diff --git a/cmd-car-split.go b/cmd-car-split.go
index c632757b..9e9d1e55 100644
--- a/cmd-car-split.go
+++ b/cmd-car-split.go
@@ -2,8 +2,11 @@ package main
 
 import (
 	"context"
+	"fmt"
+	"io"
 	"io/fs"
 	"os"
+	"sync"
 
 	"github.com/rpcpool/yellowstone-faithful/accum"
 	"github.com/rpcpool/yellowstone-faithful/carreader"
@@ -32,6 +35,12 @@ const (
 		"\x01"
 )
 
+type FileInfo struct {
+	FileName  string
+	FirstSlot int
+	LastSlot  int
+}
+
 func newCmd_SplitCar() *cli.Command {
 	return &cli.Command{
 		Name:        "split-car",
@@ -78,26 +87,94 @@ func newCmd_SplitCar() *cli.Command {
 			}
 
 			maxSize := c.Int("size")
+
+			var (
+				currentFileSize int64
+				currentFileNum  int
+				currentFile     *os.File
+				fileMutex       sync.Mutex
+				currentFileInfo FileInfo
+			)
+
+			createNewFile := func() error {
+				fileMutex.Lock()
+				defer fileMutex.Unlock()
+
+				if currentFile != nil {
+					currentFile.Close()
+				}
+				currentFileNum++
+				filename := fmt.Sprintf("%d.car", currentFileNum)
+				currentFile, err = os.Create(filename)
+				if err != nil {
+					return err
+				}
+				// Write the header
+				_, err = io.WriteString(currentFile, nulRootCarHeader)
+				if err != nil {
+					return err
+				}
+
+				// Set the currentFileSize to the size of the header
+				currentFileSize = int64(len(nulRootCarHeader))
+				currentFileInfo = FileInfo{FileName: filename, FirstSlot: -1, LastSlot: -1}
+				return nil
+			}
+
+			writeObject := func(data []byte) error {
+				fileMutex.Lock()
+				defer fileMutex.Unlock()
+
+				if currentFile == nil || currentFileSize+int64(len(data)) > maxFileSize {
+					if err := createNewFile(); err != nil {
+						return err
+					}
+				}
+
+				_, err := currentFile.Write(data)
+				if err != nil {
+					return fmt.Errorf("failed to write object: %w", err)
+				}
+				currentFileSize += int64(len(data))
+				return nil
+			}
+
+			processObject := func(data []byte) error {
+				kind, err := iplddecoders.GetKind(data)
+				if err != nil {
+					return err
+				}
+
+				if kind == iplddecoders.KindBlock {
+					block, err := iplddecoders.DecodeBlock(data)
+					if err != nil {
+						return err
+					}
+
+					if currentFileInfo.FirstSlot == -1 || block.Slot < currentFileInfo.FirstSlot {
+						currentFileInfo.FirstSlot = block.Slot
+					}
+					if block.Slot > currentFileInfo.LastSlot {
+						currentFileInfo.LastSlot = block.Slot
+					}
+				}
+
+				return writeObject(data)
+			}
+
 			accum := accum.NewObjectAccumulator(
 				rd,
 				iplddecoders.KindBlock,
 				func(owm1 *accum.ObjectWithMetadata, owm2 []accum.ObjectWithMetadata) error {
-					size := 0
-					suffix := 0
-					firstSlot := 0
 					for _, owm := range owm2 {
-						// create new car file with suffix
-						// write header to car file
-						for size < maxSize {
-							// if object is Block, update firstSlot
-							// write data
+						if err := processObject(owm.ObjectData); err != nil {
+							return err
 						}
-						// write subsetBlock
-						// close file
-
 					}
 
-					//append epochBlock to last file
+					if err := processObject(owm1.ObjectData); err != nil {
+						return err
+					}
 					return nil
 				},
 				iplddecoders.KindEpoch,
@@ -108,6 +185,8 @@ func newCmd_SplitCar() *cli.Command {
 				klog.Exitf("error while accumulating objects: %w", err)
 			}
 
+			// To do: Construct and write the SubSet node
+
 			return nil
 		},
 	}