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Specifications and the NCOP (National Code of Practice)

The NCOP has been adopted in WA. The following rules only apply in states that have adopted the NCOP.

In WA a vehicle modification application is used to list all the modifications you would like to make. If the application is approved you will be given a list of items that require engineering and references to the relevant regulations. If you are in doubt then list the modification.

WA Department of Transport Power to Weight Ratio Limits (WA Only)

The WA Department of Transport has introduced maximum power to weight ratio limits.

https://www.transport.wa.gov.au/mediaFiles/licensing/DVS_VS_IB_134.pdf

The WA Department of Transport uses 1324 kg as the heaviest variant of a 1977 Holden Torana.

Under the WA Department of Transport Power to Weight Ratio limits the power limit for an LH-UC Torana is 1324kg x 180kW / 1000 = 238 kW (317 hp).

The WA Department of Transport will take the manufacturers power rating as the basis for approving or rejecting an engine swap. Under the new rules the LS2 which is rated at 298 kW will be rejected. The LS1 is still an option but only if the peak power rating of the donor vehicle does not exceed 238 kW. For example VZ Monaro LS1 was rated at 260 kW and will not be approved. The V2.II Monaro LS1 was rated at 235kW and will be approved.

A dynamometer report on the maximum power and torque produced at the wheels after modification is to be supplied. The report must include chassis number, engine number, maximum power, torque and boost pressure - to be signed and supplied by Consulting Engineer or Signatory to prove compliance. The report must list maximum torque, power and boost pressure on the Y- axis and engine rpm on the X-axis.

A roller or hub chassis dyno may be used. As long as the peak power on the dyno sheet does not exceed 238 kW, final approval will be granted.

Maximum Tares and NCOP engine capacities

The WA Department of Transport uses 1324 kg as the heaviest variant of a 1977 Holden Torana.

		Naturally Aspirated		Forced Induction
Model	Tare kg	cc	ci	cc	ci
SL/R 5000	1281	6405	391	3843	235
SL/R 5000 A9X	1306	6530	398	3918	239
SS Hatch	1232	6160	376	3696	226
SS A9X Hatch	1242	6210	379	3726	227
WA DOT	1324	6620	404	3972	242

Source: "60 Years of Holden" Terry Bebbington pg 338

The maximum engine capacity is based on the original tare of the model vehicle fitted the the largest engine available without optional accessories. WA currently uses 1204 kg for both hatch and sedan. However you should be able to get them to accept either the SS or A9X hatch tare for a hatch and the SL/R or A9X sedan tare for a sedan.

The engine must meet the pollution standards of the donor vehicle or the year of engine manufacture, you can not fit an older engine. For example a LS3 must run CAT's and the factory computer. In WA if you fit an aftermarket computer then you will be required to pass a five gas emission test which costs around $200.

See NCOP3_Section_LA_Engine_01jan2011_v3.pdf

Rims and Tyres

The maximum tyres size is limited by the largest optional tyre fitted by the manufacturer for that model (reference tyre).

The maximum tyre width is 1.3 times the reference tyre.

The tyre diameter must be in the range of -26mm to +15 mm of the reference tyre diameter.

The only requirement for rim width and diameter under the NCOP is that is must be within the tyre manufacturers recommended rim width range for the tyre fitted.

See page 21 of the NCOP11_Section_LS_Tyres_Suspension_Steering_V2_1Jan_2011%20v3.pdf.

For the LX Torana the reference tyres are the SS and A9X tyres.

Model	Rim	Offset in.	Offset mm	PCD	Stud	Tyre	Circumference Feet	Circumference Meters	Dia mm
LX S & SL	13x5.5 JJ	1.25	31.75	5 X 4.25	7/16 UNF	175SR13
LX RTS SL/R & SS	13x6.0 JJ	1.25	31.75	5 x 4.25	7/16 UNF	CR70H13
L34 & A9X	14x6.0 JJ	0.25	6.35	5 x 4.75	7/16 UNF	DR70H14	6.3768	1.9436	619

Sources:

GMH L34 service bulletin

"60 Years of Holden" Terry Bebbington pg 338

Holden Torana Performance Handbook by Eric Blair 1993 p 115.

Rare Spares LX 6 cyl S SL SS SL/R tyre placard. Part No: 9941509

Notes:

The GMH L34 service bulletin lists the rolling circumference as 6.3768 feet (1.9636 meters). The meters conversion is wrong (probably a typo). The meters conversion 1.9436 in the "Holden Torana Performance Handbook" is correct.

NCOP Tyre Widths and Diameters

Standard				NCOP
Tyre	P-Metric Equivalent	Std Width	Std Dia	Max Width	Min Dia	Max Dia	Max Actual Tyre Size	Max Rim 65-85 Profile	Max Rim 60-30 Profile
175SR13	175/80/13	175	610	228	584	625	215/225	7.5/8.0	8.5/9.0
BR78S13	175/80/13	175	610	228	584	625	215/225	7.5/8.0	8.5/9.0
BR78S13	185/70/13	185	589	240	566	604	235	8.5	9.0
CR70H13	195/70/13	195	603	254	577	618	245	9.0	9.5
DR70H14			619		593	638
DR70H14	195/70/14	195	629	254	603	644	245	9.0	9.5
DR70H14	200/70/14	200	636	260	610	651
DR70H14	205/70/14	205	643	267	617	658	255/265	9.5	10.0

Converting Alpha-Numeric to Modern tyre sizes

The metric equivalent of a DR70H14 is open to debate. It is most likely a 200/70/14 which would convert to either a 195/70/14 or a 205/70/14. According to the Car Bible Tire Size Conversion Chart it is a 200/70/14. According to the load rating conversion table below it is a 205/70/14. It appears that 195/70/14 is used for the NCOP by some inspectors and 205/70/14 by others. Confirm with your local inspectors what they consider a DR70H14 to be in P-Metric.

Using the rolling circumference of 1.9436 meters from the GMH L34 service bulletin the diameter of a DR70H14 is 619 mm.

The first letter of the Alpha-Numeric tyre size is the load rating and size relationship. The main problem is deciding which modern profile to use to for the Alpha-Numeric profile conversion. For example 78 could be converted to 80, 75 or 70. It appears to be common practice to round down to the most commonly available modern profile.

Load rating to modern 70 series

A = 175, B = 185, C = 195, D = 205, E = 215 etc.

Load rating to modern 80 series

A = 165, B = 175, C = 185, D = 195, E = 205 etc.

Rims-n-Tires.com - Wheel / Tire Size Calculator

The Wheel and Tyre Bible Page 1 of 2

Rim Width Measurement

The trick to rim measurements is that the rim width is measured from the inboard tyre bead seat to the outboard tyre bead seat. Backspace is measured from the inboard flange to the hub. There is typically 0.5" of flange beyond the tyre bead seat. If you measure an 8" wide rim from flange to flange it will measure 9.0". If you measure from the inboard tyre bead seat to the outboard tyre bead seat it will measure 8.0".

Inboard Flange = Typically 0.5"

Outboard Flange = Typically 0.5"

Overall Width = Inboard Flange + Rim width + Outboard Flange

Rim Centreline = Overall Width / 2

Offset = Back Space - Rim Centreline

Back Space = Rim Centreline + Offset

Front Space = Rim Centreline - Offset

When comparing different width rims you should look at the offset. If the offset stays the same then the centre of the rim will be in the same position. If the offset stays the same then the backspace will increase or decrease by half the increase in rim width.

7" rim with 4" backspace has 4 - 4 = 0 Offset

8" rim with 4.5" backspace has 4.5 - 4.5 = 0 Offset

Rims-n-Tires.com - Wheel / Tire Size Calculator

Tire Size Conversion Chart

The Wheel and Tyre Bible Page 1 of 2

The middle of a 8" rim is (0.5 + 8.0 + 0.5) / 2 = 4.5". With a 5.5" backspace then the offset is 5.5 - 4.5 = +1.0"
The middle of a 7" rim is (0.5 + 7.0 + 0.5) / 2 = 4.0". With a 4.5" backspace then the offset is 4.5 - 4.0 = +0.5"

Track

Wheel track is measured from the centre of the tyres. Wheel track will vary on the front suspension depending on ride height as the control arms swing in an arc. To maintain track all you have to do is maintain the standard offset regardless of the rim width.

The track can not be reduced and can only be increased by a maximum of 25 mm. If you are fitting flares then you should be able to use the A9X track as your base track.

Front and Rear BUF calculations based on rim offset and track figures

		Imperial Measurements - inches					Converted Metric Measurements mm
Model	Source	Rim Offset	Track Front	Track Rear	Front BUF	Diff BUF	Rim Offset	Track Front	Track Rear	Front BUF	Diff BUF
LX RTS SL/R & SS	LX Owners Manual	1.25	55.30	54.40	57.80	56.90	31.75	1,405	1,382	1,468	1,445
L34	Holden Torana Performance Handbook pg. 64-65	0.25	57.89	56.82	58.39	57.32	6.35	1,470	1,443	1,483	1,456
L34	60 Years of Holden pg. 337	0.25	57.90	56.82	58.40	57.32	6.35	1,471	1,443	1,483	1,456
A9X	60 Years of Holden pg. 337	0.25	57.90	56.82	58.40	57.32	6.35	1,471	1,443	1,483	1,456
A9X	Just Holden's - A9X edition pg. 23	0.25	58.50	57.10	59.00	57.60	6.35	1,486	1,450	1,499	1,463

Notes:

I measured my LX Torana diff as 1446 mm from BUF to BUF. This agrees with the Diff BUF calculation for the LX RTS SL/R & SS.

The "Holden Torana Performance Handbook" lists the rim offset as -0.25" for the A9X and +0.25" for the L34, this appears to be a typo as the GMH L34 service bulletin lists the rim offset as +0.25".

The L34 track calculations indicate that the L34 Diff BUF is wider than LX Diff BUF which is unexpected.

The "Just Holdens" track figures for the A9X are different to the L34 track figures. I would expect the front track figures to be the same for the L34 and A9X as they have the same front suspension and rim offsets. "60 years of Holden" list the same track for L34 and A9X. The A9X diff could had a different BUF measurement to the L34 diff.

Sources:

LX Torana owners manual

Holden Torana Performance Handbook by Eric Blair

60 Years of Holden by Terry Bebbington

Just Holdens Toranas collectors series A9X

Fuel Tank

The fuel tank must be fitted with an unleaded fuel restrictor and labelled unleaded fuel only. I fitted the filler neck from a VN Commodore. You can buy press in unleaded fuel restrictors. If you have a aftermarket tank then it must comply with the departure angle rule to be engineered. Drop tanks for example Brown Davis that do not comply with the departure angle rule have been know pass over the pits but they will not pass the engineering checklist.

See page 5 and item 1.7 on page 12 of NCOP9_Section_LM_Fuel_Systems_01Jan2011_v2.pdf

Diff Housing

The LH parts and LX parts manuals list the following housings.

Description	Application	Part Number
Housing Assy - 2.78:1, 3.08:1 A.R.	6 cyl Eng	2819067
Housing Assy - 2.78:1, 3.08:1 A.R.	4.2 Litre Eng	2819067
Housing Assy - 3.36:1, 3.55:1 A.R.	6 cyl Eng	2819068
Housing Assy - 3.36:1, 3.55:1, 3.90 A.R.	4 cyl Eng	2819068
Housing Assy - 2.78:1, 3.08:1 A.R.	5 Litre Eng exc L34 Eng.	2825743
Housing Assy	L34 Eng	9935109
Housing Assy	A9X option	92002517