About the resource
Contact and Report a Calculation Issue
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Contact the publisher
Send a question or correction with the form below. Use page paths and manual titles rather than web links, which the spam filter rejects. Do not include private vehicle or payment information.
Prepare a correction report
This optional worksheet stays on your device. Copy the report into the message field above to send it, or download a local copy. Copying or downloading alone does not send a message.
Use the form above to contact the publisher about a calculation, model row or source reference. The optional worksheet prepares a report on your device. Copy its details into the message field to submit them, or download the report for your own records. Copying or downloading does not send anything.
Report a math or source error
Include the affected page and its formula version. A saved plan is useful because it keeps raw inputs and assumptions, but remove any personal data before sharing it elsewhere. You do not need to provide a vehicle registration, address or payment details.
Record these details:
- Page and version: the page path and formula version shown on the worksheet.
- Input units: inches or millimeters, and cubic feet or liters.
- Driver identity: full model code and manual revision, if relevant.
- Observed result: what the math displayed and what you expected.
- Evidence: the manual title, page or equation that explains the difference. Use a page path rather than a full web address; messages containing web links are filtered out.
Check common causes first
Check whether the target is true net airspace, gross cavity or an included-driver figure. Check that physical driver displacement was not confused with cone swept volume. For ports, keep clear inside diameter separate from outside diameter and whole inside volume.
Do not remove an unknown warning by entering zero unless zero is correct for the design. Keep the original inputs when checking a revised calculation. Rounding in a displayed dimension can also differ from the full-precision saved value.
How to describe a correction
Separate a source transcription error from a model limit. For example, a manual's published tuning is not necessarily identical to a generic equation using an assumed end correction. A report that keeps both labels makes the difference easier to assess.
The About page describes the math checks and published-data limits. Your downloaded report stays on your device. Review any report before sending it through the form. A form confirmation means the message has entered the delivery queue, not that the publisher has read it. The privacy policy explains how submitted messages are handled.