ratio'd include more total power sitting with the peak above its middle rather than at one end.

That's assuming a regularly shaped peak, and ignoring resistance increasing with speed (wind, tranny friction etc).

Steve · « **Reply #12 on:** June 19, 2005, 12:10:16 PM »

Dang, I thought this was a thread about RL.

SFRT - Frenchy · « **Reply #13 on:** June 19, 2005, 01:26:21 PM »

That's what I came up with. I have have my virtual engine at 430 HP @ 5700RPM. I have the best results by shifting setting up gears 2 to 5 to shift at 6,500 (400HP), and they grab the next gear at 5,000 (400HP).
So I always have from 400 to 430HP. After 6,500RPm, the HPs take a nose dive, it's not worth pushing to 7500.

If I set the gears to start right at peack of Hp (5,700 @430HP), it's not good because I spend my time shifting. I loose time for shifting, and it's not offset by riding the peack of the power curve more tightly.

Seems like the Tq doesn't have anything with setting up your trany. What is Tq curve usable for?

BTW, driving sims are good enought, that like in real life, setting you trany according to ur engine output, and camber/springs/rebound/damper matter if you want to drop lap seconds.

lazs2 · « **Reply #14 on:** June 19, 2005, 07:11:01 PM »

It ain't rocket science guys... I got no fancy charts but...

you have 3 to six gears of whatever ratios... makes no friggin difference.. you will drop, depending on ratio and how you shift (full power, speed shift ham fisted brit tranny shift, whatever) you will drop from 400 to 1000 rpms or more by the time you are in the next gear... if you get peak HP at 5700-6,000 rpm and drop 500 hp every shift you might want to carry the shift point up to 6200-6400...

depending on how bad the power.... HP, drops off after 6000 and below 5700..

In practice... it is simple as ****.... you hold in gear, pedal to the metal till the damn thing quits pullin and then bang off a gear. All the charts in the world ain't gonna matter if you can't feel it and if you don't know how to shift tho.

unless you have an automatic in which case it makes no friggin difference... have the "guy" set it up for you and go join the "what's your favorite tea?" thread.

lazs