My 1983 Isuzu Piazza

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Tommei
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My 1983 Isuzu Piazza

Post by Tommei »

Hi everyone,

This is my first Piazza. Ive wanted one for a decade and finally had the chance to own the right one. Its a 1983 model running a G200Z EFI motor. Fully imported from Japan for the Sydney Motor Show before the Piazza went on sale in Australia.

Its had a little bit of work done as shown in photos, some of you may recognise this car as well. As this car has an early 2000s period theme, I do plan to keep it mostly in theme with some of my own touches. The car drives ok and visually presents very well. As it has been sitting for a number of years, I plan to give the mechanicals a good freshen up and restore as much of the mechanicals as I can.

Since my ownership last week, I have given the car a quick tidy up and detail. As it is an imported model with a different motor and automatics are rare, I do need some help with finding mechanical parts.

Does anyone know if the G200Z EFI uses the same air filter as the 4ZC1-T Piazzas? What gearbox does it run? Are the ignition parts exactly the same as the carby G200Z models?

Cheers, Tommy

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IZU069
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Post by IZU069 »

Dang! Thought it might have been the G200W Piazza I saw at the Melbourne Motor Show in 1980.

Alas I'm only guessing the following answers to various degrees of confidence...


The gearbox should be the same as other GZ series and 4Z series engines (ie, not its GW twincam alternative, nor other G-series). If auto, it has the same ratios as Geminis but has the added 4th gear etc.
I suspect it has a lower ratio Salisbury-type diff (~3.5?) as opposed to the 4ZC1-t 3.9 "Isuzu" banjo types.

If it's like the G200Z manual Piazza I visited in Byron Bay it has an I-TEC EMS as opposed to Aussie 4ZC1-t Piazza Bosch copy. (I was surprised it had a mechanical dizzy as does the 4ZC1-t!)
I mention that so you are wary of interchanging sparts with local Piazzas.

Otherwise I'd expect its G200Z parts to be the same as others. Certainly bearings and bores etc though it will have a different oil pickup & sump to steering-boxed G200Zs.
Pistons may vary (domed vs flat etc) and it may have larger intake ports being EFI (though that may only apply to the G200W which was a dedicated EFI engine).
IZU069 - ISUZU means a lot to me.
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Post by Piazza_man »

What's the engine bay and interior like? Any pics?
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Tommei
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Post by Tommei »

IZU069 wrote:Dang! Thought it might have been the G200W Piazza I saw at the Melbourne Motor Show in 1980.

Alas I'm only guessing the following answers to various degrees of confidence...


The gearbox should be the same as other GZ series and 4Z series engines (ie, not its GW twincam alternative, nor other G-series). If auto, it has the same ratios as Geminis but has the added 4th gear etc.
I suspect it has a lower ratio Salisbury-type diff (~3.5?) as opposed to the 4ZC1-t 3.9 "Isuzu" banjo types.

If it's like the G200Z manual Piazza I visited in Byron Bay it has an I-TEC EMS as opposed to Aussie 4ZC1-t Piazza Bosch copy. (I was surprised it had a mechanical dizzy as does the 4ZC1-t!)
I mention that so you are wary of interchanging sparts with local Piazzas.

Otherwise I'd expect its G200Z parts to be the same as others. Certainly bearings and bores etc though it will have a different oil pickup & sump to steering-boxed G200Zs.
Pistons may vary (domed vs flat etc) and it may have larger intake ports being EFI (though that may only apply to the G200W which was a dedicated EFI engine).
Thanks for the great info! Was it 1980 or 1983 when it was displayed? Would you happen to have any pictures? It used to be silver in colour, and is now painted in Ford canary yellow.

This ones a 4 speed auto with overdrive, all Piazzas came out in Australia with manual and turbo as far as I know?

Not too sure about the differential, it may be different as you mentioned, is the diff in this one any stronger?

The fuel injection system is the ECGI multi point fuel injection system, not too sure about the differences, but I think the I-TEC came on the G200Ws? Any idea what type of ignition coil I would be looking for as a replacement, the one on the car looks like it could do with a change.
eyecon wrote:What's the engine bay and interior like? Any pics?
The engine needs a bit of a tidy up, however is pretty much factory untouched and original. Interior could do with a good detail, but it presents neatly with the Aussie turbo front seats. Still have the original Jap spec rear seats. Analogue dash and a badge that states its an XL model, which matches the specs of the car.

P.S. Eyecon, I almost bought your Piazza years ago when it went up to sale but you beat me to it hahaha. Good to see its gone to a good home and enthusiast!

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1983 Isuzu Piazza
1985 Mazda RX7
1983 Subaru Leone hardtop
1985 Nissan Bluebird TRX
1985 Mazda 626 turbo
1992 Toyota Cressida
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Post by Piazza_man »

Thanks for the extra pics Tommy. The interior still scrubs up good even without the detailing. Lol I wasn't aware you were going after David's Piazza too. I personally think I paid too much for mine, considering the amount of things I had to fix up, but as they say 'you live and learn'. Either way you still have one sweet ride. I find that yellow suits the car and it really is a retina popper (in a good way). A true stand out. I've seen other yellow cars out there on the www, probably from Japan, and they just don't quite do it for me. It must be the large chrome wheels that's the difference. Pity we're not closer to catch up over coffee and trade ideas/info. But if you ever are up my way make sure you let me know.

Not sure of the exact ratio (and I defer to some of our other more skooled colleagues out there) but I would say about 50% Aus spec Piazzas were Autos, so parts might not be an issue. And all autos came with non-limited slip diffs.
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Post by Tommei »

eyecon wrote:Thanks for the extra pics Tommy. The interior still scrubs up good even without the detailing. Lol I wasn't aware you were going after David's Piazza too. I personally think I paid too much for mine, considering the amount of things I had to fix up, but as they say 'you live and learn'. Either way you still have one sweet ride. I find that yellow suits the car and it really is a retina popper (in a good way). A true stand out. I've seen other yellow cars out there on the www, probably from Japan, and they just don't quite do it for me. It must be the large chrome wheels that's the difference. Pity we're not closer to catch up over coffee and trade ideas/info. But if you ever are up my way make sure you let me know.

Not sure of the exact ratio (and I defer to some of our other more skooled colleagues out there) but I would say about 50% Aus spec Piazzas were Autos, so parts might not be an issue. And all autos came with non-limited slip diffs.
Yes, yours is nice in a different way, more subtle and lots of mechanical goodies. I grew up idolising the Autosalon days as a kid, so this style is quite nostalgic for me. Everyone keeps asking whether Im keeping the wheels hahaha, which I am. Usually chrome just isnt executed right on cars, but its done right on this car.

The car also has custom lowering springs made up, Im yet to find out the specifications, but the body sits right on 10cm off the ground, thankfully the underbody mechanicals dont poke out further than the bodyline.

Thats handy info to know, would be nice with an LSD though. Likewise if youre ever down in Melbourne, it really is a niche community these days. Eitherway, there will be plenty of updates to come!
1983 Isuzu Piazza
1985 Mazda RX7
1983 Subaru Leone hardtop
1985 Nissan Bluebird TRX
1985 Mazda 626 turbo
1992 Toyota Cressida
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Piazza_man
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Post by Piazza_man »

It's so refreshing to have like-minded guys willing to share their rides and contribute on this forum. Keep it going Tommy. I'll be posting stuff up soon myself.

LSDs are rare these days because they poached by the Gemini folk. So if you happen to come across one hold onto it. And the tailshaft as they're a different length than autos.

Yes the rims look ideal but i suspect it could do with more offset to fill out the guards a bit more. I hope I'm not out of line here Tommy.
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Post by IZU069 »

Ditto, nice pics. And nice car! VERY nice.

The G200W Piazza i saw was in 1980. I have a couple of pics but they are on this ancient technology called "prints" unless I was still using slides, but I do recall a hardcopy (print). I should be able to find it and scan etc but they are probably of limited value. I think one was of the digidash and the other from the front with bonnet down. And quality is limited - probably taken on my Minolta 16mm camera and underlit.

Your dash is analog. That is rare here and often sought my many due to troubles with digidashes (not surprising after all these years; capacitors alone tend to dry up after 20 years...).


And yes, your EFI/EMS is ECGI which (afaik) is the typical licensed Bosch jetronic system (JECS? JIDEC?) with a mechanical dizzy.
All Piazza G200Ws were ITEC with the locked optical dizzy and electronic ignition timing. (All G200Ws were EFI but the 117 used mechanical dizzy and a Bosch. Trivially though there were "never" any (factory) G161W EFIs, there were factory prototype 117 G161 EFIs which literally used Bosch - injectors, the EMS, and even a Bosch JFUX 4 dizzy with its extra 2 injector-bank switching points. A mate has one of those factory 117 EFI prototypes.)

All Aussie Piazzas were the ECGI 4ZC1-t turbos. 700 units were imported. Manuals have LSD whereas autos (afaik) were open diff. (Yes, there were autos, and they were the 4-speed types.)

The Aussie Piazza had the typical Isuzu diff - ie, banjo type compatible with all solid axle Isuzus from circa 1965 until the 4ZE1 2.6 EFI circa 1989 though diff ratios vary - ie, typically 3.9 for passenger cars (4.1 for Florians) and tyically 4.55 for commercials (Wasp, Rodeo, Jackaroo). IE - they were not the torsionbar Salisbury/BorgWarner types like Geminis and earlier Piazzas. (The Piazza was built on a Gemini. The 117 was build on a Florian.)
FYI - though all pre-4ZE1 diff banjos interchange - eg, I had a 1985 Jackaroo LSD in my 1965 Wasp (Bellett ute) - crown & pinions may not. IE - Florian crowns were 8 bolt whereas Piazza, Jackaroo & Rodeo (and I believe LUVs and KBs) were 10 bolt. But most crown & pinions otherwise should though I have yet to confirm... I haven't yet retrofitted my scavenged auto Piazza open diff 3.9 crown & pinion into my Jack/Rodeo LSD banjos.

But I suspect your diff is the BW/Saliisbury type as was the 83/84 G200Z Piazza I recently inspected. (Damn - I wanted its ~3.5 ratio gears for my Florian!!)

Strength wise I'm not sure. Though I'm keen on the bigger 4ZE1 diff for my 400Nm Florians - in part for their disc brakes - I'm not sure it's warranted strength wise. I did twist a 5-speed Gemini box's output shaft (and I never did burnouts!) but even the old Florian diff (with Bellett 8-bolt 3.7 crown & pinion) presented no problems. And I've heard of 500HP machines using pre4ZE1 banjos/diffs without problem -not that they had anywhere near the torque I had (300Nm @ 2,000 RPM).
But yours is not the banjo type.
There are lots of writings on other forums about Gemini diff upgrades (eg OzGemini) but many such writings are suspect. ("Poida" on OzGem and elsewhere summarised & clarified the different Gemini diffs. I'm not sure what he wrote about their strength.)


As to your dizzy and igCoil, the normal solution for GZ engines - and ANY G-series engine for that matter (ie, G-OHV, GW twincams, & GS Jap SOHCs) - is the "RG" dizzy which is a Gemini points dizzy transplanted with (early) FWD RB Gemini reluctor guts and ignitor using the RB subharness to/with RB ignition coil if not later igCoils (E-types etc).
But I'm certain yours is already electronic though it probably uses the same antiquated multi-piece reluctor and inferior ignitors that early systems used (eg GWs).
WRT the different advance curves I have generally found all G-series to be overlapping in specs so RG swaps aren't a big issue. But my view in recurving mechanical dizzies is to NOT - use an electronic timing unit instead which you can remap yourself later. The initial cost may be similar but the mechanicals wear and you can't "reprogram" their curve.

You may be able to swap direct for an RG setup. Unlike the 4ZC1-t which has limited advance (being turbo, ie ~5 degrees??) and knock sensor interaction - and the 4Z dizzies run the opposite rotation anyhow - I think yours is completely standalone.
The only issue is RPM sensing for the EMS but that is either from the ignitor output (which is the same as points and generally the same for all - ie, ground firing) else from the reluctor and the RB/RG reluctor should be compatible with all (being a lower impedance than older systems).

Alas I'm not sure of your ignitor capability - early ignitors (and shit systems like Peteronix points conversions) still required igCoil ballasts else were limited in current capability (RB ignitors incorporate current limiting so ballasts can be discarded) - but otherwise I'd say for Pete's sake don't get a can-type igCoil. Modern transformer types (E- & C-type etc) shit all over cans though I know some sites say otherwise. (I'd like to investigate such claims but I couldn't be bothered; I found enough flaws in their other statements and arguments.)
BTW - use NGK splugs. Else NGK splugs. Or NGK. (Get the point?) There may be the odd exception where better splugs exist, but from one that gets over 100,000km from the st'd NGK BP6ES (gapped to 1.1mm) from an RG system in a 1969 G161-OHV that cold starts with a battery voltage of 5.2V, I reckon the RG and NGKs are bloody fine.

And don't get sucked in by fanciful systems. Last year I saw a terrific Gemini but it had a $995 Scorcher dizzy (eg, Holden Gemini Isuzu Electronic Dizzy HEI Distributer Conversion G200, G180, 2L). Whilst I question the performance of such as system compared to the RG, this Gemini had it firing a can-type igCoil! (Was it chrome-plated to boot?). For that money I can convert OEM G200Ws to the 400Nm build!

And a clarification to all readers: When I have mocked Bosch GT40 igCoils for modern use I meant the can types. There are GT40 E-types which fall under the (IMO) acceptable/good modern igCoil category.
And a comment - I've seen much written about igCoils and the interim use of ballasts (and hence 2-terminal "cranking" ignition switches) and their reasons yet many seem oblivious to the inductance of those "8 volt" ballasted ignition coils etc.
And whilst current limiting ignitors may make any igCoil seem usable, such ignitors may require dwell limitation - ie, put an unballasted GT40 direct on 12V and it may last 15 minutes or longer; do that to a Bosch MEC717 or MEC723 (like I was using on my RG) and they'll be lucky to last one minute. Many modern EMS - especially with COP systems - have dwells dependent on RPM.


I hope my short reply is of some use. :yawinkle:
IZU069 - ISUZU means a lot to me.
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Post by Skrilla »

Looks great,good luck!
If you boost it,they will run!!
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