GeminiCoupe's twin cam

GeminiCoupe · Post by **GeminiCoupe** » 26 Nov 2005, 20:56

Post some pics of what its in etc

I came close to buyinga G200 DOHC for my Gemini a few months ago. Bloke wanted 200 for a mainly dissassembled and missing G200. Turns out it was originally out of a 117 [judging by the oil filter location]. Manifolds [both exhaust and inlet] were missing as was the dizzy. It was apparently an ex-race engine - and he wasnt lieing either.

The cams looked VERY agressive, valves were fucking HUGE. What stopped me? For started i was looking at building a TURBO engine for my Gemini, so the flat tops and huge cams in this engine were useless. What was really worrying though was the head - itd been shaved that far that the base of the valve was actually protruding from the surface of the head when @ TDC [ie. Valve Closed].

Nick-

GeminiCoupe · Post by **GeminiCoupe** » 27 Nov 2005, 12:49

I should point out that i dont actually OWN a DOHC as yet. I am looking at building a G200W with custom made forged pistons, balancing work, headwork, custom made EFI plenum [similar in design to the 117 item] and a GT28RS turbo, however its been put on the back burner until i can find a sollution for the cam bearings and oil supply problems.

Nick-

Robbo · Post by **Robbo** » 27 Nov 2005, 18:42

the standard dohc cams look aggressive... they have 400thou lift... race cams usually have around 490thou lift, and of course a different profile

archangel62 · Post by **archangel62** » 21 Jan 2006, 22:30

Is a race cam very beneficial to the twincams, given this?

GeminiCoupe · Post by **GeminiCoupe** » 05 Feb 2006, 21:36

May be time to formally introduce my car as im picking up my engine tommorow morning...

Bought it off another forum member in a fairly sad state. Was originally a TD SL\E Coupe in a faded-and-cracked Atlantis blue duco. My initial thoughts were to respray it in the standard colour and get it on the road with my Weber-fed G161z however i decided to go the whole hog and havent turned back since.

Begining

Progress

http://img.photobucket.com/albums/v403/ ... ure006.jpg
http://img.photobucket.com/albums/v403/ ... ure003.jpg
http://img.photobucket.com/albums/v403/ ... ure002.jpg

Panelwork Complete

Bodywork is Nissan 350Z Daytona Blue, paintjob was bare-metal and ovenbaked 2pack. Results speak for themselves i think. Also note the shaved indicators, bootlock and antenna.

Its stayed in its current form for a while as i collect bits and pieces and store them. Limited budget you see, it sucks being a student. On top of that i have the Piazza project but thats another story for a later day.

So far i have brakes, seats and ECU covered. The seats are ex-Piazza and despite the ugliness of them are fairly comfy. I have modified the headrests and will be custom making handles, once thats done they should look good in cream leather and suede. Brakes are VZ Commodore discs and calipers, 300mm and 2piston respectively. I will be retaining the 5stud pattern and using the Hoppers Stoppers hub adapters to fit them. These will tie in with my rear end which will consist of a Borg Warner LSD ex-VLT. It will be shortened to fit, however the internals will be changed. The 3.45 Ratio will be made redundant by a 3.89 ex-R31 Skyline, and ofcourse LSD Centre. A mechanical Quaife or Kaaz centre would be nice, but at 2k a pop i may have to wait until i finish my degree. Ill also be modifying the floorpan to accept upper and lower links, and in place of the panhard rod i will be going Watts link.

ECU is an EMS Dual Sport i purchased off a mate, complete with wiring loom and hand controller. This will be running 4 x coils and fuel/ign mode. Hoping to interface it with the standard Distributor.

Now, motorvation.

Engine

Picking it up tomorrow, ex-JR130 Piazza G200WE in dis-assembledness. Engine has been pulled apart however everything is there bar the EFI manifold - gaskets seem to be in good condition too. Apparently cam bearings are good too, all will reveal itself tomorrow though. For $200, cant go wrong anyway. Lack of a gearbox doesnt faze me either, more on that later.

Engine in pieces is a hidden blessing. I will "dummy-assemble" it to get a rought idea of where everything belongs. It will then be fitted in my coupe so i can wire up the ECU and dash loom. At this time ill also be taking measurements as to where my turbo and fuel injection manifolds will sit. Im playing around with a few ideas, like an off-set runner turbo setup [like the Drift SR20T28 manifolds] along with the custom fab'd efi setup. Currently looking at 4AGE 20V or SR20 GTiR throttle bodies with a cylindrical plenum.

Turbo is a toss up between a GT28RS 440hp and a GT30 500hp. The aim is to make about 220-240rwkw while still being driveable/trackable. Expected power range is 3500-8000rpm. Cams and head will also be played with to acheive these results.

Will have pics of the engine 2morrow, sorry about the draining read.

Nick-

archangel62 · Post by **archangel62** » 06 Feb 2006, 02:11

That's sweet as! How are you going to get that kind of flow out of the head though?

I love the body mods - indicators, TX headlights and grill, sedan taillights... The paint

. That thing's going to be sex on wheels when it's done. I've heard the VLT diffs are fairly weak, but I guess replacing it with the skyline ratio and maybe even that LSD centre (yum) would fix that. Sounds like a worthwhile investment imo. I'm definitely going an LSD centre, if I can afford it (and yes I'm aware it will cost several thou). What are you planning on using this car for? Oh and are those AU Falcon indicators? If so, may I ask if they're mounted with screws or clips?

What's happening in the suspension department? I hope they're not stock springs with all that power coming

. I've earned myself the title "Body roll king" already lol. Those sound like big and promising plans for the G200W. How many pieces is it in (i.e. is the head and/or sump off)? The engine sounds as sweet as the car, hope it's in good condition. And btw: it does financially suck being a student...

GeminiCoupe · Post by **GeminiCoupe** » 06 Feb 2006, 08:20

Yes they are/were AU indicators, reverse mounted so the pointy end aims towards the back of the car. All you need is some Stickaflek and they fit, i think even the plug clipped in with abit of fiddling. Tail lights were TD SL\E, I now have TX Coupe tail lights [not on the car] much like your mates. These wont be going on until ive finished modifying the garnish. Ive sanded the plastic grain flate and fitting a recessed ISUZU badge [cut off the G161z cam cover] into the hole behind the stock badge. All bogged/smoothed over and painted in 2pack Asteriod silver. Ill be mounting small Astra clear indicators on my front bumper corners.

There are two types of VL Diffs - the 25spline non turbo diff and the 28spline Turbo/V8 Diff. The later is virtually bulletproof and was also used in the VN V8's and V8 Utes. Ratios can be interchanged with those on the R31 Skylines/Pintaras [ranging from 3.77 to 4.11]. Axles will be shortened commodore as i need the stud pattern. Ive seen the abuse they can handle [alot of mates have Commodores, the most notable being a tortured 155rwkw "mild" VP V8 and a 200rwkw VLT] and beleive me, it will be fine in a Gemini even with me driving. A normal clutch type centre is $600 brand new which isnt too bad, theres a guy in Melb that rebuilds a used one for about the $200 mark with new clutches and bearings. The mechanical centre [which is the one i want] is the expensive one, starting at around $1800. V8 Supercars use these. Very Exotic. Ill be using a clutch type centre until i can afford to make the switch to mechanical. This will be after the car is on the road and after ive finished my gearbox conversion [may do this before i rego the car, might not]

Suspension - knew i was forgetting something. I like being able to corner hence the extensive work to the rear end so rest assured it wont be stock. Front crossmember will be out soon, steering rack will get rebuilt along with getting polished, suspension arms and such are getting powdercoated black. Will be ordering a whiteline adjustable sway bar, springs will be custom made by Centreline to get the right spring rate vs height. New rubber bushes all round except for the swaybar mounts which will be nolathane [dont want any deflection, will delay the response of the swaybar]. Around this time ill be fitting my VZ brakes. Rear end will cop similar treatment, again with the adjustable bar getting nolathane bushing.
Koni adjustables will tie everything up all round.

Your car is a TX right? I suggest before any engine work you buy a wrecked TD-TG. These had the RTS setup. Its a noticeable improvement - different front sway bar and spring rates, stronger diff with a rear sway bar. Put these on and you will feel it.

Nick-

GeminiCoupe · Post by **GeminiCoupe** » 06 Feb 2006, 20:30

Picked up the engine today, have to say im very impressed with the condition of the crank, bores and in particular, the cam bearings! They look as new.

Missing the engine mounts and oil cap though

Nick-

archangel62 · Post by **archangel62** » 07 Feb 2006, 23:26

Don't you hate it when you have tons to say, click reply, and forget all of it?

For the indicators, did you put the globe assembly on the inside of the body? The ones I looked at had a protruding tube bit which I'd imagine would get in the way. I'm now comprehending ripping it off, though... Hrm. Anyway, I'll figure it out.

Does that guy that recons LSD centres do it regularly, or was it a one off? That sounds like a good bet - but how much locking do the clutch type LSDs offer?

I think I'll send you a PM so I don't hijack the thread...

The oil cap shouldn't be an issue, but it makes you wonder about whoever had it last... I once looked at an LT Celica which the guy regularly drove around without an oil cap on - and I got a defect for an oil leak in my engine bay

. I'm sure you could get the mounts off of someone with a spare parts engine, as they wouldn't have any use for them.

GeminiCoupe · Post by **GeminiCoupe** » 08 Feb 2006, 13:39

Its been a while since ive done the indicators, to the point where i cant remember what they looked like. From what i can remember, the Gemini hole is too big and the lense and backing will need to be glued onto the quarter. As for the plug, all that was needed was abit of filing on the backing of the indicator to get it to work. If you can get them just get the plug off the AU and wire that in.

LSD centres will wear, think about the principle it works on. Clutch = friction = wear, it all depends how you treat it though, along with the load its subjected to. Obviously 220rwkw/900kg isnt the same as 220rwkw/1500kg, so it should be good for a while in the Gemini. Im looking at a 12months life expectancy before it begins to single. Not sure what the actual clamping force is although this can be adjusted with the addition of shims.

Nick-

archangel62 · Post by **archangel62** » 09 Feb 2006, 00:50

How easy (how expensive) is it to get a new LSD clutch?