Sneak Peak: Craig Gibbs 1970 Volkswagen Beetle
Garrett Turbo Bug

Sneak Peek: Craig Gibbs' 1970 Volkswagen Beetle

By Justin Banner

As I mentioned in the Introduction, Volkswagen Beetles are an interesting part of the Automotive world. The car lasted from nearly the end of World War II and was built, as a new chassis, until 2003. No, you are not reading that wrong. The Volkswagen Beetle was last built new in Mexico in July of 2003. What other car can claim that it has been around since 1940 and held nearly the same chassis all that time of 60 plus years? What was amazing was that it was even a Type 1, similar to what you see here in Craig Gibbs' car. Craig was the second owner of this car in 1970 and has owned it ever since. Again, this shows the longevity of the car, but that's not what makes this car special.
 

Garrett Turbo Bug
Probably one of the more fun things about a Volkswagen Beetle is that the engine is usually proudly displayed for all to see. This is especially true for heavily modified examples, as Craig's car is. The wheelie bars, turbo, and carburetor kind of make it impossible to really set the bonnet back on, anyway. Let's get started with that showcased engine!
 
Garrett Turbo Bug
You'd be very wrong to assume that there was anything other than a Garrett Turbo pushing air into the combustion chamber. The turbo is a Garrett TA34 with a larger compressor that was built by Limit Engineering, who are a Garrett Performance Dealer. The intake and exhaust manifolds were built by Craig in the comfort of his own garage.
 
Garrett Turbo Bug
However, the real trick part is the carburetor. Now, here is something you may not know if you are unfamiliar with carburetors. Unless specifically designed or modified, they really only work one way. They require vacuum to pull fuel out of the float bowls via Bernoulli's principle. Well, a turbocharger kind of defeats that and you don't get any fuel out of the carburetor, again, if you don't modify the carburetor to work that way.

That's not to say you can't use a turbo on a normal carburetor, you can do it simply by putting the carburetor “in front” of the turbo's intake. This way, the suction from the turbo's compressor will pull air and fuel through the carburetor as Bernoulli had intended it to. What's more, because fuel is getting atomized in the intake, it does have a sort of cooling affect on the intake charge, so running an intercooler, while still wise, is not as warranted. You just can't turn up the boost to drag racing, 21psi levels on the street and expect it to live. It will run 7psi like this, be happy, and somewhat easier to tune.

 
Garrett Turbo Bug

The carburetor that is being employed is the Holley 750, Double Pumper setup 4-barrell. Again, it has retained its “draw-through” design and is not a blow-by design. 750 refers to the amount of air the carburetor will flow which is 750 cubic feet per minute (CFM). Not the biggest, but pretty big for a four cylinder car unless it has a turbo like this one does.

Some more carburetor nomenclature here, “Double Pumper” and it refers to the accelerator pump's actuation. When you blast open the accelerator, the fuel flow won't react fast enough and you have to force more fuel in or get a lean condition on acceleration. An accelerator pump prevents this by using a diaphragm or a piston to force some fuel through an accelerator jet or to the primary and secondary squirters on 4-barrel carburetors. A Double Pumper has this on both the main and the mechanical secondaries. You'll also notice the choke horn, but the choke plate is missing. Don't really need it here in California as it usually doesn't get cold enough. Usually.

 
Garrett Turbo But
To vent excess exhaust from the turbo for boost control purposes a Tial 38mm wastegate is utilized. It also uses an adjustable “boost controller.” Really, it's just an air pressure regulator, which just regulates boost instead of air pressure. At less than $20 an air pressure regulator is also far less expensive than most boost controllers, even if they don't offer the same precision as a well built boost controller. Well, in most cases, anyway and this Bug is showing that it's effective up to 21 psi!
 
Garrett Turbo Bug
Ignition is controlled by the tried and true MSD 6AL Ignition Box and it also features a two-step box as well. What's a two-step? It's an ignition control used to set two different RPM cut out points. You can use it in the water box to prevent over revving the engine while you warm up your tires or you can use it to control your launch RPM. Craig is using it for Launch control, since getting a turbo car up to boost is essential for a proper launch. You install an RPM pill for your launch RPM where boost is made, hold a button or use your clutch engagement switch to activate it, and launch. Pretty simple. The MSD 6AL-2 and newer ignition boxes incorporate the 2-step and get rid of the pills in favor of potentiometers.
 
Garrett Turbo Bug
He's also using the MSD Blaster HVC-II coil, which puts out spark at 44,000 volts! It also has a spark duration of 450 micro-seconds.

 

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