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Thread: Has ANYONE successfully modified the Z18XER VVT engine?

  
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    Suns_PSD's Avatar
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    Has ANYONE successfully modified the Z18XER VVT engine?

    Guys, I'm over here in the states where the Astras only come w/ one engine option, the Z18XER. This is the 1.8 Variable Valve Timing engine w/ 138 hp and it's very slow.

    Now keep in mind there is absolutely no aftermarket support for this vehicle in the USA.

    I tried for MONTHS to purchase parts and software for this motor from Dbilas and Regal and I got absolutely no where but another member of our US forum made some progress.

    He had already gotten a cat back exhaust as well as a nice intake system and he had his base dyno numbers. (around 124 hp I believe)

    He then managed to purchase a car tuning software system (I forget the name) and he had a custom electrical cord built so he could access the Astra's computer. He also had purchased a Dbilas plenum intake that was suppossed to be good for significant hp improvements.

    Well first he found out when he went to reprogram the car that: 1) the stock air/ fuel mixture was quite good and there was no improvement to be had there and 2) as soon as he tried to advance the timing the engine pinged due to the 10.5:1 compression and furthermore 3) the Dbilas intake LOST around 10 hp and 10 lbs torque on the dyno.

    Furthermore the Dbilas intake caused a cel because it has no provisions for the 'intake control valve'. To top it off Dbilas will not take his calls for technical assistance or possibly a refund.

    He tried to order cams from Dbilas but they don't actually exist even though they show them on the website. So he looked into making his own cams but then found that it was cost prohibitive as he would need to make custom lifters as well.

    We have one American that succesfully added his own turbo to his Astra and even though he is only boosting 5 psi the clutch can't even hold that and it slips badly.

    So here we are in America and we are reaching the conclusion that it's basically impossible to modify the Z18XER engine for more hp at a reasonable cost.

    Has anyone been able to successfully modify this engine? What did it take? Please be very specific.

    ~thanks and take care~
    2008 Astra 3 door, 1.8L 16VVT

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    No one?

    Still looking for help w/ this motor.
    2008 Astra 3 door, 1.8L 16VVT

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    It's too new over here to get any money spent on development.
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    I definitely feel your pain Suns. As far as off the shelf parts I think we are out of luck. If you know a good welder you could have an exhaust manifold made up with a good merge collector from Burns Stainless (or have them weld it up). For cams, there are definitely places that will regrind cams for around $200 for a set, you could try Webb Cams (not sure on price from them). For an intake manifold, again, find a good welder and experiment with making a box-style manifold, there are calculations available online to ball park runner length and plenum volume for engine size and peak torque RPM.

    In terms of your turbocharged friend, I would talk to Southbend (or other clutch builder) about getting a custom clutch made although you would likely have to send detailed measurememts of the clutch, pressure plate and flywheel (with step heights) or send them a complete clutch assembly. Reading around on this site, I get the idea that the transmission may not be that strong but I haven't verified what code we have (F17/18 etc?). To complicate matters, everybody here talks about trannies rated for HP when they are really rated for torque.

    For suspension, Koni now has both front and rear struts/shocks available from their website and Eibach has springs available but that is pretty well it. Whiteline has a rear sway bar but nobody in North America carries stock.

    I bought my car very early hoping that it would become popular with the racing/modifying crowd due to its success in Europe and was encouraged by the GM car at SEMA but haven't had much luck since. When I decided that I wouldn't get far with the stock engine I looked at swaps but again, nobody here was much help with what would be required/what is different between a z20let and the stock engine. It makes it difficult since we can't even sit down and look at their engines and figure out what we need and don't need.

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    Quote Originally Posted by saturnxr3 View Post
    I definitely feel your pain Suns. As far as off the shelf parts I think we are out of luck. If you know a good welder you could have an exhaust manifold made up with a good merge collector from Burns Stainless (or have them weld it up). For cams, there are definitely places that will regrind cams for around $200 for a set, you could try Webb Cams (not sure on price from them). For an intake manifold, again, find a good welder and experiment with making a box-style manifold, there are calculations available online to ball park runner length and plenum volume for engine size and peak torque RPM.

    In terms of your turbocharged friend, I would talk to Southbend (or other clutch builder) about getting a custom clutch made although you would likely have to send detailed measurememts of the clutch, pressure plate and flywheel (with step heights) or send them a complete clutch assembly. Reading around on this site, I get the idea that the transmission may not be that strong but I haven't verified what code we have (F17/18 etc?). To complicate matters, everybody here talks about trannies rated for HP when they are really rated for torque.

    For suspension, Koni now has both front and rear struts/shocks available from their website and Eibach has springs available but that is pretty well it. Whiteline has a rear sway bar but nobody in North America carries stock.

    I bought my car very early hoping that it would become popular with the racing/modifying crowd due to its success in Europe and was encouraged by the GM car at SEMA but haven't had much luck since. When I decided that I wouldn't get far with the stock engine I looked at swaps but again, nobody here was much help with what would be required/what is different between a z20let and the stock engine. It makes it difficult since we can't even sit down and look at their engines and figure out what we need and don't need.
    Z20LET's are 2.0 16v Turbos with about 197bhp as standard, I'm not entirely clued up on the Z18XER's, whether they are a smallblock or big block, so if the Z18XER is a smallblock, you'd need different engine mounts and gearbox, however if the Z18XER is a bigblock then I'm sure you need not worry about mounts

    If it is going into a new shaped Mk5 astra aswell, what you will have to take into account is the type of wiring, when the mk5 came out with the Z18XER, it uses CAN-BUS wiring, whereas the likes of the Z20LET use the standard old fashioned wiring

    IF it is possible, it may be worth looking into Z20LEL engines found in VXR's ( not sure on the American equivelant I'm afraid )
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    Quote Originally Posted by Toms1989 View Post

    IF it is possible, it may be worth looking into Z20LEL engines found in VXR's ( not sure on the American equivelant I'm afraid )

    There is not one in the states thats why he is asking.


    Maybe look into a engine from a saab

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    Saab is the suggestion I got before BUT Saabs are about the most rare car around (in Canada atleast) that are currently sold. I could wait years for an engine to turn up at a wrecker only to find out there are major complications like cutting up the firewall or rad support or needing completely custom axles. I realize that Cobalt SS uses a Saab engine (or Saab developed engine) but still, they are new, rare-ish cars that won't be in wreckers in abundance ever.

    I am sure people have swapped from a z18 to a z20 turbo variant in a MK5 but I have found no documentation. Canbus vs Older OBD-2 was one of my big questions since it could necessitate a huge re-wire and possibly a guage cluster swap. My second big concern was transmissions/axles, what do I have now and what do I need? Tranny, axles, clutch, master and slave cylinders, shifter, shift linkage...what is common and what isn't? For all I know the VXR axles are larger diameter or different spline and need a different hub/bearing/knuckle. Unfortunately, I am limited to internet research but England has all the engine/tranny options so one would think this information would have been determined by now.

    I know the original topic wasn't on swaps but it seems this thread may get some attention.

    Other questions I have are about manifold flanges, what heads share port and bolt patterns? Can a VXR manifold/turbo be bolt to any other head? Can an x16 or z16 exhaust manifold be bolted to a z18 head?

    Sorry for the long post but I get anxious when I see pics of these awesome looking VXR/OPCs and I can't even figure out what transmission code I have. I know that Suns is probably frustrated as well since we are used to picking any car and being able to get any part available for it.

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