DIRT NATION
How much kW would a woodchuck chuck? It’s a vexing question when people rely on their ‘internal dyno’ to gauge the power and torque of their new or freshly rebuilt engine.
We’re forever hearing drivers spout on in pit and paddock about the output of their engines, which have mysteriously gone from stock numbers to NASCAR outputs simply by being chopped out of a wrecked sedan in the USA and freighted to New Zealand.
With the popularity and prevalence of Chevy’s rather good LS series engines across many branches of motorsport, it’s happening in off-road racing at the moment.
I did some digging and for the record, the standard output numbers of the key LS engines are:
• Original LS1: 227-260 kW (305-350 bhp) at 5,600 rpm.
• Original LS2: 290-298 kW (390-400 bhp) at 6,000 rpm.
• Original LS3 (rare): 317-325 kW (426-436 bhp) at 5,900 rpm. • Original LS4 (rare): 225 kW (303 bhp) at 5,600 rpm.
• Original LS6: 287-302 kW (385-405 bhp) at 6,000 rpm.
So if your engine or dyno guy is telling you these figures are happening at your rear wheels, or if you are telling people you are getting better numbers than these just by bolting an LS crate engine into your truck, there’s some ripe BS being handed around.
Although (my own) Giti Chev is based around a proven four-cylinder intercooled turbo engine, I’d have to admit the LS is a stroke of genius from Chev – the US brand that has most consistently supported the street/strip racing enthusiast driver over the years.
These are pretty much perfect implant/transplant engines if you are chasing V8 grunt. All the latest (Gen V) engines feature aluminium engine blocks (except for the L8T) with aluminium cylinder heads. They are direct injection engines with piston cooling oil jets, active fuel management, variable displacement oil pumps, and include ‘plug and play’ engine computer systems and continuously variable valve timing.
However, they all retain their ancestors’ two-valve pushrod valve train and are described as ‘cam-in-block’ (Where? How many?).
In the end, the drivers who blow hard about big numbers then look a bit silly when the flag drops and they are dusted by rivals who in theory should be in the weeds behind this latest arrival and its otherwise-stock bent eight.
It’s refreshing to note that every now and then, the BS stops long before the flag drops.
In particular, the off-season rebuild has seen us do give the drivetrain a general going-over including a refresh for the truck’s British-made gearbox and the custom racing clutch that nestles inside the bellhousing.
Off-road racing puts strain on clutches that no other sport could imagine – which is often why clutch and transmission guys who think they know what they are doing will specify gear ‘good for 700 bhp’ then wonder why it failed.
Clutches in our sport have to operate in the most evil of environments: heat, dust, mud, dirt, massive shock loadings, plus the occasional transmission oil leak. The hard ‘bite’ and consistent engagement, the heat performance properties and durability of a race clutch more than makes up for its slightly aggressive engagement. If you are running anything less than a race clutch you’re on a hiding to nothing.
So we found ourselves looking to start the season with a fresh clutch – if the transmission was coming out for a refresh, you’d be mad not to also freshen the next component up the driveline.
Our first port of call was one of those performance industry guru types: “How much torque will it handle? You don’t need to know that. How much clamping force does it have? You don’t need to know that. Yeah, mate, I got what you need,” and so it went on. Friends and family will know how much I love being treated like an idiot.
So, it was refreshing to find MP Autoparts in Upper Hutt had their listening ears on when I rang. A bit of a shout out and tiny ‘plug’ for these guys: Greg asked me all the right questions: what torque does the engine make, at what revs, what power does the engine make, at what revs, what tyre size (taller tyres are much harder on the clutch, harder to push along than shorter tyres), what diff ratio, what limited slip (welded diff or a multi plate-type mechanical LSD are hardest on a clutch).
Armed with that, and based on our current clutch we’ll be in fine fettle and fending off those thousand horsepower crate LS1s like a Boss!