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Hi all,

I'm buying an R34 Neo engine and bolting it into my R33 gtst and wanted to know about what to do ect.

The Neo comes with all sensors, manifolds, turbo, coilpacks, power steering pump and ecu but no loom. Can the R33 gtst loom be adapted? Will it fit the Neo ecu?

Do I leave the gearbox in the car and drop the engine in to it or do I take it out with the old rb25 and fit it up to the neo outside the engine bay?

I'll be keeping my air conditioner pump, is it possible to unbolt it and leave it in the engine bay saving me from having to re-gas it?

Is there anyone who has done this conversion who can give me some ideas as to what is involved? Is there anyone in Perth who is bored and will want to help out?

Go the SAU information machine..

Cheers,

Cam

ps - I tried a search but couldn't pull up much..

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well ur frist question was about the engine droping in. well when u take out ur other eninge make sure u put a stand under the gearbox so it doesnt drop. u will have to get under the car anyways to unblot the gearbox from the engine anyways...

about the wiring loom it should work with the standard one now but u might have to spend sum money to get it tuned. ur better off getin the r34 neo loom and ecu.

and fot the conditioner u might have to disconnect it bcoz the hoses will be in the way depends if u take off ur turbo etc from the right hand side of the engine so it doesnt get in the way. to re-gas ur bottle its only like $70. so in my case ill dsconnect the air conditioner hoses saves alot more time

ps u might need sum mates to help u out when unbolting the gearbox from the engine..

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Jet - thanks for the feedback.

I know I'll have to remove the gearbox support and drop it down, but is it easier to leave it in or take it out with the old engine?

So it sounds like the r33 wiring loom will fit the sensors on the Neo engine, just need to look at the plugs for the ecu I guess.

Aircon - I thought it'd probably get in the way...

As for roping in some mates to help out - I'll be definitely needing to do that! :)

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Ian - yup, just found that out. I've located a R33 and R34 engine manual. Handy in telling me that the r33 loom won't work with the r34 engine.. :)

Need to search for an R34 loom. If anyone knows where to get one, please let me know..

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I know it's not exactly the same but I've recently had a Neo fitted to my R31

We found it much easier to remove the RB30 with the gearbox attached to it, and to drop in the Neo with the RB25 gearbox attached to it as well. You do need lots of hands to guide it all in properly without smacking anything though :)

As far as the wiring loom goes, you need the Neo loom and computer there's no question about it.

How different are the looms?

The first thing the electrician said when he came to wire it was "Erm, phuk."

That was coming from a guy who's done a lot on R33 RB25's but had never touched a Neo before then.

Either way he got it running in a day so don't be discouraged :)

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Mark - thanks for the info. Sounds like I'll be pulling out the lot and aligning gearbox/motor outside of the car.

I've got the computer and all sensors so just need to chase down a loom - have checked the R33 plugs and there's no way it'll fit the Neo ecu, not even with a hammer :)

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You'd definetly find it much easier to bolt the gearbox and the engine together out of the car.

Do yourself the service of doing some tidying up in the engine bay whilst it's got no engine in it, that's one thing you learn with being part of an engine conversion :)

When we were doing mine we pulled the Neo out of the halfcut with the loom still on it (Had no reason to take it off), the only thing we did with it was feed it through the firewall for when the electrician went to wire it up, so I can't really offer much insight as to the connections on the engine itself sorry.

Just looking at the engines side by side you can see a few obvious differences. If you still have the RB25 originally from your R33 I'd plonk the engines side by side and just look at them & pick the differences, preferably with an R33 and an R34 service manual at your side :)

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Mark - There will be a bit of time in between removal and fitting so I'll be taking the time to sort out the engine bay. Think I'll be taking some pics and doing up a tutorial too.. Got the service manuals so hopefully that should make things better.. :)

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Righto - I think I've now been able to source a Neo loom, but was thinking that as I'm going to have to try to wire it into the R33 chassis loom anyway, maybe I should just keep the exisiting R33 looms and adapt them to the Neo engine.

Also I've got a Mines R33 computer and have been told that these are remap-able so perhaps I could retain that and save on trying to re-wire for the Neo computer. Can anyone substantiate that the Mines computer will be remap-able?

Ideas? Comments?

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  • 2 months later...

Have finally gotten the R33 engine and gearbox out and now have the engines side by side in the garage. There are some differences but most things seem the same.

Photos of what is discussed below are here: http://members.iinet.net.au/~nunn/Neo/

Differences I've found are:

1. The throttle bodies are very different. The throttle positions sensors are plugged differently and the Neo has a second butterfly on it for traction control. I solved this by swapping the R33 throttle body over to the Neo.

2. The plug for the idle control valve (I think that's what it is - Round cylinder held in by two philips head screws at the back of the intake plenum) is different between the two. I solved this by swapping the R33 valve over to the Neo.

3. Vaccum hosing at the back of the Neo plenum is alot more complex than the R33.

Differences I've heard are:

1. The injectors are different sizes - to be solved by using an AFC.

2. The crank angle sensor is wired differently - Does anyone know if this is true? It looks like I can swap them over, does anyone know if this is the case? Otherwise they are plugged the same so will plug in directly and should work if wired the same. I am swapping over an exhaust cam pulley this week so will post photos once I've taken the cas off.

Aside from what's mentioned above, everything looks like it'll plug straight back in. I've even been able to save draining the AC and power steering pumps by just unbolting the units and moving them to the side. They will bolt straight up to the Neo when it's in place.

If anyone has knowledge about the differences between the R33 and R34 crank angle sensors and if they are the same or can be swapped I'd really appreciate the input. :(

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The s1 CAS is different from the NEO cas though i think the s2 is the same.

Problem is that the keyway is different meaning you cant fit a series 1 cas to the neo engine without modding the cam/cas. EDIT, just looked at the picks. You have a series 2 engine there so you may be able to fit the CAS.

Based on what you have said above i take it your keeping the r33 loom and ecu? Biggest problem i can see is you will lose the constantly variable inlet cam timing of the neo and have it replaced by the on/off r33 vct if it works at all. And that would be a damn shame.

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