4zc1 engine tuning, what can be done?

[Jacko]

Hello guys, 2nd post this but i've been reading the forum trying to find answers, see what can be done but still a little unsure as to how good these little engines are tuning.

I need to know the basics and i hope im not repeating other newbies questions but here goes...

What known problems do these engines have, do the water ways slowly but surely wash away and cause the fluids to mix?

What can the stock internals take and can you get uprated parts off the shelf like cams, valves flywheels, clutches etc. I've looked everywhere but as yet haven't found anything at all, i've even looked further a field (az and the states) as you chaps seem to have bought a few more than us Limeys but still can't find anything!

I will be looking at replacing the turbo for something a bit beefer and having a custom made manifold but can the std ecu be re-mapped or chipped or am i looking at getting something thats mappable?

Ok so thats probably about all your going to want to read regarding engines so what about diffs, my piazza is a HBL model with LSD and when i collected the car i jacked up the diff and spun the wheels and sure enough they rotated the same direction, brilliant i thought but unfortunately after hading over the cash and i got to have a drive and performing some tests the LSD is shagged! What i was hoping is that it can be rebuilt but unsure as to the costs and it could be cheaper to replace with a good known working one but i've not found one for sale as yet...don't suppose anyone has one for sale do they, don't mind it being shipped over seas but just need to make sure the cost isn't that high

Ok so thats diffs and engine questions asked....now onto trans...

After picking the car up, driving 140 miles home faultlessly i've now lost the clutch, fluid all over the garage floor and pedal hits the floor without any pressure and then stays there...i've never worked on a hydraulic clutch before and i know nothing about this car but i've found a little cylinder next to the brake servo thats empty of fluid but what could of caused it to have emptied? What is thats at fault, is it the slave cylinder in the gearbox (i think thats what its called anyway)

Right, i think thats enough for this post, sorry to waffle on so much, i've got a lot to learn am im hoping you knowledgeable people can help me.

Regards
Jacko

[wedgenut]

i've now lost the clutch, fluid all over the garage floor and pedal hits the floor without any pressure and then stays there...i've never worked on a hydraulic clutch before and i know nothing about this car but i've found a little cylinder next to the brake servo thats

If fluid is on the floor it IS the slave cylinder that is leaking unless the flexi hose is ruptured. The slave is just below the starter motor and bolted on the engine/gearbox flange. The master cylinder is the reervoir you refer to and if it leaks you will get fluid on the pedal and carpet inside the car. Contact Clive at Iptoc, he has access to slave cylinder kits. The [pedal should come back up so the master cylinder piston may be stuck at the bottom of the stroke as well. best you remove both and give them both a kit. Methinks you first spend a couple of quid for the CD Manual and make it your best friend.

[Bugle]

Water galleries can be kept in good shape by using good coolant and changing it at the specified interval. I had the head off mine and there was no corrosion at all.

Dunno what stock internals are good for, I think the GEmini boys have been getting some reasonably impressive numbers compared to stock using aftermarket engine management.. Not really any aftermarket support for engine internals unfortunately.
Turbo upgrade would depend on the size of the turbo and how much boost you're running. Mine was ok with a slightly larger turbo and 10psi boost, others have run more boost than that. However the UK piazza has different engine management which may hit its limit sooner..

The diff is a clutch pack type not one of those retarded cone ones so you can just get the clutches replaced I really wouldn't trust a second hand diff to be ok in that regard.

[Rodeobob]

You can buy new clutch slave cylinders from the USA on eBay.



Will work in RHD cars as the slave is on the same side of the box everywhere. Its either that or use one out of a 4ZE1 Rodeo or Jackaroo with a MUA.

The difference between the two slaves is the way the hose attaches to the slave. The Rodeo one is via a banjo bolt thats 90 deg to the piston/bore. The Piazza one exits on a 10-20deg angle and i havent looked to see if its a banjo bolt or not. Its a different thread i know that much and probably a rubber hose job.

They are the same bore/stroke and attaching arrangement.

[GeminiCoupe]

Where to start, where to start...

Theres a Gemini with a 4ZC1 backed with a manualised-Trimatic auto running 10.77's on methanol. Stock standard internals, from rod bolts to pistons.

Now, strength wise, its an Isuzu. Isuzu builds trucks. Nuff said.

Depending on how much you want to spend, and what sort of power you want to make, is what dictates how far you have to go. If the engine you have is in reasonable condition [ie decent bearings, compression test at around 160psi] then it should take some boost in decent tune and be reliable.

I would do the following modifications. Yes it will cost you money but it will wipe the fucking smile off the owners of most European "high performance" car owners.

- Aftermarket ECU. Not sure what is availible to you over in the UK, down here popular "budget" choices are Microtech's and MegaSquirts. If you can find someone to tune the megasquirt, theres a guy on the gemini forums that does the ECU with a base map [in other words, wire up and start], wiring loom, sensors etc to suit 4ZC1 for about 750AUD.

- Get yourself a crank angle sensor distributor off a 4ZE1 Rodeo. ECU will be setup to run fuel and ignition mode, youll have to ditch the bulky factory AFM and run a map sensor. If you go the megasquirt route, its just a matter of speaking to Warren and hell set everything up for you so its as painless as possible.

- Check what inlet manifold you have. Two types used on 4ZC1's - o-ring injector type and Hose-tail type. The one you want is O-ring, if you dont have that manifold you can source one off a 4ZE1 Rodeo. Fit ~440cc injectors, big choices - GTR RB26, Pulsar GTiR etc.

- Remove the factory plenum from the runners [8bolts from memory]. Youve got two choices here. What you want is a round, cylinder shaped plenum with the throttle body relocated to the front/facing forward. Any decent engineering/fabrication shop should be able to do it for you relatively cheaply [not sure what labour is worth in your part of the world]. OR, you can source one from Darren aka Gemracin [G series powered Gemini running 9.70!] for $250-300AUD.

- Bin the standard turbo and replace it with a T28 off an S14, or, if you can afford it, the ballbearing T28 off the S15 SR20DET which flows roughly 320hp. The standard manifold can be used if you cut the flange off and get one to suit the T28 welded on, or, if your feeling generous, you can buy one of darrens manifolds [see below, thats the one for my gemini] for $500AUD.



- 3" exhaust from turbo back, front mounted intercooler [front-facing throttlebody is instrumental here. cheap hybrid type intercooler will do the job fine].

Depending on the tune, i would say an easy 150-160rwkw on 15psi.

Your diff your better off rebuilding yourself. If your mechanically minded, its not that hard to re-shim the LSD. Trick is to add an extra set of friction plates to get a more vicious lock up, lsd also lasts longer.

Id look at the wayward suspension as well. The soft springs/rear end roll are what kill the LSD clutches as its putting different forces on different wheels and thus wear. The more you limit body movement, the better it is.

Nick-

[EVL GEM]

Like this?

[speedracerles]

So what are you running this set up in now?