GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: jacko16v on 31 December 2008, 16:12
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Just stripped a ABF lump to find all the inlet valves bent and a stripped cam belt,I have a spare KR head on its way, Will i get any performance gains/loss by putting the KR head on? What cams will be the best to use from the 2?
Cheers
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it'll work fine.
there are some differances, the 051 head is small port , 027 is large port , abf heads are small port but with shorter valve guides to help flow. with the 051 you'll loose a bit of power, the 027 will make less torqe in the lower revs but then go on to produce slightly more up top, but tbh theres not much in it.
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the kr head combustioon chamber isnt as large as the ABF, it raises compression a tad and can cause piston-head contact unless you use a metal G60 gasket:
http://clubgti.co.uk/forum/showthread.php?t=177940
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stock abf is the best gasket avalible, just dremmel the chambers back to the gasket, the problem is no worse than with kr on 9a
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Duh yes of course you use the abf gasket, not the g60 one. sorry about that had a brain fart :rolleyes:
Edit: the metal gaskets dont crush down quite as much as fibre ones apparently, I remember having a discussion about this with toyotec a while ago on the clubgti, though that was more to do with the different quoted compressions ratios between early/different 2.0 8vs. But I think it was determined there wasnt that much in it compression wise and the differences were to do with the pistons, or maybe it was the quoted figures were wrong. Can't remember now I'll see if I can dig up the thread...
Aha here it is, turns out pistons were different, and the metal/fibre gasket thickness is around .4 of a mm so not a huge difference:
http://clubgti.co.uk/forum/showthread.php?t=125392
I guess that extra .4 might be the difference between piston/head contact and not though!
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you acyualy get differances between chambers on same head anyway, did lots of berreting of 16v heads and pistons
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Ok sweet as then, next question is what pistons to lower compression for turbo use, been told 2E pistons will do the job?
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headwork cams and turbo ?
how much power and how much £££ btw the pistons atrnt the issue the rods go first
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Got a spare head for the headwork, turbo and manifolds already sorted and thinking cams while its all in bits. Its a long project thats well over budget allready so not really worried about the cash.
I read on vw vortex that 2E pistons and rods will be ok for turbo use, make sense or not?
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they will lower compression yes, but you can also lower it by stacking 2 metal ABF head gaskets. It does sound a bit dodge but it works and is a nice easy & cheap way to go about it. have a look for posts made by 'toyotec' on clubgti, he has been running boost on his this way for a long time, and he makes good power. If you want to fit 2e pistons to do it iirc you need to machine them to make valve cutouts? I think toyo used 2e rods as they're a bit beefy at one point, but not sure if he took them out again after. When he talks to you you have to work very hard to keep up with what he is saying :grin:
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they will lower compression yes, but you can also lower it by stacking 2 metal ABF head gaskets. It does sound a bit dodge but it works and is a nice easy & cheap way to go about it. have a look for posts made by 'toyotec' on clubgti, he has been running boost on his this way for a long time, and he makes good power. If you want to fit 2e pistons to do it iirc you need to machine them to make valve cutouts? I think toyo used 2e rods as they're a bit beefy at one point, but not sure if he took them out again after. When he talks to you you have to work very hard to keep up with what he is saying :grin:
Will have a look into his posts, 2E would be nice as i have a full engine sat in the garage that is no good to me, i know stacking gaskets is a option but i would rather fit pistons if i can. Will be able to get pistons cut for valves not a problem.
Cheers
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Out of interest, you mention cams but are they specifically designed for a turboed engine?
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abf cams work well with turbo. buy forged rods and be done with it
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Gonna go with the 2E rods on abf pistons and stack 2 head gaskets after speaking to a few people. Will get some pics up soon on progress.
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Are the 2e pistons designed for turbo use? Its not just how much they lower the compression by, but also how much more heat they can take as well as actual stregnth. A melted piston due to over boosting or wrong piston fitted is not a nice thing to find. Found a few on aircraft piston engines where the wrong piston had been fitted to a turbo charged engine after a top overhaul. Just because they look the same, does not mean that they are the same.
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(he's talking about 2E rods not pistons)
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That will teach me to read the whole section properly! :embarassed:
Pistons were mentioned in an earlier reply, didn't see the later post. I'll get my coat!
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Yeah not fitting the pistons, just the rods with abf pistons. Should work fine.
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Same point still stands, abf pistons arent designed for turbocharging but then, using 2 head gaskets isnt a good way of lowering compression either so......... Doubtless itll work if you keep the boost and rev limit down and build everything else properly but for a few hundred extra pounds you could get a much better engine out of the job and run some proper boost levels. Same goes for the rods too but hey.
I asked about the cams as I thought he had mentioned using uprated abf cams which probably wouldnt agree with a turbo conversion, stock ones should though as said.
Out of interest, have you sized a turbo yet and decided on a boost level to use?
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your not really meant to pick a boost pressure, pick a power output, from that you can work out pritty much your ideal CR and get a good ideal of how much boost is needed at what sort of CFM so picking turbo should be quite easy.
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Hmm, interesting point considering the N/A pistons and rods but OK...... Im aware of the procedure for selecting a turbo and that yes, you can do it by selecting a power output but that doesnt necessarily mean the weak links in the chain are going to agree with what you think is a nice power level for your engine. I also understand that a little bit of extra pressure isnt going to kill either the rods or the pistons but that isnt the only problem you face.
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the question is how much power, cant say what'll work till you know what is expected. or if there is a power output in mind can suggest combonations of bits.
the ABF is quite a tough enigne, leave the head std for turbo valve seat area is usefull to help keep the valves cool and abf cams are quite well suited to turbo, F all overlap but lots of lift. the cranckshaft is pitty tough and supriseingly well balanced out the factory.
you can just stack headgakets and it'll take a fair bit of stick but stackign gaskets removes the squicsh zone and premotes detonation so you'll have to run 97 juice and keep the boost pressures quite low for the compression, use notched 8 valve pistons the boost pressure can rise in relation to the cr.
the NA pistons can make good power `if you look after them but get it wrong and there will be an epic fail, feeding the engine boost is placeing a big ask on them and it used up the safty margin if it starts detonating the heat and pressure will smash them.
the other issue is the bearing shells ther really want changing for s2 items if you want it to last
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All this talk of 2E blocks has sent me crosseyed. Are we saying that a 2E bottom end with a kr or abf head (breather issues aside) leaves you with a low enough CR for F.I? Or do the pistons still need to be notched for valve clearance? Random addition to the mix.. will G60 rods improve matters?
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basicly YES
there are other issues, you need a 16v intermediate shaft and pully, you allso need 16v cranckshaft pullys for accsesory belt and cam belt.
some combonations seem to let you get away without doing it tho it is tight so would have to be clayed to make sure.
G60 won't work they are 136mm not 159 mm
the cheepest way to build a 16vt is a KR block with audi s2 pistons, rods and bearings that's meant to hold 300 ponies reliably without issue
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For simplicity sake i think I'll go with my original plan of ABF with stacked gaskets while i'm figuring out how to bolt it all together and get the management set up then go with custom pistons/rods
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Lol, im confused.
If you mean that you will set the management up with stock abf pistons and an extra head gasket you will be basically wasting your time as you will have to do it all over again when you swap to uprated rods and pistons as well as having to do another engine build.
If you go with custom pistons and rods then you dont need to use stacked gaskets, even at the planning stage, you can get almost any compression ratio you want, just tell your piston supplier what you want or buy off the shelf low compression pistons which are readily available and shouldnt need any mods to clear the valves (as long as they are abf ones anyway) and shouldnt cost any more than uprated standard compression ones. Its by far the best, if not the cheepest route as it should allow you to choose what sort of power output you want relatively freely and will let you get the best from the engine straight away.
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Going completely standalone for the management with omex and digital dash pod.. i can have that wired in and set up so that i know it runs before attacking the engine internals. Further setup/mapping after that stage will be a piece of p!ss :smiley:
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tweeking the maps for diffrent pistons ect is easy fine that most trubo converted cars go in for a few mapping sessions anyway before things are spot on. if you map it well and arn't over expectant in the power depeartmernt stock items will do.
the motor i'm working on was built from a 1Z ( yes 1.9 Diesel ). with 8.5:1 cr :smiley: