Technical

Details of the two engines used follow:

For the Austin: Cadillac Northstar quad-cam 32Valve V8, 4.6 litres, 300 hp/300Lbft, originally used in the front wheel drive Cadillac STS range launced in the early 1990′s. This engine came from a year 2000 write-off via a long series of coincidences. In 2000 the engine was upgraded and now features roller rockers, bigger intake ports but smaller exhausts. With just 26,000 on the clock it will have plenty of life left for it’s duties in my Austin hotrod. To use in a RWD car a different gearbox is needed, I eventually found one from a V6 camaro that will do the job – it needs a 60 degree V unit. It’s a 4L60E with a removable bellhousing. This is a 4 speed with lockup electronically controlled automatic, based on the older 700R4. Both the engine and gearbox will be controlled by a pair of Megasquirt ECUs running suitable code. I have a set of 8 throttle bodies that will conservatively liberate another 75 hp, plus the option of a cam upgrade (all 4 of them). But just how much hp do I need?

The other engine is a 2005 L33 5.3 litre Vortec unit, this is a HO version with an alloy block. (http://en.wikipedia.org/wiki/GM_Vortec_engine) The LS series of engines are a masterpice of good design, building on everything good that the earlier ‘small block chevy’ had, brought right up to date with appropriate design and engineering. My unit came from a low mileage write-off and also has a 4L60E transmission, albeit with the 4×4 output shaft option which I will need to swap to use in my car. Parts interchangability is outstanding within the LS range and that is where most of my parts are coming from – US forums.

The modifications are: LS6 intake manifold (lower height than the truck unit so no need to add a bonnet bulge), LS1 injectors to provide the extra fuel needed due to the fitting of a Corvette 2002-2004 camshaft, springs and pushrods (more lift and duration, 214/218, 0.555/0.551 lsa 117.5). 97-2000 corvette sheet metal exhaust manifolds – really close to the block with exit in an ideal place for the scorpio, corvette crank pulley and water pump – shorter that the truck unit leaving plenty of room for the radiator, radiator with twin pancake fans from a Mark 4 Scorpio,  GM ‘muscle car’ replacement sump (a mere $140!) as it’s a tidier fit behind the car cross member and does not hang out underneath (speed bump hazard). Reprogrammed PCM to remove surplus emission controls, vehicle security features and to take account of the modifications. Torque management via DBW throttle will save wrecking the gearbox.

Conservative estimate, 375 hp. It’s a simple sum – the 5.7 litre 405 hp engine that donated the cam is identical to this one except this one is 5.3 litres and will be running without catalysts. So 5.3/5.7*405 = 376. As and when I build a set of long tube headers (exhaust manifolds) this figure will nudge 400 hp. And it’s still ‘stock’. It also barely tips the scales at 200 Kg!! They also have a reputation for long life, up to 200,000 miles without a problem.