G180 twin cam parts wanted

[terryo]

I have a G180 twin cam engine to rebuild & modify.

i'm chasing some extractors and some forged (dome top) pistons.

Does anyone know if the G200 gasket sets are the same??

rest i've got organsied

thanks, Terry

[IZU069]

The G200W gaskets should be the same. The larger bore shouldn't matter much (whereas smaller bore headgaskets for larger bores DOES matter!).

All perishables should be available - eg, bearings (mains, bigends, cams, layshaft) & gaskets (I suggest MD Spares' E3B-G295 {KP G295VNA}).

For the G200W, the best "extractors" are the st'd exhaust manifold but they have clearance problems in those GM-Isuzu Geminis. I think the later G180Ws (blue) have a similar design but not earlier engines (eg green G180W & G161W).
Just get someone that knows how to design them for the GWs; many seem to be random designs. Maybe use G200W port lengths as a basis?

Forged pistons are ex-USA.

[lowkey]

I am about to get a custom set of extractors made for a G200W in a Gemini. May be able to get the shop to make a second set at the same time??? send me a PM.

[IZU069]

Thanks. But I already have the best - ie, the OEM G200W manifold which fits all my vehicles.

I do have a 10mm laser cut exhaust flange that may be uncommitted.

[lowkey]

I had intended the message for the new guy, happy to help you to though. I do have a couple of the cast iron manifolds but they wont work for me.

[IZU069]

Damn, there I go again! I thought you were the OP. Stupid me (as most know).

Sorry, for some reason I must have you (lowkey) on my mind - maybe something to do with PMs LOL.


terryo, I suggest take the offer. Two should be cheaper than one, and if between you you find a good designer...


I looked for some design info but couldn't find my old notes (probably part of my unrestored last big crash data) though I did find a B.Eng dissertation "Engine Optimisation and Performance Characteristics for a Formula SAE Race Car" by Melinda Rachel Pink though it lacks the factors (constants etc) that I recall for extractor design - but maybe I didn't look deep enough.
As an aside, I was kinda happy to see Melinda refer to extractors. Elsewhere I read that's an oldskool term (which IMO is fine) and how most call them headers (or hedders). But extractors is apparently an Aussie term so hey - I'm very cool with extractors.

And incidentally, it was my GURU that said the standard twincam exhaust manifold were hard to beat. Admittedly we were discussing the G200W which included the 117 G200W but I'd assume it holds for the blue (ZZR, ZZT etc) G180Ws - especially the later blues.
But we were also referring to the 400Nm G200W exhaust mod as applied to the non-Gemini Isuzus - ie, Belletts & Florians - so the clearance/interference problems that Geminis have weren't considered.
Also those discussion were back in the 1990s in case things have changed (though a few years ago I quizzed 2 manufacturers of 4ZE1 extractors that claimed "no design" - merely whatever physically fitted!!). By the 1990s we had killed the old rule that too big an exhaust is bad - that was a hangover from pre-PC & calculator days when continuing calculations for more peaks generally was not done.

Note too that GURU said the Isuzu twincams are unlike any other - especially wrt how they breath. Since then I have met several that "know" the same. And in retrospect I understand why my dyno tuners thought their dyno was faulty (LOL - they built racing engines but had obviously never crossed an expertly tuned G200W!).
Hence beware crap like fitting Celica cams (ie Celica profile grinds I presume). And unfortunately some Isuzu forums seem almost as bad... They question (IMO) well known & proven 20-30 year old tunes (eg, 400Nm G200Ws) but hey, they can't even get GW sparts!

I did sell some custom made Gemini GW 4:2:1 extractors which looked buddy terrific. They seemed to have similar dimensions to my torque G200W manifold & 2:1 section. I was so spewing they didn't fit my Belletts, Florians or Wasp.
BTW - most know how I push 4:2:1 for GW engines. IMO if you want high RPM power (ie, 4:1) then get a better suited modern 16V engine. The beauty of the G200W was its low end torque - ie, 300Nm@2k RPM without any engine mods - merely appropriately tuned Webers (twin DCOE45s or 48s or even larger) and the key 2:1 exhaust mod. Twice the vehicle acceleration with a st'd engine. Nice!

[Robbbbo666]

Any link to this 2-1 exhaust mod, went for a search but couldn't find anything?
Was thinking also about custom extractors but if I can't get any better I'll keep the standard manifold

[IZU069]

Sorry about the Post approval delay. Aren't there any other mods on this site? I'm still not getting email notifications and I must have missed this new post. Luckily I did a manual View your posts...

Any link to this 2-1 exhaust mod, went for a search but couldn't find anything?

Yes, me.

For some reason some ridicule or doubt the hi-torque G200W build. Or they are ignorant. (Some are. despite being considered experts, their repeated stupidity or misleading statements puzzle me.)

Though other posters on various forums have referred to such engines (eg, here; ozgemini), AFAIK only I have publicised build details noting that I have only contributed to this site and a few other public Isuzu & related sites and I rarely look (read: looked) at others. I no longer disseminate such details but I have not retrodeleted any posts so they should be searchable. (I say should be. I know reality can be quite different.)

It was when I sold my GW Gemini extractors and hi-torque Webers with manifolds to a colleague of the late Peter Brock that I noted the similarity to the old G180W Brock tunes. Whether he/they/HDT used the hi (low RPM) torque or a hi RPM hi-power G180W build I don't know - I was never interested in (hi RPM) hi-power for GWs.


Like I said, you'll need a good designer to meet or beat the G200W exhaust manifold design, and I'd assume likewise the later (blue) G180W design. And in my recent dealing with extractor builders I have seen no evidence of "design" other than fitment issues.
But I know GW'd T-series Geminis cannot use the st'd exhaust manifold but I don't know if this merely fouls engine mounts etc (hence diesel xmembers) or the body etc.