What is the magical ibs/hp number?

[Be-Are-Zee]

The magical answer has already been discussed.

http://www.ft86club.com/forums/showthread.php?t=44582

Please move your ibs / hp talk there.


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[dotdotdotPaul]

It's math. Maybe you've heard of power-to-weight ratio. That's what it's about.

Basically, if you increase the power of the vehicle, but also end up increasing the weight proportionately, you don't get a real increase in power. A 1-ton vehicle producing 200hp has the same power-to-weight ratio as a 2-ton vehicle producing 400hp.

http://easycalculation.com/physics/f...ight-ratio.php

So, between 100hp and -100lbs, which is the better bang for the buck? The horses. If the option was between +100hp and -1000lbs (and assuming a 2,000 lbs car), they're equally the same, because the resulting power-to-weight ratio is the same. This where the 10-to-1 ratio comes up; if the car weighs about 2,000 lbs, and produces about 200 hp, the amount of weight you'd have to shed to be equivalent to an increase of 1 hp is 10 lbs (0.5% change). This ratio isn't always true, though, depending on your baseline. If the car is 4000 lbs and produces 200 hp, you'd have to shed 20 lbs to match the power gained by +1 hp.

FWIW, the BRZ curb weight is just shy of 3,000 lbs, so you'd probably need to drop 15 lbs to match the performance gain of an extra hp...

...Paul

[2013GTRNate]

I think that I am one of the rare people that believes that leaving a car stock is better in the end.

I think this way because of all of those hours that I have spent in the garage trying to trouble shoot issues caused by me and my aftermarket modifications and all of the new items that would prematurely fail due to extraordinary new requirements placed on them from said modifications.

I have learned that in the end becoming a better driver in a stock car trumps most all of the high horse power cars. This holds true in almost all platforms.

So basically save your money for your choice of the next platform of car you pick in the future. The Subaru and Toyota engineers did a great job on this platform why not enjoy it for what it is?

To answer the OP's question… IMHO, STOCK is the magical # for HP and $.

-Nate

[brz_star21]

After all, it seems if you wanted more power and thrill you've got that GT-R in your garage.

I'm just poking fun but seriously though, it's of course wise to learn the dynamics of a stock car as you said but keeping it stock forever, what's the fun in that?

[gt8613]

Well, I am not bring this up for modifying purposes. I am just curious what power to weight ratio is preferred in a general sense.

I basically was thinking that if an engineer was designing a system...and the performance of it depended upon the output of power and the weight of the unit...and they were essentially trade offs made with a limited amount of resources available ( that could be allocated either way). What ratio would be the most efficient?

It is just a theoretical question if it even makes sense...

I think the ~10% of curb weight might be the closest answer to it?

Originally Posted by 2013GTRNate

I think that I am one of the rare people that believes that leaving a car stock is better in the end.

I think this way because of all of those hours that I have spent in the garage trying to trouble shoot issues caused by me and my aftermarket modifications and all of the new items that would prematurely fail due to extraordinary new requirements placed on them from said modifications.

I have learned that in the end becoming a better driver in a stock car trumps most all of the high horse power cars. This holds true in almost all platforms.

So basically save your money for your choice of the next platform of car you pick in the future. The Subaru and Toyota engineers did a great job on this platform why not enjoy it for what it is?

To answer the OP's question… IMHO, STOCK is the magical # for HP and $.

-Nate

[Tim_Asphalt_FRS]

Originally Posted by Luis_GT

THANK YOU!!!!

I was like... WTF is ibs???

Irritable Bowel Syndrome.


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[gt8613]

Thanks. Yea I may have sounded the question confusing but I think you answered my question well.

Originally Posted by dotdotdotPaul

It's math. Maybe you've heard of power-to-weight ratio. That's what it's about.

Basically, if you increase the power of the vehicle, but also end up increasing the weight proportionately, you don't get a real increase in power. A 1-ton vehicle producing 200hp has the same power-to-weight ratio as a 2-ton vehicle producing 400hp.

http://easycalculation.com/physics/f...ight-ratio.php

So, between 100hp and -100lbs, which is the better bang for the buck? The horses. If the option was between +100hp and -1000lbs (and assuming a 2,000 lbs car), they're equally the same, because the resulting power-to-weight ratio is the same. This where the 10-to-1 ratio comes up; if the car weighs about 2,000 lbs, and produces about 200 hp, the amount of weight you'd have to shed to be equivalent to an increase of 1 hp is 10 lbs (0.5% change). This ratio isn't always true, though, depending on your baseline. If the car is 4000 lbs and produces 200 hp, you'd have to shed 20 lbs to match the power gained by +1 hp.

FWIW, the BRZ curb weight is just shy of 3,000 lbs, so you'd probably need to drop 15 lbs to match the performance gain of an extra hp...

...Paul

[gt8613]

Ah yes!

The thread where so many displayed their ability to not be able to read or comprehend...

very befitting that you must think these two are related!

You know...I was quite tempted to instill some logic in the last few commenters...but I felt lazy and the thread was locked when I got back home.

Originally Posted by Be-Are-Zee

The magical answer has already been discussed.

http://www.ft86club.com/forums/showthread.php?t=44582

Please move your ibs / hp talk there.


Sent via Tapatalk2 using my iPhone 6.

[@Art_Mighty]

So this is how I came up with my HP goals....

M3Coupe E46
3440lbs
333hp (10.3lb per hp) --- The first two are published flywheel numbers
262lb-ft (13.1lb per lb-ft)
275whp (12.5lb per whp) --- The second two are averaged dyno numbers
245wlb-ft (14lb per wlb-ft)

Toyota GT86
2806lbs
200hp (14lb per hp)
151lb-ft (18.5 lb per lb-ft)
161whp (17.4lb per whp)
132wlb-ft (21.3lb per wlb-ft)

Power Goals:
230whp (12.2lb per whp)
200wlb-ft (14lb per wlb-ft)

For me this is a good starting point because I came out of an E46 M3 and was happy with how that "felt". To each their own... :happy0180:

[bfrank1972]

I see what you're trying to do, but keep in mind that simple power to weight comparisons don't account for various meaningful factors:

1) Torque curve - say you strap on a vortech that gives you 230whp on your 86, it won't be as quick as an E46 M3, which has a much fuller power curve. A well tuned Innovate supercharger *might* get you close, or a vortech tuned for about 260-280 whp (or a well tuned base turbo kit that will probably beat the E46 M3).

2) Driver weight - keep in mind that driver weight is fixed. So a more accurate power to weight calculation using a 200lb driver would be:

M3: 3440+200=3640lbs/275whp= 13.24
86: 2806+200=3006lbs/227whp=13.24

Also not 100% sure on this, but I thought the 86 (at least the FR-S) was lighter than 2800 lbs, and the E46 M3 was a bit lighter than 3440 lbs?

3) Power vs. air resistance - aerodynamics come into play, and I think the 86 is pretty decent from an aerodynamic perspective... but compare a 2600 lbs with 260 rwp car to a 4000 lb car with 400 rwhp (both 10lbs/rwhp), identical torque curves, the lighter car will get off the line better, but the heavier car will likely catch and outrun the lighter car as speeds approach and pass 100mph (given both cars have similar drag).