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-   -   Let's just talk about , rx-7's! (https://www.revscene.net/forums/52225-lets-just-talk-about-rx-7s.html)

NanaimoRx-7 05-29-2004 11:55 AM

Grant I wish I'd bought your car, it looks great in those pics. I'd been meaning to ask about it. If anyone see's a decent shell out there I'd like to hear about it, I need a straight frame.

RZ350 05-29-2004 12:22 PM

Well then according to your chart:

my engine displaces 1.2L total between two rotors.
Each rotor displaces 0.6L so therefore each of my exhaust primarys should, according to your info, be around 0.5" to 0.75" maximum; how can I be choking the exhaust?

Now most people consider a rotarty to be roughly equal to a motor twice the size, so lets just say that EACH of my rotors displaces 1.2L. So my exhaust primarys should be between 1.25" and 1.75", which they are

Before you point out that the bends are not made with a mandrel, keep in mind that they were done by an excellent exhaust maker and the piping is in fact considerably oversized.

I'll find a reference for the scavenging effects later.

Grant

P.S. This is all in good fun, but I do believe that you are wrong and the performance I've observed proves it.

RZ350 05-29-2004 12:28 PM

Oh and the noise is alright, especially considering there is no interior. The highway can get a little tedious after a half-hour or so, and if you gas it at any RPM around town you will get noticed. That said it is utterly un-rice sounding, just deep, raspy and a bit of a ping; so people don't like that sound but I certainly do. The big thing is to make sure that you don't get a center-in center-out one, my offset one is the only thing keeping it sane.

Grant

P.S. Nanaimo RX-7, your welcome to take a spin in it anytime your down, or I'll let you know the next time I'm in Duncan with it.

Lemon 05-29-2004 12:33 PM

sorry but i have yet to hear a NA rotary exhaust note that is deep

RZ350 05-29-2004 12:38 PM

Fair enough, it's not like "jet aircraft at takeoff" deep, but it beats the heck out of "basically stock civic with fart-can" on the deep-o-meter. I could just be the way I hear it in the cockpit, I've never heard it from outside.
Grant

Lemon 05-29-2004 12:46 PM

just when i think of NA rotary i think, weed whacker on crack

D4Damager 05-29-2004 05:37 PM

Did you ever hear my car with the RB header, magnaflow presilencer and Ceti1 SS muffler, Lemon? It was pretty bloody smooth, you're probably thinking of Ty's Dual N1 attack or Justin's broken muffler.

EDIT: This is Jeff, plus J4 is gay.

t0mmy 05-29-2004 06:26 PM

Quote:

Originally posted by NanaimoRx-7
Tommy, the man is correct in his exhaust thinking, at least for first gens. A very popular IT7 setup is dual 2" collected before it goes over the axel, and 3 inch over and out. Actually the best setup for a stock port 12A in true dual setup would be to collect it about 3 feet past the rear bumper. Porting brings the collection point closer and closer to the engine. What are you trying to say with that source? 12A's would be picking between the 2-2.5l engine size by using a 2"-2 1/2" pipe, but dual 1.75" should cover it.

How's the noise grant? I've wanted to do duals for awhile but I can't bring myself to chop up my header.

Yes 1.75" covers it but you lose out on the support of the other rotors positive pulses to further enhance the scavenging effect which kills top end. Relying purely on velocity to remove gases across the surface area of 1.75" seems a lot more restrictive than that of a 2"-2.25" collected exhaust closer. There was a huge article somewhere published written by Paul Yaw on this topic.

t0mmy 05-29-2004 06:29 PM

Quote:

Originally posted by RZ350
Well then according to your chart:

my engine displaces 1.2L total between two rotors.
Each rotor displaces 0.6L so therefore each of my exhaust primarys should, according to your info, be around 0.5" to 0.75" maximum; how can I be choking the exhaust?

Now most people consider a rotarty to be roughly equal to a motor twice the size, so lets just say that EACH of my rotors displaces 1.2L. So my exhaust primarys should be between 1.25" and 1.75", which they are

Before you point out that the bends are not made with a mandrel, keep in mind that they were done by an excellent exhaust maker and the piping is in fact considerably oversized.

I'll find a reference for the scavenging effects later.

Grant

P.S. This is all in good fun, but I do believe that you are wrong and the performance I've observed proves it.

Not dogging on your exhaust or anything (Mine isn't any better) just clearing up the point that scavenging effect is lost or at the most minimal at that point.

Lemon 05-29-2004 09:59 PM

Quote:

Originally posted by D4Damager
Did you ever hear my car with the RB header, magnaflow presilencer and Ceti1 SS muffler, Lemon? It was pretty bloody smooth, you're probably thinking of Ty's Dual N1 attack or Justin's broken muffler.

EDIT: This is Jeff, plus J4 is gay.

yeah, sorry jeff i herd it last night, thats where i got the weed whacker idea :(

bcty 05-29-2004 10:06 PM

yeah i like the turbo thing much better start @ 3" and work up

jeffraider 05-30-2004 03:11 AM

Quote:

Originally posted by Lemon
yeah, sorry jeff i herd it last night, thats where i got the weed whacker idea :(
my blue car? that's not how it sounded when i sold it :)

jeffraider 05-30-2004 03:13 AM

oh and what's this business of coal now being a top street racer

Type R 05-30-2004 03:43 AM

Jeffraider is a lil fucker, fuck that guy..

Nightwalker 05-30-2004 04:01 AM

Quote:

Originally posted by jeffraider
oh and what's this business of coal now being a top street racer
WHAT STREET RACERS?!?!?!

bcty 05-30-2004 09:10 AM

i kicked your ass.. my 60 foot time was in the 1.5secs and i had you for the first 100meters :) and that was 2 foot drive jsut wait till i use all 4.. your fucked pal

jeffraider 05-30-2004 09:54 AM

Quote:

Originally posted by Type R
Jeffraider is a lil fucker, fuck that guy..
hahahaha

Lemon 05-30-2004 09:00 PM

next time i wont run 10 psi :) just gotta get my boost controler fixed lol

bcty 05-31-2004 09:12 AM

u can borrow mine for a day or two if u wanna run around town with a bit higher boost :)

Lemon 05-31-2004 09:54 AM

i just need to get a new spring for mine from brainchild, and i cant turn the boost up as of yet cuz my fuel pump is slowly dieing

91TII 05-31-2004 10:25 AM

Quote:

Originally posted by Lemon
sorry but i have yet to hear a NA rotary exhaust note that is deep
Depends on the exhaust setup. I've heard on Video an NA with the full Racing Beat Exhaust and its much deeper then any of the exhaust's on NA's around here. Wait till Aaron gets RB on my old car, it should be a deeper tone. But yeah most NA's do sound more high pitched, but oh well, they can still sound good like that. ;)

Lemon 05-31-2004 10:35 AM

actually i think it was cams car i herd, either way it was a weed whacker lol, im sure u can make them sound good.. like by adding a turbo lol, now turbo 2 sound nice :)

PS i may have a new walbro comming my way for cheap so no 3rd gen pump for me .. sorry guys lol

DC450 05-31-2004 11:34 AM

Damn, i need to check this thing more often...

But lemon, i dont think you've heard my car... Well, i know you haven't heard my car, its barely on the road! (working) but its got a real deep exhaust, goin up hills in 4th it makes your ears pop bwaaaaa Bonez race pipe, no cats to two unknown mufflers with 4.5 inch resonators on the back

BlackFC3S123 05-31-2004 12:31 PM

i will desimate all with my RB full exhaust!

i would just like to say awesome job to George and Jeff at auto cross yesterday, awesome jobs guys......almost a perfect drift on the hairpin eh George?
no worries about that you still did an AWESOME run.

pictures of you guys are on the may 30th saratoga thread.

bcty 05-31-2004 08:29 PM

yeah its cool evan you ahve my old set.. sounds soooooooo good id say the best around here right now.. u just gotta work those bugs out..

hey why we talking about n/a's anyways.. turbo is where its at


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