Author Topic: INFO Mk3 Engine Conversion FAQ (All questions and answers here)  (Read 74064 times)

Offline Mikester

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Ok, so its getting more and more hot topic about doing engine conversions, and i for one am going to be carrying one out. I have not found anywhere really here or on other forums that compiles anything together. The simples ins and outs could be enough to put some people off, and the realisations or cost etc. So thought i would stick it all down here.

Essentially if you want to do a 16v/Vr6/1.8t/R32/other conversion into a mk3, if your starting with anything lesser than an 8v GTI then it would be sensible to just buy a mk3 8v to start, they can be had cheap enough (although in that case you may as well just buy a 16v or vr6)

1. Exhausts. The 8v has a smaller exhaust than the 16v/vr6/1.8t/R32. If you dont upgrade to the larger bore the engine will essentially overheat, and get huge back pressure. Custom exhausts cost £399 from powerflow, cat back, you would then need either a decat(illegal), sports cat (roughly £150) or a standard cat. Of course you can get a standard vr6 jobbie which will do you for all of the conversions, but that in my eyes is the cheaper, and slighlty pointless option.

2. Clutches. Now the 8v comes with a cable clutch, the 16v and Vr6 comes with a hydrolyic clutch. There is such a thing as a cable to hydro conversion peice, although i have been informed they are less than crap! So obviously 16v to Vr6/ 16v+vr6 to 1.8t involves no clutch change, but 8v to 16v/vr6/1/8t would involve swapping the pedal box and fitting a hydro clutch into the car.

This said you COULD also just keep the standard 8v gearbox and bolt the 16v/1.8t engine onto this with the 8v flywheel. This would give you different ratios to the 16v box, and might not be the best, and will also mean you dont get the top speed.

3. Engine fitment. The 8v/16v/vr6/1.8t will all bolt straight in, although you would need the correct engine mounts, or even an uprated one to help with the weight and power.

4. The mk3s come with a cable throttle, which is interchangable, so as for converting 8v 16v and vr6 you shouldnt have a problem there. If you want to convert to a 1.8t the only 1.8t that i know off is the AGU engine to have a cable throttle, this means you will be able to use your throttle. The other engines including the more popular audi BAM engine doesnt have a cable throttle, so you have to buy a new throttle body, which can be had from Qpeng for £50 when buying a conversion loom.

5. Wiring any mk3 engine into a mk3 should be a plug and play job as they were desigined to be in that car. Aslong as you have the engine loom you can just plug that into the fusebox. Although you will need the correct ECU and clocks for the engine you are installing.

A 1.8t conversion can either be done with standalone managament, or with a plug and play conversion loom from "qpeng". They charge £800 to convert the 1.8t and mk3 loom to plug and play with a mk3 car. This uses a seperate ECU, and gives you a remap. This means it is not neccesary to get the 1.8t ecu.

Ignition is immobilised with a chip in the key. With all mk3 engine swaps you either need to swap your ignition and keys locks to the ones that the car with the ECU you are using came out of. OR get the ecu you are going to be using de-immobilised.

With the 1.8t conversion i believe it still uses the mk3 ecu as well as the conversion ecu, so there will be no issues.

6. Fuel pumps, they dont need changing providing you have an 8v upwards, that one will cope just fine until you start running big power.

Other things to bare in mind are your brakes, if you start with a 8v gti with the earlier 280mm brakes, and stick a 1.8t running 230bhp it would be advisable to at least get some good pads and discs, or check out the 312 upgrade options in this thread here:

http://www.golfgtiforum.co.uk/index.php?topic=94314.0

Costs of the conversions depend on wether you will be fitting it yourself, or paying someone else.

Fitting yourself into an 8v:

16v and vr6 could be done for £1000, with the 16v being a little less, due to engine prices being a bit less.
1.8t a conversion COULD be done for £2000 or less, buying plug and play loom and downpipe from Qpeng, and getting the right priced engine.

If you want a company to fit the engine, then well add about £2000 labour onto those charges at least.

Hope some of this info helps, its a bit vague, and im sure i have missed things, and maybe got a few facts wrong. But for people who think the hardest part is getting the engine in, thats not true. But hopefully people will now be aware of the other niggly things such as clutchs, throttles, and the fact that the most expensive part of the conversion is going to be the exhaust system!
« Last Edit: 18 October 2009, 12:35 by boneybradley »

Offline Adam

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #1 on: 29 July 2009, 23:24 »
Sticky

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Offline boneybradley

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #2 on: 29 July 2009, 23:26 »
I will add a couple of things

  • You can fit a 16v/vr6 exhaust directly to the 8v by using the early 16v adaptor (at the cat back). all 16v and vr exhausts will then bolt directly on!
  • If you convert the 8v you can use a seat ibiza 16v clutch set up with the 02a box (as this is cable operated and not hydraulic on these, saving the need for the hydraulic pedal box)
  • If you change from 16v to vr power you need to change the bearbox bell housing!! and i'm guessing changing from vr to 1.8 means you need to change it too?
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Offline Mikester

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #3 on: 29 July 2009, 23:32 »
As far as im aware you can use the 1.8t on the 8/16v boxes, but not VR.

The 16v fits on an 8v gearbox.

The Vr6 wont fit on an 8v box.

The Vr6 and R32 are interchangable. But as boney says, 8/16v wont fit a VR6 gearbox.

Also an R32 gearbox wont fit on Mk3 mounts. But an R32 engine will fit on a Vr6 box, and on the mk3 engine mounts.

Offline Adam

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #4 on: 29 July 2009, 23:34 »
Can you use a 16v/vr6 box on a 8v?

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Offline Mikester

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #5 on: 29 July 2009, 23:36 »
Well the 8v is cable clutch, so you would need to convert the pedal box to the hydro one, unless u fitted a conversion peice.

The 16v would fit, the VR6 wouldnt.

Offline Wayne

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #6 on: 29 July 2009, 23:37 »
Excellent info.
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Offline Mikester

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #7 on: 29 July 2009, 23:40 »
Hoping it throws a bit more light on the subject, think some are jaded by the "plug and play" phrase. lol.

Offline boneybradley

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #8 on: 29 July 2009, 23:48 »
Well the 8v is cable clutch, so you would need to convert the pedal box to the hydro one, unless u fitted a conversion peice.

The 16v would fit, the VR6 wouldnt.

If you use the seat ibiza clutch set up you can fit the 16v box to the 8v, and the vr6 box wont fit either 4cyl cars unless you swap bell housings round.
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Offline Mikester

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Re: Mk3 Engine Conversion FAQ (All questons and answers here)
« Reply #9 on: 29 July 2009, 23:50 »
Well the 8v is cable clutch, so you would need to convert the pedal box to the hydro one, unless u fitted a conversion peice.

The 16v would fit, the VR6 wouldnt.

If you use the seat ibiza clutch set up you can fit the 16v box to the 8v, and the vr6 box wont fit either 4cyl cars unless you swap bell housings round.

Think the point to raise here is, if you find a 16v box cheap to replace your broken 8v. In the long run its not cheaper. As i cant see an other reason to want to fit a 16v box to an 8v, unless maybe you want to eaton the engine or something.