Hi , what was the best HP output holden got out of the 253 V8. Cheers Baz.

Hard question as you can't easily compare them. The early engines are properly rated with an on-dyno gross hp in controlled conditions, but the later stuff is all net and the figures are almost useless to compare to early stuff. So for regular production 253/4.2 in a GMH vehicle it is hard to say. Here are the figures (only high comp, left out low comp):

Gross figures (SAE):
HT-HQ 185hp@4400rpm
HJ/LH 175hp@4800rpm
HX-HZ/LX 161hp@4550rpm

Net figures (DIN) single exhaust [dual exhaust]:
VB 87kW@4000rpm [96kW@4400rpm]
WB/VB-VH 100kW@4200rpm [115kW@4400rpm]

Looking at the above I guess you'd try to compare the VB figures with the HX-HZ engine (same engine) and then work backwards to guess a comparable figure for the blue 4.2 to put it up against the HT-HQ engine. My money would be on the blue 4.2 in this case.

If we are looking at non regular production engines then the Hurricane's engine was a good one as it was from memory a 4BBL engine, and the HDT VH GroupII and GroupIII 4.2L engine was rated at 152.9kW DIN which is a pretty decent 253.

I think it is as their 5.0L engines were. Remember why DIN is not good is because it is affected by exhaust, air cleaner etc. HDT improved all of this.

When comparing engines no-one cares about what a dual exhaust does, you simply cannot compare engines if they are not all tested the same way, which is why DIN is totally useless for engine comparisons. Always has been, always will be! It was changed to DIN so people could compare vehicles, but that is not what is of interest here.

A VH GroupIII 5.0L (V5H) put out just under 200hp at the rear wheels, which is just under 300hp at the engine in SAE Gross terms. This is about 225kW SAE Gross. It is possible that the rated 180kW is SAE net (called the GM20 test from memory), but i'd not be banking on it as a done deal, we just don't know. Whatever it is the 4.2L 152.9kW will be the same rating method as the 180kW 5.0L engine.

Remember DIN is as installed and is drastically skewed by external factors like exhaust, air cleaner etc. You have a stock 9.2:1 blue 308 that isn't very different to a HT-HQ 308 other than 0.2:1 increase, a far better camshaft for the engine plus a non-optimal tune due to pollution requirements. The HQ made claimed 240hp/180kW SAE gross and the WB made 126kW DIN with dual exhaust. You'll pickup about 5-10kW with a decent air cleaner and a proper tune on that DIN figure. Then change the exhaust inc extractors, bigger air intake aircleaner, open the intake ports up and bigger valves, make the intake flow like a Performer (which is what HDT did), change the carb's tune and regraph the dizzy. That is an easy 34kW. If it wasn't DIN and was SAE net then what was the point, as 160kW SAE net would be about 130kW DIN?

Rot! A HJ onwards cam is streets ahead in all areas! A simple look at the timing says it all. As does the original GMH dyno curves for the HT-HQ 308, it tops out at about 225hp or thereabouts. That engine is a joke compared to the HJ engine.

A Holden dual exhaust and pollution manifolds with the thermal switch is a HUGE impediment compared to a decent exhaust and extractors.

Edit. Here is the cam timing published by GMH. Duration is I think at 0.006" lift:

HT-HJ 253 cam:

27 BTC
63 ABC
270deg
71 BBC
19 ATC
270deg
46deg overlap
0.400" lift

HT-HQ was the same cam but retarded 5deg. This is probably one of the reasons they didn't rev. So timing is:

32
58
270
76
14
270

HJ-VL cam is significantly bigger and is degreed at zero using the 253's cam gear, plus you have to remember that whilst this exact grind was used in all SBC hydraulic applications at the time other than L79 and L46, these only had 1.5 ratio rockers, the GMH engine is 1.60:1. Specs are:

28
72
280
78
30
288
58deg overlap
0.400" lift

That is a whole 10deg inlet duration and 18deg exhaust. Inlet valve is open 14deg later, and exhaust closes 16deg later. Inlet and exhaust opening is similar.

Plus the HJ 308 has the added advantage of L34 compression HJ had 9.7:1, L34 9.8:1.

HJ 308 had exactly the same emissions requirements as HQ, same engine externally including the carby. Emissions changed around 8/73 during HQ which is when the 70412 carbs were replaced with 70432. 1/75 was only a canister.

Norm Darwin put all the good stuff in his Torana tough book. Original GMH dyno plots for the HT-HQ 308 show 226hp(126kW)@4800rpm gross and 160hp(119kW)@3700rpm net, and the engine is running out of breath at 4800rpm, in the "as-installed" net test it starts to choke at 3700rpm . He also shows Redco got 190hp@4100rpm for the standard 308 on its dyno, and the L34 engine put out 270hp@4900rpm. Remember that L34 engine still uses the same cam as the HQ but has better heads and exhaust manifolds, opened up intake and higher compression. That is 80hp (60kW) improvement from the dead stock HQ 308 to the L34 engine in SAE gross terms, so it is not hard at all to believe the stock blue 308 at 126kW DIN goes to 160kW DIN (34kW improvement) with the same basic mods other than the increased compression. Noting that the improvement of 34kW DIN versus the 60kW will probably largely be due to the 160kW DIN still pushing through an exhaust more restrictive than the dyno exhaust from the Redco tests.

Edited by user Wednesday, 22 February 2017 6:01:31 PM(UTC)  | Reason: Not specified

It doesn't matter what the Redco curves are (it is an engine dyno), it is the increase from 190hp stock to 270hp that matters. There was only one L34, as GMH assembled them. However Redco also dynoed the L34 engine with the aftermarket HO kit on the same dyno and it is plotted on the same curve, it was 320hp (can't remember the rpm). They also plotted the F5000 engine. That is how it is, doesn't matter whether you choose to accept it or not! Redco did a LOT of development on these engines, and the 270hp out of the L34 is what they got. It has not been proven the L34 engine does not perform much better than a stock HQ L31. Redco proved otherwise. GMH simply hid the facts by only having the 2.78:1 rear axled cars with D70 14" tyres tested, with the restrictive standard Torana pea shooter tailpipes and mufflers (1.7" or something like that). The engine itself is a different story.

VK 177kW is the V5H engine. It is a standard cam (as in the HJ onwards cam) with big valve heads, better intake. This is the optional GroupIII 5.0L engine, same engine in VH was 180kW. The standard VK 308 is 126kW, same as blue 308. Again these figures are DIN so useless to compare, but the comparison between the stock black 308 and the V5H engine is almost the identical comparison between the stock HQ 308 and the L34 308, almost the same exact mods except for compression ratio. The black engines have the advantage of the superior camshaft.

270hp IS NOT correct for the HO kit camshaft, these were 320hp on the same engine dyno that the stock 308 put out 190hp.

The HJ cam IS NOT a pollution cam. It is a higher performance camshaft. If it was a pollution cam then it WOULD NOT have been used in SBC's from 1967 through to 1974 for compression ratios varying between 8.5:1 (1967 327/240) through to 10.25:1 (1969-70 L48 350/300)) and WOULD NOT have continued into the 1971-4 smog engines that had the same power robbing crap and tune on them as happened to HX 308. It is simple: THE HJ camshaft is a superior and higher performance camshaft, used from HJ (the highest performance standard pre-pollution 308) right through to the VL engine.

SAE claimed says 10hp, it is more like 25hp. GMH dyno curves show quite clearly 226hp@4800 SAE gross for the HQ 308 and 160hp (119kW)@3700 DIN. The 250hp@5000rpm for the HJ engine is probably telling the real story. Simply driving both gives it up pretty well. The only known road test that I know of for an un-encumbered HT-HQ 308 manual (ie something with dual exhaust and a manual transmission) was of John Bagshaw's Premier sedan (SS concept). It was slow as a wet week, and from memory only managed a top speed of not much over 110mph. There is a road test of a HJ GTS sedan with 5.0L and dual exhaust that shows how much quicker that the car was with that engine. Other than those road tests of dual exhaust 308 manuals in the day were rare.

I would put zero faith in anything published by Ellery. It is probably a typo.

VC HDT 160kW figure may not actually be the top rpm, it may well be a bit of advertising fiddle, just like the L34 claimed power of 240hp@4800. Those figures may well be true, but don't tell the whole story, like the L34 continues to make power up to 270hp whereas the stock 308 falls away. The HDT engine may well be the same, as the similar engine in a VH was rated as 180kW at 4750rpm.

Edit, L34 with HO kit got 320hp@5500rpm. F5000 engine got 490hp@7500rpm. On the same dyno that showed 190hp for the stock HQ 308 and 270hp for the stock L34.

Also GMH got as DIN 167hp (125kW) dual exhaust out of the ADR27A red 9.4:1 308. This was published as SAE gross 216hp (161kW) for the 9.7:1 version. This is as close as I can get on these too for comparison figures.

Edited by user Thursday, 23 February 2017 3:58:18 PM(UTC)  | Reason: Not specified

I know a dude who had a blue VK Group A 4 speed I think he had a bigger exhaust fitted as an option it was 3 inch and then he bought the red Brock VL Group A 5 speed and he said the Blue had much more power, but the 5 speed worked well to make it perform well, I gave him a run on the highway with my stock 308 auto p van and I had him till he walked by in top end over 200KM/H due to the 5 speed.

I don't think that them LH twin exhaust were that restrictive aren't they the same as a HQ twin system.
The L34 came with a stock cam with 253 timing.
The HJ cam grind is exactly the same as the Chev cam spec, maybe it is, but is it 100 % truly the same. the cam is used in the ADR engines as well. why would the 253 go to a smaller cam in the HJ on then.

250HP HJ SAE
240HP HT-Q SAE
161HP HX-Z SAE I agree with Holden we have a HJ with 10HP over the HT-Q and that's bugger all, the HX-Z shows it's gutless with 40 to 50HP SAE less.
I don't think anyone is going to feel 10HP much at all.
I have for HQ 196HP dyno and HT-G at 203HP net by South Africa Holden GTS brochure.
Maybe you is right at 226HP net for the HJ.

Bagshaw's could of had a 3.55 diff maybe a 3.36 but the Australian performance testing back in them days were crappy, just as the power figures are backwards SAE crap, Holden and Ford were never open about the true Net HP but any road you could find Net figures in the F100's and it sure tells the true story of what you are going to get, take the Ford 302 Cleveland 250HP was the SAE and one 302 F100 were 134HP net for crying out loud and up to 203HP net.

I could imagine some bloke with a 302 XB Falcon who believes it's got 250HP and then he's got a same year 302 F100 Oh yes 250HP he will say, but some how the F100 is a slug and that XB and if he gave a 308 HQ a go he would not have a hope at all and it's rated at only 240HP, so you see what I am on about with SAE, it's just truly crap.

LH V8 exhaust were very restrictive, the tailpipe and muffler(s) were 1 5/8" for both single and twin system. This is why the 308 on an LH Torana always got a twin system as the tiny little single system was too small. HQ single had 1.75" tailpipe and muffler which is why they got away with a single system on 308 and also on 350 auto outside GTS. HQ twin systems were 2" tailpipes but afaik used a stepdown to 1.75" mufflers.

Yes I know L34 had a stock cam, I told you that.

Yes the HJ cam is identical to the SBC grind, same lobe centres, same overlap etc. The only difference is the peak lift, it is smaller on the HJ as the 308 uses a 1.6:1 rocker, SBC is 1.5. The cam lift is ground to get the same valve lift with the different rockers as the 308 uses the same springs as a SBC for the same cam, same installed and compressed heights. The 308 didn't suffer too bad from pollution equipment most likely due to the Quadrajet, they kept fiddling with the 253 to make it pass emissions. The only really bad 308 was the HX, but it was never as bad as the HX 253. I think they got the intake manifold badly wrong on the HX, they revised it drastically for HZ and then dropped the 308's compression mid 1978 from 9.7 to 9.4. It never copped as much criticism as the 4.2 but it was down on peak power compared to the HJ engine. Internal GMH dyno tests show the HX 308 has similar peak power to the HQ engine but it never delivered as well "in-car", probably due to all the power and driveability robbing stuff on it like the exhaust flap in the passenger side exhaust, spark advance control in lower gears etc.

HT-HQ 240hp is an advertised claim, original GMH dyno charts show 226hp. The 250hp of the HJ is far closer to real and the engine revs out further as a result of the cam and higher compression. Peak power is delivered at higher rpm.

It is a 3.36 rear axle in that concept SS car, wearing polycast rims and ER70H14 tyres.

You at right that the advertised figures are not truthful, but I never use them, only use figures off internal Engineering documentation, and most show dyno curves.