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Discussion Starter #1
I drive a Vauxhall Astra G 1.8 Sri, and even though i think its powerful enough at 125bhp i cant help but want more. So it occured to me. They do a 2.0 litre turbo, so why don't they do a 1.8? It seems maybe they don't do a 2.2 turbo because the sump is biger and lower down and the engine i expect is all round larger. Not the case in the 1.8.

So ive been thinking about it and ive looked into it, and it seems to me that i can make it happen using Vauxhalls existing catalog of parts for the 2.0 litre and adapt them to my vehicles engine. The parts arnt all that incompatible. Unless someone tells me otherwise. From what I've seen the Z20LET engines exhaust manifold could be made to fit my engine (a Z18XE), the only difference is one bolt which is in the wrong place, but then that can be removed and with all the others in place it should be more than sturdy enough to work normally. Providing the scale of those exhaust ports are the same as I only have diagrams to work from.

So that aside what about the exhaust? The Astra G standard exhaust is made up of 3 sections; manifold+cat, mid-section/silencer, and back-box. So then I see that mid-sections look identical. So i just buy a new front section compatible with the turbo chargers exhaust face? Or so i hope. Cant be sure however as the part codes arn't the same. But even then, worst case scenario i can chop and shorten/lengthen a section of the new exhaust piece to compensate. Problem solved.

This in theory is the hardest part out of the way. Id appreciate it if anyone who reads this and preferably has some experience in turboin' 1.8's and lower, would give some feedback. I am just talkin crazy or am i onto something only I can't find anything on this in any forums I've found. If this all goes well Ill look next look into hookin the easier parts up such as the actuator and intercooler and everything inbetween.

The only thing that might be an issue (aside money, which could be why a 1.8 turbo doesn't exist?) would be, would the turbo cause a lag in performance at lower revs on the smaller engine? or is the air resistance before it kicks up negligable?

All views welcome. Some of the Diagrams im talking about enclosed.




 

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Discussion Starter #3
I'd love to own the turbo but i somehow don't think my insurance would agree with me, ive only been driving 2 years, in which time ive had no claims and i think i did well getting this years insurance at £600 (TPFT).

The main reason im even thinking about such an upgrade is probably because i wouldnt tell them about it. :lmao: and as its all vauxhall parts even if something did happen and it was my fault only someone who knows vauxhalls is going to know that a 1.8 shouldn't have a turbo fitted.

Besides the turbo upgrades got to be worth what? about 25-35 extra BHP.

Maybe i should just forget about it and in 2 or 3 years get the Mk5 2.0 litre turbo then.
 

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I think there's more to it than just bolting on parts that nearly fit.

And as for major un-declared mods. This is effectively the same as having no insurance. People with no insurance should be locked up.

You did say all views welcome!
 

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there is a turbo kit for the 1.8,

its £3500 available from regal etc. and gets 230bhp iirc, for the money tbh should just but a Z20LET and fit that,
 

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Syphon85 said:
The main reason im even thinking about such an upgrade is probably because i wouldnt tell them about it. :lmao:
and that would make you a complete idiot who should be allowed on the roads,

tbh cheapest option would be to just but a Z20LET and fit that, engine would be £1000 odd and fitting whatever you can pay someone you know, and insurance wouldnt be that much different to a 1.8-T
 

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Discussion Starter #7
to quote myself "probably wouldnt tell them about it" and note the smiley at the end. I wasnt being entirely serious, incase anyone couldn't tell, and i couldnt agree with people more. People who don't have insurance certainly shouldn't be on the road. Especially as its my luck that they would undoubtably run in to me. Do people actually do that type of thing though? i mean that would be like me saying my car is a Rover 214.

And incase there is still any doubt about, i also said at the end "Maybe i should just forget about it and in 2 or 3 years get the Mk5 2.0 litre turbo then." - as in leave it its not worth the hastle.

As for the last post, i don't believe buying a Z20LET would be that cheap, not with all the parts needed to make it compatable. ECU, transmission and the countless labour hours. and for what? when i could just change my car instead and have the same result with out all the headache.

i dont know much about insuring a 1.8 turbo but what i did find out was that my car, the 1.8i 16v SRi is a group 9 insurance, and a 2.0i 16v Turbo SRi is a group 15. I'm prepared to accumulate a few more years no claims first and by the time im 22 this 'young driver' thing the insurance company's label me and everyone else my age under will be no more.

for those interested :

http://www.parkers.co.uk/choosing/insurance/

All Views/Opinions are indeed Welcome! - just don't jump to conclusions, ok? ;)
 

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a modfied 1.8 to become a turbo would prob cost more to insure than just a Z20LET,
and to fit a Z20LET wouldnt be too bad, would fit straight in (as could get it out of a mk4 astra with everything you'd need)
all you would have to do if find a written off SRi-T. GSi or Coupe-T and could take all the bits you would want,
would prob be easier to just buy a new car as you said, but IMO rather than fit a turbo to the 1.8 would be better to just get a Z20LET,

the turbo kit for the 1.8 gives you 230bhp, and thats it, not much else you can do as most tuning would already be done to it to get this figure, with a Z20LET you would be starting with near on 200bhp and could get that higher easily and with enough money very high,

most sensible idea is to be patient (like im trying to be) and wait and get a mk5 Turbo, all depends how patient you are tho,

:up:
 

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Omega Tank Commander
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You can't just bolt a turbo on, you would need to lower the compression ratio of the engine to cope with the boost and that requires new pistons etc.

If you were talking about a 1.6 small block I could understand why you would want to do it (its a smaller lighter power plant and Vaux are about to release a version for the Corsa), theres pretty much no weight difference between the 2.0 and 1.8 and given the 2.0 Turbo is a volume unit its got to be the best route.
 

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VXON's middle-aged lesbian.
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Complete waste of time and money.

Build your NCB up and then fit an LET/proper brakes/proper suspension.
 
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Brakes you would need to improve, suspension is only if you plan on track racing (real not the occasional trip to the pod) so your be fine on the sports suspension standard fit on SRi spec.

As the guys have said, a turbo is a waste of money, your better off buying a LET and fitting that, then engine would costs you 1500 and around 700-800 to fit, giving you a little top play with the increase the LET bhp a little more.

Or you could do as I am doing and stick a redtop in again either the C20LET (though the Z20LET is a staright fit and around the same cost to buy) or the C20XE, it's standard 150 out the box and cheaper and easier to tune if you want to be able to have an engine you can take time and money spread over a period of time, while still have a few ponies to play with :)
 

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Mav said:
Brakes you would need to improve, suspension is only if you plan on track racing (real not the occasional trip to the pod) so your be fine on the sports suspension standard fit on SRi spec.
If I was going turbo power I'd uprate the suspension still further without a thought.
 

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Gas Powered
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the 1.8 unit in the AstraG is a small block engine (stroked and bored X16XEL)

2.0 stuff won't fit.
 

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Marks DTM Calib said:
Be careful with the engines you recommend guys, hes still got to meet the emissions specs for his car....
WHY??? i've read the MOT manual and its say's that for emmissions you go on the earlyist engine or car, but you need proof that the engine is older then the car. eg i drive an M reg astra 1994-5 but it converted to 20XE and that engine does not require a CAT, but my car should! i have proof that the engine is an 1988 and therefore does not need a cat for MOT and reverts back to pre-cat emmissions!
 

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Andy R said:
is that the same for both X18XE1 and the Z18XE just out of intrest?
yes.


The C18XE/X18XE used in MK3 Astra and Vec was big block though.
 

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Just wondering if this turbo was ever fitted?

I have the same car (2001 Astra mk4 1.8 sRi) and I'm looking to do the same thing, I'm bored, already own other faster cars and just would like to do this project for the sake of a laugh.

Thanks in advance
 

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Can I fit 2 litre head complete to my sri zafira.. if not why not. Currently saving to buy 3.2 v6 engine next summer to modify my zaffy. It currently got decat free flow exhaust manifold plus air con unit removed Tec plus remap plus extra 2 seats hidden removed plus I got Corsa turbo gearbox on it. It shifts like mad

I am just looking little bit more poke while I look to modify my v6 engine that I intend to fit.
 
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