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Revision as of 10:20, 29 July 2016

How to build a cost effective EFI turbo setup that is upgradeable in the future: Big Power from stock-block A12 can be had by adding a turbocharger. A formula for new-style A12 (1974-1994) has been developed by the legendary sikyne. With unmodified stock A12 it makes 127 HP. This turbo setup on an A12 makes more power and torque than a worked non-turbo A14, for a fraction of the build cost.

A12 Overview

Turbo EFI A12 for under $1200. Build thread
Forum: Turbo EFI A12 for under $1200. Discussion thread post your questions here
A12 Turbo Development thread (for background info)

The $1200 AUD setup uses the standard A12 inlet manifold fitted with a single Throttle Body and a single injector. The ECU is a MicroSquirt V3, which allows for future upgrades like adding multiple coils and injectors later, as well as boost control. Turbo is a single turbo from a twin turbo Nissan Skyline. And there are plenty of Upgrade options if you want more power later on.

Post 476653

80.7 Kw @ 6100 RPM with 12 lbs boost PULP
94.5Kw intercooled with 14 lbs boost (127 hp)
fuel injected with ECU ignition control
2nd-hand GT2860R turbo, upgraded to inconel
Premium Unleaded Petrol, 98 RON octane (92 R+M/2)
stock and unmodified A12 head
stock pistons, crank and rods
standard head gasket

For racing:
* add Oil Cooler to keep temps at 100c

Pluses:
* uses the standard 4-speed gearbox
* uses the standard 1200 diff
* tested with RHD Datsun 1200, may fit others
* tested with new A12 (1974-1994 style)
  will not work with 1970-1973 A12 due to alternator location

Simon: This is a stock A12 motor from eBay. Original round port head, head bolts, standard head gasket, inlet manifold etc. Just 1 injector pointing into the turbo compressor and a 40mm throttle body bolted to the original manifold.

Not needed
* EGO sensor
* O2 sensor
* dyno tuning. A12 outfitted to this formula can use 
  a standardized tuning file

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Think this is great? An A12 can do so much more
An Unmodified A12 short block with stock pistons, crank and rods, and standard head gasket makes 160HP intercooled on E85 ethanol alcohol fuel using stock unmodified H89 A14 cylinder head.

Album 23949

Engine

Head Gasket

Standard A12 head gasket was used (Durapro brand, $18 AUD).

Cylinder Head

Stock late-model A12 cylinder head was used (8.5:1 compression?). Early A12s are 9:1.

A light skim of the A12 head can be done, not to raise compression but to recondition a warped head.

Camshaft

236 deg at .050"

Contact sikyne for the exact cam details.

NOTE: The stock A12 camshaft is 248 degrees "advertised" duration, not duration from .050" lift. Advertised duration is a bigger number, and will be less when measured at .050" lift.

Manifolds

Inlet Manifold

Rather than fabricate a custom manifold, the stock one works well for a road car with a mild cam. On a turbo engine, boost is usually the thing that has the biggest impact on the torque curve. Much more so than intake manifold runner length or even runner diameter.

Unbolt the A12 intake from the exhaust, then fit short bolts into the holes to hold the bottom plate on. 3-bolt shown, some are 4-bolt
Album 13657

The X3 Excel Throttle Body is dime a dozen, easy to adapt and seal a boost hose into the top. They normally run 15 psi.

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Build

Stock A12 intake manifold
Throttle body (40mm) from a Hyundai Excel/Accent X3 SOHC $45 used
Fuel Pressure regulator from a 1997ish Misubishi Lancer or Toyota Corolla $15 used
3-5mm thick alloy plate for the adaptor
1x Fuel Injector (1000cc for petrol)

Mounting the injector, fuel rail and fuel pressure regulator
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Pressure Regulator

TB vacuum taps

Accelerator Cable
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Manifold Heat

Since the formula is not using the standard heated intake system (Heat Riser or water-heated manifold), under light-throttle conditions it may not run perfect.

post: At part load, between 2k and 2500 rpm, it seems to have poor mixture preparation causing the fuel to drop out of suspension. It is fixed by preheating the air going into the throttle body. I don't think it would be a problem if the manifold was water heated or the factory exhaust manifold was still bolted to the inlet. Without preheating the air, no amount of timing change or fueling change fixes it. Its perfect at every other rpm and load.

Exhaust Manifold

UPDATE: For the $1200 formula, any turbo manifold can be used that supports the T2 flange.

sikyne can build you the manifold documented here, but for a price.

The turbo manifold is fairly basic, a variation of a log style manifold, as merge collectors can be a bit tricky and take up a lot more space.

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Post 476642

The turbo is mounted low and rearward, and angled down slightly at the back. It hides well (for that stealth look) and the tilt down at the rear makes the dump pipe easier and cheaper to install and fabricate (less bends, better access).

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Ignition

Use a Hyundai Excel/Accent coil pack.

Post 466920

Recommended ignition module is the two-channel Bosch 0227100200 module.

Ignition timing is: 30deg BTDC at 100Kpa (atmospheric pressure) at peak torque.

Convert a points distributor to a hall input trigger for the MicroSquirt

Stock Datsun 1200 Hitachi OR Lucas Australia distributor
Hyundai Excel/Accent (1995-1999) cam sensor
12 tooth motorbike sprocket ($9) , remove one tooth
6mm allthread (50mm length)
Two 6mm nyloc nuts and one plain nut
Two 6mm washers
Hyundai #coil pack

Post 466514

A Hall-effect sensor is used instead of a simple VR (magnetic) sensor, as the Hall adds a built-in signal amplifier to a VR, producing a stronger signal. This is less susceptible to wiring issues.

Ignition modules can be either two single-channel units like the Bosch 0227100124 or a two channel module like the Bosch 0227100200. You can run 4 individual coils also (if you like the look) by using a 4 channel module like the Bosch 211($$$), but they will still be firing wasted spark (two at one time) when using the MicroSquirt V3.

ECU

MicroSquirt V3 is very capable and costs about $575 AUD. The Micro 'Squirt is basically a MegaSquirt 2 in a smaller package.

If you use this ECU and the same parts (injector, manifold, etc), a tune file from Sikyne is all you need for near-perfect tuning.

You might find less expensive ECUs second-hand, but this is commonly available and can do many things the high-dollar ECUs do, so it has room to grow if you wish to makes changes later on. For example, you fabricate a new 4 injector manifold later. You can run it semi sequential using one injector diver for 2 cyl and the other for the other two. It can also be configured to run 4 ignition coils. Although it won't do sequential EFI like the more expensive MegaSquirt V3, it won't limit power potential.

* Tune file: Contact sikyne

Boost

The MicroSquirt uses electronic boost control to limit mechanical overload of the piston, to avoid breaking the ring lands or flexing the pin and distorting the piston. These stresses are highest at peak torque. The stock A12 pistons have been surviving at 150 lb ft, so to maintain that torque (average cylinder pressure) higher into the rev range requires more boost up high.

Parts

Basic Kit $725 AUD (limited run, no longer available, minimum order 5 kits)

Throttle body, modified to fit manifold and tapped to suit the air temp sensor, TPS and wiring plug.
Inlet manifold, garnet blasted and opened up to fit the TB inc. adaptor plate. drilled for injector. brass fitting and FPR hose.
Fuel rail, bracket, regulator and new $100 large injector
Hyundai Coil pack
Modified distributor, new trigger wheel, Hyundai sensor, alloy cover and bolts, with wiring plug.
Turbo manifold, fully welded
Turbo crossover pipe, Stainless steel
Turbo hoses and clamps

In addition to the kit, these parts are needed:

MicroSquirt V3
Accelerator cable brackets off original 1200 carburetor
Wiring and #sensors
Fuel pump and second line
Turbo and associated plumbing
Post-turbo exhaust
Wiring loom
#Ignition module

Hyundai Parts

parts: The 1995-1999 Hyundai Excel (Accent in USA) is the source for the 1) Throttle Body, 2) Cam Positioning Sensor and 3) coil pack. don't forget to get the wiring harness connectors and a couple of inches of wiring for each of these components.

Turbo

2nd-hand GT2860R (707160-5) ball bearing turbo from R32 Skyline, upgraded with Inconel wheel.

Stock Turbo off twin-turbo Skyline ($100 secondhand) is limited to about 12-14psi because they are made with a ceramic turbine impeller. Much more boost than this, these turbines tend to fly apart. Upgrade to Inconel steel turbine wheel and rebuilt kit is about $380, but allows higher boost.

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Wastegate actuator bracket
Post 476655

Post 476655

Injector

1000cc injector

Sensors

The Delco air and water temp sensors can be found on GM V6 engines and others from the 1990s, get the connectors for these while you are there.

You will also need a GM 3-bar map sensor and connector, but these wont be available at wreckers.

Mount the air temperature sensor
Post 465873

Fuel Pump and Fuel Lines

fuel parts

EFI requires a high pressure pump, at least 14 psi, but usually more like 40 psi. You can use a fuel pump off a Datsun 280ZX, or a generic EFI pump like the famous Walbro: $127 USD and up

The standard fuel pump is bypassed -- just leave it in place, and disconnect the fuel lines from it. Or you can unbolt it and fit a blockoff plate like Nissan 16420-E0100.

Use the original carb feed line as a fuel return line. Remove all these original metal lines from the engine and run hose from the FPR (fuel pressure regulator) straight to the original hard line on the firewall. Removing the standard steel fuel line around the front of the valve cover. Both the feed and return lines follow each other behind the engine. The FPR is positioned so the line points toward the rear.

Post 467154

Relays

The relays have fuses mounted in the top of them to save mounting extra fuses. Just saves a bit of wiring. The fuses are not fitted in the pic.

Post 466920

Post 467154

Required Upgrades

Cooling System

You will need a radiator capable of cooling a 127 hp engine, like the N14 radiator swap. See Radiator Upgrades

* Large radiator
* 71C thermostat
* 16 psi high-pressure Radiator Cap

Clutch

With this much torque, the stock clutch won't last long. See Performance Clutches. Mainly what is needed is a higher-pressure Clutch Cover (the disc type is less important).

Engine Life

At the 11 psi boost level, I'd expect 100,000 km on a road car with sensible rev limits and general good treatment. Or a season of racing. But get something wrong with the tune and it might last 5 minutes if its allowed to detonate.

With moderate boost, the peak cylinder pressure isn't much higher than a non-boosted engine. But the pressure is maintained for more of the power stroke. Because of this, loads on rods and bearings don't go up much. Its more a matter of thermal management, things like pistons and cooling systems can be quickly overcome because the extra time the force/heat is applied per power stroke.

Ring wear would go up a bit because its forced against the bore longer on each power stroke compared to naturally aspirated (NA).

Keeping the standard pistons from overheating is probably the biggest concern. That's where E85 can be a huge help. Good intercooling plays a big part too.

The engine management system can also play a big part in saving an engine. Things like Compensation tables set up to retard ignition as intake temps rise or Electronic boost control backing off boost if EGT's get a bit high.

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$1200 EFI Turbo A12

Revision as of 10:20, 29 July 2016

Contents

A12 Overview

Engine

Head Gasket

Cylinder Head

Camshaft

Manifolds

Inlet Manifold

Manifold Heat

Exhaust Manifold

Ignition

ECU

Boost

Parts

Hyundai Parts

Turbo

Injector

Sensors

Fuel Pump and Fuel Lines

Relays

Required Upgrades

Cooling System

Clutch

Engine Life