28 November 2014

Power and torque specs Part 2 of the 1974 Datsun 160J SSS KP710 Violet Turbo

A thought experiment...

I had earlier mentioned the power and torque figures of the Datsun Violet Turbo as published by Nichimo in one of their 1/24 scale model of the car (The yellow coloured Datsun Violet Turbo).

A measly 300 p.s. at 7600 rpm and 231 foot pounds (32 kg.m) torque at 5600rpm by 2014 standards?

In 1974 this was state of the art running a non-intercooled turbocharger configuration.

I read further that boost with available petrol then was an invariably low figure of 0.9 kg/cm² or about 13 pounds per square inch (psi). I am reminded that Nissan did actually release a production FJ20ET that was non-intercooled initially boosting only 6-7 psi.

I am very pleased with the above figures. Why?

  • I love the fact that this engine produces maximum power at a relatively low maximum rpm.
  • Cam timing (to be mapped out later) would, I believe, be of mild road rally style type duration with very reasonable idle characteristics.
  • This LZ18 could in 2015 be turned into a good mid-range torquey engine.
  • Longer lasting/wearing
  • Less cam gear float/wear problems
  • L18 stroke is a good low figure of 78mm that would stress this engine minimally.
LZ14s and LZ18s of the normally aspirated versions were very high revving engines and there is an inevitable cost to this. Check the valve gear/cam train often for trouble. I've actually magnaflux checked another later model LZ18's valve train and seen cracks develop across the top of the valve buckets! This LZ18 surpasses 10,000rpm uncontrollably in 1st gear. So now I'm happy with a 7600rpm LZ18 :-).

Late model mods I am considering:
  • In 2015, I would replace head bolts with available ARP 200,000 psi items.
  • Replace injectors with late model 700 cc or slightly larger type.
  • One could custom made high silicone forged pistons for it but I've already got old style Cosworth forged pistons made and bore honed to match with Australia's Argo H beam steel rods ready to work. Piston bore is at 89mm. LZ18s are actually 2-litres in capacity.
  • Replace efi to late model speed density with intake air temp/variable fuel pressure.
  • Turbocharger could easily be optimised with a Borg-Warner EFR 6258 series unit or a Garrett GTX3071R
  • Intercooler
  • Late model CDI ignition
  • Fuel and ignition via programmable ecu.
  • Data-logging of many engine parameters

Power and torque to expect:(This is still a thought experiment)

300-380 ps at 7500rpm
231-380 foot pounds torque at 5500rpm
Max. boost of say 0.9-1.5 bar

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