g40 16 valve????? is it possible

[poloeatonm45]

i dont know if any of you guys have seen it but on club polo their is a guy selling a 16 valve head that he claims will fit a g40 whitch has got me thinking is this even possible ? i didnt think it was but he is saying it is could anyone shed any light on this ? i know alan aka polo ace was trying to do this a few years back but as far as im awere nothing ever came of it

steve

[dannyb.G40]

http://www.clubpolo.co.uk/forum/index.php?showtopic=163430

Thats the link to the thread...those dutch guys are craaazy

[Yoof]

Frode probably knows more about this than most.

You can do it, at a guess:

Cambelt tensioner
Water Pump revisions
Custom Crank Pulley
Higher grade Exhaust Valves
Modified waterways (from memory they weld up the bottom right and then skim the face)
Custom Exhaust Manifold
Custom Inlet Manifold
Custom Camshafts

That's without looking at how crap the roller rocker heads actually are.... AFH are far better.

All in all probably £2k worth (at a guess) to make it work, for a 10% increase in power at best.

[Tommo]

So the bolt pattern and the bore spacing is the same? Makes it a lot easyer than most 16v conversions, I know people fit BMW bike cylinder heads to mini a series engines and that involves plugging all the holes in the block and re drilling them, as well as all the other crap. Cant see much reason for uprating the exhaust valves, they should be fine and the cams would be adequate im sure. I dont know about the custom crank pulley, unless it needs to protrude further out because of the slightly wider cyl head. The best thing about a 16v head is it would make more power on less boost, so you could have a much more reliable high powed engine, not that high power G40's seem at all unreliable anyway.

Would it not be easyer to fit the whole engine?

[PeteG40]

custom cams as NA and FI cams are usually very different.

exhaust valves to deal with additional heat.

and the bottom ends on 16v vw engines are rather shit actually - thats why not to use them, apparently the rods are weak.  The 75bhp bottom ends in polos and lupos are alloy and often are completely worn out at 70k miles!  PLus vw regards the bottom bearings as non replaceable - therefore a new bottom end!

[hayesey]

Modified waterways (from memory they weld up the bottom right and then skim the face)

that's as I understand it too, at least one bit needs welding up.  Looking at this picture in that thread it looks like it's been done (bottom left) which must be what the "modification" is since the rest of the head doesn't look to have been touched:

Main issue with fitting one of these to a g40 bottom end is the fact that you'll need custom pistons making since both the head and normal g40 pistons have the combustion chamber in them.

[hayesey]

exhaust valves to deal with additional heat.

g40 8v big valve heads don't have sodium filled valves so I don't see why this wouldn't work without them, depends what the standard AFH valves are like really...

[hardchargin40]

Its a common conversion for the Berg Cup 1300 16v polo's, i.e. sorg etc.  So I'd guess, if you speak good german, get over to a berg event and they'd tell you.

[poloeatonm45]

just been watchin some polo vids on u tube god some of them mk1,s are quick i neeed one. this is all very interesting i wonder if it is really hard to do it must be otherwise someone over here would have done it by now i want a badge for the back of my g40 that says 1.5,twin cam 16 valve g60 gti lol

[Max]

Would it be cheaper to just G60 a MK4 16v engine and whack that in?

[Tommo]

custom cams as NA and FI cams are usually very different.

exhaust valves to deal with additional heat.

and the bottom ends on 16v vw engines are rather shit actually - thats why not to use them, apparently the rods are weak.  The 75bhp bottom ends in polos and lupos are alloy and often are completely worn out at 70k miles!  PLus vw regards the bottom bearings as non replaceable - therefore a new bottom end!

Standard NA cams tend to cope quite well as they have minimal overlap, so you can run plenty of boost with no reversion, that is with a turbo anyway. I would guess with a supercharger it dosent matter as much about your camshaft and they are closer to fast road cams.

Sodium filled exhaust valves are usually considered a luxury rather than a necessity, many high powered forced induction engines manage without them.

Mmm it seems asthough all modern VW engines seem a bit weak on the bottom ends, even the ABD that I bought has much weedyer rods than the mansize 1300 ones.

[Dan]

Even though there are two exhaust valves per cylinder it's difficult to say how they would cope with forced induction. If you are considering some decent boost, then repacing them with one piece stainless ones (oversize if possible) might be a good choice.

[samg40]

So basically its possible but it will probably be really expensive and for potentially not much of a gain and some of the head may not cope all that well with it either.

[Tommo]

Yeah looks like a big of a ball ache to me for what its worth. I dont think there are many people pushing the limits of the 8v head anyway.