Isuzu engines

[sake007ro]

Hi there!
I started to search some parts for my piazza and i bumped into engine codes like G200Z,G200W,G200 and others.
My car has the g200 simple without any Z or W.
Does anybody now what difference is between those engines?
Thanks.

[mikuni]

G200Z is the designation for SOHC (single overhead cam) and G200W is the designation for DOHC/twincam.

I think your engine will infact be a G200Z, although the casting on the block will just say G200.

The G***Z engines spawned from early G series engines which were infact push rod, ie they didn't have an overhead camshaft. These engines, were known as the G150 and G160.

[wedgenut]

yep your engine is g200z sohc, (chain driven) the turbo cars were 4Zc1 SOHC Belt driven.

[IZU069]

The G***Z engines spawned from early G series engines...

So did the G***W! This is very evident on the G161W from the Bellett GTRs and some 117s (I think).
I summary, all G's came from the early G.

[mikuni]

Oh sorry, yeah thats what I was meaning but it kind of came out wrong. I was implying that the over-head cam version came about first and then the twincam was a natural progression but thats not necersarily true.

Either way they are good strong engines and have been about for years so they must last

[IZU069]

I see the ambiguity.
I have info about the DOHC coming out BEFORE the SOHC, namely:
SOHC - 69-73 Bellett 1600, 69-71 Bellett 1600 Sport & GT, 70-73 Bellett 1800 Sport & GT; Gemini 74 onwards; 81-82 Piazza XL/XJ.
DOHC - 68-81 117, 69-73 Bellett 1600 GTR, 80-86 Gemini ZZ(R); 2L in 81-84 Piazza E/XF & 82-XG.

I know the DOHC was fully developed by Isuzu (ie, no Lotus or Alfa development despite rumours otherwise).

I don't recall the SOHC's development.
When the first Gems came out, I thought the SOHC was a "crap" Opel head - mainly because I saw a few Gems that had dropped valves, presumably from over-revving.
But the SOHC is also similar to the Datsun SOHCs.
Whilst Isuzu & Mitsubishi used to collaborate, I'm can't remember any Nissan/Datsun connection.

&FYI: The G150 & G160 OHV blocks originally had 3 main bearings.
When they changed to 5 bearing, the G160 became the G161 - ie, the "G161" includes OHV, SOHC & DOHC variants.
The 5 bearing G150 remained a G150 and OHV. Apart from diesels, the only 1500 OHCs were the later Geminis RBs etc (4X?).
(Corrections to the above are welcome.....)

[117Coupe]

I know the DOHC was fully developed by Isuzu (ie, no Lotus or Alfa development despite rumours otherwise).

After deciding to develop a SOHC and DOHC engine in 1965, Isuzu sought advice and guidance from Conrero in Italy. Conrero were renowned at the time for tuning Alfa Romeo engines. Conrero also provided advice and guidance to Honda, Toyota and Mitsubishi in the '60's.

[IZU069]

Isuzu sought advice and guidance from Conrero

Ah - the line between advice & development...

Do you have any info on the extent of advice for the DOHC?

And what's the source of this info?

Thanx.

[117Coupe]

Isuzu sought advice and guidance from Conrero

Ah - the line between advice & development...

Do you have any info on the extent of advice for the DOHC?

And what's the source of this info?

Thanx.

After deciding to develop a DOHC and a SOHC engine, Isuzu sent a G161(OHV) engine to Conrero in Italy in 1965 as a base for Conrero to work on. Conrero worked on and tuned the engine and sent it back to Isuzu. The power output for this engine was 100PS per litre and Isuzu were very pleased with the result.

Isuzu continued with the development of the DOHC engine using the Conrero tuned engine as a guide. I am unsure as to the extent of advice given by Conrero.

I have a book covering the Bellett, 117 Coupe and Piazza. This 150 page book goes into the development, designs, suspensions, models etc in great depth and includes a whole chapter on the G series DOHC engine. It is in Japanese though but it is considered the 'bible' by Japanese owners for the above models.

Conrero also make mention of their contact with Isuzu in 1965 in the history timeline on their web page.

[mikuni]

Wow 100PS per litre? Thats impressive. The road going g161w surely wouldn't have made anywhere near that..

[IZU069]

It seems that my info aligns with 117Coupe's - ie that Conero tuned (& advised) but did not "develop" (depending on your definition).
My source (with a direct translation from Japanese) was that "Isuzu sent a finalised prototype engine to Conero" and "Conero tuned the engine.... camshafts, extractors" (assumed to include porting).

My source understood that it was a DOHC that was sent (as was my understanding).

There are also likely ties with Lola with the Isuzu R6 Coupe, and definitely with the Chev V8 R7.
The R6 Spider is another "all" Isuzu.

And the 100PS per litre certainly holds true for the G200W - 220+HP is fairly easy to achieve.