My black forged Piazza

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IZU069
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Post by IZU069 » Sat Dec 01, 2012 11:55 am

Funny - I was going to ask that.

It should be done up front by offsetting the stub axle. That is quite legal because it has no (geometry) impact on steering.

The other issue is that usually the best steering (etc) is at the standard suspension height. (Except for crap cars, but we are talking about Isuzu. However I am uncertain just what GMH did do to stuff up the Piazza's handling.)
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Post by archangel62 » Mon Dec 03, 2012 1:04 pm

Thanks for the replies, much appreciated as always. Eyecon you have a PM about those springs! Ideally I'd like the top of the tyres to sit about level with the guards, or maybe have up to 10mm vertical clearance. I'm not super bothered by the legality because we can get these things approved if need be, and cops here would have no idea what they're doing when it comes to an Isuzu-badged Piazza :D plus, we don't have regular inspections yet, only random roadsides.

Peter - agreed on the dropped stub axles being ideal for geometry, but the standard springrate is absolutely horrid anyway, it's about half of what I'd like to even it up with the rear (by weight) and/or make it turn. I've been told there may be lowered stub axles interchangeable for Geminis, and therefore possibly Piazzas, but that's a whole new can of worms. Being that the standard setup bump steers and handles generally fairly poorly anyway, I'm not too bothered and will just lower it! Having said that, if I ever get reeeally bored, I might consider offsetting the tie rod end points to maintain correct angles/lengths, and I haven't ruled out bigger front brakes and steering lock spacers anyway (the latter of which would also compromise steering angles somewhat).

Oh, and I've basically finished repainting my front Isuzu badge, which was generously donated by Eyecon (you bluddy legend), hopefully it'll be on within the week!
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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eyecon
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Post by eyecon » Mon Dec 03, 2012 4:01 pm

Appreciate the recognition Eli. PM sent back mate.

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Post by Bugle » Mon Sep 30, 2013 10:40 pm

This just popped up on youtube, and your Piazza was on TV!
http://www.youtube.com/watch?feature=pl ... HsAT0#t=57

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Post by Piazzish » Tue Oct 01, 2013 5:11 am

Cool! Good to see a piazza in use!!
1989 Isuzu Piazza Lotus Turbo Red 92000km
1989 Isuzu Piazza Lotus Turbo White 183000km
1987 Isuzu Piazza Pre-Lotus Turbo Red 131000km
1984 Isuzu Piazza JR130 N/A Black 126000km

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Post by archangel62 » Tue Oct 01, 2013 5:02 pm

Bahahaha guilty as charged! It was banked up for miles ahead and no-one let me change lanes til then... Ahh well lmao I'll have pics of the car up soon... Aaaaand hillclimb and roadtrip videos should be up within a week, I'll link them in this thread!

So, bit of an update, I recently bought some Koya AE Tek 15x8s in +15, with stretched 175 rubber on them. Polished lip with gloss black centres - they look decent! I got these second hand and finally put them on the car. They fill the guards well, though the fronts get very close to the shock - clear by a few mm at full extension (most severe point of travel). In hindsight I'd have gone 0 offset on the front, maybe +5 at the rear, but beggars can't be choosers.

As posted elsewhere, I also figured out what was causing my power issues over 4500rpm. The little black plastic cube that regulates the vacuum to the fuel pressure reg (the reg mounted on the shock tower) wasn't working properly, so I bypassed it and gave the reg a direct vac signal and it now pulls great to about 6000rpm. Finally! Hooowever, the turbo manifold cracked in a big way, affecting the mating face to the gasket, and it's just been band-aided with exhaust cement.

I'll be out-sourcing to a workshop ( :o ) to have my Garrett GT2860RS "Disco Potato" turbo and aftermarket manifold fitted soon - I don't want to tackle custom piping, water and oil lines myself right now. I'll be taking it to Jaustech, hopefully in the next 2-3 weeks, though it'll be there for a few months I'd expect. I'll also be converting to Microtech in the process, fuel and spark, as well as 450cc hose-tail injectors from a Merc that I've just had serviced (they're rated at 380, but they flowed 450 at 3bar!!) - oh and a larger twin-butterfly throttle body that came with one of my G180W engines. It's almost identical to the Piazza item but the bigger butterfly is a fair bit larger, and there are less vac line fittings on the bottom. It bolts right up, so I'm portmatching it and it should help improve flow. The Microtech will also get rid of the AFM.

The reasoning behind keeping the C1 plenum and runners, as well as the factory FMIC and some of the piping, is that I want the engine bay to look *relatively* original. Obviously the aftermarket turbo and manifold, pod filter, lack of AFM and EGR, and some sections of aftermarket piping won't look original, but at least it'll still look like a "Piazza" under there - not just a generic 4Z or G series turbo setup. I'm sacrificing a little power in the process, but I should still be seeing around 180rwkw with a bit of luck, with good response, and the ability to reverse it if I'm ever so inclined (doubtful). I'll feel less bad about butchering a classic if it's paying homage, and reversible.

On that, the loom modification is taking place predominantly after the big green joiner plug to the inlet manifold etc, and I have a complete spare set. It will be a case of unbolting one inlet, bolting on the other, and plugging it in, with only a couple of wires having to be changed on the loom itself... so easy to reverse if desired, and the standard ECU will stay fitted and partially functional, for things like Idle Air Control for cold starts.

Besides that, I've just thrown the rail-type window reg on the passenger side (thanks Wedgenut!) and will be doing the driver's side soon. I gave the lower sections inside the door a quick squirt of rust-proofing Cold Gal while I was at it, re-fitted the waterproofing liner (with the help of half a roll of duct tape.. lol) and modified the speaker mounting bracket to take a 6.5" VDO split speaker. The grille "should" go back on, and then I'll need to find somewhere unobtrusive to stick the tweeters and crossovers. I've fitted rear 6x9s in wooden boxes behind the seats - again, to avoid cutting stuff.

I'm starting to really love this car!

P.S. Epic post is epic.
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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Post by Bugle » Tue Oct 01, 2013 11:17 pm

Outsourcing work on a Piazza sounds expensive!

Weird that a G180W throttle body would be larger, I always thought the Piazza one was so small because it was originally designed for a n/a G180W.


The ECU doesn't control cold start idle speed, that is what that stupid thing hanging off the bottom of the intake manifold is for. It just needs 12v and it gradually closes itself as it warms up. You shouldn't need the old ECU in there at all.

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Post by archangel62 » Wed Oct 02, 2013 10:49 am

The throttle body could also be off of a 4ZE1, I'm not sure - but it's identical besides the larger butterfly being bigger. I'll have a look at one of my other twincams when I get around to my TE Gemini twincam build - it's wrapped in about five bin bags at the moment to shield it from the elements!

Good to hear that that IAC runs itself. I assumed the signal was from the ECU based on coolant temp or something - but a mechanical device is much easier. I won't rip the old ECUs out if I can help it, but it's nice not to be relying on them.

Yeah, the work I'm outsourcing is just making up turbo piping and a dump pipe, as well as coolant and oil lines for the new turbo. Oh, and the tune. It's probably a bit beyond me, and I'd rather someone with experience makes up some nice piping, than me make a hack-job out of stainless, or a million silicone joins lol. It will cost a bit - probably $2k-$3k, but it'll be worth it. With a few other odds and ends (like the tighter LSD Elky sent me, front springs and rear shocks) it will finally drive like I always wanted it to. One day (in a galaxy far, far away) I might even get a doors-closed respray to make it look a bit nicer too, since the paint's on its last legs.

I also need to fit a front brake upgrade that I'd bought for a Gemini. They're Magna rotors with Commodore calipers, and the calipers foul on the LCA of a Gemini and limit steering lock, which is no good for the drift Gem it was intended for. The Piazza's caster rod setup allows more room, and these will fit - but I have to change the inner wheel bearings over I believe, ie Piazza inner wheel bearings into the new brakes, because I'm sure as hell not downgrading the front stub axles to the narrower Gemini items! All in good time...
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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Post by IZU069 » Thu Oct 03, 2013 5:40 pm

If you get a Microtech, ensure that you order all possible modules up front. They sting bad for upgrades (~$300 from memory).

I'd go Delco (which does adjust idle speed) but I don't know how many have cracked the turbo side. But for NAs (G-W, G-Z etc) - definitely Delco.
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Post by archangel62 » Fri Oct 04, 2013 10:48 am

Yeah no dramas there - this Microtech actually came on a G180W Gemini I bought for parts (the car was a mess, dents, multi-coloured and poor interior, and it'd blown a head gasket, but it had the Volvo 4-pot and ventilated BMW E30? discs upgrade, and the twincam). The G180W has a Variable Reluctor type dizzy and the bigger throttle body - so thankfully the Microtech should already be chipped for the Piazza VR dizzy - which I'll lock and set to 10deg as instructed. I've already got a second dizzy en route - I want to have all factory parts hoarded in case I ever go crazy and want to put it back to stock (or in case I get defected and engineering is too hard - not likely, it's achievable).

Just out of curiosity, Delcos run MAP sensors don't they - not AFM? The reason I ask is for my NA G180W project. It'll start life with a factory G180W ECU and AFM, but I want to go ITBs later on, which of course means no AFM. The Piazza won't have an AFM either with the Microtech, so I'll be able to hear some nice pidgeon-eating jet-engine turbo spooling noises lmao
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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Post by IZU069 » Fri Oct 04, 2013 9:02 pm

The VR is no problem. Microtech take both, but otherwise you use the VR ignitor to imitate a Hall or Optic output, and to convert Hall or Optic to reluctor inputs a mere capacitor is needed. [ Only "true variable" reluctor systems need the raw VR input, but I only know of the Lucas RITA system that used that for its electronic advance on motorbikes (all analog circuitry - a BRILLIANT system!). And all digital systems use digital inputs - ie, Hall or optic "modules" else the VR "module equivalent" - ie, a VR with ignitor. Some like Microtech have inbuilt VR pulse shaping/squaring. ]


Unless the G180W Microtech was turbo'd, I'd reconsider using it. The fuel re-mapping may be ok, and maybe the timing too, but to add the turbo module...
A Delco could well be cheaper, and certainly far superior.

When getting a Delco, you get the whole caboodle from the equivalent donor vehicle (eg, Camira, N13(?) Nissan, VN Commodore, etc, manual or auto as appropriate) - ie, all sensors, the AFM with self-adjusting idle, but only the HEI (ignitor) module off the distributor {the Delco VRs are shit; the 4Zs are the way to go, and for G-series engines (including the GW) RG dizzies are used with ignitor omitted or bypassed}.
Incidentally, use the same RG or 4Z reluctor for the Mircrotech. (I could never understand why people cut&shut Camira & Nissan etc dizzies onto Isuzu engines!!!!)

Anyhow, getting all the donor sensors with the Delco solves sensor issues.
And I'd advise getting the Nissan Delco though I can't recall which is closest to 2-litre mapping we seek, but you'd probably want to remap anyhow (hence even 1600cc should be fine).

RodeoBob wrote a good instruction on extracting Nissan Delcos on ozgemini.
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Post by archangel62 » Sat Oct 05, 2013 8:50 pm

It's okay, I offered the tuner I'm going through the choice of either Megasquirt or Microtech, but he chose the Microtech, so I'm sure he's used to them and will know what he's doing. I may consider Delco on the G180W later on, or Megasquirt.

EDIT: So I've done a better comparison of the two throttle bodies. Turns out the other item I was going to retrofit has a bigger main butterfly, but the other butterfly is a lot smaller... Based on surface area, the two medium-sized butterflies of the Piazza are marginally bigger! So there goes that idea. Oh well.

Anyway, here's some hillclimb and hills driving footage of my Piazza!
http://youtu.be/OoJ8A0BClPk
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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Post by eyecon » Sun Oct 06, 2013 10:09 am

Awesome production work. Music, compilations, texts, cow impersonations- it's got everything. Well done mate. I'm a subscriber now. I enjoyed it. Although there was probably as much front wheel understeering squeal as there was rear wheel squeal, but I fully understand your stock suspension setup on your Piazza at the time. Did you use Gopro for all your car and helmet work?

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archangel62
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Post by archangel62 » Sun Oct 06, 2013 12:31 pm

Haha thanks! Yeah, Ringwood's a very tight track, so understeer is frequent, especially on the uphill when you're hard on the throttle. Right from the first start, my Piazza had Koni Reds up front which are very tough compared to the crud on the back, which encouraged understeer, though it stabilised the car a lot. To offset this for the hillclimb, I ran +35mm bolt-on spacers, and Potenza RE002 tyres. The grip of these tyres is fantastic, they really transform any car. So all in all, the car was pretty balanced on a flat road, although the back end felt very "light" in that it would react very quickly rather than being smooth. Now that I've fitted the tougher rear springs and have the same tyres all around (Achilles ATRs, nowhere near as good as Potenzas, but they came on my new wheels and are near new) the car is very well balanced and the back end is much smoother. When I put Konis on the back, and tougher springs in the front, it should maintain the balance but be much better all around.

All of the car/helmet footage was GoPro this time around - usually I use my orange travel camera too (on the drift Gemini), but for one reason or another, all of these were the GoPro (Hero 2). It's a great unit, although the lack of a viewfinder screen, and occasional fogging up of the case can be annoying. However, apparently they can fall off a quad-bike and be fine lmao ... Glad you liked the video edit, I've been at it for awhile, but this one was a fairly "quick" attempt because there was so much footage, and it wasn't drift stuff, so I wanted to hammer it out pretty quick.
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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Post by archangel62 » Wed Dec 18, 2013 12:39 pm

Bit of an update, much to my frustration, my picture hosting site has carked it, so most of the media in this thread is gone...

But on a positive note, my exhaust header finally cracked badly where I'd welded it up. Why is that a good thing? Well, for ages I've been meaning to put the aftermarket ECU in, but put it off due to needing the car on the road, or having to work on other cars. Well, now that this has let go, the car isn't really driveable (although practically it drives fine, it sounds like the coming of the apocalypse) so I'm forced to drive the R31 and fix the Piazza. While I'm at it, I may as well fit the aftermarket turbo and ECU.

I've labelled every wire for the Microtech ECU, and found somewhere to mount it. I've removed the kick panel on the left side of the passenger footwell. There's a cavity in there from factory, but the ECU can't quite fit. It's still the best place, being right next to a major wiring run to the engine bay, and more to the point, out of the way. I couldn't find any space on the driver's side. One day (TM) I'll make up a fibreglass cover that fits neatly over the Microtech, and get it trimmed in a similar carpet to the factory stuff, so it will look pretty much original.

I've just finished running the Microtech loom through the existing big rubber grommet into the left wheel arch, then up behind the plastic inner guard cover, and through the existing rubber grommet by the firewall. I had to cut a big hole in each of the rubbers, but sealed it again with Sikaflex 227 to avoid leaks.

I've also nearly finished preparing my spare inlet, including fitting the 450cc injectors, new hoses etc, as well as removing unwanted accessories (ie blocking off the "pop-off valve", as well as the EGR and such). I'll also be blocking off the coolant run to the throttle body - I don't really want to boost inlet temps after the intercooler, and the only merits I could see in coolant to the TB would be assisting cold-starts and possibly heating the vac sources. Meh. There are still a few odds and ends to go, but essentially it's a functional and relatively original looking inlet setup with a little more room to access things.

I'm almost ready to pull the old inlet off and find places to tee in the Microtech, preferably without disturbing the original wiring of the car. I've also found out how to rotate the outlet of T2 series turbos, which is a relief, since the outlet was pointing straight at the rocker cover. It's happening! Slowly but surely.
Indigo - '76 TX Gemini sedan, G180W+T project,
Abigail - '81 TE sedan, white, G180W ITB project,
New Hotness - TG Gemini drift car, orange, 4ZE1+T
Tardis - 1986 Piazza 4ZC1-T, black, forged, 136rwkw @13psi
Coupe - TX coupe grip car, "do it later", G180W+twin carbs
Trevor aka Jimmy's Gem - Grandpa-spec TD
BA Falcon - Tow car

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