Need Advice on Exhaust System for 13B NA
#1
Junior Member
Thread Starter
iTrader: (3)
Join Date: Nov 2012
Location: South Dakota
Posts: 13
Likes: 0
Received 0 Likes
on
0 Posts
Need Advice on Exhaust System for 13B NA
I'm going racing with a bone stock '87 13B NA, and I need some advice on the best way to upgrade the exhaust system. I want to get the biggest power increase I can, and the only limitation I have is I need to be at 92 db or less from 50 feet away from the car.
I've been looking at some of the Racing Beat stuff, but I really have no idea where the noise would be at, and I'm not sure if there's something better out there. Any advice would be greatly appreciated.
I've been looking at some of the Racing Beat stuff, but I really have no idea where the noise would be at, and I'm not sure if there's something better out there. Any advice would be greatly appreciated.
#3
Isn't really a professor
iTrader: (1)
Join Date: Feb 2011
Location: Los Angeles
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
I run the Racing Beat header and dual exhaust on my street ported 13B, with straight pipes installed instead of the center muffler (so I only have the two rear mufflers), and my car blows 99db at 50 feet. With the center muffler installed, you might make 92db. If not, put a turndown/turnaway on the exhaust tips and you can probably fool the meter enough to be OK
#4
Full Member
Join Date: Mar 2001
Location: Huntersville, NC
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
on my ITS car i ran the RB header with two straight pipes merging into one Ultraflo muffler with an adjustable turn down tip. i don't know about hitting 92db but the power is definitely there.
#5
Mr. September FB 2011
iTrader: (9)
Join Date: Mar 2009
Location: Winnipeg, Manitoba
Posts: 489
Likes: 0
Received 0 Likes
on
0 Posts
A car at my track has an OBX header, magnaflow stainless 4" body resonator/glass pack and single flow-pro max muffler.
I can't remember the exact decibel count but i know it was less than 95. If you use a dual setup out back it may be even quieter.
That car dyno'd 173whp with fresh-ish mild street port, 850cc secondaries and factory computer. I don't know how good that power is (I'm used to modded turbo numbers) but at the time we thought it was alright.
I can't remember the exact decibel count but i know it was less than 95. If you use a dual setup out back it may be even quieter.
That car dyno'd 173whp with fresh-ish mild street port, 850cc secondaries and factory computer. I don't know how good that power is (I'm used to modded turbo numbers) but at the time we thought it was alright.
#6
Emerald Triangle for life
iTrader: (5)
Join Date: Jan 2002
Location: Fort Collins, CO
Posts: 552
Likes: 0
Received 0 Likes
on
0 Posts
I still haven't found any system that sounds better than RB. I'm running an RB header to a Bonez Superflo cat to a stock Y-pipe (RB's doesn't have larger diameter or cleaner transitions) to a pair of RB mufflers. It flows pretty well and noise level is 92db at 18 inches. My only real gripes are that a better header would make more power and my catback is only 5lbs lighter than stock.
For absolute max power, I recommend a custom header. All of the OTS header designs appear to turn too soon after the port exit, most have poor/undersized collectors and/or unequal length primaries.
My next system (I AutoX in CSP) will be a custom header to 2.5" cat for street duty (and either a resonator or an expansion chamber for race duty) to a 2.5" single catback. I expect that a RB Power Pulse muffler behind one of their pre-silencers should produce a reasonable tone without too much weight.
For absolute max power, I recommend a custom header. All of the OTS header designs appear to turn too soon after the port exit, most have poor/undersized collectors and/or unequal length primaries.
My next system (I AutoX in CSP) will be a custom header to 2.5" cat for street duty (and either a resonator or an expansion chamber for race duty) to a 2.5" single catback. I expect that a RB Power Pulse muffler behind one of their pre-silencers should produce a reasonable tone without too much weight.
#7
Junior Member
When I ran a street ported 13B ran racing beat intake with Holley 650cfm and on the exhaust side custom measured headers with resonators four of them keeping seperate pipes 57 mm I think until a collector muffler before rear axle and a serviceable custom box at the back. Was running very competitive lap times. Booze was within rules at the time the rear silencer was able to open so you can pack with fibre and stainless steel wool. I'm busy designing a box at the moment based on the classic megaphone design
Trending Topics
#8
Racer
Join Date: Sep 2013
Location: Trussville, Heart of Dixie, Al.
Posts: 97
Likes: 0
Received 0 Likes
on
0 Posts
ISC header, 3" outlet into a Borla SS muffler, 3" to a Borla oval muffler in the rear. Suspend rear with chain because system grows about 3" on track. If necessary I can get you muffler numbers.
#9
Emerald Triangle for life
iTrader: (5)
Join Date: Jan 2002
Location: Fort Collins, CO
Posts: 552
Likes: 0
Received 0 Likes
on
0 Posts
According to the reading I've done here and elsewhere, pipe sizing in an NA should be planned as close to 250fps as possible at peak flow, or slightly larger. Anything larger might contribute slightly to top end with progressively smaller gains and larger losses down low due to lack of exhaust velocity.
That said, a 2" (50mm) .125 wall pipe should flow enough for about 130RWHP, so perfect for a true dual system on a max effort street port or bridge port motor that's going to spend a lot of time around the rev limiter.
A 3" system with .125 wall pipe should flow enough for around 320RWHP, so perfect for bridge port peripheral port setups, but it seems a bit much for a stock or street port.
A 2.5" single should flow enough for about 220RWHP, which is already pretty ambitious for a stock port or street port motor.
Of course these numbers change a bit if you run thinner-walled stainless pipe. Speaking of which, does anyone know how thin you can go on a stainless system before they start having issues?
That said, a 2" (50mm) .125 wall pipe should flow enough for about 130RWHP, so perfect for a true dual system on a max effort street port or bridge port motor that's going to spend a lot of time around the rev limiter.
A 3" system with .125 wall pipe should flow enough for around 320RWHP, so perfect for bridge port peripheral port setups, but it seems a bit much for a stock or street port.
A 2.5" single should flow enough for about 220RWHP, which is already pretty ambitious for a stock port or street port motor.
Of course these numbers change a bit if you run thinner-walled stainless pipe. Speaking of which, does anyone know how thin you can go on a stainless system before they start having issues?
#10
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,780
Received 2,565 Likes
on
1,824 Posts
after playing with a bunch of FC's over the years, Mazda used 50mm ID pipe, and this actually seems to be a good size for a stock, or street ported car. the restrictions seem to be the cats, and mufflers
so anyways, 50mm ID i think was a 2.25" OD pipe.
it does seem like by the time you get to a 3" pipe, it gets hard to muffle, and i think its past the point of big returns
so anyways, 50mm ID i think was a 2.25" OD pipe.
it does seem like by the time you get to a 3" pipe, it gets hard to muffle, and i think its past the point of big returns
#11
Junior Member
Join Date: Jun 2014
Location: Grosse Pointe, Michigan
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
From experience, I cannot recommend any system more than the RB cat back with a straight pipe from stock headers back. After my cars rusty stock pipes met a grisly fate with a particularly energetic backfire, I got the RB system and was very happy. The increase in power with no emissions equipment and a free flowing car back couldn't be beat, especially with the bearable in cabin noise and excellent tone.
#12
Information Regurgitator
I can really only regurgitate what I have read on here over the years plus the evolution my current system which is the only one I've ever had. Popular opinion is the RB true dual is the best off the shelf system for a stock port car. Ported engines need the primaries collected at some point. Where depends on the porting and intake setup. I don't know what db numbers it is at. If you start with this system you can put a collector in it later and even convert to a custom single if you chose and/or if you port your motor. It gives more options as you will have the road race header and pre silencer allowing you to play with primary lengths in the future.
As to my system it started with their(Racing Beat) collected header and pre silencer to their Y-pipe to stock mufflers. Power gains were good and noticeable. Sounded like crap above 4000rpm. Don't know the db's but it was louder than my current setup inside the car. I currently have the old HKS sport cat back but it hasn't been on the market since the early 2000's but the RB mufflers with this setup should give about the same gains maybe better but are a touch louder. These mufflers made a noticeable difference over the stock cans. None of this probably helps without db numbers.
I would get the true duals for the above reasons as there is probably nothing better out there( off the shelf) without building something custom and tuning it on the dyno.
You might look at Defined Autowork's header if you have lots of money( it's $850)and you'll have to fab something custom from there back. It is all stainless and looks to collect mid chassis, but with no pre muffler provisions meeting 92 db may be a challenge.
As to my system it started with their(Racing Beat) collected header and pre silencer to their Y-pipe to stock mufflers. Power gains were good and noticeable. Sounded like crap above 4000rpm. Don't know the db's but it was louder than my current setup inside the car. I currently have the old HKS sport cat back but it hasn't been on the market since the early 2000's but the RB mufflers with this setup should give about the same gains maybe better but are a touch louder. These mufflers made a noticeable difference over the stock cans. None of this probably helps without db numbers.
I would get the true duals for the above reasons as there is probably nothing better out there( off the shelf) without building something custom and tuning it on the dyno.
You might look at Defined Autowork's header if you have lots of money( it's $850)and you'll have to fab something custom from there back. It is all stainless and looks to collect mid chassis, but with no pre muffler provisions meeting 92 db may be a challenge.
The following users liked this post:
ablesnead (03-13-18)
#14
I run the Racing Beat header and dual exhaust on my street ported 13B, with straight pipes installed instead of the center muffler (so I only have the two rear mufflers), and my car blows 99db at 50 feet. With the center muffler installed, you might make 92db. If not, put a turndown/turnaway on the exhaust tips and you can probably fool the meter enough to be OK
Thread
Thread Starter
Forum
Replies
Last Post