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The Datsun 1200 used a 1-1/2 inch exhaust system. The cast iron exhaust manifold has a flat two-bolt flange. A built-in bulge of the pipe was used to seal to the exhaust pipe, which extended past the rear axle. Finally a very, very quiet muffler with a short tail pipe was suspended by two rubber rings. The factory Datsun 1200 muffler was so quiet you couldn't hear the engine at idle.
Contents |
Overview
Terminology
Exhaust insulators: Rubber tailpipe hanger, Ring muffler hangers
Original mufflers came with integrated exhaust pipe
album
Bottom (old) is the factory piece
B210 is similar: 20100-H5000
A12GX exhaust from A12GX Engine (twin carb) models used a quieter exhaust with a small resonator as well the regular muffler:
Notice the GX also used a cast header with dual outlets -- See Exhaust Manifold
In addition the rubber hangers at the very end of the pipe and the muffler rubber hangers, B310 used a solid hanger at the end of the transmission:
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Sizing for Performance
A large diameter exhaust pipe is needed for maximum high-rpm horsepower. However, a small diameter pipe is needed to boost low-rpm horsepower. So you can see that a properly sized pipe -- not too big or too small -- is advantageous.
Single Exhaust
- Stock 62 horsepower A10: 35mm (~1-3/8")
- Stock 68/69 horsepower A12: 1.5" (38mm)
- A12 GX 83 horsepower: 1.5"
- modded A-series engine: 1.75"
- Max fuel econdomy: 1.5"
- 108 hp engine: 1.75"
- 144 hp engine: 2"
- 185 hp engine: 2.25"
- 232 hp engine: 2.5"
- 339 hp engine: 3"
Of course you can vary this. For example:
- The larger the engine relative to your car, you can get away with a larger pipe
- For better street driveability, go a size smaller
- For drag racing where it is flat-out full throttle, a larger size may work fine
2.5 inch works too, but results in less HP than 1.75 inch pipe
Although the larger pipe cuts down on low-rpm horsepower, if you have a big engine it's not so bad. Large exhaust increases high-rpm (peak) horsepower slightly while dropping low-RPM hp significantly.
Large pipes with "turbo" type mufflers sound great, but tend to have annoying resonances.
To solve the vibation & drone problems encounted with straight-through (turbo) mufflers:
- Change to a chambered muffler which is baffled
- or, adjust pipe diameter and length, possibly adding a resonator chamber in the middle of the exhaust system
- OR, cancel out those specific pipe resonant frequencies. For example, if your exhaust drones loudly at 2,500 RPM, add a side branch pipe that is 28" long. It will cancel the drone and leave all other RPMs alone
Options
Chrome tailpipe extension (bell-shaped)
Also see Options
Coupe vs. Sedan
coupe muffler
- The bends are slightly different.
- The hanger near the end of the tailpipe (in the photo: where the price tag is) is a different place for sedan vs coupe
Sedan/Coupe/Wagon differ
left: exhaust pipe, right:muffler/tailpipe
Part Numbers
See Exhaust Piping Part Numbers
Truck, Early
To 1978, a single muffler was used.
FRONT EXHAUST TUBE ASS'Y 20010-G0002 SB 20010-G1601 SB 7510-8503 20010-G1401 LB 20010-G1611 LB 7510-8503
MUFFLER WITH REAR TUBE 20100-G1003 20100-G1600 7510-7907 20100-G1660 7908-8503 > 20100-G1600
Truck, Mid-model
From 1978 to 1989, a rear resonator was used.
FRONT EXHAUST TUBE ASS'Y 20010-G1900 SB 8504-8910 20010-G1910 LB 8504-8910
MUFFLER WITH REAR TUBE 20100-G1901 8504-8910
20673 CLAMP-EXHAUST TUBE
Nichira manufacture
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Truck, Late
From October 1989, a Catalytic Converter was used.
FRONT EXHAUST TUBE ASS'Y 20010-95W00 8910-9401 20010-95W02 9402-
MUFFLER WITH REAR TUBE 20100-95W01 SB 8910- 20100-95W11 LB 8910-
20711 GASKET-EXHAUST 20691-G5100 8910-9401 20691-51E01 9401- 20711M GASKET-EXHAUST 20692-02E00 8910-9208 20692-1E810 9208- 20520 INSULATOR-HEAT, EXHAUST TUBE CENTER LOWER 20532-95W10 LB 20522 INSULATOR-HEAT, EXHAUST TUBE CENTER LOWER 20530-95W00 SB 20530-95W10 LB 20540 INSULATOR-HEAT, EXHAUST MUFFLER 20540-95W01 SB + LB 20731 BRACKET-EXHAUST MOUNTING 20720-95W00 SB + LB 20802-G5126 THREE WAY CATALYST 8910- <> 20802-81A26
Muffler
Muffler measurements from my 1200 sedan (original muffler?):
* 11-5/8" Shell length * 8-1/4" Shell oval width * 3-3/4" Shell oval height * 1.5" front inlet, centered * 1.5" rear outlet, on far left of oval
There is enough room under a sedan that a muffler about 2" longer may fit.
Nissan JDM Catalog * 20010-H1000 TUBE ASS'Y-exhaust, front - ALL (exc. GX, Automatic)* 20010-H1020 TUBE ASS'Y-exhaust, front - Automatic * 20010-H2301 TUBE ASS'Y-exhaust, front - GX 4-speed * 20010-H3400 TUBE ASS'Y-exhaust, front - GXA (GX Automatic) * 20010-H7200 TUBE ASS'Y-exhaust, front - GX-5 * 20603-H2300 GASKET-exhaust tube - GX and GX-5 * 20602-27700 NUT-fixing, tube end (2) - ALL (except GX, GX-5) * 20602-27700 NUT-fixing, tube end - GX-5 * 08915-13810 WASTHER-spring lock (3) - GX-5 * 20635-18000 STOPPER-muffler bound - ALL * 20100-H1000 MUFFLER ASS'Y-with rear tube - Sedan * 20100-H1400 MUFFLER ASS'Y-with rear tube - Van * 20100-H2500 MUFFLER ASS'Y-with rear tube - Coupe * 20630-18000 RING-rubber, muffler clamp (2) * 20620-H1000 CLIP-tube, exhaust
* 06915-43810 WASHER-plain (2) * 08915-13810 WASHER-lock * 08110-85510 or 08110-86010 BOLT * 08911-10810 NUT * 20640-18000 STRAP-exhaust hanger
* 20641-18000 WASHER-plain (2) * 08911-10810 NUT (2) * 08915-13810 WASHER-lock (2) * 08110-82210 BOLT (2) * 20321-H2500 FINISHER-exhaust - GL, GX * 20720-N2225 SEALER KIT-exhaust tube joint - ALL
USA Catalog * 20010-H3100 ASSY-TUBE EXHAUST FRONT Sedan Manual Trans > 20010-H1000 $34.92 * 20100-H7001 ASSY-MUFFLER WITH REAR TUBE Sedan Manual Trans > 20100-H1000 $84.72 NLA * 20321-H2000 FINISHER-EXHAUST (chrome extension) NLA * 20321-H2500 FINISHER-EXHAUST (chrome extension) $18.36 NLA
A15E EGI dual exhaust (92 hp)
Converter
CATALYTIC CONVERTER GASKET
Nissan 20692-M3060
BECK/ARNLEY 0396035
* 720 L20B, Z20/Z22/Z24
* 910 L24E
* B11 E15X/E16S
* N10 A14/A15/E15S
* N12 E16S
* S110 Z20E/Z22E
* S12 CA18ET/CA20E
* S130 L28E/L28ET
* T11 CA20S/CA20E
Truck
20624 INSULATOR ASSY-EXHAUST MOUNTING
20630-G1001 ALL (2)
* fixes muffler to chassis
9401- Front Exhaust Tube (uses 51E donut type gasket)
EXHAUST GASKET manifold-to-pipe 20691-G5100 flat type 8910-9401 20691-51E01 ring type 9401-
EXHAUST GASKET pipe-to-converter 20692-02E00 8910-9208 20692-1E810 9208-
20691-51E01 BECK/ARNLEY 0396441 $3 rockauto.com FEL-PRO 60905 VICTOR REINZ F31814 * A32B 0601- VQ30DE * A33B 0499- VQ30DE * B13 0890- SR20DE * B15U 0100- SR20DE/QG18DE * D22U 0898- KA24DE * L30 0697- KA24DE * U13U 0893- KA24DE * WD22 0599- KA24DE
20691-51E01 Steel ring gasket
Exhaust Pipe Gasket
Muffler
The muffler should flow at least 2.2 cfm per flywheel HP. For a 69 hp A12, that is 152 cfm
Aftermarket 1.5
- Dynomax 17700 ("Thrush turbo"),similar shape to stock. Oval 3.25 in. x 7.75 in. Case Length: 11 in. Overall length: 16 in. Width: 7.750 in. Thickness: 3.25 in.
1-1/2 pipe clamps:
- Merit M112 or U112
- Napa BK 7335325
Rubber Donut Hangers
- Merit 8166 ???
Aftermarket GX (is it the same as the S110 gasket?)
- Gasket: Merit 8696
- Pipe: (1981 Nissan 720), Merit 48316
Exhaust Tip - 1-1/2" diameter
- Merit 9821
Aftermarket 1.75
- Walker Super Turbo WLK-17771
- Dynomax 17771, 160 cfm
- WALKER Pro-Fit Muffler, 1.75" offset/center, #17881
- Magnaflow 11123 with offset. Might be too long, it is 14" body, but it is Stainless Steel, best buy
- Borla XR-1: BOR-40483 Stainless Steel, 1.75 in, 2.25 out
Search for these using http://google.com or http://www.napaonline.com
Can Muffler
Hot-dog style mufflers (cannons or "fart cans") are mainly for looks. Having the muffler at the very end of the exhaust makes it louder, and most cans are fiberglass packed tubes ("glass-pack") which are by nature noisy. They are simply a straight-through pipe with baffles in the tube sides.
When fitting a can muffler, it is advised to also fit a large normal muffler under the car.
Arms
ARMS - stainless side tubes to fit 1200 ute. Volume 94db. Main pipe φ50, tail end φ50 (2" pipes). Dual slash cut or straight cut.
Nismo
"FISCO" and "NISMO" was fitted to Sunny Truck with A15
Extractors
See main article: Headers
System
David Vizard says exhaust pipe diameter makes a significant difference.
In practice though it is better, especially for a street-driven machine, to have pipes a little too small rather than a little too big. If the pipes are too large a fair chunk of torque can be lost without actually gaining much in the way of top-end power.
More interesting is about the tuned-header and collector lengths:
on a well-tuned race engine ... the exhaust system draws on the intake port as much as 500 percent harder than the piston going down the bore...the exhaust is the principal means of induction, not the piston moving down the bore.
Vizard recommends a sized extractor and a resonator box placed at the correct length. Then after the resonator it doesn't matter how long the exhaust pipe is or what muffler type is used (open chamber or glass pack). Without a resonator the type of muffler makes a huge difference on horsepower.
- For racing, don't worry about equal length extractors, it's a waste of time.
- For a downdraft induction system, don't mess with the length of the extractor primaries
- The collector length is where you should concentrate your efforts
- At the end of the collector length fit a large expansion chamber (pressure wave termination box)
- The chamber should be 8 to 15 times the volume of one cylinder (larger is better). For an A12 this works out to about 3 liters.
Collector Length:
Pick an appropriate length from the collector. This makes a huge difference on high overlap camshafts and not just a "dyno difference". There is no "correct length" for all A12 engines. It depends on how you build the engine. What cam do you have? Where do you want the max HP to occur? Via the length you can shift the power band somewhat.
Having a proper length (long) collector can provide a lot more HP while in the power band. Up to 22% more. So it's definitely worth doing.
Discussion by jmac: Extractor selection
Long collector
stock collector
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