Configure TimeBoost

TimeBoost is Arbitrum’s express lane mechanism that gives the winning bidder a 200ms sequencing advantage for each 60-second round. ouroborai includes a TimeBoostBidder that automates round bidding, MEV estimation, and express lane resale.

How TimeBoost Works

Rounds last 60 seconds each
Bidding closes 15 seconds before the next round starts
Auction is sealed-bid, second-price (you pay the second-highest bid)
The winner can submit transactions via timeboost_sendExpressLaneTransaction
Express lane access can be resold to other searchers

Setup

Initialize the bidder

Create a TimeBoostBidder instance with your configuration:

import { TimeBoostBidder } from "@arb-agent/timeboost";

const bidder = new TimeBoostBidder({
  privateKey: "0xYOUR_PRIVATE_KEY",
  rpcUrl: "https://arb-mainnet.g.alchemy.com/v2/YOUR_KEY",
  auctioneerUrl: "https://arb1-auctioneer.arbitrum.io/",
  minProfitThresholdWei: 1_000_000_000_000_000n, // 0.001 ETH minimum
});

Configuration options:

Option	Type	Default	Description
`privateKey`	`Hex`	required	Wallet key for signing bids
`rpcUrl`	`string`	Arbitrum public RPC	JSON-RPC endpoint
`auctioneerUrl`	`string`	Official auctioneer	TimeBoost auctioneer RPC URL
`minProfitThresholdWei`	`bigint`	`0n`	Skip rounds below this expected value

Start the bid loop

The bidder continuously monitors round transitions and bids when profitable:

await bidder.start();

The loop runs every 5 seconds and:

Checks if a new round has started
Estimates expected profit using configured strategies
Fetches the average winning bid from the auctioneer
Caps the bid at 90% of the average to avoid overbidding
Submits the bid if profitable

Stop the loop with:

bidder.stop();

Listen for events

bidder.on("roundWon", (round) => {
  console.log(`Won round ${round} -- executing priority trades`);
  // Submit your time-sensitive transactions here
});

bidder.on("roundLost", (round) => {
  console.log(`Lost round ${round}`);
});

bidder.on("resaleSold", (slot) => {
  console.log(`Sold express lane access to ${slot.buyer}`);
});

Manual bidding (optional)

For fine-grained control, bypass the automatic loop and bid manually:

const round = await bidder.getCurrentRound();
const nextRound = round + 1n;
const bidAmount = 2_000_000_000_000_000n; // 0.002 ETH

await bidder.bidForRound(nextRound, bidAmount);

The auctioneer only considers the most recent bid per address per round. Submitting a second bid replaces the first.

Send express lane transactions

When you control the express lane, submit transactions with priority sequencing:

if (bidder.isExpressLaneController) {
  const txHash = await bidder.sendExpressLaneTransaction(signedTx);
  console.log(`Express lane tx: ${txHash}`);
}

Express lane transactions use the timeboost_sendExpressLaneTransaction RPC method and bypass the standard sequencer queue.

Resell express lane access

Monetize winning rounds by reselling access to other searchers:

const slot = await bidder.resellExpressLane(
  "0xBuyerAddress",
  5_000_000n, // 5 USDC
);
console.log(`Resale valid until: ${slot.validUntilMs}`);

The on-chain TimeBoostVault contract handles USDC collection from buyers. See Contract Methods for the vault’s purchase_express_lane_access function.

MEV Estimation

The bidder includes a built-in MEV estimator that calculates expected round value based on available strategies.

Per-Strategy Values

Strategy	Estimated Value	Risk
`arb`	~0.002 ETH	Low
`liquidation`	~0.005 ETH	Low
`sandwich`	~0.0015 ETH	High
`backrun`	~0.0008 ETH	Medium
`resale`	~0.003 ETH	Low

Using the Estimator

const estimatedValue = bidder.estimateRoundValue([
  "arb",
  "liquidation",
  "resale",
]);
console.log(`Expected round value: ${estimatedValue} wei`);

The estimator subtracts estimated gas costs (~0.00002 ETH on Arbitrum) and applies a historical performance multiplier.

Historical Calibration

Record actual profits after each won round to improve future estimates:

bidder.recordRoundResult(round, actualProfitWei);

The bidder maintains the last 100 round results. The history multiplier adjusts estimates:

Fewer than 5 recorded rounds: neutral (1x)
Average profit below zero: reduces estimates to 0.6x
Average profit above 0.005 ETH: boosts estimates to 1.2x

Auctioneer Stats

The bidder periodically fetches aggregate stats from the auctioneer to inform bidding:

const stats = await bidder.refreshAuctioneerStats();
if (stats) {
  console.log(`Average winning bid: ${stats.avgWinningBidWei} wei`);
  console.log(`Recent rounds tracked: ${stats.recentRounds}`);
}

Stats are cached for 5 minutes to avoid excessive RPC calls.

Getting Started

Agent API

Features

Contracts

Bots

Guides

Configure TimeBoost

How TimeBoost Works

Setup

MEV Estimation

Per-Strategy Values

Using the Estimator

Historical Calibration

Auctioneer Stats

​How TimeBoost Works

​Setup

​MEV Estimation

​Per-Strategy Values

​Using the Estimator

​Historical Calibration

​Auctioneer Stats

How TimeBoost Works

Setup

MEV Estimation

Per-Strategy Values

Using the Estimator

Historical Calibration

Auctioneer Stats