Parts & Accessories For Vintage Volkswagens
High Performance Engine and Drivetrain Specialists
The Kadron Solex H40/44EIS Carburetor Masters


Thinking of adding horsepower by removing your air cleaners altogether to race your buddy at the track?

Don't do it!

We've recently been doing dyno testing with different air cleaner options and modifications, and have come up with some VERY interesting data. The modifications discussed below were done on a 2180cc Kaddie Shack motor with the following specs:

82mm crankshaft x 92mm pistons/cylinders
9.1 compression ratio
Norris 408S camshaft, 1.1:1 rockers
KSR-4000 ported cylinder heads, 40mm x 35.5mm valves
1-5/8" AA Sidewinder Exhaust
Kaddie Shack EMPI Kadron-style 44mm dual carbs

All testing done in house at the Kaddie Shack on our Stuska engine dynomometer. We will be continuing testing on various other Kad-Powered motors with different displacements, cams, heads, etc over the coming months. The results of this particular test were absolutely stunning, and well worth sharing at this point. Note: EVERY engine is different. Some will see drastic results. Others will see less drastic improvements. All, however, based upon our current information and preliminary testing, will see some sort of improvement with the modificaitons discussed.

First things first: We started with standard aftermarket air cleaner assemblies, like would come standard in our "Turn-Key" sets, or our "New Modified" carb sets, just to get a baseline dyno reading of what our litle "21" would do. After noting the horsepower and torque throughout the entire range of the powerband, we performed another test: One with air cleaners and mounting brackets totally removed. With the A/C's removed, we found the engine actually LOST 3 HP.

Next, we added our Hi-Flo kits, which move the air cleaner mounting bracket up and out of the carburetor throat for increased airflow. The results of this simple modification added 8 horses over and above what the stock air cleaners provided, and 11 ponies more than running without air cleaners at all!

Very cool!

After that, we removed the air cleaners entirely, and installed our velocity stacks to the carburetors. This simple modification added a whopping 14 horsepower to the output of the engine over standard air cleaners, and 17 HP more than running with no air cleaners at all!!!

Now that's worth writing home about!

For yest another test, we decided to try installing our velocity stack nylon filters on the stacks we were running. With the filters installed, the engine still gained 12 HP over stock, and 15HP over running with no air cleaners at all.


We did one more test, just for the sake of future development: We modified our velocity stacks, and ran them in conjuction with a modified Hi-Flo kit, and under the stock air cleaner. This was a "test only", to see if a future product was worth developing. We did see a 10HP impromvement over the stock air cleaner, leading us to the conclustion that it may be worth further investigation and development.

For now, though:

- Our Hi-Flo kit (click here) gained 8 horsepower over stock.

- Our Velocity Stacks (click here) gained 14 horsepower over stock.

- Our Velocity Stack Filters, when used with the stacks, gained 12 horsepower over stock.

- Removing the stock air cleaner entirely actually lost 3 horsepower!!!


These air cleaner improvements really do work. This particular engine saw tremendous gains. For smaller displacement engines, and engines that have camshafts with less duration, you'll still see gains, but not as large as the gains above. Normally, on a smaller engine, say a 1776cc, with a smaller cam, you'll see 3 horsepower more, which is still a definite power advantage (6% more HP than a stock 1600!) with our Hi-Flo kits, and similar numbers with velocity stacks. These gains will be seen mostly at the 4000 RPM range and up, where you need them for pulling hills, merging into traffic on the highway, passing cars, and racing, of course! If you have a counterweighted crankshaft, and the motor is making power to 5500-6000 RPM's, these upgrades are a no-brainer. Do it! If you're running a 1900 cc motor or larger: It's defintely a recommendation, as well. The larger the engine, the more you'll gain. If you're running a smaller engine: 1776cc, 1641cc, etc..., with a stock crank, it will still be beneficial, but the upgrade is not as imperative.

There are two reasons these upgrades work: 1) By improving airflow without disruption to the carb inlet, and 2) By minimizing reversion pulses caused by valve overlap in large cams. Look for future articles covering these two occurrances in greater detail.

© 2010-2013 Kaddie Shack - 1609 E Walnut St - Pasadena, CA 91106 - 714-752-3766 or 714-7-KADRON -
Back to Kaddie Shack Home Page