Gemini TD Sedan - Daily/track hack

[F3ARED]

Figured I may aswell post the car up now that im on the forums fishing for info.

I bought this one mid 2008 after my previous Gemini dislodged its bonnet at 100kmh. This was 2weeks after id resprayed it, and 2days after I got the DOHC in it. To say i was ******* ****** off would be an understatement. So at the tender age of 21 i was now on Gemini number 8 [gee theres been a few].







Typical little old lady car, completely un-molested and came with a whole stack of reciepts and paperwork, including reciepts for all the engine machining, respray circa 1995 etc. I usually RUN away from Geminis that have been sprayed but it was so clean and solid [solid part yes, clean no - oooops ] that i had to grab it. So in all its angry G161z Auto glory it breezed through its RWC and i was off on the road. Had promised the previous owner it would remain standard....didnt realise just how bad/slow the SOHC auto combo was, especially after id just sold my previous daily [modd'd S15 200sx] which didnt help. So...

I lasted all of 3months before i did this -





While the car in general was clean, the interior [with the exception of the seats] was pure filth. So that came out and abit of a clean up was done...







...and this was slotted into the bay.





1x G200w EFI ex-JR130 Piazza. Was previously running on a Haltech E6k with crappy 4-2-1 extractors and that rotted dual-butterfly 'thing' Isuzu calls a throttle body. Turfed that for a VS V6 65mm item, got it retuned and made 82rwkw. As for how it went - ******* well! Used to suprise the crap out of alot of people, especially as i was still rolling around on the 165/75 pizza cutters and hubbies.







Unfortunately it didnt last. Driving down the western ring road one day it started knocking. Knowing the engine was now stuffed I turned the music up and kept going, until the knocking was now persisting over the radio. And then the oil pressure light, which had been glowing for the last 15mins, flashed twice and it was all over, eerily silent as it rolled to a stop on the side of the freeway.

What ended up happening next was I had a slight brain snap and went crazy with the car. Rebuilt the head on the original motor, bolted a 5spd to the back of it....and got carried away bolting more stuff to it. Ended up like this:











Completely standard G161z save for a set of heavy duty valve springs, ran it on 17psi and spun it to 7500rpm. Took it like a champion although I had no end of stupid problems. Clutch went after the dyno [like, 35km after], tail shaft bolts rattled loose, a ball joint fell out [that scared the crap out of me], some oil seals went, wastegate got jammed on 30psi [that was fun ] it started rattling. But still it went, and for a good year and a half too. Until the rattling and oil leaks got unbareable, i parked it and got a 4X4 and promptly forgot about it. Tried selling it but the problem with Gemini people is they dont want to pay for anything. Couldnt sell it for 3k, and that was with the monster turbo [genuine garret 500 roller], EFI, mint interior, mint body except for one quarter panel etc. So i left it sit in the drive way.

After what was possibly the 15th arguement with my dad about it sitting in the driveway [sat for 6months] we made a bet - if i could start it within 15mins, hed give up his side of the garage and the Mercedes would live outside. Jumper leads on for 15sec, started first crank.

After pulling it apart and stripping the engine down, ended up finding the cause of the rattle.



The old bloke that owned this was a retired mechanic, except he mustve had a brain snap because reciepts for the crank showed 20/20 os....and the big end bearing said STD 0.00. It shouldnt have even had oil pressure but testament to how tough these engines are, the oil light never went off [maybe it didnt work ], it went HARD and it only started rattling in the last 3months. Fair effort.

Unfortunately, this was worrying me.



After abit of excavation...





Crap. The bad? Itd been rear ended HARD at some point, so hard it was actually 10mm short on the LHS. The good? Despite two little spots in the rear beaver panel, it was rust free. Sent it out to my panel beater to get it pulled on the jig, he sent it back....and i went crazy.









Almost ready to paint the old girl after a year of frustration. Colour is antelope [light metallic gold] as per my old mans first gemini, and our first family car.

Engine wise:









Nick-

[Glenn]

interesting story there Nick !

those butterfly's look nice. Are they from from the Nissan GTIR ?

and you have spare pair too... (hint)

glenn

[F3ARED]

Its abit quiet at work today so i thought id bore myself and whoever is reading by writing that up

Yep they are GTR items....pretty damn good too! Centre-to-centre they are the same distance as a webber carb and the G series DOHC which is handy, plus being a plate-only setup they are pretty thin and give you the freedom of mounting the injectors where you feel like it. For $180 i cant complain!

Unless your doing a 2cyl the last plate is useless

[Glenn]

Don't have a 2 cylinder but interested in some dimensions. Just what is the centre to centre dimension?

can you post more pictures of them, eg from the top etc.

Be interested one day to fit EFI to a Bellett engine.....

where did you get them from ?

There are advantges and disadvantages on where to place the injectors and runner lengths etc for more torque etc. Off the top of my head i have no idea, would have do some searching.

glenn

[F3ARED]

Centre to centre is 90mm, identical to the G series DOHC's. Will have to get some more piccies, need to clean em up first seeing as the oil burning 'zilla they came off has made them filthy.
Depends on which one you want to EFI - easy as with a SOHC or DOHC as theres a whole heap of bolt-on Isuzu stuff

As for the injector placement, its kind of a hot debate over on Ozgem. Ill be placing these as close to the butterfly as possible whilst still being downstream of the butterfly. Reasoning below:

To elaborate:

E. Where is the best place for the injectors?

For performance at low RPM, economy and low emissions the injector needs to be close to the valve and firing at the back of the valve head. This is the favoured position for production vehicles.

As per most standard OEM/Factory EFI setups - injectors are generally as close to the port/flange area as possible. Example - Rodeo 4ZE1 manifold. Injector seats are roughly 2" from the port entry [been a while since ive looked at one]

For higher RPM (very approximately 8,000+) the injector needs to be near the intake end of the induction tract to give adequate mixing time and opportunity. The higher the RPM, the further upstream the injector needs to be. As a result, use of speeds above approximately 11,000 RPM may give best results with the injector mounted outside the inlet tract altogether (see our remote injector mounting). It is common to fit both lower and upper injectors in such a system to cover starting and low RPM as well as high speeds.

Refer to picture below:



The above describes systems where the injector is placed PRIOR to the butterfly, generally fitted with one injector as race cars spend their time on full throttle. Not suitable for a street car as the fuel pools when the butterfly is closed and the driveability at lower rpm is shithouse. The only example i can think of that uses the dual injectors is the Nissan R390 GT.

Where one injector is to be used per cylinder the best compromise position is immediately downstream of the butterfly. This gains maximum advantage from local turbulence and gives results surprisingly close to the optimum at both ends of the rev-range. This is the recommended position for most applications.

This is what i was referring to - positioning the injector just after the butterfly but away from the port. For example, if my throttles are placed 400mm from the port then the optimum as described above is to position the injectors just under this. Lets say i can place them 50mm from the throttles, this would mean injectors are 350mm from the port.

Nick-

[oz_toffa]

Thanks for sharing all those great photos.

love following the journeys that our fellow car owners make, good to see the start and the finish...

love classic Gemini's too




cheers

OZ

[redback]

WOW - and I though I was into Gemini's when I was younger.....


Nice work (a couple of times) on bringing back better than new (and faster)

Cheers

[F3ARED]

Thanks fellas. My family will tell you im sick but its my dads fault - he had two over the course of the years, taught me to drive in them etc. Didnt help he banned me from buying the HQ monaro i was looking at when i was 15 - apparently there was no way he would let me pay $4000 for a 35yr old rust bucket. Oh how times have changed!

Good to see people appreciate the gems - they seem to be abit love it or hate it if im honest. The people that love them love them, the people that hate em...wellll....
Seeing as todays quiet i might post some photos of the other Isuzu's ive had up.

Some more Gemini crap...



Rear door and front chin spoiler finished





And heres an ordeal id much rather forget - my girlfriend calls it the drivers door from hell.



...to this



....



Nice and straight....



...until my dad dropped it face down on some paint tins. FFS! 3weeks down the drain.

[redback]

It is always quicker the SECOND time.........

Thanks for the stories and photos.

Neil

[F3ARED]

Figure it might be time for an update on the car itself, as soon the engine will be going together and ill be on here more frequently asking stupid questions.

Early September it went to jail.





I laid the basecoat down, screwed up the clear so got the beater to reclear it. Came up pretty good by the end of it.

[redback]

Love those rims dude!!!

[dave]

Hey man, I like that you've stuck to an original colour. I like original! I also like sleepers....

Nice work! There are a few Gemini people on here sort of... I've still got my TD Panelvan but it got sick again in 2011 and hasn't seen the light of day again... and I imported a Buick Opel by Isuzu from the USA for shiz and giggles. I'm still awaiting the final stage of my grand shed/carport extravaganza, so that's currently with GToo keeping his GT company!

Cheers,

Dave

[F3ARED]

Havent done much on this, been too busy with reno's to my house and working on the girlfriends Gemini. Just a little teaser then...

Before.





After porting.





Now has HD springs from an Alfa DOHC along with new guides and big, reground cam sticks.

[flying]

Love your work

With the reground cams what specs are they?

I see on the gem site they mention L1 and L1 with L1 being the preferred option

Cheers Flying

[F3ARED]

I have no idea where people get thisn "L1" grind from. Every time I've asked someone no one either knows the specs, or no one has even heard about it. This includes Alfa people [their DOHC is very similar].

Cam grinds are the biggest i could go without re-welding. Duration is 292 advertised / 242 @.050", timing is 34/78. Lift is .3830.

With the 4x 45mm butterflys and 4 coil setup im hoping for 110ish rwkw.

[flying]

Agree

trying to find consistent data on how to make these go is difficult

I 've been trawling the Japanese sites to glean info from, seems a lot use Toyota 2tg data

http://www.microsofttranslator.com/BV.a ... 2548732%2F

your build sounds great

Cheers Flying

[Glenn]

Agree

trying to find consistent data on how to make these go is difficult

I 've been trawling the Japanese sites to glean info from, seems a lot use Toyota 2tg data

http://www.microsofttranslator.com/BV.a ... 2548732%2F

your build sounds great

Cheers Flying

We used 2TG shims when re-building a DOHC way way back.

Somebody local must know how to extract power from these engines as DOHC Gemini's were raced here as we know.

[F3ARED]

The shims are the easy bit as getting some made up is relatively cheap/inexpensive [i think it was something like $8 a shim]. The unfortunate part is though, despite the fact they were raced here, reliable info is veeeeeeeeeery scarce. Have spoken numerous times with different people and the "L1" thing comes up heaps of times...yet when you press for more details there is no idea. The fact the bloke was quoting torque figures obtained on a dyno [LOL!] should have indicated the lack of knowledge. Anyone with half an idea wouldve realized the torque multiplication through the gears makes torque readings inaccurate but anyway...

When i first started this build i did as much homework as I could, including a half hour conversation to Phil Brock about the Group C ZZ/R they raced. That didnt turn up much other than Bruce Garland was basically given a catalog from Isuzu and they just went tick-tick-tick. Tried getting a hold of Bruce to see if he'd remember anything but no dice.

Did look at 2TG/18RG engines because the head is very similar on these but alas same issue - most info is in Japanese, and any info in Aus is thorough unreliable. You'd ask someone for cam info and you'd get yeah ive got HKS #333....so what are the specs? Duration? Lift? Uhmm...

In the end I just sat down with the engine builder that did the headwork and had a chat about limitations etc. Agreed on a cam spec based off an Alfa DOHC grind, he ported the head to suit and we go from there. For those playing at home/after valve springs, search Victor Pace - Alfa specialist. The Alfa springs are smack bang perfect for high lift cams in terms of seat pressures etc and cost $160 posted. He did say he had worked on the Isuzu DOHC's before and that they did outflow the Alfa heads whilst being very similar.

Since then, i have managed to find someone that actually rallied a ZZR in the early 90s who seems to know what hes talking about. His concerns [besides the hemispherical chambers] are the exhaust ports flow too well in these engines which can cost power. Kanaris did mention this also and i think ported the head to suit.

[Glenn]

do you have a year or whatever model range for the Alfa engines ?

Maybe a small turbo or blower would be simpler all round for more power.

[F3ARED]

I think it first appeared in oz mid 65 and ran through till about 82ish just prior to being replaced by the twin spark model. Was used in pretty much everything from GTV's to the Alfetta.

Boost is always simpler....but then again, so is just using a G series SOHC. Wanted something different that revved, and something i can set up to handle right.

Been watching too many japanese cartoons i think...hope i dont regret this!