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[mdbs]

New Member. So Hi everyone.

I dont drive an Omega but I am thinking of putting a V6 from an Omega in an MX5 I have lying about.

Reasons for registering, I might need some help down the line with odd details but my first question ( I know its probably the wrong place)  does a manual gearbox from a 2.5 V6 fit a 3.2 V6? And are there any clutch or flywheel issues. Thanks

[serek]

will fit with out of any problems

[Andy H]

IIRC the 2.5 uses the R25 box and the 3.2 uses the stronger R28 gearbox.

My guess is that an MX5 won't weigh enough to stress either gearbox even if you do use an R25 with a 3.2.

[mdbs]

Thanks, that was my thoughts, the MX5 is less than a ton.

[MutantCav]

I would personally thing that the much increased torque from the 3.2 would rip an auto box apart but I dont think it would have the same issues with the manual box...they seem to cope a lot better Should be fine...

[richdrury]

I would personally thing that the much increased torque from the 3.2 would rip an auto box apart but I dont think it would have the same issues with the manual box...they seem to cope a lot better Should be fine...

IIRC anything bigger than the 2.5v6 uses the stronger ar35 autobox.

[mdbs]

I am not going to use an auto, its not right for an MX5 as its a sports car, well sort of anyway.

I am best bid on an Omega MV6 auto, 3.2, but this morning I am not sure I have bought it as the site has not confirmed the sale. We will see later.

This MV6 is an auto so I will sell the auto and buy a manual. But there seems to be lots more 2.5 boxes around. So if I cant find a bigger box I will try a r25.

Another consideration apart from the vehicles weight is the traction available, as I will probably only use 195 maybe 205 tyres as I will not want to modify the arches, the tyres will let go fairly quickly so letting the drive train have a slightly easier time.

Some forums say an MX5 diff will only cope with about 200bhp, so I thinkl I will keep the Omega diff in case I need to use it. Have no idea on the ratio though. I dont need the car to do more than about 135- 140 mph its the fun factor up to those speeds I am looking for. But as I will use 15" wheels that will lower the final drive ratio.

To avoid using a dual mas flywheel is there a standard Vauxhall one I can use?

[Kevin Wood]

Either manual box will be fine, especially in an MX5.

What you might want to bear in mind is that the 3.2 uses an electronic drive-by-wire throttle whereas the 3.0 has a conventional cable throttle.

If you're thinking of using the Omega engine management that might be a consideration. if not, I'm sure the manual throttle body from the earlier V6 could be fitted with no problems.

Sounds like a nice project. Keep us updated on progress.

Kevin

[Martin_1962]

Never heard of any issues with an Omega DMF.

Something to do with a decent amount of cylinders

[Andy B]

Never heard of any issues with an Omega DMF.

 ......

Local Vauxhall parts manager said the Police used to get through DMFs in Omegas for fun, probably due to it not being their car & driving like they stole it - £1000 or so a go.

[Kevin Wood]

Never heard of any issues with an Omega DMF.

 ......

Local Vauxhall parts manager said the Police used to get through DMFs in Omegas for fun, probably due to it not being their car & driving like they stole it - £1000 or so a go.

I think if I were doing a conversion like this I'd ditch it for a conventional, lighter, flywheel, all the same.

Kevin

[mdbs]

With regard to the 3.2, that car fell through, but I have bought a 3.0 off Ebay so heres hoping etc. And its a manual.

Might be pleased the 3.2 fell through as I am not into electronics so thanks for the heads up.

Does anyone have any ideas on the wiring needed to make the 3.0 V6 run? As I will have the whole car I will have access to all parts.

I have been told DMF were fitted to Omagas, I am not a fan, they seem pointless to me. I had a single mass fitted to my wifes TDCi Mondeo and I cant notice any difference.

Also they are heavier I think. I do fancy a lighter one but not sure I can warrant £250 odd for a lightened one.

[Kevin Wood]

Might be pleased the 3.2 fell through as I am not into electronics so thanks for the heads up.

Yes, I think you'll have an easier time getting the 3.0 to run due to the simpler engine management.

Does anyone have any ideas on the wiring needed to make the 3.0 V6 run? As I will have the whole car I will have access to all parts.

You will need the engine ECU, Immobiliser transponder from the ignition keys and the immobiliser module that sits on the ignition lock barrel. These three items are coded together so you need them as a set.

Obviously, the whole engine loom and all ancillaries on it - engine sensors and actuators, Lambda sensors, main and fuel pump relay.

You might as well ditch the whole secondary air injection system although you'll need to load the output of the ECU that feeds the solenoid to stop the ECU complaining.

I have a feeling there's a wire that codes the ECU for auto/manual transmission that you need to take care of. Air copnditioning feed for the clutch relay passes through the engine ECU. Not sure if it gets upset if this is not present. (please don't tell me you're fitting air con to an MX 5  ). On that ECU I don't think there's much else that will cause a problem as long as everything else is wired back up as it was.

Also they are heavier I think. I do fancy a lighter one but not sure I can warrant £250 odd for a lightened one.

I'm not aware of specifics, but I'm sure there will be a combination of off-the-shelf bits that will replace with a solid flywheel without going down the route of a "performance" (read: expensive) aftermarket flywheel.

Kevin

[mdbs]

Thanks Kevin,

some of what you write seems Dutch to me but I hope it will become more plain as I get into it. Can you point me to a wiring diagram?

TBH the wiring was always going to be my weak point. My last conversion was a good old simple Yank V8 with a coil.

And no, no A/C. It does not even have PAS, yet. I will fit a power rack though. No central locking or elec windows either.

Push comes to shove I will MegaSquirt it I think, but I am trying to do it on the cheap. Not sure its realistic but I told my wife about £1000. running. We shall see. I get alot of satisfaction in doing things myself, except wiring lol.

[Kevin Wood]

Thanks Kevin,

some of what you write seems Dutch to me but I hope it will become more plain as I get into it. Can you point me to a wiring diagram?

The one in the back of the Haynes manual is about as good as they get for that system. Can often pick manuals up on Ebay for a fiver or less.

Push comes to shove I will MegaSquirt it I think, but I am trying to do it on the cheap. Not sure its realistic but I told my wife about £1000. running. We shall see. I get alot of satisfaction in doing things myself, except wiring lol.

Ahh.. I have trodden that path a few times too. I have been running a Megasquirt on my Westfield for about 7 years and used to write code for it.

I reckon you should be able to get the stock system working without too much difficulty, though. Megasquirt will come into its' own if you want to tune the engine, of course.

Kevin