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Revision as of 06:38, 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. Unmodified short block with stock pistons, crank and rods, and standard head gasket makes 160HP.

1 A12 Overview
2 Fuel
3 Turbo
4 Head Gasket
5 Cylinder Head
6 Camshaft
7 Boost
8 Inlet Manifold
9 Exhaust Manifold
10 Ignition
11 Sensors
12 ECU
13 Engine Life

A12 Overview

See:
* Turbo EFI A12 for under $1200. Build thread
* Forum: Turbo EFI A12 for under $1200. Discussion thread
* A12 Turbo Development thread See how he got to the $1200 A12 Turbo EFI

The basic initial 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 (there are plenty of Upgrade options if you want more power later on).

160+ rwhp @ 15 lbs boost(standard H89 Head)
fuel injected with ignition control as well
$1200 AUD
2nd-hand GT2860R (707160-5) ball bearing turbo
E85 fuel, intercooled
stock and unmodified H89 head
Cam: 236 degrees at .050 lift
600cc Siemens injectors
Maximum advance at 16 psi boost: 23 degrees
ARP head studs
stock pistons, crank and rods
standard headgasket
E85 fuel
71C thermostat
16 psi high-press radiator cap
about 120 Lb. ft. from 5100 to 6800 RPM @ 15 psi

dyno chartAlbum 23949

For racing:
* add oil cooler to keep temps at 100c

* uses the standard 1200 air cleaner assembly
* uses the standard 4-speed gearbox
* uses the standard 1200 diff
* clutch?
* tested with RHD Datsun 1200, may fit others
* tested with new A12 (1974-1994 style)
  may or may not work with old A12

Not needed
* EGO sensor
* O2 sensor
* dyno tuning

Fuel

E85 alcohol fuel is superior to high octane pump gasoline for turbo applications. Similar to, but more available and less expensive than Racing Gasoline. It's also legal for highway use where racing gasoline is not.

Lambda is set to be .86 at 100Kpa richening to .75 at 175Kpa

Turbo

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.

GT2860R (707160-5)

Upgrade to Inconel steel turbine wheel and rebuilt kit is about $380, but allows higher boost.

Head Gasket

Standard A12 head gasket was used (Durapro brand, $18 AUD)
ARP head stud kit

Cylinder Head

Light skim of the H89 head, not to raise compression but to recondition the used head.

Camshaft

236 deg at .050"

That's probably one of the biggest reasons it was falling over as much as it was after 5800 RPM (increased the boost past where peak torque was to keep it holding torque). Its actually increasing from 16Psi at 5500 up to 22psi at 7200 to keep the torque curve climbing slightly.

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.

Boost

16 psi @ 5500
22 psi @ 7500

Under electronic 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. If I ran 22 Psi everywhere, the cylinder pressure could be too high for the pistons.

The 150 Lb Ft torque figure is derived from torque at the axle, divided by the diff ratio. so its like the engine torque, but not including the driveline losses.

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.

Post 464761

The X3 Excel TB's are dime a dozen, easy to adapt and seal a boost hose into the top. They normally run 15Psi.

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; 1300+cc for E85)

Mounting the injector, fuel rail and fuel pressure regulator
Post 465339

Pressure Regulator

TB vacuum taps

Exhaust Manifold

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.

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).

Ignition

Coil on Plug ignition was used to generated the 160HP. But a move to ordinary coils and leads makes it easier. Use a Hyundai Excel/Accent coil pack.

Ignition timing is: 30deg BTDC at 100Kpa (atmospheric pressure) and 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

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.

Sensors

1995-1999 Hyundai excel is called the Accent. This is the car the US guys will be looking for the Throttle body, cam sensor and wasted spark coils. don't forget to get the wiring harness connectors and a couple of inches of wiring for the TPS and cam sensor.

The air and water temp sensors(Delco)can be found on GM V6 engines and others from the 90's, 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. Ignition modules will also be needed. 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), but you will need a 4 channel module like the Bosch 211($$$), but they will still be firing wasted spark(two at one time) when using the Microsquirt.

Mount the air temperature sensor

Post 465873

ECU

MicroSquirt V3 is very capable and cost 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. You could do 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 wont limit power potential.

Engine Life

Engine life, is an interesting question.

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 is 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.

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.

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$1200 EFI Turbo A12