How to Choose the Right Silicone Hose: Shapes, Sizes and Applications Explained

When planning an intake system and you’re looking for inspiration, you’ll often see photos of systems online with either no silicone hoses, or very minimal. These tend to be complete aluminium tube systems that require TIG welding, which for most, is out of reach from a financial and or skills standpoint.

The same system can essentially be produced using a combination of various silicone hoses and aluminium tubes. Strategic use of 90 degree bends for tight angles and 45 degree bends for less dramatic direction changes can often yield similar results to fully fabricated systems.

How do I Know What Size Silicone Hose I Need?

Firstly, we need to lay down the general rule of thumb for measuring hoses and tubing/pipes:

• Silicone hose is always measured by its internal diameter (ID) as the hose is always going over a tube, turbo outlet or intercooler inlet/outlet.
• Tube (or pipe) is typically measured by the outside diameter (OD). This would only change if the tube is classified as a “slip fit”, but those are mainly used for exhaust systems.

Now that we understand how to measure the hoses, you can now measure your turbo, intercooler, throttle body etc. to determine the suitable hose sizes for your application.

You’ll often see sizes start from 76mm (3 inch) however on smaller engines, sizes will be smaller.

If you have components with mismatched sizes e.g. a turbo outlet of 4 inches and an intercooler of 3 inches, then that is where reducer hoses come into play. For this example you would fit a 4” to 3” straight reducer to adapt the larger turbo to the smaller intercooler.

Additionally, it is always good practice to confirm your measurements in both metric and imperial as this product line can sometimes be listed in one but not the other. Takashi’s range simplifies this as all hoses are listed with both measurements.

Important note: some measurements of particular components and tubing can see deviations of 1mm, however this is acceptable as silicone is flexible enough to account for this slight variation in diameter.

The Takashi Silicone Hose Range: What Sizes are Available?

Takashi offers an extensive range of sizes and shapes to suit most applications. Refer to the below table for the full range.

Takashi silicone hoses are precision manufactured from multi-ply high grade silicone and are designed to handle cooling, heating, and charges air applications including turbocharger and intercooler plumbing. Available in a range of variants covering straight lengths, 45 and 90 degree elbows, reducers and joiners in sizes up to 127mm internal diameter.

What Clamps Should I use with Silicone Hoses?

This is a fairly simple question to answer however there is one big aspect to keep in mind, and that is the size. A common mistake that is made time and time again is ordering a clamp at the same advertised dimensions as the silicone hose, however most people fail to remember that the measurement for the hose is the internal diameter, not the external diameter.

Takashi silicone hose, for example, has a wall thickness of 5mm; therefore if you have a 51mm silicone hose you have to add 5mm either side making your 51mm (ID) hose actually 61mm in overall diameter. Clamps will typically be advertised with a size range from its smallest to largest effective size.

Getting back to the actual question of clamp style, the most common and preferred style is the T-bolt clamp. These clamps provide an even 360 degree spread of clamping pressure; additionally they tend to have a wide band or strap which helps to spread the load over a wider area when compared to a worm-drive style clamp.

The worm-drive clamps often have a narrow band with serrations (for the worm drive) which over time dig in to the silicone and create points of potential failure.

Common Mistakes When Buying Silicone Hoses

Measure, measure, measure! The biggest mistake we see is people purchasing the wrong size, but this can be avoided if you take the time to measure and make a list of the sizes you need; even drawing a map of the system will help immensely.

The confusion between the internal and external diameters is the biggest offender with regards to the sizing. Providing you can remember that silicone hose is measured by the internal diameter, and tubing is outside diameter then your chances at ordering the wrong size is vastly reduced.

Additionally, your tubing or component inlet/outlet will have a raised bead or bump; this is designed to prevent the silicone hose from slipping off when clamped in place. When taking your measurements do not measure the diameter of the bead as this will cause the resulting hose to be too large for the tube and will not clamp-down evenly; not to mention that the size of a bead is generally not a standard size making it difficult to find the correct size.

Low grade silicone often has a low ply count and is not suitable for boosted applications and will be more prone to bursting under pressure. Buying the wrong grade of silicone hose will more likely than not cause issues in the short-term. Low ply count hose should only be used in naturally aspirated systems, such as a cold air intake system, as this is a far less demanding system.

Silicone hose with a 4-ply construction, such as the range from Takashi, should be your prerequisite when building a forced induction system.

Choosing the right silicone hose comes down to matching the shape to the routing, the ID to the pipe OD, and the build quality to the application. For most performance and forced induction builds, a 4-ply hose like the Takashi range is the safer long-term choice. You can browse the full range (straight lengths, elbows, reducers, joiners and humps in sizes from 38mm to 127mm) on the Takashi silicone hose collection page.

Frequently Asked Questions

• Q. Can silicone hose be cut to length?
• A. Yes, in fact the straight 1 meter lengths such as the Takashi 5” straight is specifically designed to be cut to length; but make sure you have a sharp blade to ensure a clean cut. There are dedicated tools for this purpose but these are expensive and are more targeted at workshops. A handy trick is to attach a clamp to the hose to act as a guide for your knife blade.

• Q. What is the difference between black and blue Takashi silicone hoses?
• A. The only difference is the colour. Functionality-wise the colour does not change any characteristic of the hose. Some black hoses may feature a blue inner, however this still has no effect on the function. In recent years blue has fallen out of favour due to it not blending into the engine bay as nicely as black. Black hose can pair well with any colour whereas blue will have a difficult time looking good for instance against a green engine bay.

• Q. What clamps should I use with silicone hoses?
• A. T-bolt clamps are the go-to choice for silicone hose due to their ability to apply even pressure around the circumference. Traditional worm-drive clamps should be avoided, however there are versions available that have a protective inner liner that prevents the worm grooves from contacting the surface of the hose.

• Q. Are silicone hoses suitable for classic car restoration project?
• A. If restoration is the aim, then no. Silicone hose has a very different appearance to factory rubber or plastic and therefore will stand-out too much. Additionally changing to silicone for a factory setup will provide little to no advantage in an intake system as the added benefits of quality silicone hose will not be fully utilised.

However, if originality is not a concern then silicone hose is a valid option, however if you are still wanting to keep an OEM style appearance then it is best to steer clear of coloured hoses; black will match anything, blue won’t.

• Q. What is the difference between a silicone elbow and a silicone reducer ?
• A. A silicone elbow is a bend with equal diameters at both ends of the hose. A reducer is a hose with a larger size at one end and a smaller diameter at the other end. A reducer elbow is a combination of the two types; a bend with a larger diameter end than the other.

• Q. Silicone vs rubber hose. Which is better for my performance build?

• A. Basically, for anything performance rated to do with the intake system, silicone hose is the only option. Not only will it withstand the pressures of a boosted engine, but it will last longer.