10 replies to this topic

[yel327]

This is a pretty straight forward conversion. I'll post up tomorrow and tell you what you need. You can even run the Memcal as a double stacked program and run 2 x spark maps chosen by the position of the LPG switch, allowing for optimal spark on LPG and petrol. Holden actually ran the VP V6 with a dual map on LPG using the 808 ECU that the VQ will have. You use the ECU to shut off the fuel pump so you don't need some of the LPG gear.

[yel327]

OK, this is the basics:

ENGINE.

Remove the sump, pickup, dipstick and engine mount adapters from the VQ engine [check the condition of some of the bearings whilst your there - one of the main bolts has to be removed for the HQ pickup so you may as well check there first].
Bolt on the 253's sump, pickup and engine mount adapters. I'd also check out the welch plugs and the harmonic balancer seal whilst it's upside down. You are best off buying a genuine Holden 1-piece sump gasket (about $25).
If you are keeping standard exhaust headers I would throw away the stainless steel ones and get some late VP onwards cast examples as the stainless ones tend to crack badly. When I did this I used cast headers and the standard HQ dipstick fitted fine, I just had to bend the hold down bracket a bit so it fitted under one of the manifold bolts.
Unscrew the oil pressure sender, and hunt down a little brass T piece off a early red 6 inlet manifold (where brake vacuum comes from) and screw it into the pump. Screw the EFI sender and your guage sender into the T.
Remove the screw in water temp sender under the throtthe body at the front of the manifold and screw your guage sender in here.
Engine done. You'll need a Chev pattern bellhousing so unless yours is a Hadfield dual pattern bellhousing you'll need another. The 253 flywheel and clutch will all fit. Leave the square blade fan on the engine.

ENGINE BAY.

I think the best way to do this is to move the battery over to the passenger's side BUT that means you lose the neat WB washer and overflow bottle. If you are happy to use different ones of these mounted elsewhere, remove the canister bracket and water bottle. Move the battery tray over and drill the holes for it and bolt it in (I think only 3 of the 4 bolts will work).
See if you can find a VN 6cyl in a wreckers and take a battery drill with you and drill the spot welds out that hold the bracket in that holds the engine bay fuse box. Get that bracket and cut the fuse box out of a wiring loom from a VN, making sure you get all the connecors in this area with it. Also grab a 6cyl VN accelerator cable whilst you're there plus an airbox and mounting rubbers. Also grab a charcola canister and it's mounting bracket plus the plastci pipes and joining rubbers.
Sit a battery on the relocated tray (you might have to get a reversed terminal battery - can't remember) and attach the fuse box bracket so it sits roughly right as if it was in a Commodore.
Mount the airbox over where the battery was. it might be easy to fit a battery tray back in and mount it to that.
Put the engine in and either fit the extractors or it will already have the cast manifolds on it. Make sure the engine has the factory battery and EFI wiring harness on it.
Lay the harness out and mount the Map sensor in a convenient location on the firewall. Also mount the spark module in a convenient location. From memory you may have to relocate the coil to the firewall as well.
Use a holesaw and cut a hole the right size for the EFI harness in the passenger's firewall down below the heater box.
Connect up all the radiator hoses etc. You'll be able to use the factory WB V8 radiator but track down a factory V8 shroud.
Mount a radiator overflow and washer bottle somewhere that works (scavenge the wreckers in Jap cars for one that works).
File the speedo cable square hole in the firewall round so it suits the VN 6cyl cable and fit it.
Do some measurements and get an exhaust shop to make you up a suitable stainless pipe to join the airbox to the throttle body using the factory rubbers.
Install the VN charcoal canister over near the battery off the radiator support and plumb it up using the factory VN pipes and also to the WB vent pipe.
Connect the EFI fuel return to the original WB fuel line.
Get the exhaust hooked up - you'll have to tilt tray it to an exhaust shop for this. Get them to weld in a socket for the O2 sensor in a convenient spot. which then plugs into the engien harness.

ENGINE WIRING.

This is where you'll have to get a wiring diagram (Gregory's number 258 is good) and check a few things out. You'll have to do a bit of surgery on the VN fuse box and remove un-necessary stuff. You only really need the EFI relay and fuel pump relay. BUT, if you take a bit of time here you can replace the WB horn and headlight relays with those in the VN fusebox to make it all neater. Also leave the electric fan relay for possible later use. The engine and battery harnesses just plug into the donor VN harness, and these contain the water temp and alternator excitation wires, which you'll have to patch into the WB harness. From memory you'll have to run another wire for the oil pressure guage sender. The fuse box has a jumper wire that bolts straight to the battery so that sorts your EFI power. The car itself wll still pickup power from the connection to the starter motor.
Make sure you change the globe on tha dash for the alternator excitation - get the same wattage as what is in a VN.
As you said there is only about 6 wires or so to connect up at the fuse box to the WB, but I didn't write it all down when I did it so you'll have to figure that part out or get an auto electrician to do it for you if you are not confident
Connect up a wire to the fuel pump relay and send it down towards where you are putting your fuel pump.

CABIN.

Mount the ECU up behind the gloebox or under the LH side kick panel.
Connect to the EFI harness.
Mount a light somehwere on the dash and run a wire over to the EFI harness and connect as per the wiring diagram. This is your engien check light.
Run 12V from the WB fuse box to the pink wire in the VN plug that originally went to the dash. There may be a ground here to connect up too. The speed sensor also connects in here, so run 2 wires from the plug down through the original aussie 4speed reverse switch hole and to near to the speedo cable connection on the box.

SPEED SENSOR.

Buy a CRS speedo T-piece adapter and screw it into the side of the Supra box, with the speedo cable on the end and the original VN/VP speed sensor on the T. Connect it to the wires from the cabin (see above).
You'll have to get the Memcal modified in the ECU for this to work. Get someone to modify the ppk constant for you, You'll have to work out the ppk (pulse per kM) by working out the tyre rolling diameter and converting that into axle revs per kM and multiply that by the diff ratio and then multiply it again by the ratio of the supra speedo drive gear to driven gear and then again by 10 (speed sensor is 10 pulses per rev). That will then be spot on.

FUEL.

The cheapest and nastiest way to do this is as below. You should really use a swirl pot but i'll leave it up to you to research that.

Mount an EFI fuel pump near to the WB ute tank down as low as you can. Install a new high pressure rubber fuel line from the pump to the engine with a high pressure filter in line. Run a normal fuel line from the tank pickup to the intake of the pump using a normal filter between the tank and the pump. You really should install a small low pressure electric pump before the EFI pump to keep it primed and wire it in parallel with the EFI pump. Run a piece of rubber fuel line from the original fuel line to a T-piece in the breather on the filler neck so it returns fuel to the tank. A better way is to remove the sender and get a return pipe soldered onto it.
Connect the fuel pump(s) up to the wire you ran when doing the engine.


Sounds like a lot of work, but if you aren't in a rush it's not hard, just fiddly in some areas.
As for the LPG well you'll need a donut to go in the intake piping. The cheapest and nastiest way is to just get it re-connected up and when running on LPG have the injector pulses turned off via a relay (instead of a fuel switch). The better way is to find a Delco ECU guru and get them to double stack a larger EEprom in a memcal so it has 2 x programs. Buy one of Craig Moates's memcal switches (http://www.moates.net/) so that when you change the LPG/fuel switch the ECU switches programs. You want the LPG map modified so that it has an LPG happy spark map and the injector pulse and fuel pump are turned off. I'm not sure of the legalities of the LPG certification, but you could also use one of the spare VN fuse box relays wired in parallel with the fuel pump relay to turn off the LPG valves when the coil stops firing - this is exactly how the LPG safety switch works and also how the ECU controls the fuel pump relay.

Good luck!

There are a few other things you can do, like fit a VN V6 knock sensor to the block (goes in the block water drain hole) and install a factory patch harness, so you can then run a HSV/HBD 180.185kW program.
Also you can run the factory VN/VP cruise control but if you intend to do that buy a 2 pulse per rev speed sensor instead of the factory 10 pulse as the cruise uses a 2 pulse signal. It all bolts to the engine and you just need a mounting bracket from a factory cruise VN/VP. A few extra switches/buttons on the dash and a WB Statesman 2-pole brake switch (plus one on the clutch pedal) and you are away!

[yel327]

I missed the tacho question. Just join a wire from the 3 pin connector on the firewall near to the brake booster - I think it's 2 x pink and 1 x brown wire - join the brown wire to the little brown wire hanging out of the EFI harness. When you lay the harness out and mark what each plug is for you'll find it. From memory it's a single round connector.

If you are in Newcastle I may have some of the bits you need including Chev to Supra WB V8 bellhousing.

Edited by yel327, 24 October 2008 - 12:43 PM.