NoPistons -Mazda Rx7 & Rx8 Rotary Forum - Why Are Rotaries So Good

8.54 say no more!

Just when we thought that Dave McPherson's little Corolla was fast with an 8.60 - it went to Adelaide and PB'd again…

When you flip through the Guinness Book of World Records you find feats of amazing achievements. Maybe Dave McPherson should give them a call; after all he now owns the title of quickest Un-tubbed Rotary on Earth.

Current Un-tubbed Rotary rules are vague at best as the class isn’t really recognised in terms of ‘real’ drag racing. It is, however, extremely popular as the cars competing do somewhat resemble what people drive on the roads. At the moment whatever you can stuff under the guards without touching them is basically the only requirement to compete in this category.

This was the exact reason for Dave choosing this 1972 Toyota KE20 Corolla. Having previously owned a Mazda 626, Dave decided to build something a bit more dedicated to the quarter mile. “The 626 was really a circuit/burnout car and really wasn’t setup for drag racing at all but still ran a 9.93 at 143mph. I wanted something a bit lighter and smaller so I went around to all of the car yards to see what was out there. I took along my measuring tape and measured the guards on a lot of the cars and walked away with the Corolla.”

Vlad Berak of Rotorworx adds, “We were expecting the car to run mid to low 9s straight out providing we didn’t have any problems. We did some calculations and realised the car definitely had the potential to run into the 8-second zone. Our first time out and Dave went 8.81 at 152mph which left us absolutely stoked. We had boost problems on the day with boost dropping off to 23psi so we knew there was more left in it yet”.

The fireworks under the bonnet are the result of Vlad’s extensive experience with rotary engines.

“Dave has never even come close to having an engine problem with this car. The motor is actually from his old 626 – we didn’t even freshen it up before we raced the Corolla,” he says. “You can tune a car to make power on a dyno and you can tune a car to run fast at the track. We prefer the latter.”

The engine itself is a race-prepared Rotorworx 13B Series 4 RX-7 import engine. “We use standard 2mm seals in all of our engines as we think they are more reliable under high boost pressure. Dave’s engine has additional dowelling and custom porting,” says Vlad. Induction wise the Corolla isn’t so standard. Dave explains: “I’ve seen a lot of guys have problems with conventional thrust bearing turbo’s and basically didn’t want to be pulling it off the car for maintenance so we went straight for the roller 45.” Mounted on a custom Rotorworx exhaust manifold, the Garrett GT45 is basically a TA45 turbo with a roller bearing core and runs at 30psi of boost pressure. This is fed through a PWR intercooler plumbed to and fro by Nik Stavreski from Turboworx. The inlet manifold is also a little different from most. “We tried something on Dave’s car which I’d been wanting to do for a while and we think it’s working pretty well but I really think the power from this setup just comes from the tune itself.” A MicroTech LTX12 takes car of the fuel and ignition curve and controls four Indy Blue injectors.

As Mazda rotaries have so much potential to run fast, the gearbox is often a weak link. “Instead of building a car, running quick and then having to continually modify everything as I progressed, I decided to do everything properly first time out so I bought a second-hand Liberty 5-speed from a Pro-Stock car. The gearbox is a ‘clutch less type’ so as soon as I take off, the throttle stays floored and, if I lift, the gearbox will automatically select neutral meaning I can’t get back on the throttle again without coming to a stop and resetting it.

“I could adapt an air shift mechanism to the gearbox but I prefer to use the stick shift. It can get a little hairy with only one hand on the wheel though,” Dave relates.

The diff is a custom 9-inch unit with a modular full spool centre, 35 spline billet axles and a heavy-duty 3.5-inch tail shaft. Sitting nicely under those back guards are 15 x 8-inch Weld rims on 28 x 9-inch MT drag slicks and 4.5-inch Michelin front runners. Stopping the car wasn’t left to chance with a parachute mounted on the back and deployed via a lever above Dave’s head in the cockpit.

“Once we ran the 8, we were hoping we could reset the world record which we believe was 8.72 at the time. The car ran 8.71 at a Heathcote test and tune before we ran 8.62 at 157mph at the All Performance Shoot-out. At the 4, 6 & Rotary shootout in Adelaide I was keen to run an 8.5 as I knew the track would be really good.” With the air temperature dropping to 18 degrees in the evening, the Corolla scorched the track in the finals with an 8.54 at 159mph pass.

So what are the plans now for this blue projectile and how much faster can the Corolla run? “I would like to see the car run into an 8.4 as it is now. We have plans of putting Nitrous on the car as it really doesn’t 60ft as well as we’d like.

Dave has to drop the clutch at 10-grand to keep the engine from bogging down, but the car just smokes the tyres by doing so. With a small shot of Nitrous we should be able to launch at eight grand and hopefully that will bring the 60ft times down and the car could run an 8.3 at 160+mph,” says Vlad.

And what does Dave think? “Well a 20B would look nice under there I reckon!”

Want more? Then click here for bigger and better shots of this and all your favourite feature cars!

Fast Fax

Vehicle: '72 Toyota KE20 Corolla

Engine: Series 4 13B Turbo

Induction: Garrett GT45, Rotorworx inlet and exhaust manifolds, Turbosmart 45mm Pro-gate, Supersonic blow-off valve, E-boost electronic boost controller, MicroTech LTX-12, 4 x 1700cc Indy Blue injectors, Bosch Motorsport fuel pumps

Internals: Rotorworx porting, additional dowels

Ignition:

Exhaust:

Drivetrain

Gearbox: Liberty clutch-less 5-speed

Differential: Ford 9-inch

Clutch: Precision race twin plate

Brakes: Standard front, XF Falcon rear, parachute

Wheels & Tyres

Front & Rear: Front - Weld Racing Pro, Michelin Front Runners / Rear – Weld Racing Pro, M/T 28x9 Drag slicks

Power Output: Race weight is 2350lbs, you work it out!

Quarter Mile: 8.54 @ 159mph on 28 x 9-inch MT slicks

Good Work Mate..............

Muzza