T7Design Alternator Underdrive Pulley Honda K-Series K24 20% Underdrive
£66.00
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Description
The T7Design Alternator Underdrive Pulley increases performance by reducing the force needed to overcome the inertia of the alternator during acceleration and gear changes, this will result in a snappier throttle response and more horsepower reaching the wheels.
Alternators, in general, have a broad generating power band with the Honda K20 alternator producing a reasonable output from just 1,500 rpm, with max output being produced from 4,000 to 18,000 RPM, with this latter figure technically being the maximum warrantied rev limit. In some applications, where the engine is spending most of its time in the upper half of its rev range, you simply do not need to drive the alternator at such a high speed. However, the only issue you would potentially face is a lower output at idle, in which case you may need to increase the idle speed to ensure the alternator is producing more current than is being consumed by the vehicles electrical systems. An underdrive pulley should also be considered if you have raised your rev-limit of your engine, for example if it is now 10% higher we would recommend fitting a 10% underdrive alternator pulley and so on.
- Underdrives the alternator pulley to free up additional Horsepower.
- Hard anodised black for superior finish, corrosion resistance and wear resistance.
- Precision machined to very tight tolerances.
- Almost half the weight of the OEM steel pulley.
| Specification | Metric | Imperial |
| Weight – 10% Underdrive | 0.145 kg | 0.319 lbs |
| Weight – 20% Underdrive | 0.175 kg | 0.385 lbs |
| Weight – Stock Steel Pulley | 0.275 kg | 0.605 lbs |
| Construction | Billet 6061-T6 Aluminium | |
| Finish | Hard Anodised Black | |
| Manufacturer | T7Design | |
| Part Number | C91-83D-4D7 | |
ATTENTION
- It is recommended to use an impact gun to remove the original alternator pulley.
- Fits both models of Honda K20/K24 alternator.
- For road applications we would not recommend going less than the 10% underdrive pulley, any less and you may find the OEM alternator cannot provide enough charge at idle with all electrical accessories turned on.
RETURNS & Warranty
Returns Policy
We want you to shop with confidence at Sansoms Specialist Parts. If you are not completely satisfied with your purchase, you may return eligible items in accordance with the policy below.
Returns must be requested within 14 days of delivery
Items must be unused, uninstalled, and in original packaging
Products must be returned in a resaleable condition
Proof of purchase is required
Custom-made, special-order, or clearance items may be non-returnable unless faulty.
How to Request a Return
Please contact our support team before returning any item. Returns sent without prior authorisation may be refused.
Email: support@sansomsspecialistparts.co.uk
Include your order number and reason for return.
Refunds
Once your return has been received and inspected, we will notify you of the outcome. Approved refunds will be processed to the original payment method within 5–10 working days.
Original shipping costs are non-refundable unless the item is faulty or incorrect.
Warranty Information
All products sold by Sansoms Specialist Parts are covered by a manufacturer’s warranty, where applicable.
Warranty coverage typically includes:
Manufacturing defects
Faults occurring under normal use
Warranty does not cover:
Incorrect installation
Wear and tear
Damage caused by misuse or modification
Track or competition use unless stated otherwise
Warranty Claims
To make a warranty claim, please contact us with:
Order number
Description of the issue
Supporting photos or videos
Claims are subject to inspection and manufacturer approval.
Important Notes
Professional installation is strongly recommended
Warranty may be void if parts are incorrectly fitted
Vehicle compatibility is the customer’s responsibility
Need Help?
If you have any questions regarding returns or warranty, our team is happy to assist.
Delivery & Stock
Delivery Options
We aim to get your performance parts to you as quickly and safely as possible.
Standard UK Delivery: 3–5 working days
Express UK Delivery: 1–2 working days (subject to availability)
International Delivery: 5–10 working days (depending on location)
All orders are carefully packaged to ensure your parts arrive in perfect condition.
Shipping Costs
Standard delivery is charged at checkout based on weight and destination
Free UK delivery on orders over £100
We offer tracked shipping so you can monitor your order every step of the way.
Stock Availability
Most parts are held in stock for immediate dispatch
Some specialist or custom parts may have longer lead times
Stock levels are updated regularly, but occasionally items may be temporarily unavailable
If a product is out of stock, we will notify you immediately and offer alternatives or an estimated delivery date.
Order Processing
Orders are typically processed within 1–2 working days
You will receive a confirmation email once your order has been dispatched
Large or heavy items may require additional handling time
Important Notes
Performance parts may require professional installation
Delivery times are estimates and may vary during peak periods
International shipments may be subject to customs or import fees
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