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  5. Grok 4.1 FastvsQwen3.8 Max Prime
Updated Sep 2026

Grok 4.1 FastvsQwen3.8 Max Prime

Qwen3.8 Max Prime is the newer model, released after Grok 4.1 Fast.

Grok 4.1 Fast and Qwen3.8 Max Prime compared across 19 shared prompts
SpecGrok 4.1 FastQwen3.8 Max Prime
Input price—$4/M tokens
Output price—$12/M tokens
Context window—1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedNov 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 prompts both answered. Formatting stripped, words untouched.

Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Grok 4.1 Fast385 words
Simplified LBO Model (FY2026–FY2030, $m) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF After Debt Service* End TL End Mezz End Total Debt FY26 972.0 136.1 43.2 21.6 17.8 29.2 0.4 19.1 456.1 183.6 639.7 FY27 1,040.0 156.0 41.1 22.0 23.2 31.2 0.3 33.6 417.9 187.3 605.2 FY28 1,102.4 176.4 37.6…
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Qwen3.8 Max Prime673 words
HarborTech Services (HTS) – LBO Underwriting Memo Entry & Capital Structure Item Amount FY2025 EBITDA $120.0m Entry Multiple 12.0x Enterprise Value $1,440.0m Transaction Fees (2.0% of EV) $28.8m Total Uses $1,468.8m Term Loan (4.0x, 9.0% cash, 1.0% amort) $480.0m Mezzanine (1.5x, 12.0% cash + 2.0% PIK) $180.0m Sponsor…
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Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Grok 4.1 Fast208 words
Pantry Raid Garlic Tomato Pasta A savory, garlicky one-pan wonder that's ready in under 20 minutes—perfect for when hunger strikes and the fridge is empty! Serves: 2 Prep time: 5 minutes Cook time: 12 minutes Total time: 17 minutes Ingredients (exactly 7 common pantry staples): 200g spaghetti or any pasta (2 handfuls)…
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Qwen3.8 Max Prime223 words
🍯 Golden Hour Noodles A sweet, savory, garlicky pasta that tastes like it took way more effort than it did. Ingredients (7) # Ingredient Amount 1 Spaghetti 8 oz (half a box) 2 Butter 3 tablespoons 3 Garlic, minced 4 cloves 4 Honey 2 tablespoons 5 Soy sauce 1 tablespoon 6 Red pepper flakes ½ teaspoon 7 Parmesan cheese…
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Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Grok 4.1 Fast922 words
Technological Implications Immediate Advancements (1920s-1930s): Transistors replace bulky, power-hungry vacuum tubes by mid-1920s. Radios become pocket-sized and cheap by 1925 (vs. 1954 historically), accelerating mass media.
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Qwen3.8 Max Prime2,943 words
The Transistor in 1920: A Counterfactual History Through 1980 Preamble: The Invention Itself The transistor's actual invention required quantum mechanical understanding of semiconductor behavior. In 1920, this theory didn't yet exist.
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Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Grok 4.1 Fast1,106 words
Analysis of Exploitable Clauses Below, I identify all nine clauses as potentially exploitable against the Contractor, explain the risks (how they could be abused), propose specific modifications to make the contract more balanced, and provide legal reasoning grounded in general principles of U.S.
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Qwen3.8 Max Prime2,126 words
Contract Analysis: Exploitative Clauses & Recommended Modifications Executive Summary This agreement is severely one-sided in favor of the Client. Nearly every clause shifts risk, cost, or obligation onto the Contractor while granting the Client broad unilateral rights. Below is a clause-by-clause breakdown.
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Grok 4.1 Fast555 words
1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: Diet, Exercise, and Sleep. These pillars drive longevity by reducing inflammation, building resilience, and optimizing recovery. Commit to small, consistent changes—aim for 80% adherence.
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Qwen3.8 Max Prime473 words
Your 1-Month Foundation Plan A simple, progressive plan built on three pillars. Each week, you add one small layer. No perfection required—just consistency. 🏃 Pillar 1: Movement Why: Even modest activity reduces all-cause mortality risk and improves mood, sleep, and energy within days.
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Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

Grok 4.1 Fast501 words
Solution Claim: "94% accuracy" for decoding neural patterns into text via EEG headband Why it's weak: This is by far the most exaggerated technical claim, as current non-invasive EEG-based brain-computer interfaces (BCIs) for text generation achieve nowhere near 94% accuracy in real-world conditions.
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Qwen3.8 Max Prime834 words
The 3 Weakest Claims in the MindMeld AI Pitch The TAM Calculation (Slide 4) The Claim: "We're targeting the 3.5 billion smartphone users worldwide. TAM: $180B." Why it's weak: This is a textbook example of TAM inflation that will immediately erode investor trust.
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Our Verdict
Grok 4.1 Fast
Grok 4.1 Fast
Qwen3.8 Max Prime
Qwen3.8 Max PrimeRunner-up

Not enough votes to call it. On the specs, Grok 4.1 Fast has the edge: bigger model tier, major provider backing.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Grok 4.1 Fast
Input
—
Output
—
Qwen3.8 Max Prime
Input
$4.00
Output
$12.00
Where to run it

1 host

Grok 4.1 Fast

No hosts listed on OpenRouter.

Qwen3.8 Max Prime1 host
HostInOutContextUptime
Alibaba Cloud$4.00 in·$12.00 out·1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Grok 4.1 Fast is developed by xAI while Qwen3.8 Max Prime is developed by Qwen. You can compare their actual outputs across 19 challenges on Rival to see how they differ in practice.

It depends on your use case. Grok 4.1 Fast and Qwen3.8 Max Prime each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 19 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of Grok 4.1 Fast and Qwen3.8 Max Prime across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Model pages

Grok 4.1 Fast logo
Grok 4.1 Fast59 outputs, specs and price
Qwen3.8 Max Prime logo
Qwen3.8 Max Prime19 outputs, specs and price
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