LS1 vs XU1 revisited...

[desert rat]

Back in November 2004, there was a thread regarding the performance of the XU1...specifically the 1/4 mile times etc...this is not an easy, one answer fits all, type question. One of the reasons would be the variety of different rear end ratios available, and the other is the spec of the engine.

There were 5 rear axel ratios available for the LJ XU1...2:78, 3:08, 3:36, 3:50 and 3:90....the 2:78 ratio was used by most teams at Bathurst in 1973 and the cars were capable of more than 150MPH on Conrod.

The shorter ratios, particularly the 3:90 was used in rally's and rally cross it didn't give you great top speed but it did allow maximum acceleration.

The XU1's engine specs, changed considerably over the years (70, 71, 72 and the last production batch in August 73)....for example, the original production batch of LJ XU1's built between January and July of 1972 (1,317 cars) featured a relativly mild .345 lift cam....the 200 "Bathurst" XU1's built in August - September 1972 featured a pretty hot .429 lift cam and the very last batch of 150 XU1's built in August 1973 had the radical .456 lift "HX" cam.

This last batch of 150 XU1's (August 73) were specifically built with the new group "C" rules in mind and in addition to the "HX" grind cam they featured improved suspensions, brakes, diff (detroit locker and fine spline axels) and special engine mod's (toughened cranks, light weight flywheel, tougher con rods, bigger rod bolts, special high rev harmonic balancer, extra head mods including bigger valves modified ports and combustion chambers, anti surge baffles in the sump etc) because under the new rules the cars were now running slicks oil starvation was found to be an issue hence the sump baffle and the crank and rods allowed a 7000rpm redline.

I owned an August 73 build XU1 fitted with the "HX" spec cam and it was not a happy car when driven in traffic, the engine was not really happy unless it was spinning at 3000rpm or better. Incidently Brock's 73 XU1 was tested by Modern Motor in May of 1974 and pulled a 13.5 standing 1/4 ans it was fitted with a 2:78 (Bathurst) ratio diff, I can't stop wondering what kind of time that car could do if fitted with the 3:90 ratio diff....maybe not down into the 12's but definately low 13's.

The road tests of the LJ XU1's at the time did quote standing 1/4 in the mid 15's, I would bet that these cars were probably the regular production cars with the .345 lift cam, I don't know of any published tests of the 72 "Bathurst" specials or the 73 "Group C" specials.

Another thing about the "73" cars they were definately under carbed with the 1.75 in Strombergs....Webbers would definately give a lot more poke but at the expense of drivability.....anyway that's my 2 cents worth...Cheers, Desert Rat.

[Oztrack Tuning]

In "Super Street" Bracket meets i have been racing a number of LC and LJ Toranas equipped with 350 Chevs. They run typically around 11.3/118mph with a biggish cam and large stall converter - getting traction through slicks and weighing with driver around 2600lb.

[VX2VESS]

you know much on this, guess your an Aussie in the states.

they were/are a good quick car ! As you say it would depend on which variation and options they had as to the times.

didn't mind the later V8 Torana's either. The hatches were an interesting car, esp the one that came with the tent bits so you could sleep in the back. Don't see many of these around now, very rare model.

[desert rat]

I too loved the v8 toranas, particularly the A9X, all that V8 goodness plus a tough rear end 4 wheel discs, T-10 gearbox and the horny hatchback body...a real beauty...I've been living o/s for the last 12 years so I'm not really up to speed with the local car scene nowadays, but I love the fact that GMH and Ford are still building real sports sedans....there really is no such thing in the states, you either have to go really upscale to the BMW M5 or Mercedes E55 or the nearest us built car is the Cadillac CTS spec V. The Monaro (Pontiac GTO) is a hit and miss thing over here they love the performance, handeling and value for money but almost all of the motoring press over here shit cans the styling (looks like a Taxi - Car and Driver) I love it and am very proud that we are selling hi-po cars here in the US.....love the thread by the bloke down in Texas who has fitted a monaro body kit to his GTO...keep up the good work...cheers - Desert Rat.

[IIV8II]

Sounds like you need a holiday... :driving:

[team illucid]

yoThe hatches were an interesting car, esp the one that came with the tent bits so you could sleep in the back. Don't see many of these around now, very rare model.

Yep - and I got me a black beauty in the garage. Worth a pretty penny :) more than a Gogo too :lol:

[Smitty]

There were 5 rear axel ratios available for the LJ XU1...2:78, 3:08, 3:36, 3:50 and 3:90....the 2:78 ratio was used by most teams at Bathurst in 1973 and the cars were capable of more than 150MPH on Conrod.

245kmh to be exact
and it is a 3.55:1 ...not 3.5:1 (thats on GT Falcans)



The XU1's engine specs, changed considerably over the years (70, 71, 72 and the last production batch in August 73)....for example, the original production batch of LJ XU1's built between January and July of 1972 (1,317 cars) featured a relativly mild .345 lift cam....the 200 "Bathurst" XU1's built in August - September 1972 featured a pretty hot .429 lift cam and the very last batch of 150 XU1's built in August 1973 had the radical .456 lift "HX" cam.
the first lot of street LJ's used the LC camshaft spec
(yes even though it was a bigger engine) and of course used a different
jetted (but still Stromberg CD )carb with the bigger engine
and
the HX cam was not that radical......
I had a HX based (roughly same timing/overlap) cam in my LJ
but with .48 lift



This last batch of 150 XU1's (August 73) were specifically built with the new group "C" rules in mind and in addition to the "HX" grind cam they featured improved suspensions, brakes, diff (detroit locker and fine spline axels) and special engine mod's (toughened cranks, light weight flywheel, tougher con rods, bigger rod bolts, special high rev harmonic balancer, extra head mods including bigger valves modified ports and combustion chambers, anti surge baffles in the sump etc) because under the new rules the cars were now running slicks oil starvation was found to be an issue hence the sump baffle and the crank and rods allowed a 7000rpm redline.

Holden NEVER built any LJs with Detroit lockers in them, yes the diffs
went to fine spline axles but used Holden spring based LSDs
The Detroit locker was able to be fitted to replace the Holden LSD in racing applications.
Also the harmonic balancer on all XU1s from late LCs on ,was standard Holden issue but with a reinforcement plate and all LJ 202s got anti surge baffles in the sumps (well all the ones I have pulled apart have)

btw
Group C rules were not introduced back in '73
you are thinking of the 'Improved Prod series' rules that were introduced

..snip..



The road tests of the LJ XU1's at the time did quote standing 1/4 in the mid 15's, I would bet that these cars were probably the regular production cars with the .345 lift cam, I don't know of any published tests of the 72 "Bathurst" specials or the 73 "Group C" specials.

AutoAction did an article on Brocks '73 ManChamps LJ
...got it somewhere (and if I can find it will post it)



Another thing about the "73" cars they were definately under carbed with the 1.75 in Strombergs....Webbers would definately give a lot more poke but at the expense of drivability.....anyway that's my 2 cents worth...Cheers, Desert Rat.

the street cars always had CD strommies but with the new Prod Series rules
in '73 the HDT fitted double choke sidedraft Webers to their race cars
and to comply with the rules ...blanked off one choke

hth


cheers

[desert rat]

Smitty you are correct on the 3:55 ratio on the diff options, I think I must have had a brain fade, also Improved Production were the rules that came into effect in 1973, and if you do find the Auto Action road test I would love to see it posted...all of those old articles are so hard to come by, most people probably have never seen them....I know I haven't...

There are actually several bullitens from both GMH and C.A.M.S. regarding the availability of/recognition of the Detroit Locker/Detroit No Spin Diff in the LJ XU-1 Torana, both the September 72 and August 73 build cars.

In a GMH bulletin (inter office memorandum) Dated August 31st 1972 about halfway down the page there is an ammendment stating...1/IV 1/7/1972 - final drive. Variation in supplier. May be either "Borg Warner Limited Slip" or "Detroit No Spin".

In an July 14 1972 C.A.M.S. ammendment in reference to final drive #290 - Variation in axel shaft dimension when alternate Detroit Locker limited slip differential unit is fitted. 26.5mm. O/D 24 Splines

And also in another C.A.M.S. Ammendment (#9/2E) dating from August 15th 1973 it is stated regarding axels and differentials....Diferential- Side Gears with 24/48 serration - used with "Borg Warner limited slip" or "Detroit No - Spin" (alternate suppliers) differential units. to match axel shaft 9934102.

So it seems that the detroit locker WAS available, but probably on a need to know basis, that is if you ran an XU-1 as a race car, GMH would definately let you know that the Locker was available, the average bloke on the street would probably have no idea it was available as an option because there was no need.

The oil pan for the 1973 cars was different it incorporated different - improved hindged baffle welding and con rod clerance scollops in side - part #9930759

[Swordie]

Here’s some stats from Wheels June 1983 Magazine comparing various Toranas. The statistics provide kW / 0-96 km / 0-400 / Max speed


LC GTR – 93 kW / 10.6 sec / 17.2 sec / 168 km
LC GTR XU-1 – 119 kW / 8.4 sec / 16.3 sec / 192 km
LJ GTR XU-1 – 142 kW / 8.3 sec / 16.0 sec / 200 km
LH SL/R 4.2 – 127 kW / 8.5 sec / 17.0 sec / 180 km
LH SL/R 5000 – 170 kW / 7.7 sec / 16.1 / 194 km
LX SS 5.0 – 186 kW / 7.3 sec / 15.6 sec / 186 km
A9X – 161 kW / 7.8 sec / 16.0 sec / 206 km

[seldo]

There are actually several bullitens from both GMH and C.A.M.S. regarding the availability of/recognition of the Detroit Locker/Detroit No Spin Diff in the LJ XU-1 Torana, both the September 72 and August 73 build cars.

In a GMH bulletin (inter office memorandum) Dated August 31st 1972 about halfway down the page there is an ammendment stating...1/IV 1/7/1972 - final drive. Variation in supplier. May be either "Borg Warner Limited Slip" or "Detroit No Spin".

In an July 14 1972 C.A.M.S. ammendment in reference to final drive #290 - Variation in axel shaft dimension when alternate Detroit Locker limited slip differential unit is fitted. 26.5mm. O/D 24 Splines

And also in another C.A.M.S. Ammendment (#9/2E) dating from August 15th 1973 it is stated regarding axels and differentials....Diferential- Side Gears with 24/48 serration - used with "Borg Warner limited slip" or "Detroit No - Spin" (alternate suppliers) differential units. to match axel shaft 9934102.

So it seems that the detroit locker WAS available, but probably on a need to know basis, that is if you ran an XU-1 as a race car, GMH would definately let you know that the Locker was available, the average bloke on the street would probably have no idea it was available as an option because there was no need.

The oil pan for the 1973 cars was different it incorporated different - improved hindged baffle welding and con rod clerance scollops in side - part #9930759
At the time, very few of these "alternatives" were actually available ex-factory. Most of them were concocted by Harry Firth who used to supply us with whatever we needed in the way of new parts. We used to joke at the time that Harry had a typewriter and a pile of blank GMH Service Bulletin letter-heads and used to type up whatever he wanted/needed at the back of the pits and produce it to the scrutineers to back-up his latest mod. We would ring Ray Borrett (still head of GM-H motorsport) and ask about the latest bulletin and he'd send us what ever was needed to up-date the car. Sometimes it was axles, a diff ratio or No-Spin centre, a camshaft or even a special reamer to open the valve throats to the latest spec. But few of these so-called production changes ever saw the production-line - they came in a plain-wrapper cardboard box courtesy of Harry Firth

[chilly]

i have a video of Brocky doing Bobby Morris [Craven A falcon ]
at calder drags
Brock ran 12.69 ...in the 1980 bathurst winner
and in those days Brock was hopless on starts

the videos to big to post

[Smitty]

i have a video of Brocky doing Bobby Morris [Craven A falcon ]
at calder drags
Brock ran 12.69 ...in the 1980 bathurst winner
and in those days Brock was hopless on starts

the videos to big to post

ummm..wasn't Brockie in a VC Grp A racer..not Torrie???:confused:

[chilly]

ummm..wasn't Brockie in a VC Grp A racer..not Torrie???:confused:


he was
you know that
i know that
whats ya point.............:confused: :confused:

i read Swordies post and put those comments up for general info
ok....

[Smitty]

At the time, very few of these "alternatives" were actually available ex-factory. Most of them were concocted by Harry Firth who used to supply us with whatever we needed in the way of new parts. We used to joke at the time that Harry had a typewriter and a pile of blank GMH Service Bulletin letter-heads and used to type up whatever he wanted/needed at the back of the pits and produce it to the scrutineers to back-up his latest mod. We would ring Ray Borrett (still head of GM-H motorsport) and ask about the latest bulletin and he'd send us what ever was needed to up-date the car. Sometimes it was axles, a diff ratio or No-Spin centre, a camshaft or even a special reamer to open the valve throats to the latest spec. But few of these so-called production changes ever saw the production-line - they came in a plain-wrapper cardboard box courtesy of Harry Firth

and let me say this umm...practice continued on thru LH (even with L34 parts)
and into LX with A9X bits.....A9X GrpC racersfor example had a very non-factory front suspension setup :confused:
(anyone remember Moffats appeal??) and L34 Torries had Aussie 4speeds that did last races
(with some special assembly bits)


cheers