Cars

Blower vs. Turbo: Frank Harder’s 2,000HP 1967 Chevrolet Nova

It’s been a debate that has been going for decades: which is better, turbos or blowers? It’s not often that you find someone who has run both at a high level, and it’s even less often that you find a person who’s run both on the same engine. Luckily for us, Frank Harder of Anderson, California has, and he’s willing to spill the beans on both setups!

The engine that Frank built for his big-tire tube-chassis ’67 Nova wagon is no slouch in its own right, as 565ci of big-block Chevy power is a pretty serious start. But then there’s the boost—a lot of it. For a number of years Frank campaigned the car with a Littlefield 10-71 supercharger along with an Enderle injection hat. The methanol-powered big-block was a handful, but it propelled the car to low 5-second eighth-mile passes.

Frank is a big no-prep fan, which meant the blower was a bit, uh, uncontrollable. Frank might run low 5s, but might go 800 feet to get there instead of the normal 660, as the blower was kind of an on-or-off deal if it spun. I think we even have pictures somewhere of the wheelie bars hitting the guardrail as the car spun and hit dirt. Something had to change.

Frank had the chops with the 565, but he needed some more advanced power. That meant it was twin-turbo time, along with a Big Stuff 3 engine management system and electronic fuel injection. “It wasn’t cheap, but with the boost-ramping nature and turbo top end it was still worth it though!” he notes.

So, we haven’t got apples-to-apples passes yet, but Frank has made progress. “I’ve been sneaking up on the boost, and things are coming along way quicker than we thought,” says Frank. “At 17 psi of boost, we’ve already equaled our blower times at 36 psi, so that’s quite the improvement,” says Frank. Next year he plans to turn the boost up into the mid 30s and get things moving, and we’ll get to see just how fast this boosted wagon can go!

Long Block
The engine was built by legendary Northern California racer Jeff Simpson of Jeff Simpson Racing Engines in Oroville, California. Starting with a Bow-Tie block, a Callies crank swings a set of GRP aluminum rods and 11.5:1 Ross Racing pistons to arrive at 565 cubic inches. A DRC solid-roller camshaft bumps Morel lifters, Smith Brothers pushrods, and Jesel rocker arms that are attached to some serious 18-degree Big Chief cylinder heads.

Camshaft Swap
Although Frank went from a solid-roller to a solid-roller, the camshaft was one big change going from a supercharger to turbos. With the blower, a DRC cam with 290 degrees at 0.050 with 0.850-inch lift was the hot ticket, but the turbos saw a dual-pattern cam with a little less duration at 278 degrees on the intake, 285 on the exhaust, and a 0.799/0.802-inch lift.

Supercharger to Turbos
Frank was initially addicted to the ear-shattering noise of a 10-71 Littlefield supercharger but the writing on the wall was there when the turbo cars started going fast. The new setup has twin 94mm Precision turbos with 60mm wastegates and twin Tial blow-off valves. The headers also had to be refabricated, as did the intake piping, which was all done at Reed’s Rod Shop in Redding, California.

Mechanical to EFI
The injection system was another area that got a revamp with the turbo change. The car still runs on methanol, but no longer uses the Enderle injection system, or Falk carbon hat. Now a Wilson Manifold and 105mm throttle body takes in the air, and a Big Stuff 3 stand-alone engine management handles the fuel through eight Precision Turbo and Engine 225 lb/hr injectors, and eight more 500s for when things really start to get serious. An MSD ignition system was used in both cases, but it’s now controlled through the computer.

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Thanks !

Thanks for sharing this, you are awesome !

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