Exhaust
The Datsun 1200 used a 1-1/2 inch exhaust system, which is very good for a 1.2 liter engine, and adequate for a 1.4 or 1.5 liter moto. 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.
See also: Muffler
Overview
Terminology
Exhaust Pipe, Muffler, Tail Pipe
Exhaust Manifold and Exhaust Pipe
Exhaust insulators: Rubber tailpipe hanger, Ring muffler hangers
http://datsun1200.com/uploads/photos/31086.jpg
Original mufflers came with integrated exhaust pipe - Bottom (old) is the factory piece
B210 is similar: 20100-H5000
http://datsun1200.com/uploads/newbb/174_69015e0f76ada.jpg http://datsun1200.com/uploads/newbb/174_69015e1ee8e64.jpg http://datsun1200.com/uploads/newbb/174_69015e01097b9.jpg
#A12GX Exhaust from twin carb models used a quieter exhaust with a small resonator as well the regular muffler:
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:
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/DSCF4058_.jpg
Factory muffler: B110, B110A, PB110, PB110A, B110 GX, B110 GXA, B110 GX5
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 economy: 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
3" exhaust system is possible under a 1200 sedan
Muffler and Tail Pipe
Main: Muffler
Exhaust Pipe
In Datsuns, the exhaust pipe is the section from the exhaust manifold back to the muffler.
Automatic pipe differs from Manual pipe, it has a different bend in it.
FRONT EXHAUST PIPE * Automatic * Manual * GX #twin inlet pipe with resonator * 1978-1988 #B120 medium pipe * 1989-1994 B120 short pipe for converter usage
B110/B120 exhaust pipe
http://datsun1200.com/uploads/photos/31098.jpg
GB120 long wheelbase
http://datsun1200.com/uploads/photos/31099.jpg
Options
See also: Options
An exhaust tube finisher adds a luxurious accent to the rear view. Just by installing it, the impression will be greatly improved.
20321-H2000ᴳ B110 chrome tailpipe extension (bell-shaped)
20321-H2500ᴳ B110 option, B210 option exhaust finisher
Coupe vs Sedan vs Wagon
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
Sedan
http://datsun1200.com/uploads/newbb/174_6901a825d8133.jpg http://datsun1200.com/uploads/newbb/174_6901a81e67333.jpg http://datsun1200.com/uploads/newbb/174_6901a80df2193.jpg http://datsun1200.com/uploads/newbb/174_6901a7f0815d3.jpg
A12GX Exhaust
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
downpipe portion of the exhaust pipe
GX used the stock muffler (coupe or sedan version) along with these special parts:
20010-H2301 ASS'Y-TUBE, exhaust front GX 20010-H3400 ASS'Y-TUBE, exhaust front GXA 20010-H7200 ASS'Y-TUBE, exhaust front 5 speed 20321-H2500ᴳ FINISHER-exhaust GL,GX < 20321-H2000
chrome tail pipe Finisher
For the B110 1200 there were three different GX tubes:
- GX
- GX Automatic
- GX5
Only difference being the bend of the tube. Subtle difference
Exhaust Tube with resonator
Exhaust good for an engine with 20% more HP. Same tube diameter as regular
Complete the GX exhaust with Sedan or Coupe muffler/tail pipe assemblies. Result is super-quiet yet more powerful.
Part Numbers
Main: Exhaust Part Numbers
Truck, Early
To 1978, a single muffler was used.
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/exh_early.jpg
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.
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/exh_mid.jpg
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
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/Parts/20100-G1901.jpg
Nichira manufacture
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/Parts/20100-G1901_.jpg
Truck, Late
From October 1989, a Catalytic Converter was used.
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/exh_late.jpg
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
20624 INSULATOR ASSY-EXHAUST MOUNTING 20630-G1001 ALL (2) 
* fixes muffler to chassis
9401- Front Exhaust Tube (uses 51E donut type gasket)
https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/20010-95W02-.jpg https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/20010-95W02.jpg https://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/20010-95W02_.jpg
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
Converter
To meet 1988 'R' emission standards, a 3-way catalytic converter was fitted. Due to the converter beneath the floor, a special passenger seat is used.
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 https://i297.photobucket.com/albums/mm219/ddgonzal/wiki/BA0396035.jpg
20802-G5126 THREE WAY CATALYST < 20852-81A26 コンバーター、カタリスト ウイズ シェルター 20802A 01121-00751 BOLT 4 20853-53A00 LOWER SHELTER シェルター、コンバーター ロア 22740-95W00 [EXH TEMP] SENSOR ASSY-CATALYST センサー アッセンブリー、カタリスト
Racing Pipe for replacing the converter.
Budget racing pipe
Slimline catalyst
B211 catalyst piping
Exhaust Pipe Gasket
The factory exhaust pipe bolts to the manifold using a ring gasket (A12), dual-outlet flat gasket (A12GX) or single-outlet flat gasket (B121/B122/B140).
Main: Exhaust Manifold Gasket
Extractors
Tubular headers look great and can increase horsepower if the length is carefully chosen. But they don't last as long as stock cast iron manifolds, and for a relatively stock engine don't make more power than the #GX cast manifold system.
Main: 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). By contrast, without a resonator the type of muffler has to be carefully chosen as it can gain or lose a huge amount of 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
Turbocharged
2.5" off turbo for about 2" then 3" all the way all mandrell bent a straight through offset centre muffler and a resonator at the rear with a 3.5" tip
エキゾースト テユーブ & マフラー
¤