4zc1 Vs G180/200

[mccaughey77]

I want to start building a Gemini. Nothing to outragous but neat, and for a gemini powerful (roughly 140 hp at the wheels). Having been a Gemini owner previously i know their ups and downs but would still love to make one deliver the goods!
Ive got three realistic options for the motor (the forth is a Nissan SR20det- but I think that will probably add up out of my price range.)
1. 4ZC1 Turbo from a Piazza.
2. G180/200 rebuild (+ new cam, exhaust, carbies)
3. G180/200 rebuild + turbo.

what are the advantages and disadvantages of each- including price? I would prefer a turbo because it'll be something different- but what results can i expect from a carby motor if i go for the third option, in comparison to a solid engine rebuild- I have read in a gemi' mag a guy who got 200HP out of his G200 with no forced induction!

Keep in mind i want to drive it often so dont give me any ideas that require me to run AVGAS or anything stupid like that

please reply so i can make an informed decision
thankyou

[Adam]

I've debated which engine makes a good streeter gemini for months, in the end I decided upon the CA18DET, $1650 for a manual halfcut... 175BHp at the flwyheel which should net a nice 130hp at the wheels (at least)... factory idle, hot starting, better fuel economy, smoother... I could go on and on...

[Ben Wight]

Number 2 is probably the easiest to do, with the least power potential. To get good power from it, you probably would have spent as much as it would cost to do either option number 1 or 3.

The piazza motor would be the hardest to do, particularly becuase of the efi side of things.

I personly think number 3 is the easiest, (carby), but for someone paying someone else to do the work, the piazza conversion wouldn't be much different in price.

Possible power from the two turbo engine options are about the same, in stock form, the piazza engine is nothing crazy, but the efi is more refined. But then again, there are plenty of turbo + carby cars doing 9 second quarter mile times.

Really depends what work you can do yourself, and what your preferences are. The piazza fuel management would be harder to adjust for things like bigger turbos or more boost than a carb is, a carb is simply a matter of changing jets.

Ben Wight.

[Mooch]

Adam, sure the half cut costs $1650, but it's the engineers report, the cat and fuel neck mods, the fabrication and the electrics that you need to sort out. Then there's the heater hoses, radiator mods, fuel pump, uni joints etc etc. If you can do this yourself it's fine - and i know you can Adam - but and i'm not sure bout this guy though? If you can mate then seriously consider this option.

However, for eaz of rego and installation i'd go the G200. Not because i have one but because that's the reason i have one! It bolts straight in and requires no mods @all.

If you don't want avgas, which is a pain in the arse, i'd just go steelite valves in the head and run PULP, say BP98 with an octane booster. Keeping the comp around 9.5ish:1 will be good. Don't run a huge overlap cam or you'll bleed most of your comp through your exhaust. However some good port work on the head with good sized valves, and a solid bottom end. Coupled with an electric dizzy and twin carbs should see close to your target. i am getting 107Kw @ the flywheel. I could have more power but this is with a 34adm weber, not twins.

The turb option would greater power than n/a but if u get pulled over i don't know how you'd go. It's up to you at the end of the day however, it's ur car and ur $. speak to people who have done different things and get them to take you for a spin, ask whats been done and how much it cost. Use that to help ou deac.

Good luck
Adam

[Adam]

Ok, engineers report isn't a problem for me because one of my colleagues out at Queensland Raceway is an 'approved workshop' in his own right.

Sorting the electrics is just a matter of being really really patient and sitting down with the loom and a wiring diagram, should only take me 2 weeks (or anybody else 3 days).

The fuel system ain't cheap... you could use 2nd hand bits and have it all for $350... but instead I am going for a 'total overkill' fuel system for about $700

As for the tailshaft, graft the silvia front yoke onto a gemini tailshaft cut to suit, get it balanced and robert is your mother's brother.

Heater hoses are easy, don't know what I'll do for the rad. yet.. my point being... with the exception of knowing someone who can do the mod plate, anybody who can change an engine (G161z-G180/G200) should be able to do this... you just do as much as you can and pay someone to do what you can't.

[mccaughey77]

what about mounting and instalation are there any problems, major or minor with usind the nissan motors?

[mccaughey77]

thanks adam:
seems youve already thought it all through for me. Are you running a smaller head on your g200 to increase compression?

[MatMan]

I would expect that all you would need are custom engine mounts ( or adapt some other ones) and gearbox mounts.
Oh, try to get a half-cut, it will make every thing so much easier, especially with the engine management. The stock Nissan computers are great ( tunable and reliable and everything)

[MatMan]

Of course thats just for physically fitting the engine, there LOTS more to it - always is hey.

[Mooch]

here, i just cut and pasted my engine specs from my website below coz i couldn't be bothered writing it.

Steve from Cartech was called upon for the new mechanicals. A 2 litre block was purchased, as was a big valve 1800 head. Bob Sherry decided my existing, small valve head was not really good for performance. So i hunted through the phone book and eventually an 1800, big valve head turned up and was in really great condition. The shit water here in sa means that most alloy heads are stuffed after 10 years. The block took some searching to find, and finally one was found - but it was stuffed. It took a lot of work from the machine shop to get it up to scratch. I sat down and spent 4 hours deburring the block once it had been stripped, crack tested and acid dipped.

The bottom end was bored 40 thou, number 1 had to be sleeved. The rod bolts were then resized, and the pistons replaced with ACL Duralites. ACL also suplied the rings and bearings. The whole lot was then balanced. The head needed some welding here and there and was then sent off to Bob Sherry. He was cautious with his die grinder for fear of thin walls but was pleased when a final figure of 160 Hp was gained and a air speed of 301.

The manifolds were also match ported With flow figures in hand, Steve sat down on the desk top engine analyser and played with cam profiles. The best one for drivability vs power was a crow who also supplied the double valve springs.. 284 deg duration and 425 thou lift. The block had been decked and the head also refaced so compression was a bit high - especially when fitting the 1800 head. Around 10.5:1 was the final figure which meant AVGAS for fuel. The carby of choice was a 34 ADM Weber off of a leaded XF.

Overall power is 107Kw @ 6000rpm @ the flywheel. Not too shabby. Should be good for 16's i thinks. The car only weighs 950 or so, power to weight is in my favour atleast.

As a bare block, it was etch primed, primed, hand rubbed and painted in engine enamel custom mixed to match the suspension. As too was the head.

[Ben Wight]

Adam, with good launches, your G200 should do low 15's.

This is from relating it to my low 16 second quarters gained with mediocre launches with my 95-100hp@flywheel(approxiamte) 1600 using the same cam you are using incidently.

Ben Wight