*Another* JRSC review in combination with a full exhaust, daily driver

[glamcem]

Originally Posted by bfrank1972

Hi, unless I'm misunderstanding your post, there are some things that might need clarification:

1) As speed increases, drag coefficient becomes exponentially more important, not less important.

I think you're reading the equation little differently , what I meant to say was ; the power to overcome the drag (Pd) is a lot more dependent to the speed than the drag coefficient (Cd), considering all things being equal..when we start changing things like cars everything start changing (tq, power delivery, gearing, weight, surface area ..etc)

2) We're making broad assumptions based on power/weight ratios, but ignoring engine flexibility/area under the torque curve/gearing when comparing 2 cars.

that what I was trying to say in my initial post that's the exact reason why power/weight ratios and the HP figures alone cannot be the indicators of the real world performance

Assuming we have two cars, exact same shape power curves, exact same power to weight ratio, exact same drag coefficient, same drive layout, we can say the following:

- The heavier car will be at a disadvantage compared to the lighter car because the heavier car will have to overcome greater inertia, which at some power point will create traction issues. High powered heavy car can't put the power down.

- The heavier car will have an advantage at higher speeds because force required to overcome the inertia and the associated traction problems will become less of an issue, and drag will become more of an issue. Given equivalent drag coefficients, the heavier/higher powered car will pull away

.
that's actually the complete opposite and the reason why lighter cars (again all else being equal) need more down force to put the power down whereas with the heavier car drive shaft and axle does that for you

That said, the FR-S is ligther AND has a lower Cd than most cars with equivalent power to weight ratios. Where the Jackson SC (and all other gear/bet driven centrifugal compressors) fall down is the power curve. They build boost on a slightly exponential curve relative to engine speed. The power is all on the top end, unless you have some fancy variable ratio drive to spin up the compressor at lower RPM's.

that may become a disadvantage or advantage depends on the application, all things being equal, area under the TQ curve is always desirable and I think no can argue about that .. the problem is "all things are not equal"

This is why you see positive displacement supercharger kits making around 240-250rwhp easily matching & possibly outpacing centrifugal kits making 270-280rwhp. More area under the curve - especially important on street driven cars.

again depends ..see above

[Yoda]

Originally Posted by bfrank1972

Hi, unless I'm misunderstanding your post, there are some things that might need clarification:

1) As speed increases, drag coefficient becomes exponentially more important, not less important.

2) We're making broad assumptions based on power/weight ratios, but ignoring engine flexibility/area under the torque curve/gearing when comparing 2 cars.

Assuming we have two cars, exact same shape power curves, exact same power to weight ratio, exact same drag coefficient, same drive layout, we can say the following:

- The heavier car will be at a disadvantage compared to the lighter car because the heavier car will have to overcome greater inertia, which at some power point will create traction issues. High powered heavy car can't put the power down.

- The heavier car will have an advantage at higher speeds because force required to overcome the inertia and the associated traction problems will become less of an issue, and drag will become more of an issue. Given equivalent drag coefficients, the heavier/higher powered car will pull away.

That said, the FR-S is ligther AND has a lower Cd than most cars with equivalent power to weight ratios. Where the Jackson SC (and all other gear/bet driven centrifugal compressors) fall down is the power curve. They build boost on a slightly exponential curve relative to engine speed. The power is all on the top end, unless you have some fancy variable ratio drive to spin up the compressor at lower RPM's.

This is why you see positive displacement supercharger kits making around 240-250rwhp easily matching & possibly outpacing centrifugal kits making 270-280rwhp. More area under the curve - especially important on street driven cars.

That.

[glamcem]

Keep in mind, area under the curve is also responsible for catastrophic failures since it will add more stress when car is constantly under boost which also responsible for heatsoak snd overheating.., it sure feels nice though I have to agree... LS engine creates over 300 wtq on idle, go try race one :P


For my purposes making the peak boost at around 6500-7000 rpm (vs 3500-4000 rpm) seems more logical since it will do a better job mimicking a bigger displacement NA engine (think like a high revving inline 6)

If our engines didn't cost as much as $3500-4000 things could've been different of course

[Yoda]

You just have to find a kit that fits your driving style. I for one don't really like revving all the way up to get the power I need. I thought it would be cool but I tried driving like that for a week and just not my style. I find myself hovering around 3-4k and that is where I want the power so when I press the gas I go. I don't street race or drag or even track so that top end power is wasted on me. Too many people are concerned with peak power imo.

[glamcem]

Originally Posted by Yoda

I find myself hovering around 3-4k and that is where I want the power so when I press the gas I go. I don't street race or drag or even track so that top end power is wasted on me. Too many people are concerned with peak power imo.

if that's the case I think you got the wrong car :/ A WRX would be a lot better choice for what you described above

[jaycee842]

Originally Posted by CSG Mike

This is in a straight line, with stock wheels and tires, from a roll.

You have to remember that while every car listed has more power and torque, the FRS/BRZ is a much, much lighter car, in some cases, 1000+ lbs lighter.

It's the exact reason a ND Miata is faster than an FRS, stock for stock, with only 155hp.

I drove the new 2016 Miata a couple days ago for about 30 miles. It was a blast to drive. Couldn't stop giggling. ☺️


Sent from my iPhone using Tapatalk

[JS + BRZ]

Awesome review. Thank you.

I personally don't care how my car drives for DD. I treat my DD as driving from last track/canyon day to next track/canyon day. haha

[autograph]

Originally Posted by SPCorBUST

Your overall cost with those other cars would be much higher, so to me at least, the comparison doesn't make any sense. You could just as easily throw a GT350R into the mix, spend the same money and get great results, but it would cost you something like 2.5x more overall.

I have the Perrin system, and its nice and quiet. Quiet enough that people have asked me if the car is even on, if the car has stalled, or if I plan on getting a full exhaust. And thats with already having uel headers, a full exhaust, and of course the JR SC.

Last year, I walked away from an RS5 from a dig and an M6 from 55 on a similar setup. With my current JR setup, I think I could do it again.

the evo is the most expensive of the ones mentioned, starting at 34k, GT at 32k, 370z at 30k, WRX 26k, FRS 25k (all before fees and taxes of course). there is a 9k gap between the highest and lowest in that list, we're not talking about 60k to 70k cars. and while the other cars in the list do cost more, they also come from the factory already having more power and all of them being faster in stock form than a stock FRS. all of them are in the 25-35k price range

I'm guessing you have the perrin resonated?

[Phantobe]

Originally Posted by glamcem

if that's the case I think you got the wrong car :/ A WRX would be a lot better choice for what you described above

Quite a bold statement to tell someone that they bought the wrong car, being only given a small bit of criteria. >_>

[Yoda]

Originally Posted by glamcem

if that's the case I think you got the wrong car :/ A WRX would be a lot better choice for what you described above

I can see how you might think that but I love this car. The light weight and how easy it is to toss around and the rwd. Just want the power band to be a bit different but that will be fixed one I go FI next year. My first rwd car and I am not leaving.

[glamcem]

Originally Posted by Phantobe

Quite a bold statement to tell someone that they bought the wrong car, being only given a small bit of criteria. >_>

since when speaking from personal experience considered as making bold claims?

he already mentioned his type of car he prefers in his initial post, the thing is what he is looking for is the exact weak spot of our cars ( "mid range punch" vs "mid range torque dip" in ) ..so my "bold" statement still prevails stock vs stock,

it's not like I was judging his preference on an RWD or AWD ..
if you read the whole thread we were initially talking about why Rotrex SC'd BRZ/FRSs and why they cannot keep up with the EVO, WRX/STI, 350Z/370Z ..

I personally don't care who likes what type of car (RWD vs AWD, coupe vs roadster vs sedan) , I was just pointing the facts

I repeat "you can never, I mean never hang with a bolt on Evo with a Rotrex SCd FRS/BRZ" ..now that's a bold statement written in bold (no pun intended) but I still don't care b/c it's a fact

[SPCorBUST]

Originally Posted by autograph

the evo is the most expensive of the ones mentioned, starting at 34k, GT at 32k, 370z at 30k, WRX 26k, FRS 25k (all before fees and taxes of course). there is a 9k gap between the highest and lowest in that list, we're not talking about 60k to 70k cars. and while the other cars in the list do cost more, they also come from the factory already having more power and all of them being faster in stock form than a stock FRS. all of them are in the 25-35k price range

I'm guessing you have the Perrin resonated?

Those are all more expensive. Yes they have more horsepower. So does a GT350R. So does a GTR. I don't think comparing more expensive vehicles in a dollar-to-dollar comparison is an apples-to-apples comparison, but whatever floats your boat.

Anyhoo, I think the comparison is off-topic to your original post. I mainly meant to chime in that if you're looking for more power and wanted to quiet it down, there are some things you can do.

And yes, I do have the Perrin, its a 2.5 system but for the life of me I can't recall if it's resonated or not. I had a TopSpeedAuto catback before that, and it sounded great but it was so loud that I received complaints.

[CSG Mike]

Originally Posted by glamcem

I repeat "you can never, I mean never hang with a bolt on Evo with a Rotrex SCd FRS/BRZ" ..now that's a bold statement written in bold (no pun intended) but I still don't care b/c it's a fact

I beg to differ. Your experience, clearly, varies from mine.

[glamcem]

Originally Posted by Yoda

I can see how you might think that but I love this car. The light weight and how easy it is to toss around and the rwd. Just want the power band to be a bit different but that will be fixed one I go FI next year. My first rwd car and I am not leaving.

Dude,,, I am not judging your preference or anything ..
I was just talking about the power delivery and the mid range characteristics of our cars that's all

of course RWD is fun, of course being lightweight is something you cannot replace easily but those were all out of the scope of our initial conversation

the thing you said you want in a car is not here, that's all I am saying

..FA20 engine is a high revving NA engine designed to be driven hard all the way up in the power band (just like the NC2-NC3 Miatas) so anytime I hear "limited RPM to 6800rpm " thread I just wanna cry especially with a Rotrex that is also designed to be revved up to the sky..

all that said, if you ask me which one is a better car (BRZ VS WRX) or all the others cars in that list (including the ones I owned in my signature), I would still say the BRZ .. since it's the best car I've ever owned, even with its BS mid range and torque dip, with FI it's better but power delivery still cannot be as healthy as other cars that don't have this problem ..