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- Dolhaus
You are right in that my transmission notes need improving, I'm constantly trying to learn the ins and out of tuning them but the process is difficult to write up. I will try to work on a better explanation but it may take some time unfortunately. đź‘Ť
I'm not going to go into a long drawn out explanation about the difference between torque and horsepower (Bhp) as it involves a lot of maths and makes my brain hurt.
If we imagine a man pushing a boulder we can visualise torque as his ability to get the boulder moving in the first place, his overall strength so to speak which dictates how easily he moves the weight and whether he can push it up an incline. Bhp is represented by his ability to keep the boulder rolling once he has gotten it moving, the more Bhp he has the faster and easier he can keep travelling at speed, almost like his fitness level.
To use another analogy, torque is like a weight lifter, Bhp is like a 400M sprinter.
Instead I will run through the way I choose parts in order to get the best performance from a car when I am building to a PP/BHP limit.
The important thing to remember is that torque is just the amount of twisting force delivered to the wheels by the engine, it can be both a good and a bad thing depending on what you want to do with a car and what the car is capable of in terms of grip.
When changing parts in order to get improve our torque we must first observe our toque curve within the tuning menu and understand what this represents in terms of our driving experience/performance.
One important thing is not to get too caught up on peak values, just because we have a bigger number doesn't mean we will go faster. We must understand how the gearing will utilise the power through all of the gears.
As we go up through the gears while racing you will notice that you start the new gear at different point in the rev range:-
1st: 1000 Rpm (idle) - 7500 Rpm (redline)
2nd: 3000 Rpm - 7500 Rpm
3rd: 4500 Rpm - 7500 Rpm
4th: 5100 Rpm - 7500 Rpm
5th: 5800 Rpm - 7500 Rpm
6th: 6000 Rpm - 7500 Rpm
As we can see, we are using less and less of the rev range as we go up through the gears, this means that we need to look our power curve to reference how much of this performance we are able to access.
Torque gives us our low speed pushing power, it is extremely useful on courses that involve climbing up a gradient and is essential for heavier vehicles. As a downside, if your tyres can't handle the force generated by the torque you are going to get a whole lot of wheel spin when exiting low speed corners. When applying these tuning principals we must think about what we want as a result, do we want low end grunt or top end performance?
If the course is full of low speed corners and/or hills and the tyres are up to the task then we will be looking for more torque. Conversely if the track is fast and open we are looking for a better Bhp range
Lets look at some examples so we have some visuals to better explain the ideas.
Car: Hyundai Genesis 3.9 - Stock
359 Bhp @ 6500 Rpm
42.3 Kgfm @ 5000 Rpm
Redline: 7500 Rpm
Power limiter: 100%
As we can see the car has a fairly normal power curve. The Bhp grows fairly equally until its peak at 6500 Rpm before dropping off quite steeply in the last 1000 Rpm of the top end. The torque curve grow gradually to its peak at 5000 Rpm where it holds until about 6400 Rpm before dropping off sharply. This pattern means that the car has good mid range torque which will allow it to pull strongly through the mid range and will keep accelerating well until near the redline.
Now we will set a tuning limit of 400 Bhp and see what various parts are doing to the power curve and what this means to performance.
Tune 1
400 Bhp @ 6400 Rpm
53.4 Kgfm @ 4500 Rpm
Redline: 7500 Rpm
Power limiter: 97.7%
With the Low-Rpm turbo fitted we see a change in the shape of the torque curve, it is peaking slightly earlier and then dropping off at almost the same rate it climbs. We are making more peak torque but less in the higher ranges. In terms of gearing this means that we would get better performance in gears 1-3 but would begin to see performance drops in 4-6 because we are starting the gear past the peak on the downward slope. In those higher gears we may actually be producing less torque than stock.
The Bhp is in a similar state to stock, the peak/drop off haven't changed enough to cause a major difference to performance.
Tune 2:
Parts fitted: Mid-Rpm Turbo
400 Bhp @ 5600 Rpm
60.0 Kgfm @ 4500 Rpm
Redline: 7500 Rpm
Power limiter: 95.1%
Again we see a higher peak torque figure but a more peaky range where it quickly climbs and then drops off. The drop off is slightly more aggressive than the previous tune but the peak is substantially higher so road testing would be necessary to decide which was best.
The Bhp on the other hand looks much better, the peak is earlier and sustains itself well without facing a nasty drop off in the high Rpm's.
Tune 3:
Parts fitted: High-Rpm Turbo
400 Bhp @ 5600 Rpm
54.6 Kgfm @ 5300 Rpm
Redline: 7500 Rpm
Power limiter: 97.7%
We can see that the lines are much less peaky with this parts configuration, there are no dramatic inclines or decline in power. We may be making less peak torque than the Mid-Rpm turbo but we are making a lot more within the usable range, this would give us great drive through the higher ranges and smooth power delivery in the lower gears. Because we are using a larger % of engine limiting we see a flat line at the top of the Bhp curve, it hits a peak and doesn't decline. This setup would definitely go on the short-list if I was looking for options.
Tune 4:
Parts fitted: Stage 1 engine tuning, Isometric exhaust manifold
400 Bhp @ 6600 Rpm
46.7 Kgfm @ 5100 Rpm
Redline: 7600 Rpm
Power limiter: 99.3%
We see a very similar power curve to the engine in stock form, the redline has increased by 100 Rpm and the peaks have moved in a similar fashion. This would be a good way to increase your power output without changing the engine characteristics too drastically if you liked it in stock form.
Tune 5:
Parts fitted: Stage 2 engine tuning
400 Bhp @ 6500 Rpm
47.0 Kgfm @ 5200 Rpm
Redline: 7700 Rpm
Power limiter: 97.2%
Again we see a similar trend as we would expect with engine tuning, the Redline is again raised and the peaks follow along in a similar fashion. Because we are using increased % of power limiter we are again seeing a flatter Bhp peak.
Tune 6:
Parts fitted: Stage 3 engine tuning
400 Bhp @ 6400 Rpm
50.4 Kgfm @ 5300 Rpm
Redline: 7800 Rpm
Power limiter: 89.3%
Here we are starting to see the engine being strangled by the limiter, the decline in torque is slightly steeper than before for a small increase in peak figure. I try to avoid using the limiter past the stage where it is flattening the torque curve where possible as it often makes the power less progressive through the range.
Tune 7:
Parts fitted: Stage 3 engine tuning, Sports ECU, Racing exhaust, Isometric exhaust manifold, Intake tuning, High-Rpm turbo
400 Bhp @ 5100 Rpm
62.8 Kgfm @ 4600 Rpm
Redline: 8300 Rpm
Power limiter: 50.5%
Here we see what happens when we go for maximum peak figures, we end up with a very odd torque peak where the power drops off sharply and dramatically but the Bhp peaks early and maintains to the redline. If you were looking for high speed performance this would be the option for you because of the Bhp consistency but your low speed grunt would be reduced.
Hopefully this answers your question, feel free to ask further questions if I've missed anything đź‘Ť
Edit:
Reply removed
Sorry @DolHaus I just realized this was your tuning thread and not the physics one. Quick glance and only saw the 1.09, it is not my intention to step on another tuners thread/toes.
No worries mate, easily done.
As long as the answer is mostly correct I really don't mind people answering other peoples questions, always good to have a second opinion
Great analogy
