News, March 2005

Throttle Body Injection kits are now available!!!

If this is your first Throttle Body Injection (TBI) update I hope you take a few moments to look over the info on the web site. The goal of the TBI project is to create an affordable, dependable fuel injection system for Triumph TR6 cars that use Zenith Stromberg sidedraft carbs. In addition, the system is adaptable to work with any car using these carbs.

Update – Performance and Fuel Economy

It’s been quite a while since my last update. Here is what has been happening. As the very short sports car season in Maine ended in October a few minor changes were made to the TBI test car. Aaron Cropley’s pride and joy, a 1971 TR6, has been used as a test bed ever since this experiment started. The car runs great, better beyond original expectations. It starts easily and is immediately drivable without any of the normal carb issues. The acceleration is remarkable even at highway speeds and since the last program change the fuel economy is far better than ever. The last chip update was designed to keep the same performance and increase the fuel efficiency. On a 5 hour trip to Stowe, Vermont the car got nearly 30MPG, before the latest chip adjustments. And late in the season after reinstalling the chip with a new performance and fuel efficient profile in around town driving of about a 100 miles, the car went from 18MPG with carbs, to 27 MPG. The car is wonderfully smooth and a pleasure to drive. The profile for Aaron’s car is just about as good as it gets for street use, not to say that if he were a serious autocrosser or racer it wouldn’t require some adjustment. Hate to admit it but his car is easier starting, better mannered, and gets much better fuel economy than my multiport car.

Features and Benefits:

The TBI setup is a wonderful daily driver in that it starts exceptionally well, runs beautifully while warming up, and is overall a smoother running car. In comparing the two different set-ups, my multi port car is best described as a violent ride. In a drag race it will probably beat Aaron’s TBI car but it is still in need of a lot of tuning. It needs to crank a bit before it starts compared to instant starting of the TBI car. Drivability when cold still needs to be tuned. Guess what I’m saying is that the TBI car runs great and doesn’t need any further tuning unless you want to alter the engine with a cam etc. Both systems are datalog capable, programmable fuel and ignition, and the GM ECM for TBI even has the ability to learn. While there are similarities between the two cars they are quite different. Considering the alternatives for price and installation of different fuel injection systems out there, the TBI set up is quite reasonable. That really isn’t the case with my car. Just the computer and harness for the multi port car is $2,000 and then you need an intake manifold and crank sensor and in my case a cam sensor too. All involve machine work.

A real advantage of this TBI conversion is the ease of installation. You don’t have to build or alter an intake manifold. You use the existing carbs, air cleaners, linkage, and actually converting the carb portion of the set-up into fuel injectors can be done in less than an hour. Figure the complete conversion will take a full weekend. The process can also be reversed quickly as no parts have been damaged or altered. As you can see I’m very pleased and proud of the TBI set up.

Pricing and Availability:

My throttle body kits are just now coming to market. Here is the latest pricing: My portion consists of two billet 6061 aluminum TBI conversion adapters with bypass block offs at $125 each, a hardware package consisting of a mounting bracket and actuating lever for the TPS and a mount for the ignition module for $50. I can also supply a new TPS sensor for $34.99. Add shipping within the US, the cost for the above package is $350.

CustomEFIS will supply the custom TR6 harness, relays, ECM, sensors, fuel pump, regulator, ADL cable, convert your TR6 distributor to electronic, and the software support for $850. Injectors are now included in the base price, CustomEFIS will supply tested, matched injectors. If you want your own Flash programmer to make changes to the software yourself or make immediate changes they email to you, it’s an additional $100. You can visit his web site for more details of his kits or contact them by email.

Both CustomEFIS and I guarantee our components.

Elimination of IAC:

For those of you who have been following this project all along, the idle air control circuit has been eliminated. For an in depth explanation see the web page. Fast idle is controlled by the original choke high idle cam. The short version is simply that at very low idle, the IAC was supplying intake air as it should but not picking up enough fuel at the throttle plates. By using the existing choke you can control high idle in order to warm up the engine. The car will start and idle just fine without the IAC, even if the engine is cold and the outside temperatures are cold.

New Shop:

Late last Fall I sweet talked my wife into converting the family room in our basement into a machine shop. She agreed and off we go. The basement is daylight so all that was necessary was to cut open the concrete wall and add set of double doors. I traded the pool table to the contractor who helped with the concrete cutting. The first piece of equipment moved in was a Bridgeport milling machine at about 2,400 lbs. Since then we’ve added a 5 ton punch press to make brass carb bypass block off plates, a large horizontal band saw, a metal lathe, and a bunch of smaller items.

New web site:

I am working on a new web site that is devoted to TBI conversion. It is of course, one amongst many projects that I have going. The intent is to provide specific details, many more pictures and step-by-step instructions for the conversion.

Feel free to contact me at

Can’t wait for the snow to melt,


For more TBI details and pictures see Product Support or the new TBI Frequently Asked Questions page.