G180w Turbo?

ONLYA4 · petrol head Joined: 12 May 2003 Posts: 1114

Ok, i asked someone about G180w turbo's whether or not i should do it, this was his response.
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Having had a bit of experience with all the twin cam types made by Isuzu, I would recommend that you don't run turbo unless you can modify the oil pump for greater output. By that I don't mean just shimming the pressure relief spring, but by increasing the overall volume capacity of the pump...Drastically.
This is the greatest problem with the twin cam's oil system, the pump is simply too small to handle the engine alone, let alone a turbo on top of that.
I would recommend you go with the G180z (z signifying single cam chain drive) and using a 2 litre (G200z) pump which has a larger capacity than the G161z or G180z pumps.

Otherwise, turboing a standard G180w twin cam engine will cause problems due to their naturally high compresion ratios; to decompress them requires the fitment of flat top pistons. Also, valve stem sealing can become an issue as they don't use valve stem seals. The valve stems are lubricated by a 'act of God' system which really defies reason, however judging by the rate of wear I get out of a set of sintered brass guides (and they cost a shitload), they obviously aren't getting oil anyways. My point being that the inlets will blow the crankcase full of boost pressure; these engines already have difficulty keeping the dipstick in unless restrained at over 7000 rpm. All my twin cam engines use a spring to retain the dipstick. It's just a harmonic flutter that the rings seem to get at relatively high revs, and pressurise the crankcase as such...

rod · tinkerer Joined: 14 Apr 2003 Posts: 380

hay mate
how would a 180w twincam perform too my

g200 single overhead
large cam
webber

??
any responce would be great!

ONLYA4 · petrol head Joined: 12 May 2003 Posts: 1114

I think it all depends on what work the engine has had done to it.

QldRobbo · tinkerer Joined: 11 Apr 2002 Posts: 455

your engine would probably have around 55-60rwkw rod, a 1.8l dohc stock would have around 70rwkw.

That's all stock, with the stuff you mentioned for your engine.

rod · tinkerer Joined: 14 Apr 2003 Posts: 380

oh ok cool.. cheers QLDROBBO
Smile

FLYINLoW · backyard mechanic Joined: 08 Oct 2001 Posts: 924

doesnt the g200w come stock with 101rwkw

gem · tinkerer Joined: 23 Dec 2001 Posts: 152

In your dreams. 101kw is at the flywheel.You will be lucky to get 80kw at the wheels depending on who's dyno you use.My race engine is puting out just over 100kw at the wheels and this it at its limit and the engine is worth a fortune.

gem · tinkerer Joined: 23 Dec 2001 Posts: 152

You could get yourself a drysump oil system,this will solve your oiling problems. I also have to romve my dipstick and i have a hose blanked off and clamped over the dipstick pipe.You will definately have to change your piston to lower your compresion or run really low boost. I used to have a formula to work out what the final comp ratio was by the comp ratio and amount of boost you have for example 9.5 to 1 with say 3lbs boost would have the same overall compresion as 7:1 comp with say 8lbs boost and one last thing the 9.5:1 engine would drive better when not on boost.
I hope this helps
gem

ONLYA4 · petrol head Joined: 12 May 2003 Posts: 1114

Thanks mate, thanks for actually answering my question heh, but i'm probably going to get a g180 and ive been looking into buying a turbo kit from Ben Wight, he's good bloke that one.