Welcome to Bob’s Blog! This is where Bob will post tips, tricks, and experiences he has with other racers. Check back often to read what Bob has been up to.

NA Racing Engine Intake Design vs Cylinder Volume

Friday, September 8th, 2023

Normally aspirated (NA) racing engines are popular throughout the world, both in land and water motorsports.  When the intake valve opens in this design, the piston changes direction from exhaust evacuation to intake inlet.  As the piston goes down the cylinder, air pressure drops.  Atmospheric pressure that is higher is outside of the engine.  That higher pressure feeds air through the intake system into the cylinder.

FYI: Fuel is introduced in the intake system for an air to fuel ratio for subsequent combustion.

The amount of air that enters the cylinder is a function of the intake system that feeds the intake valve.  Most NA engines have an intake port and manifold pathway that feeds the cylinder.  For example, in a stack type fuel injection system, the intake pathway is normally a combination of segments.  These are:

  • the intake port in the cylinder head
  • a casting or billet throttle assembly
  • a ram tube.

For example, a V-8 racing engine would have 8 of these pathways.

There is a strong relationship between the volume of air in the intake pathway and the cylinder volume.

When the intake valve opens, the volume of air in the intake pathway port, throttle assembly, and ram tube fill the cylinder.  Keep in mind that racing engines normally operate at high RPM.  So the time to file the cylinder with 60+ events per second is quite short.  The intake event is terminated by the cylinder going to the end of its stroke and the intake valve closing.  If the volume of the intake pathway is smaller than the cylinder volume, then air is pulled from above the ram tube.  It may be open air such as in a nostalgia dragster, or it may be from a plenum feed by an air cleaner such as in a sprint car.  Here are some examples of a brief study from intake dimensions from various racing engines:

  • record holding nostagia dragster with a small block GM engine with a tunnel ram manifold and hat injection — intake-to-cylinder volume ratio 1.1 to 1
  • formula one engine from 2001 from published data in “Racecar Engineering” magazine — intake-to-cylinder volume ratio range from 1.05 to 1 to 1.1 to 1.
  • drag racing ProStock carbureted engine from the 1990 era — intake-to-cylinder volume ratio 0.8 to 1 for quickest elapse time; higher ratio for highest horsepower.

More information in our “5000 HP on Methanol” book.

Drag Racing FC Chaos, Texas Motorplex, 2022 World Finals Recap

Tuesday, June 20th, 2023

We enjoyed entertainment of the FC Chaos world finals at Texas Motorplex, in October, 2022.  The racing facilities are quite first class.  Our thanks to Homer Doherty who met us at the entrance for the facility.  Homer transported us (and many others) around the pits in his electric cart, where-ever we needed to go.  This service was provided as a free courtesy to the spectators.

We met the FC Chaos race director, Chris Graves.  Chris and his wife, Tera, put on quite a show of supercharged alcohol and nitro powered drag racers. (more…)

HP Gain from Small Opening in Roots Blower Case

Tuesday, June 20th, 2023

Roots blowers are popular in motorsports for making more power. They are made up of a simple blower case with two rotors inside. The rotors spin from an engine driven blower drive. This pumps extra air into the engine. With extra air and the appropriate extra fuel, extra power!

The blower case design was changed in later years to improve performance. One of these areas is the size of the blower case discharge opening.

Original Roots blowers ran on industrial engines. They were simple mass flow devices running at atmospheric pressure. In the mid 19th century, motorsports racers put them on racing engines. They pumped a lot more air into the engine causing boost. This became an easy way to make more power.

However, because they were originally designed to operate at atmospheric pressure, they were inefficient with boost. While they made more power, it was not that much more for the amount of increased air into the engine.

One of the design areas affecting efficiency is the blower case discharge opening. That is discussed in several of our publications. Here are two examples: (more…)

AutoRama Custom Car Show, Sacramento, Ca, USA

Tuesday, March 14th, 2023

That time of the year again for Sacramento Autorama, California.

Or call for info: 877-763-7469

Previous shows included hundreds of professional custom vehicles, low riders, boats, great food, vendor booths, and entertainment.

Quite a few drag and land speed racing vehicles were displayed.

As usual, we were particularly interested in the racing mechanical fuel injection setups.


Converting from Gas To Methanol

Friday, February 10th, 2023

Considerations for converting from gas to methanol for motorsports:

Methanol is corrosive.  Fuel systems need to be upgraded to corrosion inhibitive components not necessary in fuel systems for gas.

Methanol requires approximately twice the amount of fuel for the same power level as gas.  Fuel pumps and jetting need to be upgraded for the higher volume.

Methanol has a higher heat of vaporization.  That together with the increased volume can condense the inlet air, increasing the weight of air into the engine.  That together with the proper air/fuel ratio will usually increase engine power.  A power increase as high as 10% is reported by several racers who converted to methanol.

Methanol cooling throughout the intake system of a drag racing engine may eliminate the need for a cooling system that would otherwise be needed for gas.

Methanol is widely available throughout regions where racing is common.

Methanol absorbs moister.  For long term storage, it should be kept in sealed metal containers.  Methanol in plastic containers may get contaminated from humidity from long term storage.  Plastic at the microscopic level is porous and will let moisture in.

Methanol is poisonous in all forms.  It should be handled with protective clothing and eye protection.

More info in our book: 5000 Horsepower on Methanol.

Added Tax Tips for Motorsports Businesses

Wednesday, February 8th, 2023

In our previous article about tax tips for motorsports businesses, a basic sole proprietorship was described.  It is a simple business form from a taxation standpoint.  Once business activities, income, and expenses become significant, a sole proprietorship may not be the best.  More indemnification and accounting flexibility may be needed.  An accounting example would be a business fiscal year for tax obligation reporting that is more in-line with your annual business fluctuations.  It may be different than your calendar year required for person income tax.


Forming a corporation is the next step.  This can provide less business liability to the owner and with different accounting that sets up the business as a separate entity.

Various forms of corporations exist.   Information about various forms of corporations are in many books and info on the web.  Also, an attorney or accountant can be consulted to find the right corporation for your needs.

The following information is based on our experiences several years ago forming and running a C-corp. (more…)

Tax Tips for Motorsports Business

Thursday, January 26th, 2023

They say nothing in life is certain except for death and taxes. In most parts of the world, taxes are part of life and part of running a motorsports business.  In the US, large expenses associated with running an engine building business are federal, state and local taxes.  This article will focus on the United States tax system, but similar ideas may be applicable to similar businesses in other countries as well.

One of the largest advantages to the US tax system is that profits are taxed after expenses are deducted.

This means that most expenses associated with building or running your business do not get taxed.  Smaller businesses may only require a sole proprietorship, but larger businesses may require a corporation.

Sole Proprietorship

For tax filing purposes, a sole proprietorship is the simplest form of business.  It can consist of a single person or a married couple.  Annual accounting is required, and the owner is liable for all taxes.   Profit should be shown for a minimum of two out of five years.  Retirement contributions and medical expenses are usually not part of business expenses and are done according to personal 1040 tax filing rules.



Friday, December 2nd, 2022

Developed from and tech info in our fuel injection publications