A Look Inside, Technosquare’s Ultimate Street Car Turbo Nissan VQ35DE
by Mike Kojima
Cheston Chiu’s turbo Nissan 350Z is well known in the Nissan Z community as being a fast well rounded machine. Cheston’s car is more than just good looking, its been the runner up in Sport Compact Car’s Ultimate Street Car Challenge placing just 10 skinny points out of first place.
We were lucky enough to be hanging around Technosquare when they were in the process of freshening Cheston’s engine after many street and track miles and can bring some of what goes into his motor to our readers.
It is interesting to know just how stock Chestons motor actually is with most of his parts simply contributing to reliably of his VQ35DE under boost with demanding track conditions. Unlike hot street cars or even cars that see strip use, a track day car must run under peak boost for up to 30 minutes at a time, something much more demanding on an engine that what a street car will ever see.
|The Nissan VQ35DE block is machined 0.5mm oversize for 96 mm Cosworth 8.8:1 compression turbo pistons. With free standing bores, the machining is pretty uncomplicated as free standing cylinders do not distort much when the cylinder head is bolted on like closed deck blocks do. The open deck does not seem to be detrimental to boost sealing or reliability until power levels over 700 whp are reached.|
Cheston’s motor puts out a little over 500 whp @ 18 psi of boost on Technosquare’s conservative chassis dyno using a Power Enterprise twin turbo kit. This equates to around 550 whp on your typical dynojet. The engine isn’t built for big power amounts but to make a broad powerband with long term reliability. So let’s take a look inside and see what makes it tick.
|The bores have a pretty fine finish, around 600 grit hone with plateau honing, just what the Cosworth piston rings need. The deck is checked for flatness and lapped on a surface plate to be absolutely flat. Essential for optimal sealing when using the metal Cosworth head gasket. You can see the nozzles for the piston coolers oil jets. These are stock on the VQ35DE but they are useful for keeping the piston cool allowing it to withstand more boost and resist detonation. Many aftermarket pistons have skirt clearance issues with these nozzles. You have to be careful when assembling engines to check to make sure there is sufficient clearance at BDC to the piston skirt. Cosworth piston are engineered to have clearance.|