Turbocharging is one of the modifications that causes the most insurance complications — it increases power dramatically, often in conjunction with many other supporting modifications, and forced induction is consistently flagged by insurers and industry guides as one of the highest-scrutiny modification categories.1 Getting turbo insurance right requires declaring the full modification ecosystem, not just the turbo itself.
The Turbo Insurance Ecosystem
When you add a turbocharger, you typically also add: intercooler, upgraded fuel injectors, fuel pump, ECU tune, intake and charge piping, exhaust manifold and downpipe, potentially wastegate and BOV, and often a boosted-specific clutch or transmission upgrade. Every one of these must be declared.
Power Levels and Premium Impact
Insurers don’t publish a fixed percentage per power band — the loading depends on the specific insurer, the car, and how the build is documented. As a real published reference point, comparisons of everyday turbo variants versus their naturally-aspirated equivalents put the increase at roughly 5–15%, while genuinely high-performance turbo builds have been reported at 25–60%+ — and the highest end (heavily modified, undeclared, or combined with other performance work) can go well beyond that.1 Treat these as illustrative bookends, not a quote: get an actual figure for your specific power level and build.
Single vs Twin Turbo Declarations
Single turbo setups are generally easier for insurers to assess — one turbo, one power figure, one intercooler. Twin turbo builds (particularly factory twin-turbo cars with upgrades) are more complex because the modification scope is larger. Both are insurable through specialist modified car insurers. Twin turbo builds benefit from more detailed documentation: dyno sheets showing power under full boost and at multiple pull points help underwriters establish a fair agreed value.
Street vs Track Turbo Builds
A street turbo build (driven daily on pump fuel) is assessed differently from a track/strip turbo build (running E85 or race fuel, slick-tyred, caged). The latter requires motorsport insurance rather than an extended road policy. Be specific about how the car is used when getting quotes — describing a heavily boosted E85 drag car as ‘a modified road car’ will produce quotes that don’t accurately reflect the cover needed.
Documentation Best Practices for Turbo Builds
- Before/after dyno sheet (same day comparison preferred)
- Boost controller calibration (target boost, overboost settings)
- Full parts list for the turbo system and supporting modifications
- Photos of engine bay showing turbo system, intercooler, and piping
- Tune sheet or map notes if available
Sources
Frequently Asked Questions
Does adding a turbo void my standard car insurance?
Adding a turbo without notifying your insurer voids your policy. The turbo itself does not void insurance — but failing to declare it does. Contact your insurer or switch to a specialist modified car insurer before or immediately after installation.
Do I need to declare my boost level to the insurer?
Yes. Boost level determines power output, which is the primary risk factor for forced induction modifications. Provide both the standard boost level and any overboost figure. A dyno sheet is the most credible way to support the declared power output.
Can I get turbo car insurance online?
Standard comparison sites rarely return valid policies for turbocharged cars with declared modifications. Use specialist modified car brokers or insurers (Adrian Flux, Footman James in the UK; Heacock, Grundy in the US). The online quote forms for these specialists are equipped to handle forced induction declarations.
Ready to protect your build?
Compare specialist modified car and drag racing insurance in 60 seconds.
