Since 1991, the great debate among Nissan’s S-chassis fanatics has been between the SR20DET and the KA24DE. On the one hand, the JDM chassis’s were equipped with the turbocharged SR engines, offering out-of-the-box forced-induction power from the factory. On the other, the USDM variant received the torquey-yet uninspiring KA24DE engine. Many felt short changed by Nissan’s decision to equip the 240SX US drivers with a truck engine. But as more tuners researched and developed the KA24DE, some began to appreciate the potential that this powerplant has to offer. To really get a feel for the contenders, a detailed comparison was in order. A variety of factors including cost, peak power and dyno graphs will be used to evaluate the merits of each engine. In the end, a greater understanding of these powerplants will guide the enthusiast’s tuning decisions.
By Richard Fong // Photos by Darin John
Originally Published in DSPORT Issue #86
KA24DE
Strengths:
• Iron block is stronger than aluminum
• Greater displacement equates to more low-end torque
• Affordable and readily available since it is a USDM-spec engine
• Superior bucket-over-shim valvetrain
• DOT, CARB and EPA compliant engine
Weaknesses:
• Low factory horsepower
• Not originally designed for racing applications—internals need to be reinforced for forced-induction duties
• Aftermarket support and development is limited due to lack of initial popularity
• Distributor ignition
• Long stroke limits redline
SPEC SHEET
| SPECIFICATIONS: | |
|---|---|
| Engine Code: | KA24DE |
| Displacement: | 2,389cc |
| Bore & Stroke: | 89mm x 96mm |
| Peak Horsepower: | 135.3 whp @ 5,100 RPM |
| Peak Torque: | 148.4 lb-ft @ 4,200 RPM |
| Dyno Type: | Dynojet 248C Dynamometer |
| Pistons & Rods: | 9.5:1 Compression, 21mm Wrist Pin, |
| 53mm Rod diameter | |
| Camshaft Profile: | 232-degree Duration (Intake & Exhaust) |
| 8.9mm, 9.1mm Lift (Intake, Exhaust) | |
| Valves: | 36.5mm Intake, 31.2mm Exhaust |
| Throttle Body: | 60mm ID |
| Injectors: | 370cc/min Side Feed Injectors (x4) |
KA24DE- 135.3 whp @ 5,100 RPM, 148.4 lb-ft @ 4,200 RPM
SR20DET
Strengths:
• Designed for forced induction from the factory – respectable horsepower capacity in stock trim
• Variable cam timing on the intake camshaft (1995 and up)
• Short stroke allows high RPM
• Massive aftermarket support
• Lightweight aluminum block helps chassis weight balance
• Coil-on plug ignition system
Weaknesses:
• Aluminum block and alloy sleeves are not as strong as iron
• Would require resleeving in order to increase bore beyond 87mm
• Lacks low-end torque
• Valvetrain is weak and often fails in stock form
• Peak power is limited by balance between response and power
• Turbocharger sizing determines peak output capacity, however too big and response suffers, too small and peak power is limited
• Not DOT/CARB/EPA compliant for street use; off-road use only
SPEC SHEET
| SPECIFICATIONS: | |
|---|---|
| Engine Code: | SR20DET |
| Displacement: | 1,998cc |
| Bore & Stroke: | 86mm x 86mm |
| Peak Horsepower: | 206.8 whp @ 6,400 RPM |
| Peak Torque: | 191.9 lb-ft @ 4,800 RPM |
| Dyno Type: | Dynojet 248C Dynamometer |
| Pistons & Rods: | 8.5:1 Compression, 22mm Wrist Pin, |
| 51mm Rod Diameter | |
| Camshaft Profile: | 240-degree Duration (Intake & Exhaust) |
| 9.2mm Lift (Intake & Exhaust) | |
| Valves: | 34mm Intake, 30mm Exhaust |
| Throttle Body: | 50mm ID |
| Injectors: | 480cc/min Side Feed Injectors (x4) |
| Turbocharger: | Garrett GT28R |
| Frame: | T25 |
| Compressor Wheel Specs: | 60 Trim, 0.60 A/R Housing |
| Turbine Wheel Specs: | 62 Trim |
| Turbine Housing: | 0.64 A/R |
SR20DET- 206.8 whp @ 6,400 RPM, 191.9 lb-ft @ 4,800 RPM
Challenge Rules:
1. Engines to be tuned on pump gasoline (91-octane)
2. DOT Street tires
3. Reinforced rotating assembly permitted
(rods, pistons, crankshaft)
4. The same size turbocharger must be used
5. Stand-alone engine management permitted
6. Improvements to suspension permitted
7. Improvements to driveline permitted
8. Nitrous-Oxide Injection ProhibitedThe Contest Categories:
1. The Dyno
2. The Circuit
3. The Drag Strip
4. Grudge Match on Circuit and Drag Strip (Richard vs. Jeren)
SR20DET Attack Strategy:
• Level the playing field with a displacement increase and reinforced shortblock internals.
+ Resleeve the block with ductile-iron sleeves bored to 90mm
+ TOMEI POWERED 91mm stroker crankshaft
+ Carrillo connecting rods
+ Mahle forged-aluminum pistons
• Improve air flow through the engine with a performance cylinder head
+ TOMEI POWERED hand-ported cylinder head with combustion chambers custom shaped for larger bore
+ TOMEI POWERED oversized valves with dual springs and titanium retainers
+ TOMEI POWERED 270-degree PROCAM camshafts
• Larger turbocharger
+ Increase the size of the turbocharger to take advantage of the increased displacement and higher flowing cylinder head.
+ Peak Boost top-mount turbo manifold with external wastegate.
+ New intercooler piping
KA24DE Game Plan:
• Reinforce the bottom end with stronger internals
+ Eagle rods
+ JE pistons
• Improve the air flow through the head
+ Port Flow Design ported cylinder head
+ Complete Supertech valvetrain (valves, springs, retainers)
+ BC Brian Crower Stage-3 Race camshafts
+ Xcessive Mfg. intake manifold
• Turbocharger
+ Peak Boost top-mount turbo manifold
+ T3 turbocharger
+ Intercooler and piping
+ AEM EMS ECU
The Challenge
These DSPORT project cars will undergo further development in the coming months in preparation for the contest that will settle the debate once and for all. The rst contest will be held on the dyno for peak power and torque. The second contest will be held on the circuit. A professional driver will pilot each car in order to get unbiased and consistent lap times for each vehicle. The third contest will be held at the drag strip, measuring both elapsed time as well as trap speeds. The data gathered in these categories will determine the victor. The final portion of the challenge will pit the vehicle owners (Richard and Jeren) against one another in a grudge match on both the circuit and the strip to settle the score. Stay tuned.
Follow the KA24 vs SR20 Battle
1) SR20DET vs KA24DE | Which is Nissan’s Best Four Cylinder?
2) D’Garage Silvia | Preparing For the KA vs SR Battle
3) KA24DE vs SR20DET Act II | Preparing the KA for Boost
4) KA24DE vs SR20DET Act III | SR20DET Heads Up
5) KA24DE vs SR20DET Act IV | Port Flow Design Readies our KA24DE Head
6) KA vs. SR Battle: Act V | International SR23 – Built Right And Ready To Fight
7) SR20 Steps Forward, KA24 Gets Knocked Back | KA vs SR Update