New JRSC install, sounds normal?

[Zardoman]

Originally Posted by tomm.brz

try to pinch the vacuum hose and see if it disappear when bypass valve is forced closed.. Attachment 219591

did that today, doesn't appear to make any difference. it feels like coming from the pulley/belt area.
i'll need to have someone rev it while i sniff around the engine bay.

[Clipdat]

Call me crazy but in a situation like this where something clearly isn't "right", and you are not satisfied, shouldn't the shop that did the install be doing all this legwork/testing/investigating until the source of the issue is identified and resolved?

It just feels somewhat frustrating to me, like the shop isn't standing behind their work. I'm sorry that you're going through all this hassle and headache.

[Zardoman]

Originally Posted by Clipdat

Call me crazy but in a situation like this where something clearly isn't "right", and you are not satisfied, shouldn't the shop that did the install be doing all this legwork/testing/investigating until the source of the issue is identified and resolved?

It just feels somewhat frustrating to me, like the shop isn't standing behind their work. I'm sorry that you're going through all this hassle and headache.

i totally agree with you, but as i mentioned before, JRSC is claiming this is "normal" sound and IF i want to get it checked out, they can send my Rotrex unit to Rotrex for analysis, if no issues found they charge $350.

the shop is basically going with what JRSC is saying and said they can swap out the unit for me, but it sounds like the source of sound still not quite determined, and the shop is not really bothered to really do much since they said they installed as it was instructed. (also it's an hour drive so im trying to gather more information before I take the car up (since i am not sure why they can do for me)

[alex87f]

If it were me I’d get some written confirmation by the shop that you should drive it some more and see if it goes away.

Otherwise it’ll be too easy for them to say « well you should have brought it back immediately so screw our liability ».

[Ohio Enthusiast]

Originally Posted by Zardoman

did that today, doesn't appear to make any difference. it feels like coming from the pulley/belt area.
i'll need to have someone rev it while i sniff around the engine bay.

Try a DIY mechanics stethoscope (or a real one, if you want to splurge) - a long screwdriver or other long piece of metal that you can place against suspected sources of noise and press other end near your ear (for bone conducting the sound). Of course be extra careful around moving belts and pullies (even more so if you have long hair/beard/jewelry/loose clothing)!

[Zardoman]

Originally Posted by alex87f

If it were me I’d get some written confirmation by the shop that you should drive it some more and see if it goes away.

Otherwise it’ll be too easy for them to say « well you should have brought it back immediately so screw our liability ».

good idea, will do thx!

[Zardoman]

Quick update,

today i took the air filter off while the car is idling and had my friend rev it above 2k rpm, i can clearly hear the sound coming from the Rotrex unit, so I believe the source is identified, I have emailed Rotrex (just realized they in Denmark) couple of days ago with the support comment from my shop and see how it goes. Fingers crossed.

[tomm.brz]

but when you rev it it disappears? it s only present under 2k rpm?

[Zardoman]

Originally Posted by tomm.brz

but when you rev it it disappears? it s only present under 2k rpm?

800rpm to 1500rpm is most prominent, outside of that band the sound is minimal.

[Zardoman]

Alright ladies & gents, here's a quick update on my investigation on the loud whining noise on my JRSC system:
Thanks for couple of nice dedicated FT86 members who was nice enough to meet up with me to show me their JRSC systems and how they sound, i was able to figure out how they measure up compared to mine.
We had 3 BRZs with JRSCs, one C30 kit and 2 C38 kits.
I attached 2 videos of the idle (5-10 mins after cold start)

1. with sound meter:
https://youtube.com/shorts/TSE3zHZAv8o?feature=share

2. no sound meter

Right off the bat i noticed the C30 kit was much quieter (83dcb) than the C38 (idle 1kRPM), and the C38 on mine was about (93dcb), while the other C38 was the loudest (98dcb)

Both of my friends BRZs have modified headers just FYI, I don't believe it has much weight on the sound of the whining (all 3 cars idle same range), but the obvious part was that the C30 Rotrex looked smaller than C38, I wonder if that's the reason.

With the hood closed the C30 you can hardly notice the whining noise (it's what i recall as my previous encounter with JRSC owners), as for mine and the other C38, both of ours you can definitely notice the whining even with the hood closed.

So far neither one of my friends had any issues with their JRSC and seems to perform as expected...

My questions for the forum are:
1. C30 vs C38 differences, does anyone know? on JRSC website both kit description are verbatim except the part number of the Rotrex and Billet bracket.

2. C38 owners - is your whining noise most noticeable at idle 800-1500rpm?

3. Anyone can explain why it is loudest in that range? I emailed Rotrex still pending response.

Lastly, i also want to thank Stacyu18 for troubleshooting with me over the phone for hours trying to see if everything was installed correctly, you rock!

[tomm.brz]

c38 is bigger but with a different internal ratio between its gears. it spins less with the same pulley compared to c30 but moves more air anyway... one of the advantage is cooler charge air

potentially if you put high pulley into the c38, it becomes a beast and will snap your rod pretty quickly)

[Zardoman]

Originally Posted by tomm.brz

c38 is bigger but with a different internal ratio between its gears. it spins less with the same pulley compared to c30 but moves more air anyway... one of the advantage is cooler charge air

potentially if you put high pulley into the c38, it becomes a beast and will snap your rod pretty quickly)

it sounds like i should have gotten the C30 for the same hp gain/performance without having a bird living under the hood, not to mention i save $100!

i don't expect to make more hp gain upgrade that will further stress the engine.

just odd there's no difference between the kit performance wise? C38 has more potential for upgrades?

cooler air is good and all but if both can do the same, why have 2 kits?

[Zardoman]

Rotrex update:

We do have some cases of units having whining noise at low idle speed only (below 1600 pulley RPM) this is not harmful for the unit when only experienced at low speed. The simple answer is that the sound will be more prominent at the low speed due to internal frequencies in the traction drive (This is IP and we can’t get into details) together with the reduced lubrication at low pulley speed.



The C30 kit is based on the C30 C-range supercharger with power range 120 – 320kW and the C38 kit is based on the C38 C-range supercharger with power range 200 – 530kW. Meaning higher power transfer through the traction drive at a lower drive ratio for the C38.

i guess that's another way of saying I need to live with the new found bird in the hoood.

[tomm.brz]

well cooled air charge is a profound improvement in a FI car..

c38 has just mor potential, but you d need to start changing pulleys for that... well they answered you!