First published in the November 2003 issue of Street Machine

Paul Knott owns this argument-settler. What you’re looking at began life as an MGB, but 450hp worth of Chev-roo-lay V8 caged under the bonnet takes this car away from the mainstream and into the realms of extreme sports.

“I built this one for myself,” Paul smiles. “I decided I’d build an MG and I’d never seen a really tough MG road car.” And yes, he does mean really tough. The muscle of a 5.0-litre Chev breathing deeply through an ex-V8 Supercar eight-throttlebody intake system makes this one a real freak.

Paul’s business, PK Automotive in Sydney’s west, has carved itself a niche by doing trick engine swaps. Slotting V8s into 4WDs is something Paul can almost do with his eyes closed. He also stuffs plenty of injected twin-cam fours into old Datsuns and Toyotas.

He started this monster with a 1971 MGB that he bought out of the classifieds 18 months ago. He took a look at a Chev V8 and figured it would fit. Somehow. That said, there’s surprisingly little in the way of metal massaging or mauling done to fit the engine — a couple of clearance cuts for the exhaust is just about it. The exhaust looks like last night’s spaghetti, but it fits.

But there’s no room between the chassis rails to use conventional mounts. Instead, Paul has employed an engine plate, bolted to the front of the block, to support the donk. It rests on the chassis rails in front of the water pump and is isolated with Valiant V8 mounts. The water pump is an electric unit (no room for the original). Likewise, the alternator has been kicked out of its home and now hides, hot-rod style, next to the diff.

Precious little else remains of the MGB’s running gear. Almost everything was stripped from the shell and replaced with gear selected by Paul. The gearbox is a super-strong Tremec TR3550 five-speeder with an internal clutch release to steer clear of the ‘shrink-wrap’ floor pan. The diff is a narrowed Borg Warner from a Commodore, using factory rear disc brakes and sprung from the MG’s leaf rear end. Paul has used Commodore upper arm brackets to fit a pair of tramp rods to reduce rear-axle wind up and axle tramp. They run forward to a simple, solid brace that is mounted between the top shock mount and the front spring hanger.

Even with only 1000kg to haul down, Paul went overkill on the brakes. The rear discs back up 330mm front rotors – familiar to anyone who knows their HSVs – clamped by Nissan four-piston calipers. By machining the DBA discs’ outer bearing race, Paul could fit them to the stock MG stubs. Knowing what wheels he wanted to run made the choice easier, and the HSV-style wheels have plenty of clearance over the brakes. Paul selected this style because he reckons they “kinda look like the old Minilites”.

The radiator is a Ford item and Paul thinks it’s an XF. It’s tilted over in the engine bay because it’s around twice the size of the MG’s original. The hose inlets have been played with to line up with the Chev block.

Manufactured by MoTeC, the eight ram tubes are cast magnesium. They’re what you could have found under the bonnet of a Bathurst V8 Supercar in the mid 90s — these ones are ex-Wayne Gardner Racing. Paul built the engine himself with a Scat crank, Ross pistons, Carillo rods and a rather large cam. Engine management is taken care of by a MoTeC M48 system that controls the Optimax-fed Ford SVO injectors. The boot houses the fuel tank and the battery.

With most of the static photos done, Paul hits the key and the B cranks into life before settling down to a trembling idle. We’ve cheekily removed the bonnet for the on-road part of the photo shoot and I’m dead keen for a ride. Photo man Tony Rabbitte has found a suitable section of road without too much traffic for us to do the car-to-car shots.

A couple of pops from the intakes and we’re away. Not surprisingly, it has the angry snarl of a V8 Supercar. A bit muddy down low, but the further the tacho climbs, the clearer and louder the yelling becomes. I’ve got the sun on my face and my elbow on the door, so the sound I’m hearing doesn’t quite align with what I’m seeing. I’m in a little old MGB but, eyes shut, I feel like I should be wearing a helmet, surrounded by a roll cage…

Sports car? Hell yeah. Big engine, small body and no roof. Just the way it should be.

SHELL SHOCKED

Like the appeal of a roofless and ruthless road warrior? Most MGBs were powered by a 1.9-litre four-potter that gave the car good performance in a Pommy sports car kind of way. But there have also been factory V8 MGs. The first was launched as the GT (MGB coupe) in 1973. At the time, BMC claimed the lidless roadster shell wasn’t strong enough to cope with the V8. However, in the early 1990s, the situation changed. Rover produced the RV8, using a body based on aftermarket restoration shells produced by British Motor Heritage, powered by Range Rover’s all-alloy, EFI, 4.0-litre V8.

Paul Knott
1971 MGB Roadster