3" exhaust and failing aux ports

[mnrthrt]

Im new to rotary theory and application. I have a chance to pick up an HKS Silent Hi-Power exhaust for VERY CHEAP! I have a 91 N/A with stock exhaust and no internal mods.

I heard anything more than 2" will keep the aux ports from opening because of back pressure issues? If i picked this exhaust up is there a way i can combat the backpressure issue? I plan on getting a racing beat or corksport header with this set up. If I street port or bridgeport would that help? Thanks for any help!

I plan on doing a t2 swap in a little less than a year so I figured that exhaust would be great with the downpipe they make for the future install. Would rather not waste money on a 2" cat back for a soon turbo'd rex as im already tossing money in the header. Again Thanks for the help.

[Howru]

S5's (89-91) activate the aux ports by the air pump, so you should be ok. It's the S4's that have to deal with the exhaust back pressure for aux ports to work.

[mnrthrt]

Oh. Thanks for the response. So I should go for it then? Will probably be loud as hell! ha

[Silver86]

Oh. Thanks for the response. So I should go for it then? Will probably be loud as hell! ha

i would... but youd be surprised... i have a corksport cat-back on my 86 N/a, and its actually surprisingly quiet. but whats loud to someone else might not be loud to me...

[mnrthrt]

i actually ordered the corksport header back system but it was back ordered, waited a month, dude never got back to me in time so it looks like im gonna grab the hks :) found a 3 inch pre-silencer from racing beat i think i might couple with this.

[josh18_2k]

the stock manifold really quiets things down. With a header it will indeed be loud as shit. I had a greddy power extreme dual exhaust (two very big cans) and it was still intolerable. I would never put a header on a daily driver

[Silver86]

the stock manifold really quiets things down. With a header it will indeed be loud as shit. I had a greddy power extreme dual exhaust (two very big cans) and it was still intolerable. I would never put a header on a daily driver


this excites me.

[mnrthrt]

josh: think i will have any problems with power loss with that 3" exhast?

[josh18_2k]

i dunno, i never dyno'd or anytting like that. there is definately a power gain on the top end (10-15hp maybe?), since the stock brick manifold thing doesnt flow very well. im sure you can find before/after dyno charts somewhere. my car was my daily at the time, and i got sick of it quick after putting on the header. i dreaded driving it.

[NYsNumba1Man]

I'm currently running an hks silent hi power exhaust..... Does that mean my aux ports aren't activating?

I have all stock cats and headers, i think i might have an exhaust leak somewhere near the headers though (sounds like an exhaust leak in the engine bay)

how can you test to see if your aux ports are working?

[Nismo]

I'm currently running an hks silent hi power exhaust..... Does that mean my aux ports aren't activating?

I have all stock cats and headers, i think i might have an exhaust leak somewhere near the headers though (sounds like an exhaust leak in the engine bay)

how can you test to see if your aux ports are working?

Put grease/Vaseline on the rods of the actuators, take the car for a rip and make sure to rev above 4k if the grease has moved your ports work.

[My5ABaby]

the stock manifold really quiets things down. With a header it will indeed be loud as shit. I had a greddy power extreme dual exhaust (two very big cans) and it was still intolerable. I would never put a header on a daily driver

I disagree. I'm running the RB header, RB presilencer, stock y-pipe, and 2 cheap Midas mufflers and find it very tolerable. This includes not having a radio to cover up any of the noise.

[mnrthrt]

I have no radio either. I actually got in touch with corksport and they are shipping the header back exhaust system after all. Still picking up the HKS exhaust though for my future turbo app, or resale. Can't wait to just drive my car when I get home. lol

[project86]

I disagree. I'm running the RB header, RB presilencer, stock y-pipe, and 2 cheap Midas mufflers and find it very tolerable. This includes not having a radio to cover up any of the noise.

+1 to this. I think alot of the noise has to do with muffler choice.

[NYsNumba1Man]

Put grease/Vaseline on the rods of the actuators, take the car for a rip and make sure to rev above 4k if the grease has moved your ports work.

Location of actuators? Would there be a BIG notice? My car gets to redline without any problems at all, it doesn't strain or hesitate or anything.

[Silver86]

Location of actuators? Would there be a BIG notice? My car gets to redline without any problems at all, it doesn't strain or hesitate or anything.


left side of the engine bay. attached to the LIM, above exhaust manifold. cant miss them.

[bryant]

my 87 na was open header no exhaust and was so loud you had to scream at the person next to you just to talk to them. at idle
at 3000rpm the hat on my head was vibrating like i had two 15's.
i loved the way it sounded but the cops sure didnt.

funny thing when you would drive by people they would look at you and cover there ears.lol

[project86]

my 87 na was open header no exhaust and was so loud you had to scream at the person next to you just to talk to them. at idle
at 3000rpm the hat on my head was vibrating like i had two 15's.
i loved the way it sounded but the cops sure didnt.

funny thing when you would drive by people they would look at you and cover there ears.lol

haha i drove mine for 2 days right off the presilencer... i know exactly what you mean. She was settin off car alarms :001_005:

[NoDOHC]

I had RB headers feeding through a straight pipe to dual Dynaflow mufflers and with a stock port, it wasn't loud at all.

With the streetported 4-port, I had to add a presilencer.

If the headers are really thin, you will get a loud exhaust, thick headers are your friend.

[diabolical1]

... thick headers are your friend.

where a rotary's exhaust noise is concerned, thick pipes in general are your friend.

[NYsNumba1Man]

Alright, i'll check out my aux ports tomorrow then.

If i DO have an exhaust leak at my headers will replacing with RB headers make it sound better? or will it just be louder?

[Phoenix7]

the stock manifold really quiets things down. With a header it will indeed be loud as shit. I had a greddy power extreme dual exhaust (two very big cans) and it was still intolerable. I would never put a header on a daily driver
I have RB headers, midpipe and HKS old-school catback on our NA...we DDed that car until we got the bimmer. You CAN have straight pipes on your NA but you need to have a GOOD catback to quiet it down.

Before the HKS (52mm) catback we had Apex-i N1 Duals and they were definitely LOUD and intolerable...to the point that we bought earplugs. Maybe I'm just too old for the loud exhausts?

If you have an S4 you also have to make sure you get the S4 midpipe that incorporates the "split-air pipe" so you can actuate the Aux ports via backpressure.

[My5ABaby]

Also make sure you get the S5 midpipe that incorporates the "split-air pipe" so you can actuate the Aux ports.
S4...

[Phoenix7]

yeah, I edited it to reflect right info. I wonder how the RB rotary mufflers sound on open pipes.

Also, the HKS catback I have doesn't shoot flames...Just thought I'd throw that out there. It really makes the NA quieter than open pipes but no fire.

[NYsNumba1Man]

^^Same. I get backfire but no flames......

[Phoenix7]

Here's the HKS 52mm catback:
http://rotarycarclub.com/rotary_forum/images/rotaryrides/696/6964ad2118f215c1.jpg
http://img.photobucket.com/albums/v164/madrx7racer/Our%207s/RAJAH/Exterior/HKS52mmExhaust.jpg
http://s256.photobucket.com/albums/hh197/PhoenixRX-7/Thundehill/?action=view&current=Trackday1.flv
^^Please ignore my commentary and listen to the sounds around 15 seconds in...that's as loud as the car was. I don't have any other sound clips but I'll make sure to get some once I finish installing the new motor.

OLD N1 Duals:
http://img.photobucket.com/albums/v164/madrx7racer/Our%207s/rexansrajah.jpg

[mnrthrt]

OLD N1 Duals:
http://img.photobucket.com/albums/v164/madrx7racer/Our%207s/rexansrajah.jpg

Holy shit! ha Huge tips on those Apexi's. Wish I could have heard a sound clip of that. ha

[project86]

Holy shit! ha Huge tips on those Apexi's. Wish I could have heard a sound clip of that. ha

they are retarded loud. I had a single... it might have made me def

[mnrthrt]

ha One good thing about being in Afghanistan is that with all the low flying planes and rockets and other shit, I'm pretty much already def. lol HEADERS WITH NO EXHAUST HERE WE COME! hahaha j/k

[Phoenix7]

it sounds like sex on wheels for about 10 minutes...then the drone at highway speeds vibrates the whole car and the insides of your head. Even at LOW RPMs the car was loud.

[mnrthrt]

Sounds like I need to do it at least once. When I get home and install my Corksport system I will run around the neighborhood with the header for an hour! ha Will take some video. :)

[Phoenix7]

no way....NA running off the headers HURTS!