Isuzu G-series Twin Cam

Hello Friends.
Just joined this forum to get some more info into the twin cams. (Especially G200W)

I'm about to buy a Gemini with a G200w in it.
It's carbie fed at the moment but I'm thinking about going down the turbo line.

One thing I would like to know is have anyone had many issues turboing a G200w?
What sort of power can these handle stock? Anyone had any issues with getting after market cams?
Or is it easier to get a regrind?

I've noticed that Gaskets seem to be at rare source to.

From reading it seems that few people are using delco systems.

Is that because they are relatively cheap?
I'd be looking at getting a haltech or microtech and using that for an efi conversion. Any issues with running either of these?
Also with the quad coil ignition setup?

Going from cabie to efi should I be looking for a factory fitted set of runners? Is there another option?
I read here that 4zc1 Piazza are no good.
Also going down the turbo line custom manifolds the way to go?

Sorry about all the questions.
I want to get myself up to speed so I know what I'm looking at and dealing with.

Assistance would be great!

Welcome!

For EFI I'd suggest Delco. Why would you want Haltech or uTech? (Hopefully not multiple maps and expensive upgrades?)


And you'd probably need to regrind the cams - but make sure you know which grind, there are lots of stupid ideas out there (like Celica cams!).


What sort of carbies does it currently have?
If Weber or Delorto sidedraughts, what manifolds?


I added twin DCOE45 Webers to a standard G200W which added about 15HP, but a minor exhaust mod was all that was needed to double the torque (from ~186Nm@5k to 300Nm@2k & 383Nm@3k). (Not bad for an extra $200! But that was not in a Gemini and it used the standard G200W exhaust manifold.)
With forged pistons, a cam grind, and minor port job, that build is good for ~220HP.


There is a 400HP turbo G200W in a GT Bellett that was built by another reliable person (formerly of the NSW Bellett-Gemini club, maybe too the ICCA) which may have been based on the same build (the almost 400Nm@3k is similar to the HDT G180W builds).

Yeah I want to run multiple maps and yes I want excessive upgrades.

It's got the 45s on it as well

There is a 400HP turbo G200W in a GT Bellett that was built by another reliable person (formerly of the NSW Bellett-Gemini club, maybe too the ICCA) which may have been based on the same build (the almost 400Nm@3k is similar to the HDT G180W builds).

I'd be keen to look into this.
Not as excessive power out put as I need but I would be interested to see/read up on the build.

Any idea on the build spec of these "HDT G180W" builds?

My opinion on multiple maps is it's great for those that think they need them. (But they don't... there are far superior methods.)
If I could pose the issue another way, how is <whichever> map selected? (Do you hence see their failure?)


Alas I don't know the build of the turbo G200W, I only know of its builder. It was sold in a GT Bellett some years ago - in Adelaide as I recall. The original asking price was $13,000. (eBay) But I think that builder also used the HDT once upon a time. But I don;t even know of that GT was EFI or carbs. (The eventual builds required twin injectors, but that was a decade or 2 ago and things may have changed. However that twin-injector guru (and once a Haltech aficionado, then others) eventually settled with Delco.


But with 45DCOEs, you should get almost 400Nm. You'll need a clutch with double the torque rating (to quote: "clutch is torque"; ie, not power related). Keep in mind that that doubles the acceleration (double the torque at half the RPM) with no engine modifications. That beats almost all V8s and WRXs etc (in Geminis, Belletts, Florians etc).
The staring point is F2 emulsion tubes, but the is available on the web... (from years ago.)

Are you running stock exhaust manifold? (IE using a Gemini diesel cross-member if I understand the Gemini's DOHC dimensioning correctly).


The HDT tuning is essentially the above; F2 etc and modified exhaust for torque.
They change pistons only if they increased HP above the standard piston handling (about 180HP).

It's definetly not standard extractors.


Yeah I'm still not convinced on the delco system.
I'd rather run with something I've used before and know. I want to be able to hook into my pc and tune it on the fly sorta thing
Not having a go at you or anything. I'm not that narrow minded

Where abouts did you get the Cams done, fresh new ones or just regrounded? Got the grind spec?

As for the rods are you using a custom make or found from a supplier?

Could you go down the path of using something for example like SR/FJ20 turbo pistons and rods??

As for clutch, seeing as everything seems to be really hard to track down, what clutch are you running or what's recommended?

At the moment I'm still pretty keen on the turbo so I would need at the vary least a heavy duty clutch behind it.

I'll have to check what x member it's got and what's the F2 emulsion tubes? Are they just the way the exhaust is bent? or am I going down the wrong path?

I appreciate the help to

Cheers,

F2 is the Weber emulsion tube. Don't bother tuning Webers for a DOHC until you have those.
Standard was a manifold (4:2) with a 2:1 exhaust. Extractors were not standard. Nor are extractors likely to be better than the standard manifold (though some have been designed properly) - but those I know of use the G-W's torque rather than high-RPM power (get a fracken 16V engine if you want that - stop wasting precious G-W engines!).


Like I said, my 400Nm is a STANDARD engine.

Rods and all else are fine (why go for that SR shit?) and should be good for 500HP+.
Just get forged pistons to suit.

I was gonna get my cams reground for the HP boost to ~220HP, but never did 'cos I didn't have the pistons (but I do now!). Being for road use (not racing) I was going to get L1 profile cams.


Like I said, unless you increase torque, you won't have to change the clutch.
Personally, I'd go for Exeedy - why not stick to OEM?


As to EFI - I guess you'd have to tune that old crap on the fly since they can't even select the best map to use. But stick to what you know, maybe even the DCOE45s since they perform better.
Delco can be done on the fly as well, but a good Delco would cost a fortune - probably $300 for the ECU, sensors & loom. Then a bit more for the other stuff ($200?, plus laptop).

Ok I'll look into these F2 tubes

I'm thinking I'll stick with the extractors I have for the time being and run the 45s. until I have everything sorted. I'm thinking I will be putting a turbo on it further down the track (ie. next year)

I'll keep the extractors and cut them down and use the flange for the manifold.
I was thinking SR pistons & rods as they seem to be easier to come by.

I guess If I can source a set of forgies for it I'll use them, unless you can point me in the right direction in where to go for them.
I might have a shop around aswell for cams to suit then.

I can get exceedy clutches fairly easily so I'll probably just pick one of them up.

Are they same flywheel as a G200 flywheel?

Cheers,

Are your extractors 4:1? (4 into 1; or 4:2:1?)

I got a Heavy Duty Rodeo clutch for mine, but I don't know what sort. The pressure plate was marked ASCO CG-006 5EL-2, the clutch plate was an R847W. But use hydraulics if you can - clutch cables would only last a few months....


The forgies (from USA) tend to be $1,000 - $1,200. But decide first what you want to do - ie, turbo or not.

Yep definitely going turbo.

I'll sit on the current setup until next year and accumulate the bits and peices then put it all together.

Oh well, get low comp pistons then. And whatever EFI to suit (ie Delco).

In the meantime you can go for the torque boost - it's virtually free with a 4:2:1 exhaust - just extend the twin section to about 26"-29". (That's from the standard manifold.)

Don't be mistaken, advantages of using Delco are it's robust, cheap, able to do all you'll need.

I use free software from TunerPro and low cost hardware from Moates APU1 AutoProm Package.

antus can also show you a locally sourced method of reprogramming the Delco using similar means. More details at DelcoHacking.

Either way using Delco means you cxan bulid mnultiple EFI systems for multiple cars without any more cost than a chip and adapter for each ECU.

The initial cost to buy the tuning pack is cheaper than any after market kit, the Delco is robust and readily found in wrecking yards and you can make multiple packages cheaply. oh yeah, how many tunes do you want in reserve?? The Delco can support 4 switchable individual tunes on a single chip. Is that enough??

Thanks Poida.

I still get a laugh when anyone mentions the advantages of <various EFIs'> multi-maps - it appears they still don't get it. (Or is it me - still not getting why people MANUALLY chose maps or use Hall-Effect ignitions or oil-pressure controlled fuel pumps... Oh... I do know - people like to spend & repair & ...!)

BSTD200 wrote:Ok I'll look into these F2 tubes

I'm thinking I'll stick with the extractors I have for the time being and run the 45s. until I have everything sorted. I'm thinking I will be putting a turbo on it further down the track (ie. next year)

I'll keep the extractors and cut them down and use the flange for the manifold.
I was thinking SR pistons & rods as they seem to be easier to come by.

I guess If I can source a set of forgies for it I'll use them, unless you can point me in the right direction in where to go for them.
I might have a shop around aswell for cams to suit then.

I can get exceedy clutches fairly easily so I'll probably just pick one of them up.

Are they same flywheel as a G200 flywheel?

Cheers,

dont cut up the extractors! i have a laser cut flange here i can swap you if you like, no point wasting extractors by cutting them up, i got a few sets here and like to swap and test em

AGREED!!!
IMO never cut up existing well-made stuff for the G-W series.

Having said that, very few DOHC extractors are better than the standard exhaust manifold - at least for the G200Ws. It is best to extend from the manifold.
However in Geminis you may have no choice (unless perhaps if using the diesel cross-member?).

And if Elky has the same or similar laser-cut plates that I do, they are probably far superior to other extractor plates.
Besides, it should be much cheaper else better fabricating all new piping rather than removing or joining existing pipes.


Besides, most extractors I have seen are geared for (hi-rev) power- 4:1 instead of 4:2:1.
IMO go for torque, ie 300Nm at 2k RPM - compare that to V8s & Audi twin-turbos! And the peak ~400Nm @ 3k RPM remains reasonably high above that. (In my case with standard engine 320Nm@5k, 270Nm@6k - but add a cam and forged pistons (which IMO are required above 180HP - hence my torque limits.)

I can't understand using the (8-valve) G-Ws for power when newer 16V are far more suited. But those 16V engines will never get the same low-down torque (else not for a small $ outlay!), and that's what tends to win (yamcars and similar excepted, maybe!).
And speaking of The World Fastest Indian (torque!!) - it's showing here this weekend on TV.