New JRSC install, sounds normal?

[wheelhaus]

FYI my C38 sounds identical to the two C38 cars in the video. I went with it vs the C30 because I liked the idea of the lower ratio drive, eased my brain pain about mechanical stresses. But, I'm also using the HBP with headers at Denver altitude so I'm really just back somewhere around normal seal level power. I was told the same thing, they function virtually identically within a certain power range, but the C38 unit just has more overhead depending on how its built (ratio, impeller, pulley, etc). the C30 has the benefit of being a bit lighter and more compact.

I saw a video where a shop was disassembling a C30 and it showed the internal mechanisms are pretty simple. They consist of only a few parts- a plate and outer drive ring that are externally driven by the belt, three large rollers/bearings, and the shaft that spins the impeller. That's really it. The three bearings stay in place, but the outer ring drives the inner shaft via the three bearings (spinning the shaft in the opposite direction). The internal drive ratio comes from the difference in diameters between the outer ring and inner shaft, the bearings are just the vehicle to transfer the torque. So being an entirely metal-on-metal system with plenty of rolling parts and a thin-ish oil for lubrication, it makes sense that certain mechanical noise and harmonics might be present at low speed, and two different size units would sound a bit different.

Regarding noises, mine even has a noticeable metallic whistle exactly at 3100 rpm. It was 3400 rpm with the standard pulley, which makes sense as I'm pretty certain there's exactly a 10% difference in pulley diameter (90mm vs 100mm). I believe its just another harmonic.

[Zardoman]

Originally Posted by wheelhaus

FYI my C38 sounds identical to the two C38 cars in the video. I went with it vs the C30 because I liked the idea of the lower ratio drive, eased my brain pain about mechanical stresses. But, I'm also using the HBP with headers at Denver altitude so I'm really just back somewhere around normal seal level power. I was told the same thing, they function virtually identically within a certain power range, but the C38 unit just has more overhead depending on how its built (ratio, impeller, pulley, etc). the C30 has the benefit of being a bit lighter and more compact.

I saw a video where a shop was disassembling a C30 and it showed the internal mechanisms are pretty simple. They consist of only a few parts- a plate and outer drive ring that are externally driven by the belt, three large rollers/bearings, and the shaft that spins the impeller. That's really it. The three bearings stay in place, but the outer ring drives the inner shaft via the three bearings (spinning the shaft in the opposite direction). The internal drive ratio comes from the difference in diameters between the outer ring and inner shaft, the bearings are just the vehicle to transfer the torque. So being an entirely metal-on-metal system with plenty of rolling parts and a thin-ish oil for lubrication, it makes sense that certain mechanical noise and harmonics might be present at low speed, and two different size units would sound a bit different.

Regarding noises, mine even has a noticeable metallic whistle exactly at 3100 rpm. It was 3400 rpm with the standard pulley, which makes sense as I'm pretty certain there's exactly a 10% difference in pulley diameter (90mm vs 100mm). I believe its just another harmonic.

sounds like i need to start "appreciating" this annoying whining...

[CSG Mike]

Originally Posted by Zardoman

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?

If you've seen my posts, I always recommend the C30 over the C38 unless you KNOW you are going for big power.

[Zardoman]

Originally Posted by CSG Mike

If you've seen my posts, I always recommend the C30 over the C38 unless you KNOW you are going for big power.

Yea i wish i did, tbh i think JRSC should provide those information to differentiate the 2 kits, upgradability should be #1 on that list, and sound differentiation may be 2nd/3rd comparison....

[PulsarBeeerz]

Often enough when I see a Rotrex failure it is a c38. The drive ratio is lower sure but does that produce a meaningful positive result in the real world? When you switch to a lower ratio while pedaling up hill on a bicycle, is it easier or is there more stress on your legs, the traction drive gears in the case of the SC? I’ll stick with my lil C30. FWIW when Drift Office Bob was around he wasn’t too impressed with the C38 on the FA20 either.

[tomm.brz]

well might be just a coincidence, c38 with stock pulley spins less than c30
the advantage is colder charge air, the disadvantage is since it is bigger and spins less, you have less under-the-curve torque until you reach high engine rpm

you really need a high boost pulley for it to. make the most out of it but then the boost and air that enters are really high at high rpm so you need supporting mods and strong internals so it has a sense only if you plan on reaching very high power

[JDMChris]

Originally Posted by Zardoman

Yea i wish i did, tbh i think JRSC should provide those information to differentiate the 2 kits, upgradability should be #1 on that list, and sound differentiation may be 2nd/3rd comparison....

They sound the same. The C30 sound in your video was probably being dampened by that dirty filter.

[Zardoman]

Originally Posted by JDMChris

They sound the same. The C30 sound in your video was probably being dampened by that dirty filter.

most definitely not the filter can reduce the sound by that much.

[JDMChris]

Originally Posted by Zardoman

most definitely not the filter can reduce the sound by that much.

Actually, it can. I have been using Rotrex units since 2007. I have had C15's, C30's, and C38's. The sound gets dampened when the filters are that dirty.

[Zardoman]

Originally Posted by JDMChris

Actually, it can. I have been using Rotrex units since 2007. I have had C15's, C30's, and C38's. The sound gets dampened when the filters are that dirty.

well since you've been having the C30 and the C38, do they sound the same, or is C38 is obviously louder at idle? how does each system whining sound, does it have the same observation (800-1500rpm loudest?)

if what you are saying it's true, then i guess in time i'll have the dust kit on this air filter and the annoying sound will dissipate on it's own!

FYI, i did try to cover up the air filter partially on my own system, i did not notice any change in sound. For it to really change, i would imagine it had to be pretty clogged and likely danger-ing the system if the sound really dampened that much??

[jeepmor]

No fret Zardoman, they'll just think its crickets from your fuel pump.

Good read on this one seeing the seasoned input. Looks like you have to live with it.

[Zardoman]

Originally Posted by jeepmor

No fret Zardoman, they'll just think its crickets from your fuel pump.

Good read on this one seeing the seasoned input. Looks like you have to live with it.

Well behold, just when I start to accept the annoying wheezing (not really), my car start throwing the P0172 code with the traction and engine light on.
P0172 is "fuel too rich, Bank 1" code.

Has anyone with JRSC gotten this within 1500 miles of the install? is it due to factory tune kit not so "well-tuned" that i need a custom tune still?
I also youtubed and seen some of BRZ/FRS owner found the cause was air intake clog or o2 sensor (sensor 1 or sensor 2). I am willing to DIY the O2 sensors myself but if the cause is the JRSC tune i need to bring back to the performance shop to see if they can help the tune (with post dyno that i didn't do yet)

Thanks in advance on your comments!

[Zardoman]

Figured out the issue (for now)... it was a dirty MAF.
i noticed there was a yellow stain puddled at the bottom of the intake tube (JRSC kit) right below the MAF sensor was mounted, so i figured there may be some mist or droplet got onto the MAF (since i was not able to visually tell the MAF was dirty), so i bought the MAF cleaner and sprayed it, reset the code and it hasn't come back since a week ago (previously it came back within days).

either way, it was still JRSC related so i wonder if other JRSC owner can tell me more about the yellow stain, should i try wiping it off or leave as is?

[CSG Mike]

Originally Posted by Zardoman

Figured out the issue (for now)... it was a dirty MAF.
i noticed there was a yellow stain puddled at the bottom of the intake tube (JRSC kit) right below the MAF sensor was mounted, so i figured there may be some mist or droplet got onto the MAF (since i was not able to visually tell the MAF was dirty), so i bought the MAF cleaner and sprayed it, reset the code and it hasn't come back since a week ago (previously it came back within days).

either way, it was still JRSC related so i wonder if other JRSC owner can tell me more about the yellow stain, should i try wiping it off or leave as is?

Wipe it off, and see if it recurs. There's only a few places the yellow stuff can be coming from.