(ENGINE) SHORT BLOCK VR38 4.3L STEP Pro+
ENGINE BLOCK COMPONENTS
【SHORT BLOCK VR38 4.3L STEP Pro+】
VR4.3L STEP Pro + short block is strengthened for stages that require even higher torque
Concept
Capable for high torque, the VR43 STEP Pro+, contains special designed I-beam con-rods which have a high buckling strength compared to the H-beam con-rods. In addition to the specifically designed crankshaft and to further enhance the torsional rigidity. The pin diameter have been enlarged, and by adopted an asymmetrical design, the cross sections between pins #5 and #6, where stress is the highest, have been reinforced.
In response to the increased weight of the pin section, the counterweight was redesigned to improve the balance ratio.
Features
- As with the STEP Pro, the material for the crank is made of high-end racing grade nitriding steel. Exclusively for the STEP Pro +, the crank is treated with ion nitriding, which increases surface strength and toughness that are required of high cycle performance crankshafts.
- By increasing the inside corner radius to 3.5 and enlarging the crankpin to D57, the structural torsional strength is improved.
- The newly developed, billet I-beam con-rods improves bucking strength by 26%.
- The front end of the crankshaft is extended 10mm to prevent crank pulley fretting.
- Designed specifically for the STEP Pro+, the pistons are coated with a special double layer coating, which is effective for both high-load and high-speed sliding.
- HKS original oversize main stud bolts are used
- Chrome Molybdenum is used to create the #2 and #3 journals to increase durability.
- Line boring process is done to ensure the roundness of the main journal
- The main bearing and connecting rod bearing were selected after numerous tests.
-
Crank pin diameter and inside corner radius are enlarged to increase torsional rigidity.
(Only available for STEP Pro+) -
Newly developed Billet I-Beam connecting rods that improves buckling strength by 26%.
(Only available for STEP Pro+) -
Double-layer coated lightweight billet piston made from highly hear resistant A2618 alloy (Only available for STEP Pro+).
-
I断面コンロッドに合わせて専用のオイルジェットを3Dプリンターで制作
-
＃2・3のベアリングキャップをクロモリ材で作り替え強化しラインボーリング加工で精度向上
諸元
| HKS 4.3L | 純正 | |
|---|---|---|
| ボア | 95.5mm | 95.5mm |
| ストローク | 99.0mm | 88.4mm |
| 圧縮比 (t=0.8) | 8.6 | 9.0 |
| 許容回転数 | 7,400rpm | 7,000rpm |
| 排気量 | 4,255cc | 3,799cc |
SHORT BLOCK VR38 4.3L STEP Pro+
| ブロック加工内容 | #2・3クロモリ材キャップ |
|---|---|
| クランク干渉部の逃がし | |
| メインベアリングネジサイズのアップ | |
| ラダーキャップの穴拡大、座繰り | |
| ジャーナル穴のラインボーリング | |
| ホーニング | |
| メインボルト | HKS M12スタッドボルト (625+) |
| ピストン | HKS 削り出し（専用2層モリブデンコート） |
| コンロッド | Pro+専用 HKS削り出し I 断面 |
| オイルジェット | Pro+専用 3Dプリンター製造 |
| クランクシャフト | Pro+専用 窒化鋼削り出し イオン窒化熱処理 ピン径拡大φ57、フィレットＲ拡大品 ダンパー取り付け部延長 |
| メインベアリング | ACL |
| コンロッドベアリング | ACL（幅狭加工） |
| クランクプーリー | VR43専用ダンパー |