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

Howdy folks. Just want to quickly share my experience after spending a good deal of money on my current setup with a word of caution.

I have a 2014 MT FRS. My first new car. My first sports car -- previously, I drove a bone stock 1997 Honda Civic coupe for 9 years. I only got into cars about two years ago, a year prior to purchasing the FRS.

First, modifications. I have a JDL uncatted UEL, nameless fp/op w/ hi flo cat, and a dezod catback. I also recently had the Jackson Racing supercharger installed back in May.

I recently had a custom tune done at R/T tuning (they did a great job), and with redline limited to 7100RPM (MAF sensor apparently couldn't read past 7200RPM, so set it to 7100 for safety), I put down 270whp peak on a dynojet, with about 205wtq.

I've had absolutely no problems with the JRSC kit in terms of reliability so far. I DID have some boost leaks, but R/T caught and corrected such prior to the dyno pulls.

So how does a JRSC fitted, full exhaust, custom-tuned FRS behave? Power from 5k to 7k rpm is great, the car definitely pulls nicely in that area, but its not "holy shit" fast.

My main caution of warning actually is not with the JRSC by itself. Its largely daily driving a full exhaust FRS and being somewhat conscientious. With a full exhaust setup with only one cat, you've got a fairly loud automobile when it comes to these cars. The SC, being centrifugal, doesn't really start to go until 5k. So, if you shift at 3k-3.5k as to be courteous and not subject your motorist neighbors to the sound of your boxer soaring, you will still be neck to neck with the minivan accelerating next to you. Below 4.5k you're making a lot of noise with not much to show for it. It is only from 5k-7k that a loud FRS with the JRSC finally is able to have its bite match its bark. If you try driving like a reasonable human being, moderately increasing the revs and shifting 3.5k or below, the car is very much like stock -- you won't be accelerating particularly fast. Either you're going too slow, or you're extremely loud and obnoxious (albeit moving).

My exhaust sounds great, but when you're not doing full out enthusiastic driving, and trying to be a reasonable human being and not look like a hooligan/asshat, the powerband of a JRSC (or stock) FRS with a full exhaust does not make such a task easy -- if you want to keep up with the pace of traffic. I will also note that there are a lot louder FRSs out there than mine. Its loud, but its certainly not crazy loud.

And while the acceleration from 5-7k is great, its still not crazy fast. Nor is it effortless to go fast either. You can't just mash the accelerator -- you need to make sure you are in the 5-7k area, and thus will need to downshift. Now if only Subaru could make a 8 cylinder boxer a slap it into a 2000lb. version of the FRS/BRZ. One can dream!

TLDR: think twice about going with a loud exhaust setup. Of course what I have said applies not just to the JRSC w/ a full exhaust, but to any full exhaust setup up, SC or NA. Its just that with the car's stock or JRSC powerband, and a full exhaust setup, its not particularly easy to keep things civil. If you're looking for a fast reliable car that will last a long time I would probably look elsewhere than the FRS/BRZ. True, you could turbo for more power but who knows how long your engine / tranny will hold up. I went with the JRSC wanting more power but also wanting to keep things relatively safe. And while straight line performance is not everything about a car, having a generous amount of power certainly doesn't hurt.

If I had to do it again, I might consider the JRSC, but I would have gone with a different exhaust setup (or left it stock). I love the style and relatively lightweight design of our cars, but as everyone has recognized (else why would there be such a large FI market), our engines really do not have impressive output.

For track junkies, as long as you meet relevant regulations obvious the sound level of your exhaust doesn't matter, but for daily drivers -- trust me, while it may sound awesome at first, it can also be embarrassing when your car is making a lot of noise but the 90's honda accord next to you is keeping up.

A video of the car pulling from a driver's perspective would be greatly appreciated.

@ATL BRZ I will try to get one for you, but I do have a video of a dyno pull: [ame="https://www.youtube.com/watch?v=P9H7V1vAgDI"]FRS Dyno - YouTube[/ame]
video doesn't do the sound volume any justice. when i was standing there it was damn loud

Have you considered putting your stock exhaust back on? You should see how difficult it is to get under 90dB for some Laguna Seca days.

I'm surprised your tuner didn't recommend getting an upgraded MAP sensor (~$100 or less), so that you can rev to your heart's desire.

my tuner did mention it to me but only after the tuning had largely been done (poor guy spent 3+ hours on my car -- he had never done a JRSC before, completely new map for my car). It was nearing the end of their hours so they told me that I could come back in the future for the upgraded MAP sensor.

alas, due to not having the space I got rid of the stock exhaust parts

Ok so it doesn't really bite until you're in sky high rev zone but it is still a supercharger? Um doesn't that defeat the point of it being a supercharger? Did you know that could be the result going in? Or could the other mods in part be the cause for that?

that's correct. I did know that the centrifugal chargers had that characteristic, but I went with the JRSC because reliability was a big thing for me.

When driving once you reach 3400rpmish it starts to pull but you're still not accelerating fast; once you hit 4500rpm you are really moving and then from 5-7 it almost feels like a burst of power, as if the engine becomes free-er and free-er the higher it revs (which is in part because boost is growing and growing as you rev it)

its definitely quicker than stock, and its definitely fun doing 2nd and third gear pulls, its just that there are many cars out there that would murder a JRSC frs, despite it being quick

Get tuned for e85, it helps alot in the midrange. Also get a quieter exhaust. UEL + anything free flowing is going to be ridiculously loud. The rotrex kits give the car vtec pretty much.

no E85 easily available in my area -- i think the closest is newark, way too inconvenient. and yeah I think i might have to switch out my exhaust but it really sucks because i already spent a lot on my exhaust (and switched out my catback)

Very well written and reflects my personal thoughts very closely. I applaud the OP for being so open and honest.

I've been bouncing back and forth with the JRSC for a while now. Being in CA, CARB is a huge part of my decision and having so many options come out is great, but definitely makes it much more difficult to decide. The gains combined with the reliability and simplicity of the design is a huge plus and is a main draw for others shopping around, but as you mentioned, not a lot of current owners talk about its real-world day to day behavior. As you pointed out, not everyone is at red line all the time and completely inconsiderate to other people.

The way you describe power delivery is very much inherent to a rotrex type of SC, which is perfect for someone who spends most of their time high on the rev range (ie track). This was a little bit of a trun-off for me. For somebody who plans on mostly using it for street use, such as myself, a roots/twin screw type would be a better option, which is why I've been following the E-force thread very closely.

Yeah it's a bit of money lost to sell but if you're not enjoying the sound level - you are going to continue to convince yourself you don't like your car anymore. If you go back to the stock exhaust, you might enjoy revving it out without your fear of being obnoxious. The sleeper exhaust also jives well with the sleeper power band of the jrsc... Seems stock until it doesn't.

I upgraded the exhaust on my last car, and that was enough for me to decide to keep the exhaust stock on this one. I much prefer to not be noticed while I'm putting around town.

My suggestion, sell the exhaust - or at least the stuff past the headers to quiet it down and enjoy the boost more often!

thanks for your input, great points and advice! the "sleeper" way has been becoming more appealing

First off thanks for the review. What gas was used on the dyno?

There is always something else that is quicker and faster. Its a never ending chase for power, chassis, balance, etc.

Humor me what other cars were popping in your head when you said there are many other cars that would murder the FRS/BRZ? I'm genuinely curious:

EVO?
350z/370z?
Wrx/STi?
Focus ST?

Maybe others can chime in on this?

I feel JRSC hit on all notes when it comes to making a good increase in power while not sacrificing reliability. I know Kraftwerks has a SC available that can make more power but that setup shreds belts left and right and has some reliability issues.

If you are going to change your catback go with Invidia Q300 or even Perrin RESONATED. Hopefully that quiets it up a bit.

Have you considered installing silencers on your Dezod catback?

I have basically the same exhaust setup as you and I've considered getting these to try and quiet it down on demand: http://www.speed-element.com/tsudo-4...ment-silencer/

They are 4.5" and should fit the Dezod tips after drilling small holes in them.

i have nearly the same exhaust setup. only difference is i have 3.0" perrin resonated catback. absolutely love the sound and noise levels. its not ridiculously loud but u know people are hearing u when u want them to. im waiting for edelbrock to release their SC. i think it will be a fun system with power from the get go.

A CARB JRSC will walk:

- Stock EVO
- Stock 350Z/370z
- Stock WRX/STI
- Stock Focus ST

It is about even with:

- bolted EVO on pump
- Flashed/bolted 370z
- fully bolted STI on pump
- Fully bolted ST
- E9x M3

It will lose to:

- Any factory FI car on E85
- F80

Straight line or track comparison O_o

Dang and that is with the carb tune!? I was gonna ask about a JRSC with bolt ons but yeah that is more than enough for me.

Thanks CSG always helpful here on the forums :thumbsup:

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.

no problem -- I use 93 octane. True there is always something else faster. As to your question, and also to CGS Mike's reply, its my understanding that the best number on these forums for a quarter mile in a JRSC is 13.4. I suppose a flat 13 is feasible. I've never taken my car to the strip. We don't seem to have too much data on 1/4 times.

I did have EVOs and WRXs in addition to mustang GT's in mind. Thing is, a lot of enthusiasts go after more power, and while its great that a supercharged FRS is faster than those vehicles when they're stock (except for the GT), as soon as the owner's put in the same amount of money that most FI FRS owners have, the FRS of course will lose. That's largely because, at least in the case of supercharging, it takes horsepower to make horsepower, and if you start with more, you make even more with a SC. So for instance we might go from 200 crank to 320 crank with our centrifugal setups, a GT would go from 400 (I'm just using general numbers) to 600. Our setup got 120 ponies from our money, and probably from a similar amount of money the GT got an additional 200. Its easier if you start out with more power in the first place.

Mike is right about the weight being a factor in our favor of course. I am jealous of the new miata's weight.

A quarter mile in the 13's is not particularly fast, albeit quick, by today's standards. A stock 370 has a 13.0 quarter mile -- a JRSC FRS at its best might be able to do that.

Yeah I thought about perrin resonated, not sure I like the note though.

I found this:
[ame="https://www.youtube.com/watch?v=QERcB63JbVs"]BRZ equiped with Jackson Racing Super Charger - YouTube[/ame]

Quarter mile times mean almost nothing to me but I still think that is a very respectable time for our cars that wasn't designed for straight line speed. I would think most people here on this forum bought the car because of the chassis/driving connection(ok maybe the styling as well). I know I did. Power isn't everything.

I can agree with most of those points.

You mentioned this is your first Sports Car and are fairly new to being a car enthusiast, its kinda crazy that you think that even with the JRSC with bolt ons you still don't feel it is quick enough. Perhaps maybe some track time combined with some sticky tires with would change your mind. Maybe even a different Final Drive.

I know 10stars, I know lol, maybe it is crazy. I already do have sticky tires (235s, potenza re-11s). Yeah lets be honest, the car's styling is a big selling point. It might not be the fastest car around but our cars sure look good :thumbup: And of course, they're fun

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.

:clap:

I heard your exhaust setup on your build thread a while back. Jesus that sounds amazing. Makes me question if I should just stick with Perrin instead of the Q300.

Thanks, it seems considerably quieter with my new tune, especially in the rpm range most used for city driving.

Sent from my SM-G925T using Tapatalk

Take it to the track. You will realize power isn't everything. You will appreciate the car for what it is really meant for.

Congrats on your JR kit , I hope you'll enjoy the Rotrex setup :)

One thing to note though, limiting the redline due to Map sensor cannot be considered as a "good job" IMHO since the Rotrex Supercharger kits (at least the base models with pump gas power levels) like @CSG Mike mentioned your tuner should've told you to opt for an aftermarket Map sensor (if it didn't come with the kit)

you're most likely leaving some power on the table because of that and also lowering the RPM limit changes the whole character of our cars .. keep in mind we also have shorter gears compared to other cars that have similar weight/power ratio since those gears are not designed for extra power ..with the turbo where there are so many other variables changing lowering the RPM limit could be more understandable (like maxing out the injectors, boost creeps ..etc)

my suggestion would be connecting with other tuners since tune makes a big difference on driveability, throttle response (which already sux on these cars in stock form), power and most importantly the reliability.. lowering the RPM limit on the other hand is a band aid solution

Any preferred MAP sensor you recommend?

Thanks

it's partially true Mike, I've driven/owned almost all the cars you mentioned above (except Focus ST ,or the E9X M3s).. roll from 30-40 mph you have some window to keep up with those cars but as soon as you shift the cars you mentioned will start walking away for multiple reasons:

• advantage of the power/weight ratio will diminish (talking about highway pulls of course) after certain speed say about after 70-80mph since after that HP will start make up for the difference and after 100mph more powerful car will almost always walk away (opposite can be said for the lighter cars at the tracks with tight corners, if we think about it; Lotus Elise doesn't really have a good Power/weight ratio compared to big dogs.. say for instance than a Challenger Hellcat, but it will possibly kill many of them on a tight/medium track since weight advantage overcomes the other disadvantages regardless of the power/weight ratio)
  
  
• gearing advantage in stock form slightly becomes a disadvantage with the added power, if the boosted BRZ/FRS makes more than 300whp having a slightly taller tires might be good way of cheating :D if taller gears is not an option
  
• OEM power (especially in NA form) is a lot healthier and more repeatable so after a couple of pulls car with an aftermarket FI kit will start losing power due to overheating (even with the best cooling methods), of course Rotrex kits still has the upper hand compared to turbo (since heat soak is not an issue like a turbo) on that department but still subject to the shortcomings I mentioned above

with all that said, with a proper cooling and supporting mods, Rotrex SC'd FRS/BRZ still has a huge advantage on a track but not proportionally with the power it makes on a dyno since real world power will suffer from..this is just another example of the power on paper and power on real world conditions :)

Damnit....so what do I do now? Edelbrock, JRSC, or sell for an E92 M3 like was about to? :bonk:

lol, thanks.

depends on your goals:

• if you're like me; appreciate almost every aspects of the the car (lighweight, lower center gravity, handling, practicality, mpg etc.. ) especially for having fun at track days but find it very boring due to lack of power, you're options are limited IMO, Rotrex based kits (JR or KW)
  
• if you like everything above but prefer more low end torque and not planning to attend track days as much (it would be a shame with this car IMHO) Cosworth Supercharger may be good option..then again it will generate a lot more heat at the track (thanks to a water intercooled system) and only handle mild track use and also not sure if it's worth the added cost
  
  
• if you like really fast car on highway, pulls, 1/4 mile ..etc (I am not saying quick car) you probably got the wrong car and your best bet is to consider other alternatives..

@ck-GT86 keep in mind this general rule doesn't really change much:

"FAST - RELIABLE - CHEAP

pick two"

Anything 2.3BAR or higher will work.

- The FRS/BRZ has a smaller CdA than every car listed. The higher the speed, the larger the CdA advantage. The STI and Evo is a flying brick.

- Gearing is moot; tight gearing is better for the JRSC powerband anyways. It's not ilke you deal with turbo lag.

- Repeatability... is debateable, but none of the setups listed above will have issues repeating performance from a roll.

I fall into the first two, with the exception to occasional track days. I hardly drive my car now as it is thanks to free public transportation, but I do find the power boring when I do.

.ck

@autograph -

Great to hear you like your Jackson Racing supercharger system! Yeah, open exhaust TIY kits are pretty loud. I still run a completely factory exhaust on my street FR-S.

There should be a good bump in power throughout, with it getting stronger as it heads towards redline. Think of it like a bigger engine being in the engine bay.

We have had quite a few customers order TIY kits then call and order the CARB calibration to improve their overall drivability. They drive a friends Factory Tuned system and notice it drives completely different. A proper ECU calibration is important to overall performance and drivability.

-Oscar Jr.

beware of rod bearing issues if you plan to go that way lol

Oh crud, I wasn't aware of those. I see you previously owned one!

.ck

yes Evo and STI has a slight disadvantage on drag coefficient figures (.27 vs .30X something) but that disadvantage becomes negligible especially when the speed increases ..see below formula:

https://upload.wikimedia.org/math/e/...82a89503b1.png

I was referring to the highway pulls :) not the transient lag that is inherited in turbos, I should've said "better matched gears" because taller gears only have advantage for that specific power levels ..M3 with it's longer gears will almost always walk away from the SC'd FRS/BRZ with less than ~300whp


compared to other FI choices yes but compared to NA? well we know the answer :)

I love wikipedia.