I have a question… How much thought do the rest of you put into the whole power to weight ratio when deciding on your next build?? It’s a big deal IRL but I’m finding it may not be as big of a deal here as I thought. I’m trying to find speed in a certain car that by the numbers, should have plenty of, but it don’t. I’m not going to name the car nor am I looking for any advice because I entered this particular car in a tuning comp and where I thought this car would excel, it just aint. Lol. I’m just curious if it’s something I can just not worry about in my future builds. Or maybe there are other circumstances that I don’t know about.
Something to keep in mind, weight has no effect on top speed. Also, if you’re making a no aero build leaving a little weight in can actually improve the handling and give it better traction in exiting turns.
The main benefit of a good power to weight ratio is acceleration, which is the key factor to good laptimes on the majority of circuits.
if you building for racing, weight reduction>power>compound
Agreed.
Power to weight ratio is more of a big deal in real life when race classes have rules. If you have to run certain tires and have limitations on engine modifications its important to start with something decent. On forza because they’re no restrictions on anything other than PI it’s not as important for example you can have good power to weight ration and no tyres and your ratio means noting on short tracks
Usually I’m not thinking power to weight too much, I just try to make the car light, althuogh going up to higer classes with car that weights less then 2000lbs might end up being bit of a handfull and I might sacrifice weight to grip for ease of driving, despite being slightly slower overall. And in lower classes on tracks that don’t need too much acceleration, but require somewhat high top speed (Nordschleife for example) I might go for high weight high power, if I get it to handle well enough, and brakes are not lettingit down.
Overall my upgrading strategy is
Adjustables → Remove weight → wings-> power → wide tires → power → compound (possibly narrower tires) → power
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Power to weight ratio is just a piece of the pie. Many times the first thing I look at is what kind of tire widths are available to me with the car I’m tuning. Then I play with power to weight ratio’s, if you don’t have the rubber to put the power down then you’re just going to be spinning your wheels. Try to be either track specific or specific to the type of tune you want to obtain ie. Grip Tune or Speed Tune.
Depends on the car’s ability to accelerate and gearing.
I have an Eclipse that should do well over 170mph or 160mph on the track I was tuning it for based on experience with other cars. The car struggles getting to 140 mph despite having super light weight and respectable power.
Then I have other cars that are 300-500lbs higher than an ideal setup, but they dominate.
Some cars are just turds for certain tracks.
It’s a great idea to have a certain benchmark to achieve based on experience, but those rules can be broken.
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Some posters above say they value weight reduction over power, but regarding power-to-weight ratio (I’ll call this PTWR here), the two cannot be discussed separately, as they are a single entity.
If you reduce the weight of the car, then that car’s PTWR increases. If you increase the power of the car, then that car’s PTWR increases. Thus, they are both directly related and are equal in value.
For any given car, the best you can do to see which to tinker with is this:
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Reduce the weight as much as possible and calculate the car’s PTWR, which is basically Horsepower/Weight. Write this number down.
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Reset the car to default tune.
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Increase the car’s horsepower as much as possible and calculate the car’s PTWR. Write this number down and compare it to your first calculation.
If reducing weight, alone, gave you a higher number, then stick to this tune. If increasing power, alone, gave you a higher number, then stick with this tune.
PTWR is important in this game. People saying it’s not because different tracks provide different levels of grip are forgetting one thing…just like in real life, for different tracks you are supposed to change your tires’ pressure levels for different levels of grip. To get even more technical, you would actually retune the entire cars’ suspension setup, but since most tracks in Forza 6 are fairly similar in grip, you are safe in focusing on PTWR alone and tuning grip to an average of your liking.
I will say, however, that Forza 6’s physics/engine can be a bit wonky and inaccurate, so that sometimes, no matter how great/realistic your tune is, the car will just not handle/drive properly.
Hope this helps!
PTWR ( Im stealing that) is more then just power to weight in circut racing. Weight is a common enemy not only because you need power to move it but grip to turn it and brakes to stop it. That is why when looking at all three (power,handling,brakes) lowest amount of weight is a good thing.
Granted its not 100% that the lightest is the best but it normally is the best place to start.
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Several factors here.
#1 Low weight is preferred for many circuits because it implies a lower speed. Basically weight reduction is one of the best uses of PI.
#2 The aerodynamic drag of the car body has more affect on high speed handling than power to weight. There are cars with 300hp that can blow the doors off a 500hp muscle car because of the aerodynamic drag.
#3 You are mostly grip limited when it comes to acceleration in A class and above. AKA the ‘fun to drive’ cars. I would imagine that in B class and lower, power to weight becomes more important. But you also get cars on the goofy end of the spectrum with ridiculous high drag coefficients.
#4 The engine type matters. Unbalanced I4’s have 3rd order harmonic resonance. While not modeled in the game I’m sure, you’d be hard pressed to get top speeds out of a Mini Cooper no matter how much turbo pressure you jam in there. Its probably just an assumption as part of the cars drag. V6’s, V8’s, and Boxer engines are perfectly balanced and better suited to hammering away at max rpm. (Can’t forget the straight 6’s, they are balanced)
#5 RPM matters. This is a quirk of Forza I believe. 300HP at 6,000 RPM is not equivalent to 300HP at 9,000 RPM. I’m sure some people here will disagree. Thats okay. Forza seems to favor higher RPM engines as the power seems more direct to the road. In say 5th gear at 120mph 68HP makes it to the road from 300HP at 6,000 RPM. It seems like if you make 300HP at 9,000 RPM & 120mph, 72 HP makes it to the road. Something like that. There is an RPM bias. I honestly have no idea if this is how it works in real life, but its how it works in Forza in my experience.
If I remember correctly, in real life, the average engine (sports included) gets the most torque during mid-RPMS, which would explain the part I bolded above. As to your 5th gear question, HP tends to drop in higher gears because the engine requires less to move itself once it’s at those speeds. It’s kind of like a natural overdrive in engine theory. Your horsepower comes into most play in low-mid gears because the engine needs the power to get up to cruising/high speeds; same goes with torque. That’s why, if you look at the in-game HP/torque-curve graphs, at the very end of the RPM/Speed range, torque and HP tend to plateau or drop off. This is not a mistake, nor does it mean your build is weak…it’s just how engines work. You’ll notice the highest peaks in the graph are near the middle. For example, turbochargers cause torque to suddenly increase in midrange RPMS, which is why the graphs for turbo engines just jump up. Superchargers provide consistent torque at all RPM ranges, which is why, in real life, they are very important in drag racing…they literally get you off the line the quickest and keep you moving. I don’t know much about centrifugal chargers, so I can’t explain them well, but from what I know, they are similar to superchargers.
Hopefully that provides some insight for you!
Its a complicated topic. Torque basically IS power, at a specific RPM. I think around 5250rpm torque will always equal power. Given the size of the engine, turbo pressure, etc. you have a pretty good idea what kind of torque you have to play with across the power band. Poor valve and ignition timing causes the torque to drop off at high rpm.
Because operating at higher RPM requires less leverage, this gives more direct power to the road. You can calculate the leverage with the final drive and gear ratios.
In the game at least, I’m absolutely positive you will have better top end acceleration at high rpm, enabling a bit of engine swap shenanigans. All the diesel engines under perform in terms of PI. Cams cost you so much in PI because of the increase in speed. Cams + Race trans is actually quite viable in terms of PI if you run a high final drive, like 5.00+ It makes some cars that are duds into viable tunes.
Definitely, I have added cams to so many weak builds because it hops up their power band like nothing else. For example, I have a Hummer drift build that actually nets me well over 100k+ per round. It performs so well because of an engine swap, cams, and a turbo.
This would imply that Cams would be a dominate upgrade, but this is generally not the case. Or it could be that the PI cost of Cams is too high compared with superchargers and exhaust.