TDI Crank

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panic-mechanic
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Re: TDI Crank

Post by panic-mechanic »

Dummy assemble with your std bearings and check the clearnces with plastigauge. Then You'll know if they will work or not.
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Re: TDI Crank

Post by berry »

panic-mechanic wrote: Mon Feb 11, 2019 9:33 am Dummy assemble with your std bearings and check the clearnces with plastigauge. Then You'll know if they will work or not.
So the bottom is assembled but now i have the problem of the pistons touching the head 🤦‍♂️... Can i use 2 head gaskets?
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Re: TDI Crank

Post by PapaJo »

berry wrote: Thu Feb 14, 2019 7:12 pm
panic-mechanic wrote: Mon Feb 11, 2019 9:33 am Dummy assemble with your std bearings and check the clearnces with plastigauge. Then You'll know if they will work or not.
So the bottom is assembled but now i have the problem of the pistons touching the head 🤦‍♂️... Can i use 2 head gaskets?
How far is the piston sticking out from the block to touch the head? Picture or measurements will take our guessing away.
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Re: TDI Crank

Post by berry »

PapaJo wrote: Fri Feb 15, 2019 1:19 am
berry wrote: Thu Feb 14, 2019 7:12 pm
panic-mechanic wrote: Mon Feb 11, 2019 9:33 am Dummy assemble with your std bearings and check the clearnces with plastigauge. Then You'll know if they will work or not.
So the bottom is assembled but now i have the problem of the pistons touching the head 🤦‍♂️... Can i use 2 head gaskets?
How far is the piston sticking out from the block to touch the head? Picture or measurements will take our guessing away.
Tried to measure it.. About 1.3mm
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Re: TDI Crank

Post by PapaJo »

Give us background about pistons used, rod length and crank. What I can gather is you have a short block (220mm) with tdi crank and 144mm rods. What pistons are used?
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Re: TDI Crank

Post by berry »

PapaJo wrote: Fri Feb 15, 2019 9:35 am Give us background about pistons used, rod length and crank. What I can gather is you have a short block (220mm) with tdi crank and 144mm rods. What pistons are used?
Nisaam Ca18 84mm pistons
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Re: TDI Crank

Post by berry »

Already removed about 4mm off the piston top..
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Re: TDI Crank

Post by PapaJo »

You are getting thin on the piston crown now. 1,3 above block is goong to give you very high compression on 8V. If it was 16V head that would have worked, once pistons are cut for pockets for clearance on intake valves.

Only possible option would be to have a special thickness head gasket made up to give you the correct clearance between piston to head on 8V. You need minimum 0,8mm piston to head clearance.

Special thickness head gasket to be calculated to reduce compression to acceptable safe compression and ckearance between piston and head.
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Re: TDI Crank

Post by berry »

PapaJo wrote: Fri Feb 15, 2019 12:29 pm You are getting thin on the piston crown now. 1,3 above block is goong to give you very high compression on 8V. If it was 16V head that would have worked, once pistons are cut for pockets for clearance on intake valves.

Only possible option would be to have a special thickness head gasket made up to give you the correct clearance between piston to head on 8V. You need minimum 0,8mm piston to head clearance.

Special thickness head gasket to be calculated to reduce compression to acceptable safe compression and ckearance between piston and head.
Im sorry if i forgot to mention that it is a 16v....currently have 1 steal gasket on
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Re: TDI Crank

Post by PapaJo »

berry wrote: Fri Feb 15, 2019 1:40 pm
PapaJo wrote: Fri Feb 15, 2019 12:29 pm You are getting thin on the piston crown now. 1,3 above block is goong to give you very high compression on 8V. If it was 16V head that would have worked, once pistons are cut for pockets for clearance on intake valves.

Only possible option would be to have a special thickness head gasket made up to give you the correct clearance between piston to head on 8V. You need minimum 0,8mm piston to head clearance.

Special thickness head gasket to be calculated to reduce compression to acceptable safe compression and ckearance between piston and head.
Im sorry if i forgot to mention that it is a 16v....currently have 1 steal gasket on
Ah ok, 16V.

In my above comments, you need to pocket the pistons for intake valve clearance or else piston will push against valves in head.

You will need to measure amount the valve head is sticking out under head with valve fully closed, take that value and subtract that value and amount that piston sticks out above block from the measurement of a compressed (previously torqued head gasket) to calculate the base line depth that the piston valve pockets needs to be. Add atleast another 0,5mm depth to allow for rod stretch during high revs. Do a dummy assembly with a layer of clay ontop of piston head with cambelt fitted and motor on timing marks. Turn motor over by hand, strip head off again and measure remaining clay thickness in the pockets to ensure you have enough piston to valve clearance.

Hope this explanation makes sense.

Post some pictures of piston top.
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Re: TDI Crank

Post by berry »

Okay i understand tnx alot... The pistons already has pockets but now the space between the head and pistons is not sufficient in order for the engine to turn a full 360°...so can i add another head gasket and if so will it have a negative influence on cr?.. Will post pictures tomorrow
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Re: TDI Crank

Post by PapaJo »

Thicker head gasket will inluence compression ratio. I will not recommend two head gaskets on top of eachother to run motor like that.

If you want to use it to clay up and measure valve to piston clearance, yes.

You need to calculate the static compression ratio of the motor to determine what is the compression in that setup.

You cannot just add another head gasket and get clearance and guess compression ratio is right.
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