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Shooting Starlet: 11,000rpm In A Toyota KP62

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Shooting Starlet: 11,000rpm In A Toyota KP62


Power For The Clouds

Some of the builds you see that utilize the 4A-GE are rather impressive for the aging 1.6L engine. However, when you’re trying to get 160hp/liter without forced induction, it requires an engine that can rev beyond what Toyota had in mind when the twin cam four-cylinder originally debuted.

Fortunately, Finland’s Mikko Kataja and VHTRacing are rather familiar with building impressive horsepower engines and know what it takes to make power reliably – something we saw firsthand while catching up with Mikko and his amazing little KP62 Toyota Starlet at Gridlife Midwest.

When Mikko purchased the Starlet in 2000, it was a stripped-out and well used and abused. However, it was perfect place to start a Group F rally car build – he just needed a 1,430cc engine that could rev to 7,000rpm and make 115hp. This all worked fine until 2011 when Mikko decided to rebuild the chassis, but also wanted more power. So a 1,580cc, 8-valve pushrod engine pushing 200hp at 8,700rpm went in with a Lampola T50 dogbox and a Cusco LSD-equipped AE86 rear end. Finally, in 2014, a Bosch Motorsport MS3.1 engine management system was added along with a DDU7 display/data logger unit, and Mikko took the Starlet to KW Suspensions in Germany where their 7-post rig was used to set up and optimize the car’s KW Motorsport dampers.

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Last year there was more evolution; the car was heading to the 100th anniversary of the Pikes Peak International Hill Climb, so out went the old engine and gearbox and in came the 4A-GE 16-valve with a Sadev sequential gearbox. This required some extensive knowledge and work with engine electronics, which is something that has always interested Mikko.

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“The most interesting part with this car for me has always been the engine and electronics,” he said to me. “I have built a lot of engines over the years and when I had my VHTRacing Engineering shop in Finland I built small displacement turbo engines way past 1000hp. But my race car has always remained with a high screaming, small naturally aspirated engine.”

To get the power Mikko was looking for, extensive engine work would also be required.

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The block is from a 20-valve version of the 4A-GE, but to keep the displacement within the rules the bore could be no more than 81.25mm with the 77mm original crank stroke. The original 20-valve connecting rod is around 122mm, but that rod/stroke ratio isn’t good for a stratospheric redline needed to make 250hp, hence why 135mm AutoVerdi rods are used here. To make the pistons fit, Wiseco made a 3D model of the head so that the piston domes could be increased but with the absolute minimal valve reliefs for piston-to-valve clearance in the 18mm compression height. While each piston only weighs 189 grams, the combination of the AutoVerdi rod and Wiseco piston makes them 680 grams, and that requires a very strong crankshaft. Moldex’s Joe Flowers II made sure this custom billet piece could take the pressure.

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The cylinder head comes from the ‘Blue Top’ 16-valve 4A-GE and was massaged by Jari Kosunen. At high engine speeds, intake and exhaust flow must work together or your engine is not going to be breathing well; this also means that both the intake and exhaust had to be custom, handmade pieces. Mikko did the design for them from scratch, even getting the barrel-style throttle printed for proofing before finally building them out of metal. They look massive but work with the 8,000 to 11,000rpm range.

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Of course, the drivetrain needed to be the best you can get, and here the Sadev 6-speed sequential is built so that sixth gear has a 1:1-ratio that heads out for the AE86 Corolla GT axle. That axle is modified to fit the Starlet 4-link design and runs a Cusco LSD with either a 5.10:1, 5:375:1, or 5.85:1 rear gear, depending on course requirements. All of this comes together and works thanks to a Bosch Motorsport MS6.4 engine management system installed via a VHTRacing scratch-made wiring harness.

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The final result is 250hp at 10,200rpm – that’s 156.25hp/liter and darn near Mikko’s self-declared requirement for power-to-engine displacement.

It’s also enough to power this Starlet up Pikes Peak in 11 minutes, 42-seconds, and recently up Mount Washington for their hill climb in 6:58.98 for a P3 Prepared class win and 10th overall – check out the in-car video clip above.

When you consider that Mikko and his Starlet are taking on cars with far more power, those are some impressive times.

Words by Justin Banner
Instagram: jb27tt
Facebook: racerbanner
Twitter: RacerBanner

Photos by Larry Chen
Instagram: larry_chen_foto
larry@speedhunters.com

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