d_rotary_rocket_b

just wondering how the best setup for a dual exhaust would work?
for a straight pipe and no cats. how wide should the straight pipe be before it splits into the "Y", and then how wide should the pipes be after the "Y" split into the mufflers

my car right now is an 89 n/a with a cone intake that thats pretty much it

p.s. i know that a single muffler straight pipe is the best, but i love the look of the 2 mufflers on the *** of the rx

gingenhagen

true duals, 3", i would say

turbine

iTrader: (1)

3 inch to 2 1/4 s

NZConvertible

That's is not necessarily true. It depends entirely on pipe sizes.

A 2.5" main pipe is fine for a mildly modded NA. Splitting it into two 2.25" pipes will result in less restriction than a single 2.5" pipe.

snub disphenoid

If you have a 2.5" test pipe, I would say use a 2.5" single pipe that Y's off into two 2" pipes.

Uhhh...no. I have 2" true duals and they flow way too much for my stock port supercharged engine. Considering that 2" true duals seem to be ideal for PERIPHERAL PORTED engines, I'd have to assume that 3" true duals would be way too much for an NA.

gingenhagen

edit: nvm, i'm an idiot

d_rotary_rocket_b

thanks for the feedback guys. what about the exhaust manifold, would it be way too much airflow if get rb headers or should i just use the stock exhaust manifold

1987RX7guy

iTrader: (3)

True duals.

NZConvertible

No such thing. Airflow = power.

RotaryEvolution

iTrader: (30)

you are a professor now?

more is not always better.

NZConvertible

I see you're still way better at contributing smart-*** comments than useful info...

If airflow through an engine increases, its power output increases. If airflow decreases, power output decreases. This is fundamental engine stuff, no doctorate required. We even have a device that can do this for us. It's called a throttle.

mack123

iTrader: (4)

I have been looking into getting a 3 inch header that goes into a 2 1/4, then out to the mufflers, its a total setup front to back, and offered by one of the better rx-7 aftermarket places.

It would be for my turbo 2, in fact its designed for the turbo 2 and they claim.. about 50 hp gain. Whether or not it would be that much is open to debate, perhaps thats only at or above 7,000 rpm..

my question is.. If I installed this on my stock T2, would it adversely affect my idle quality, or would the computer be able to catch up and re-map itself easily for the added power?

I like a nice idle, I dont want a thumpety one.

More exhaust out would mean I would need more air in, so I would add a K and N filter or equal setup.. other than that the car is100 % stock, except for msd wires.

mack123

iTrader: (4)

they also said I need a fuel cut safety thing that plugged in somewhere because the added boost, created by the new open exhaust { they said boost would increase 3-4 } would tell the computer that boost was too great and shut off fuel,etc. a 50 gain sounds kinda unreal, i would think more like 30.

d_rotary_rocket_b

so how would you actually do that, don't headers actually go and merge to one outlet???

BlaCkPlaGUE

lmao, smart assed kids...

We've talked about this before, and the more flow is not necessarily better. The principle of it is right, but with the seven theres an example or more restriction being better in a sense.

The collected header. When its collected (like we talked about before) the exhaust pulses from each rotor help pull one another through the pipe at the collection point. People have had more power with a collected header, than with a true dual exhaust. This has been what I've been told like 4 times now.

1987RX7guy

iTrader: (3)

Racing Beat makes a "Road Race" header. Most people use them to make their custom long primary/short primary or true duals.

Racing Beat has their own Road Race exhaust. So does Mazdatrix. The latter I own but it is now more expensive than the RB so RB is more cost effective.

totallimmortal

I always though true dual was better but anyway what about true dual with an equalizer p;ip like an h or x pipe? would that be better then plain true dual?

1987RX7guy

iTrader: (3)

Theoretically its superior, but you have to know where to put in the collection(x-pipe) to make the best of it for your specific purpose. I've yet to see someone do a back to back tho. I told MS7 a few times he should do it but he hasn't to my knowledge.

totallimmortal

Where do you think the collection should be for a stock port s4? Many people say that true dual isn't needed for stock ports but i'm trying to max out my stock port NA before any major mods just to seen what it can do header and true dual i expect mid 14s i can't wait

d_rotary_rocket_b

does anyone have pics of an h or x pipe thats been set up?

1987RX7guy

iTrader: (3)

it all depends on what you want. from what i have read(not much) the collection point decides where the power is maximized by the scavenging. So you need to figure out where you are making your peak with the rest of your mods then do the calculations so that you can put the X pipe in the proper spot. Also I think the H pipe is kinda the ghetto way to do it. The X pipe I think is the better solution.