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HKS Forged Pistons and Connecting Rods for Nissan GT-R
HKS have released their awaited forged pistons and conrod package for the VR38 engine recently as a compliment to their GT800 turbine upgrades. Designed to offer high durability, the HKS pistons are also designed to cope with much more power than standard.
Before getting too steeped in the technical specs, let’s run over the highlights of the HKS forged piston product. These pistons offer the same bore x stroke of the OEM pistons meaning the same displacement volume and that they’re a direct fit. What does change is the crown volume (concave) which increases from 4.49cc per cylinder to 8.01cc. This has the effect of decreasing the compression ratio from the standard 9.0 down to 8.7. Thanks to the forged hollow channel construction, the HKS pistons also weigh in at 25 grams less than the OEM items (420g vs 445g).
For full specs for the pistons and the conrods see the data below from HKS. For pricing, contact your HKS distributor for local pricing but expect to pay around 367,500 yen if you’re in Japan for the full set.
| Â | HKS Product | OEM | |
| Bore x Stroke | 95.5 X 88.4mm | 95.5 X 88.4mm | |
| Compression Ratio | 8.7 | 9.0 | |
| Â | Gasket Thickness | HKS t 0.8 | t 0.80 |
| Total Displacement (cc) | 3799 | 3799 | |
| Piston | Bore | 95.5 | same |
| Compression Height | 34.30 mm | same | |
| Concave Crown Volume | 8.01 cc | 4.49 cc | |
| Material | Forged (hollow channel) | Cast (hollow channel) | |
| Reference Weight | 420 g | 445 g | |
| Pin | Dimensions | 23 X 60mm | 23 X 62.5mm |
| Rings | Dimensions TOP B | 1.2 mm | same |
| Dimensions SEC B | 1.2 mm | same | |
| Dimenstions OIL B | 2.0 mm (3 pieces) | same | |
| Conrod | Small End Dimensions | 23mm | same |
| Big End Dimensions | 59mm | same | |
| Length | 165.1mm | same | |
| Material | SCM treated | Cast Steel | |
| Reference Weight | ~722 g | ~724.6 g | |
| Weight Variation | less than 1.0 g | – | |
| Bolt | M9 X P1.0 / 14.9T | same | |
Mine’s Super Response Complete Engine and Turbos Launched, Priced
Well it’s been quite a while since we got to experience first hand this Super Response monster that Mine’s have born out of their Yokosuka workshop. The time has finally come though that the Mine’s VR38 is ready to officially go on sale with full published specs.
We have said much of the emotional and overview stuff back in our January first impressions so those that are truly interested in this beast should go back and review our article from then to get a feeling of how it goes.
Link: Mine’s Complete Engine First Impressions by GTRBlog.com
If you’re interested just in the raw numbers and specs, here they are straight from Mine’s. First up let’s talk pricing. The Super Response Complete Engine will cost you 3,465,000 yen in Japan provided you trade your original OEM engine. If you can’t supply an engine then Mine’s can supply one for you but at a total cost of 5,565,000 yen in Japan.
Add the Mine’s Super Response Turbines to these and you’re looking at 3,990,000 yen with OEM turbo trade-in or 6,615,000 yen without engine or turbine trade in at the upper end of the scale.
For that money you get a out of the box engine utilizing all of Mine’s know how including…
| Mine’s R35 GT-R Super Response Complete Engine | ||
| Part | Material / Specifications | |
| Cam Gear | Lightened | |
| Cam Shaft Shore Pro | IN 256°/ LIFT 10.2 mm | |
| EX 264°/ LIFT 10.5 mm | ||
| Shim | Space Adjustment | |
| Valve Spring | Uniform Rating | |
| Valve Guide | Phosphor Bronze | |
| Valve Seat | Resurfaced | |
| Seating | Modified | |
| Valve Re-surfacing | Modified | |
| Port Surface Smoothening | Modified | |
| Ignition Chamber Machining | Modified | |
| Head Polishing | Modified | |
| Head Deburring | Deburring | |
| Head Gasket | Original Metal Gasket | |
| Head Bolt | WPC Application | |
| Crank Cap Bolt | WPC Application | |
| Piston | Original Forged Wrought Aluminum Alloy Pistons | |
| Connecting Rod | Super Light Weight Titanium | |
| Connecting Rod Weight | Detail Minute Balancing | |
| Crank | OEM Modified/Lightened | |
| Dyanamic Balance | ||
| WPC Application | ||
| Crank Pulley | Balancing | |
| Crank Bearing | WPC Application | |
| Block Polishing | Polishing | |
| Block Deburring | Deburring | |
| Thermostat | Low Temperature Thermo(68 degrees C) | |
| Spark Plugs | NGK(#9 equal) | |
| Mine’s Turbine Data Sheet | |||
| TURBINE WHEEL NAME | GT-R OEM | MINE’S ORIGINAL | |
| COMPRESSOR SIDE | BACK SIDE DIAMETERf(mm) | 56.0 | 71.00 |
| INLET DIAMETERf(mm) | 43.4 | 51.20 | |
| TRIM VALUE | 60 | 52 | |
| NUMBER OF BLADES | 12 | 12 | |
| TURBINE SIDE (EX) | BACK SIDE DIAMETERf(mm) | 53.0 | 52.85 |
| EXHAUST DIAMETERf(mm) | 39.8 | 46.07 | |
| TRIM VALUE | 57 | 76 | |
| NUMBER OF BLADES | 9 | 9 | |
| CUT BACK | PRESENT | ||
| POSSIBLE POWER OUTPUT (PS) | approx 600 ps | approx 800 ps | |
| PRICE | 526,000 yen | 690,000 yen | |
| REMARKS | STOCK TURBINE TRADE-IN | ||
For more information on all of the above, or to contact Mine’s, head over to their website linked below…
Link: Mine’s R35 GT-R Super Response Complete Engine Website (English)
Gruppe-S VR38 Stroker Crank Officially a Work In Progress
When the Hankook Dynamic AutoSport Gruppe-S Nissan GT-R drift car debuted at SEMA in 2009 we were fortunate enough to get an advanced preview from Dynamic Autosport’s Eddie Kim on what we could look for in terms of GT-R development. He mentioned that on top of the drift car’s chassis development they’d also be putting some focus on the VR38 development itself.
While they aren’t set on using the VR38 in the drift car just yet, (they’ll most likely be opting for a worked VQ engine), they’re very much going to be developing parts for it including a 4.0 – 4.3 liter stroker kit.
First up in the development of such a kit is to build a crank. That’s what’s happening right now and is expected to be completed in around a week. Pistons and rods up next we suppose and it should all slide nicely into their sleeved block. Should be an interesting competitor to the existing JUN 4.0 liter stroker kit which is quite a pricey item…
Link: Gruppe-S Blog
Forged Performance’s First Set of Arias FP Spec Pistons for Nissan GT-R
Forged Performance have been seeing great results using Arias FP Spec pistons in their VQ motor builds for years now so they decided to spec out and order a set up for a VR38DETT build they’re carrying out for a customer.
These are made from Zero Silicon Aluminum for maximum strength and feature tool steel offset wrist pins, and a pressure seal groove. They’re moly coated for lower friction and are capable of supporting a 1000hp build. The specs are 95.5mm, standard bore and built for a 9.0:1 comp ration.
Forged have these in stock in 95.5m so if these sound like something that might interest you, hit up the guys at Forged Performance to have a chat to see how they can help you…
Link: Forged Performance Website
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