Hi Gonzo, here you have it.

The numbers and characters on the plugs, are the product number, wire thickness, and thermal range of the plug’s body. Example: The Mega Turbo 2315 6TF

Product Number: 2315
Wire Thickness: 6
Plug Type: T (Turbo)
Thermal Range: F (Fredda)(Cold)

The plugs with cold thermal range F(Fredda), have a body with thinner walls, so they dissipate heat better and faster to the engine head. So because of that:

·When the ambient temperature is high, we have to use a plug with thicker wire.
·Humidity determines if we use a Cold (F) thermal range, or Hot (C)(Calda) thermal range.
·With high humidity percentage we should use a Hot (C) thermal range plug.
·If we have high temperature and high humidity, we should use a plug with thick wire and a Hot(C) thermal range.

The best instrument to determine which Turbo Plug to use, is those weather panels they sell for Yachts, that have Temp, Humidity and Barometric Pressure on them. Have it calibrated at your local weather station, and bingo, you’re ready like the Pros.
That is the key to success or failure tuning engines with Turbo Glow Plugs, because they are so sensitive to weather variations that is unbelievable.

Following is a selection chart for Novarossi Turbo Glow Plugs:

Type Thermal Range Nitro% Temp.C Humidity%

C5TC Hot/hot wire 10-20 0-10 70-100
C6TC Hot/average wire 10-20 10-16 70-100
C7TC Hot/cold wire 20-30 16-25 70-100
C8TC Hot/ultra cold wire 20-30 25-up 70-100
C5TF Cold/hot wire 20-30 0-10 40-70
C6TF Cold/average wire 20-30 10-15 40-70
C7TF Cold/cold wire 20-up 16-25 40-70
C8TF Cold/ultra cold wire 20-up 25-up 40-70

Hope this helps

AFM