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This is my first V6 conversion and write-up on my astra mk4.I never usually bother following my projects online as i don’t usually find the time to make a write-up pretty much but the reason i am writing is to help others with the same conversion as there is absolutely nothing on the web to help. There is only one page i found that had info about the conversion but it was minimal and quite vague and everyone else decided to copy and paste the same info all over other forums and there was no way of being 100% confident on what i was trying to achieve but yes it was of some help though so i am going to fill in the gaps as i go. There aren’t any pictures as most of this work was carried out at night with portable floodlight and i was too busy too worry about them but if anyone needs pics I can take for them :p

I needed to get the following items for the conversion:-

1) Vectra fuel lines from the fuel tank to the engine
2) Astra F23 gearbox
3) Astra F23 mounts
4) Custom drivers side mount
5) Vectra driveshafts (or can use astra ones)
6) Driveshaft 23mm spacer
7) Astra cable shift and stick
8) C20xe flywheel
C20xe clutchplate
C20xe flywheel bolts
C20LET friction disc

9) Astra Throttle cable
10) Astra Accelerator pedal
11) Vectra V6 engine
12) Vectra 3.0 cams (optional)
13) Vectra 3.0 inlet Divider (optional)
14) Vectra 3.8 bar fuel pressure regulator (optional)
15) Vectra wiring loom
16) Pulse convertor to change speedo from 4pot to 6pot reading
17) Vectra ECU, Chip from key and ignition barrel sender unit

My car started life as a 1.6 and i had been busy doing various things to it for a while now as you can see and during winter i decided to store it as i cant use 10” wide tyres in snow lol, so hunting for a donor car i drove 106 miles and bought a black, low mileage vectra B 2.5 V6 to run around in and later convert (which came sooner than i thought) once it had stopped snowing for a couple of days i decided to change the exhaust gaskets as it was blowing so i took the vectra off the road and went to take my astra to work but it overheated on the dualer to work and cracked the block. So pissing of rain left my motor and walked the rest of the way to work and said to myself. I am going to get this done if it kills me

So after a pissed of late night Thursday at work i got both cars home with some help and started my conversion while i used a (hyundai, lol embaressed ) to get around in.
My first job was to get access to the v6 engine, so off with the bonnet, slam panel and front member from the vec and got to work. I unbolted the battery (obviously) I Unbolted the subframe and suspension topmounts, then unbolted the ECU cover and pulled the ECU out from the passenger side cowl panel. There seemed like millions of wires when i cut the wires from the driver bulk side into the firewall but half of them don’t get used anyway, I unplugged the heater matrix pipes and disconnected the powersteering pipes as the astra doesn't need the powersteering pump due too it having electric powersteering.
I disconnected the gearstick rod and then the fuel lines.

Once everything was disconnected i then pulled out the engine along with the subframe and wheels which was easier and gave me a way of moving it around and into the garage.
The next step was the astra. I unplugged the astra loom, removed the driveshafts and dismantled the engine along with its gearbox ( i left the subframe on as the v6 engine was later dropped in from the top ) we had to pull the engine out in bits by hand as i couldn’t get a shot of my neighbours crane at that point. Nightmare getting the block out! Once it was done i decided to paint the engine bay matt black too as it was still silver, then i took the v6 into the garage to get started on it.

It had done around 60,000 miles so while it was out i decided to overhaul it..i stripped it down and replaced the gaskets and thermo ect. I decided to upgrade the power too, you can replace the cams with 3.0 ones and change the inlet divider whilst there but i found it a nightmare getting a hold of 3.0 cams ( they have a G along with two varying numbers stamped on the collar at the pulley side to show that it’s a 3.0) and especially hard to get the inlet divider to up the bhp.
I tried phoning absolutely everywhere and emailed folks and so on and was running outta time and patience so i ended up buying a whole 3.0 omega engine from a breaker to get the parts as they were unwilling to split it.
I built the block up again along with these parts and then timed it...i read alot about how to time it. I almost got it right first time without tools! but lost confidence as the last thing i wanted to do was risk the belt slipping so i bought a timing kit which gets the job done in minutes, well worth the £££, the only pain is getting hold of the 29mm ring spanner for the timing guides (nothing else works trust me, adjustables,molers,NOTHING so dont waste your time)
Job done!

The next step was to detach the gearbox and start on the clutch. I couldn’t use the f25 that came with the vectra as the mounts on the f25 are different to tha astra.the f25 is mounted to the side of the box to the subframe and the astras box is top mounted along with different front and rear mounts. I searched for ages to get an f23 gearbox that most astra mk4’s come with...GSI's, the 2.0 SRI and some diesels, i.e 2.0 di and some others, they use different gear ratios but should all still bolt up okay, i ended up with the SRI box. You can’t use the box from the 2.2’s as the starter motor is on the wrong place (apparently they can be modified to fit but i aint looked into that option) It was another job getting an F23 anyway as they are expensive and kinda rare by the looks of things! I got a good deal on eBay, lucky me. I also needed the clutch cables and gearstick along with the mounting bracket from the top of the SRI box to hold the cables
ADVICE NOTE: change your slave cylinder before bolting back on as my one was faulty when i recieved my box but I didn’t find out till i tried too bleed the clutch, stupid me, i got it changed after a long days work on a Sunday with my pal ripping apart the box after i had already put into the car.
I wanted a lighter flywheel too which some say doesn’t really suit as it stalls easier and is bad on hillstarts, but i think it could just be the driver! But it does rev easier which feels good J so instead of wasting cash on a ‘lightened billet’ one ( £200 or so) I used the same setup recommended as follows.
Use the early flat type flywheel from a (C20XE redtop) as
the newer shape Z20LET fly’s are only a 6 bolt pattern and the v6 engine is 8.
I used the c20xe pressure plate to match the flywheel, but had to use the C20Let turbo friction disc to match the input shaft from the f23 gearbox. The f23 and f28 have diff number of splines from other boxes i.e the f20/f18/f25)
You can also use the whole C20Let setup, but it’s heavier as it has the ‘pot’ type wheel. The pot weighs 9.6kgs, and the flat 6.5kgs, and the v6 is 15.5 god damn kgs. You can’t use the v6 flywheel bolts as they have a bigger head and protrude which can hit the clutch which would be a bad thing! ya have to use the C20Let bolts because they are a flat head.

Now with that out the way it’s time to lower the engine in.
Off with my carbon bonnet and in with the engine crane.
My original Failed plans for fitting the engine before i got the F23 were...

PLAN A- use the F25 with the vec frame...the front monting bolt holes are about 10mm wider which wasn’t a huge problem and the back holes seemed okay, but the problem was that the rear gearbox mount would fowl the powersteering and firewall. Wouldnt fit in a million years so DONT ATTEMPT IT.

PLAN B- was going to be taking down the astra subframe and then putting the engine in from the bottom but there’s too much stuff to unbolt like suspension components and looked like the steering components too which was just hastle i didnt need to deal with

PLAN C- slot it in from the top, surprisingly there is loads of room to get it in and it was easy enough to slot it in (i had the plenums off to make life easier anyway)
once the gearbox mounts were in i used a paddy stand to support the engine as i still had to make a drivers side mount. I used the vectra driveshafts as they are of equal length and give less torque steer which is very noticeable with wide tires. Or ya can just use the driveshafts from your astra F23 if it had one already. The housing on the F23 box is 23mm shorter than the Vecs F25 so you will have to space the driveshaft mount over (i havent found a spacer yet but have emailed a couple of people. I am considering getting my own madeup. Apparently there used for a few other conversions but I aint sure which and cant find them anywhere online! ) and now it will meet up with the mount holes on the back of the engine.

One thing to watch out for when dropping in is the oil sensor next to the crank as mine snapped off on the way down so had to get a new one and its a tight squeeze against the brake fluid resivour
I used the vectra radiator and made brackets for the top mountings onto the slam panel then plumbed it in and connected it up.
The bracket at the drivers side is made custom to fit the mount on the wing. I made mines using 3mm stainless steel so its bloody solid. The astra uses electric steering so there’s no need to use the power steering pump on the engine,there are two ways to do This....
Either use the power steering deletion bracket that you can buy
Or Just loop the pipes on the pump with a small reservoir for oil to keep it lubricated, but this will take up extra room at the front of the bay

Next problem is some astras don't have ABS and you can't get a speed signal from the F23 box so ya have to fit an ABS hub to get a signal from and then connect upto the clocks but the signal is weak without the ABS ECU so you have to run an amp. I had already converted to 5 stud hubs so i had this hub problem sorted
The fuelling was the next thing causing me problems as i only seemed to have one fuel line and the connections for the v6 are two nut type connections to the injector rail.the astras two fuel lines from the tank both go into the same filter and come out as one and the pipe from the filler neck comes out from along side it and to the filter in the front wing.
So i had to take the two fuel lines from the vectra all the way from the top of the astra fuel tank along with its inbuilt filter to the engine.I Ran two fuel filters, one in each fuel line which cant be a bad thing and joint them up according to the vectra setup.
Now for the scary part...the wiring! The wires are wire for wire, vauxhall is good this way.On the v6 there is a whole pile of wires that came from the Vec but you lose half of them anyway as you take apart the loom. I had my dashboard removed at this point which was 100 times easier.

The astra ECU is on the firewall behind the fuse box which is behind the battery. Its a nightmare to get to and its held on with a 10mm bolt. I removed it from the firewall and pushed the rear half into the car and the front half out. Snip the wires from the interior side of the ECU and connect them to the wires at the engine side of the ECU (bypassing the ECU basically) But leave the blue temperature sensor wire plugged into the ECU as the car needs this connected to the original astra ECU to run it as the V6 one won’t read it.
The fuel relays from the vectra loom will go in place of where the astra ones were in the relay box behind the battery and the Main harness yellow fuse can find a spare slot for power in the big fuse box next to it. The rest of the unused vec loom can be removed (eg. The lights and starting/charging parts of the loom.Your mess of wires should be about half of what it was )

Take the following Astra wires needed then connect them to x7 plug and that’s the wiring sorted
(there will be some left over wires.
Anyway here are the Vectra V6 Loom Connectors you will need to sort out.
X7 plug (for instruments and Diagnostics)

1. Red/Blue - Fuel pump.
Wired to the fuel pump

2. Black - Ignition supply to DIS pack
ignition live.

3. Brown/White - Diagnostics Data.
Connected to Brown/White

4. Brown/Yellow - Diagnostics Blink.
Connected to Brown/Yellow

5. Brown/Blue - Engine Management Light.
Wired to engine management light

6. Gray - Traction control
Left disconnected

7. Not Used.
Left disconnected

8. Red/Black - SAI Valve solenoid - Not Used.
Left disconnected

9. Not Used.
Left disconnected

10. Blue/Red - Immobiliser.
Wired up to 7 on Transponder Blue connector (Speed signal to Engine ECU (Transponder signal)

11. Blue - Coolant temperature sensor.
Left disconnected as its running the original astral ECU

12. Black/Brown - Fuel signal.
Left disconnected

13. Green - Rev Counter.
Connected to the green rev counter with inline pulse converter

14. Not Used
Left disconnected

15. black/blue - AC Fan Pressure Switch.
Left disconnected.

16 Brown/Violet Compressor Clutch
left disconnected

17. Black - Coolant pump
Left disconnected.

18. Not used.

19. Not Used.

20. Black - Auto Box Ignition Live.
Left disconnected.

21. Black/White - AC High/Low Pressure Switches.
Left disconnected.

22. Brown/Grey - SAI Pump relay Coil.
SAI is part of the car loom, You have to cut the brown relay plug out of the vectra fusebox on the NS strut and connect a 12v and ignition live connection on brown relay, then join the brown/grey from the relay to brown/grey in the X7 plug (You don't have to, but the engine will still run but will be left with ECU light on all the time).

23. Red/Black - SAI Pump relay Coil.
Left disconnected.

24. Red/Black - Traction Control.
Left disconnected.

X5 starting and charging loom. Just swap over from original astra engine onto the v6, but here's the connectors anyway.

1. Not Used.

2. Blue/White - Alternator D+

3. Blue/Green - Oil pressure switch.

4. Black/Yellow - Ignition to Reverse switch.

5. White/Yellow - Auto Gear Selector.

6. Black/White - Reverse Lights.

7. Not used.

8. Black/Red - Starter solenoid.

9. Not used.

10. White - Auto Gear Selector.

11. Brown/Green - Oil level Switch.

12. Green - Auto Gear Selector.

13. Grey - Auto Gear Selector.

14. Brown - Oil level switch.

15. Not used.

As for the exhaust I just used the vectra downpipe connected to my powerflow system (i got a bolt flange welded onto the end of the astra pipe where i cut the length to meet the vectra pipe)

Make sure you have this all done before starting and do not do what i did and jump start it either as i managed to Lose the code on the ECU. It’s a common thing with jump starting an immobilised car so if you have to jump it make sure you dont do it from a running car or even better just use a fully charged battery
It will idle a wee bit rough though with the 3.0 cams so dont worry about that
Once this is done and everything is bolted back together with the wheels on the ground you will have yourself a V6 astra .

I still have a few loose ends to tidy up and it seems fine at the mo but as you know every conversion has teething problems.

Hope this helps those who need it.
Any questions just drop me a message
 

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Re: Astra mk4 1.6 to V6 conversion

Quite a good write up this mate, be a very usefull thread once all the pics are up too. Is there any particular reason you didnt just use the 3.0 engine instead of the 2.5?
 

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Re: Astra mk4 1.6 to V6 conversion

Very detailed write up. You seem to have everything covered which is a great starting point. Cant wait to see the pictures and updates of this.
 

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Discussion Starter #7
Re: Astra mk4 1.6 to V6 conversion

Very detailed write up. You seem to have everything covered which is a great starting point. Cant wait to see the pictures and updates of this.
thanks paul i will get pictures up tonight if i can.
I do have a 3.0 in my garden now but i want to tune it up and change the pistons and internals to support a half descent supercharger then make it look pretty :)
the 2.5 is just to get me started as its going too be expensive and time consuming rebuilding the 3.0
im just having trouble with the fan at the moment...it aint kicking in so im in process off testing the CTS and stuff. apart from that the conversions finished!

I just hope i can help folk doing the same thing
 

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Re: Astra mk4 1.6 to V6 conversion

when you put the engine in was it the drivers side mounting that had to be altered was there any problems with the other engine mounts?
cheers
 

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Discussion Starter #11
Re: Astra mk4 1.6 to V6 conversion

yeah i still need to get a pic up...the other mounts are all on the gearbox so you dont need too worry about them...just the drivers side mount bud
 

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Re: Astra mk4 1.6 to V6 conversion

Very detailed write up. You seem to have everything covered which is a great starting point. Cant wait to see the pictures and updates of this.
Quite a good write up this mate, be a very usefull thread once all the pics are up too. Is there any particular reason you didnt just use the 3.0 engine instead of the 2.5?
It is considering 99% of its from my write up on aoc and aon lol A little astra g v6 conversion info i wrote - Astra Sport and Astra Owners Club - Mk1 | Mk2 | Mk3 | Mk4 | Mk5 | Mk6 | Astra Van | 888 | VXR - All Welcome

i will get more of the drivers bracket and so on later
Here's a post i replyed to about the mounts a while ago, http://www.astraownersclub.com/vb/showthread.php?t=191587
 

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Discussion Starter #15
Re: Astra mk4 1.6 to V6 conversion

i think you better read my opening paragraph again mate! i was elaborating on what you failed to pick up on...no need to get cheeky!
 

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Discussion Starter #16
Re: Astra mk4 1.6 to V6 conversion

thanks for the comments mike and andy...i still got loads of bodywork to do and it aint a copy of the caliber, i just like wide cars...its going to be original i have a few body mods to alter like bumpers and so on so keep posted. thanks
 

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Discussion Starter #17
Re: Astra mk4 1.6 to V6 conversion

oh and try maybe 15% of what you said...the REST is mine! why get defensive anyway, were all here too help each other
 

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Re: Astra mk4 1.6 to V6 conversion

i got it online a couple years ago but cant remember where...search for i think its GT-1 bodykit but dont hold me too that...it was a **** fit i had to extend the skirts to meet in the middle, redo the whole back bumper as boot shut didnt line up and one side was 2 whole inches short! the front bumper was too short on the top where it sits under the front panel. apart from all that i reckon its worth the effort haha. i still need to spray the thing as paint is in a mess but like i said i have tonnes of tweeks before i go for a spray.
 

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Re: Astra mk4 1.6 to V6 conversion

Great write up there. Where do you connect the black wire to when you cut it out of the loom? It's not got a home to go to, and I'm getting no sparkle.
 
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