The Nissan S30 was one reason why GMH canned the GTR-X. They knew that their 6cyl engines and cars didn’t hold a candle to what was coming from Japan performance wise. GMH rarely even sold a 6cyl car that could even reach 100mph, only a few ever could. To them if you wanted performance you bought a V8. The XU1 was the exception but wasn’t built to be an everyday car either. The 6cyl cars were the reliable workhorses and not aimed at the enthusiast or for spirited driving. GMH made the decision to drop the HQ GTS before release and that also will be what killed off the 2850S engine for LJ GTR. I’m in no means saying the Holden 6’s were bad engines, they were simply nothing like the 6cyl engines that Nissan and Toyota had to offer. The red 6’s after HG and LC S engines were not designed for performance.
And given the 6cyl cars were pretty pedestrian, the 4cyl cars prior to Gemini were downright awful. Chris Young (of Young and Green) told me they were always in trouble with their zone managers that they weren’t selling enough 4cyl product. Their response always was “build decent ones and we will”. They didn’t have anything to compete.
On that note I never understood the Opel 1.9 in the LH and the Starfire in the Commodore. What was the point? Sure it was 1.9L, but it also had a 3.9 rear axle and in the Commodore 13” tyres. It revved its guts out and was no more economical than a 173. GMH had the answer. They fitted it to both Holden and Torana - the 130ci (2.1 litre) red 6 for export. Later (into HJ) they fitted the 138 (2.25 litre), which they also used in local Torana but dropped it. A 130ci or 138ci red 6 in an LH with a 3.36 rear axle would be a far better economy car. Same with Commodore. And surely the cost to fit would be cheaper as it fitted the same as a 173 or 202, and didn’t need special tailshaft, gearbox, engine crossmember, radiator spacer etc etc. plus the 130/138 was already fitted to later LJ and LH for export cars. Today if I wanted to build myself a really economical HK-HG ute or van for putting around I’d probably build an original spec 138 or 149 with a column shift all synchro 3spd and 3.36 rear axle or even maybe a Trimatic with 3.08 rear axle. Would be slow but still be a reliable an economical car.
Regarding the lower comp 260Z. You are forgetting ULP introduction in Japan which was 1972. Their engines would have changed for it just like the US engines. The best example that we can relate to here even though it is zNorth America rather than Japan was the L48 350. In 1970 it was 10.25:1, courtesy of flat top pistons and 64cc fuelies. This is the HT-HG engine. For 1971 the L48 dropped to 8.5:1, simply by increasing the combustion chamber to 76cc and putting a dish in the pistons. This is the HQ engine. To GM they are the same specification, one for high octane leaded fuel, the other for low octane ULP. The engine spec changed to suit the US pollution laws. Exactly the same as what happened here HJ-HX and mid-series for LX. Every engine went backwards literally overnight, 308 dropped from 250hp to 216hp. You can imagine in the USA when the 1970 Camaro SS came with a sweet 300hp L48, Muncie and 12 bolt. Come September 1970 the car lost 30hp but looked almost the same. The Z/28 also lost 30hp and the 396 lost 50hp.

Edited by user Friday, 26 March 2021 7:41:50 AM(UTC)  | Reason: Not specified

Stock Lc 2250 3 on the tree 3:08 diff.
I could just get past a mates 2lt cortina in a top end run, probable had 2mph on him lol.
100 mph speedo and a big hill would wind it of the clock and as long as l didn't go up hill it would stay their all day.

The X2, 186S, both GTR engines plus HT and HG 186 except Trimatic all used the same cam. The one that should in theory rev the best is the 186 X2 or S as it has the more over square engine.
As I said very few standard 6cyl engines would crack 100mph. The only Holden I know of, the HK-HG 186S 4spd fitted with 3.36 rear axle could just get over 100mph.
The Toranas were a little different. XU1 did it easily. LC GTR’s would do 106mph with 3.08 rear axle. I’ve never seen any other LC though even crack 90mph, possibly the later 173 auto versions? I’ve seen road tests for an LJ 173 auto just hitting 100mph but manuals only 97mph. Fastest for a 138 manual 95mph. The manual 2250/2850 were 3.08, auto 2.78. 3300 manual LJ would do 101mph, also with a 3.08.
Fastest LH road test, standard SLR 202 manual 3.08, 96mph. In LX a hatchback, 3300 auto 2.78 155kmh.

Doesn’t take much in mods to give the few extra hp needed to go a bit faster. My 2/76 LX hatchback 3300 auto 2.78, when it was just over 10 years old. I put extractors and a 2.25” system on it and it had 14” wheels but tyres were 245/50/14 so probably similar in diameter to the 13’s. It would go off the 160 speedo, but only just. Speedo was close to correct, they checked it during a chassis dyno tune. I guess on a 2250 or 2600 or 2850 LC/J, just a decent exhaust and maybe a better air cleaner and you’d pickup the few mph to crack 100mph.

Edited by user Saturday, 27 March 2021 1:41:13 PM(UTC)  | Reason: Not specified

True, it was probably GM with the GTR-X forcing GMH’s hand, but given what was coming from Japan in the same market segment they knew it was trouble. They would have also known that by September 1973 the triple carb engine would be killed of by ADR27 and that if the GTR-X was to run past then it would be with a far less powerful 6 or it’d have to move to a V8. The XU1 was the final performance 6 and in reality even it should have ended mid 1972 with the V8 XU1 becoming the performance Torana. The LJ GTR was meant to be fitted with the 2850S engine, the info on the pilot builds still shows the 2850S, but probably the culling of the HQ GTS meant the end of S engines so it was changed to the stick 202 with its tiny 161 camshaft. It may well have been the knowledge of ADR27 planned to be coming into force in 1973 that changed their mind too?

I hear what you say about the mindset about Japanese stuff, and it was even made a joke of in Back to the Future. However the refinement of fully imported Japanese cars by the end of the 70’s was or real concern to local manufacturers. The quality and performance difference between say a 1980-81 5M-E Cressida compared to a VC-VH SLE with its vintage 3.3L engine and Trimatic was huge. Sure you could opt for a V8 SLE but the majority of Aussies bought 6cyl cars. The later 5M/6M/7M-GE Toyota’s made the Holden 6’s look prehistoric which they were.
If it was me buying a new car in that time period, I’d have been buying a 5.0L TH400 VB or HZ or maybe a VC or VH with TH350. However if I was a car for my wife that was well built, economical, overdrive, and bugger all to ever touch the Cressida was the pick. Or maybe one of those early Supras with the same engines. Same reason I bought a 6cyl petrol Hilux 11 years ago, nothing ever goes wrong with them.

Edited by user Saturday, 27 March 2021 6:10:46 PM(UTC)  | Reason: Not specified

Agree the blue 3.3 was streets ahead of the red equivalent. I drove both when they were new or near new. Drove a new WB 3.3 4spd van when on my L plates. But in a car like a VH SLE, it was archaic compared to the Cressida. If it was for me I wouldn’t have even considered a blue 3.3, in the WB or the VH I’d have bought a V8.