# Rotax MAX Jetting vs GridCall

The clearest difference is update cadence: GridCall at every 5 days against Rotax MAX Jetting's every 3 months. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Rotax MAX Jetting ships an update every 3 months, GridCall every 5 days. The most recent releases landed on October 24, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | Rotax MAX Jetting | GridCall |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[1.9 (8 ratings)](https://appshunter.io/ios/app/rotax-max-jetting/id1152315347/reviews)** | — |
| Number of ratings | **8** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 5 days** |
| Monetization | Free | — |
| Size | 13 MB | 8 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | iPhone, iPad | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [BRP-Rotax GmbH & Co KG](https://appshunter.io/developer/1152315346) | [Asymptoticsolutions LLC](https://appshunter.io/developer/1892503809) |

## What reviewers say

### Rotax MAX Jetting

[App page](https://appshunter.io/ios/app/rotax-max-jetting/id1152315347)

This app helps users find the ideal carburetor main jet size for Rotax kart engines. It calculates settings based on ambient conditions like temperature, altitude, and air pressure, either automatically via GPS or manually. Supports various Rotax MAX engine types.

**Highlights:** Optimal main jet calculation, Supports multiple Rotax MAX engines, Automatic GPS weather data, Manual ambient parameter entry, Celsius/Fahrenheit toggle, Meters/Feet toggle

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### GridCall

[App page](https://appshunter.io/ios/app/gridcall/id6801165000)

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Rotax MAX Jetting free?

Rotax MAX Jetting is free to download, with no in-app purchases.

### Is GridCall free?

GridCall is free to download, with no in-app purchases.

### Do Rotax MAX Jetting or GridCall have ads?

Neither Rotax MAX Jetting nor GridCall shows ads.

### Which is updated more often, Rotax MAX Jetting or GridCall?

Rotax MAX Jetting ships an update every 3 months, and GridCall every 5 days. Most recently, Rotax MAX Jetting was updated on October 24, 2026 and GridCall on October 3, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*