C32B OEM intake snorkel vs C30A - huge differences

[Eric KS H]

Hi fam,

Just wanted to share this, as I have not seen it being mentioned or compared on the web. So it may be a first.

During my C32B I noticed a big difference between the OEM intake snorkels where the OEM air box connects to.
- C30A is equivalent to a SRI(short ram intake,) it seems to have a wider opening for more volume and a single opening.
- C32B has a tuned long tube ‘T shaped’ intake pipe that has dual openings, with the shorter end having a butterfly valve that is vacuum operated by a solenoid switch to open in the higher rpms(possibly during or before VTEC engages. The longer end runs towards the rear bumper with a ‘90 degree’ snorkel pointing upwards.

See for yourselves.

 

[nsxvtecvtec]

because of extra 0.2L

 

[Honcho]

This is a very cool observation. The design may be intended to take advantage of the negative pressure area behind the rear tires. Honda calls the filter-looking piece a "noise absorber," so it's likely this change was made to improve acoustics and also perhaps to increase power.

Interestingly, several aftermarket intake designs have copied this long tube layout and report increased power and torque.

Also, all U.S. market NSXs use the smaller snorkel- the long tube was never offered on our cars.

 

[Old Guy]

That is not a C30 versus C32 thing. That is a North American (and maybe other places) versus non North American (maybe JDM) thing. The intake assembly with the short resonator (the dusty one) was used on the the North American NSX from 1991 through to 2005. The shiny new plastic piece is a non North American assembly which may be Japanese market specific and was used in those markets from 1991 to 2005.

I expect that this is an intake noise issue. The more complicated intake plumbing may make less, more or different sucking noises. I expect less noise is the objective because the square box / filter arrangement is described as a noise absorber with a damper opening up the front entrance (the one that would always be open on the NA version) at high engine output. Don't expect a change in horsepower.

 

[Eric KS H]

This is a very cool observation. The design may be intended to take advantage of the negative pressure area behind the rear tires. Honda calls the filter-looking piece a "noise absorber," so it's likely this change was made to improve acoustics and also perhaps to increase power.

Interestingly, several aftermarket intake designs have copied this long tube layout and report increased power and torque.

Also, all U.S. market NSXs use the smaller snorkel- the long tube was never offered on our cars.

Very cool tbh. I just love all the little details and how every bit of upgrade they made was worth the R&D investment they had to make.

The B/K Series Honda Type R motors has so many Dyno runs to show the differences between pipe size, diameter, and length as to how it affects the HP and Torque curve. You’re right about how long tube CAI making more torque especially in the midrange and broad RPM over the SRIs. It’s repeated proven over n over.

So even the ‘02+’ C32B NSXs didnt have these? That’s weird..

 

[Eric KS H]

That is not a C30 versus C32 thing. That is a North American (and maybe other places) versus non North American (maybe JDM) thing. The intake assembly with the short resonator (the dusty one) was used on the the North American NSX from 1991 through to 2005. The shiny new plastic piece is a non North American assembly which may be Japanese market specific and was used in those markets from 1991 to 2005.

I expect that this is an intake noise issue. The more complicated intake plumbing may make less, more or different sucking noises. I expect less noise is the objective because the square box / filter arrangement is described as a noise absorber with a damper opening up the front entrance (the one that would always be open on the NA version) at high engine output. Don't expect a change in horsepower.

My NA1 and NA2 are both in the local market. The last characters of the VIN are T500021 and T000036.
It would definitely be weird if you guys were excluded though.

Yes its designed to have better noise compliance for sure, I suspect the contrast in the VTEC roar is greatly enhanced by this design lol

 

[MaxGeek]

Yup I have a 2002 NA2 and it does not have the extended design.

 

[NZNick]

My late 1999 C32B (JDM) Type S) has the extended intake system:

https://honda-img.amayama.com/img/11SL001/3/sl01b010.5b.png

B-1-5 ｴｱｰｲﾝﾃｰｸﾀﾞｸﾄ for Honda NSX frame GH-NA2 - Amayama

www.amayama.com

 

[Eric KS H]

Just checked the part numbers and diagrams on Amayama.
The NA2 NSX-R also uses this same long dual opening intake. It seems to be a C32B thing for the RHD market.

All NSX models (91-05) that are running the C30A engine regardless AT or MT (including the NA1 NSX-R) have the short intake. Every C32B power train has the long tube intake.