THE 1.8-2.0 16v head info thread

Discussion in '16-valve' started by Xiotis, Sep 20, 2006.

  1. Xiotis Forum Member

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    16V Mk2 Head Types

    I've noticed a few different part numbers on the 16V heads. I have already spotted part numbers 051103373 and 027103373E .

    Does anyone know if these heads differ in chamber design, is one head better then the other??
     
  2. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    1.8 heads have better intake ports (051) and (053) heads have better exhaust ports.

    There are 4 16v valve head castings:

    Part no* Engine code
    051 103 351 KR,PL NB the KR,PL and ADL are all 1781cc the rest are 1984cc
    053 103 351 6A,9A and later KRs
    053 103 351 B ACE,ADL and early ABFs
    053 103 351 C ABF and Late ACE

    * Found on front of head.

    Early Castings 051 103 351, 053 103 351 1986-1995
    What makes the KR the most revvy 16v all other factors equal, is the intake cam which is 027 109021AH which has extended duration compared to the cams found in the PL,9A,and 6A which is 027109021AL. The exhaust cam is the same on all of these listed as pt# 027109022G.

    Later Castings 053 103 351 B, 053 103 351 C 1992-2000
    Again the ABF was the most powerful of the lot part due to the intake cam amongst other things. I got the part no as 051 109 021 B for the ABF motor where as the rest including the 1.8 ADL engine used 051 101 921 C for the intake cam. Exhaust cam on all was listed as 051 109 022 B.

    I have never been able to compare valve sizes between the various heads but careful study of the part numbers shows that KR, PL and 6A motors have the same inlet and exhaust part numbers of 027 109 601 C and 027 109 611 B respectively and the other engines got 051 109 601 B for intake and 051 109 611 B for exhaust. If any of you know more data about this pls dont hesitate to correct.

    Hope my 2p helps.
     
    Last edited by a moderator: Dec 14, 2013
  3. Xiotis Forum Member

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    Thanks a lot for sharing.:clap:

    So if my head is a 027103373E, that makes another 16V head to add to the list. :)

    What we need is a flow bench and a couple of heads to compare. :lol:
     
  4. STU

    Stu Forum Junkie

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    Just to add to this, the head I took off my 6A engine last week appears to be a 051103373 which is the same number as the flowed head I put on. I thought KR and 6A heads had a different code as above?

    Perhaps the head I removed wasn't in fact the original 6A head but a KR one as I bought the 6A engine complete and ran it as it was for a year or so, could have had a head swap previously? Just wondering if there's a difference as I intend to sell the spare head so could do with knowing exactly what it is :)
     
  5. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Stu, It might well be 051103373, with no letters following, if the KR was a late one.
    I went in the back of the house last night. I got 2 1988 KR motors one 1994 ACE and an ABF. Checked out the heads. The KRs had the 027103373E heads, as said by Xiotis, and the ACE and ABF had 051103373D heads. I will add these to the list on the top but I believe it does not change what was said in principle. The only difference I saw between engines was the ports.
    DarrenE is very good when it comes to UK part numbers. The list I generated was from www.vagcat.com which seems to have the last 3 digits different '351' followed sometimes by a letter. If you were to substitute this with the numbers we have on our engines here you will see the same pattern emerging.
     
  6. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    16v heads complete and bare head castings part numbers

    Just an update on this 16v head part numbers question.
    The numbers that end 027/051/053 *** 373 refer to the part number for the complete head with cams valves springs etc and NOT the casting. I comfirmed this with VAG. So you can feel free to use the info I supplied about the castings part nos which end *** *** 351 and apply them to your code of engine.
     
  7. davidwort Forum Member

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    from what I can see on ETKA another difference between the early and late heads is the valves, and this is not specific to the ABF/ACE it's based on chassis number and means late 6A/9A's also have the same valves as ABF's.
    The change is chassis No. 50-P-008 000 onwards. Top spring disks and split cotters change too.
    I don't think it's valve diameter that changes though, there's not enough room in the combustion chamber.
     
    Luvmuscle likes this.
  8. King Kwik

    King Kwik Forum Member

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    how about some flow bench numbers.

    Lee
     
  9. FaTT mk1 Forum Member

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    Dont know if this helps but KR heads have 28mm exhaust valves but a 27mm seat.

    ABF heads have a 27mm exhaust valves and 27mm seat.
     
  10. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    You are correct as I done that measurement myself and was discussing that last night with a buddy of mine. This means that the abf engines's exhaust i.e. valve and port will flow better. You will find this size valve on the ACE and ADL engines as well. On my piont about lift, the chap I was talking to said to me that he once turbo'd a 2E 8v block with a 16v head. A complete KR head was used and this was fine for a while. Then he went for an ABF complete head and this was damaged when the motor was on high revs as all 8 intake valves crashed with the pistons.
     
  11. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Interesting on the spring retainers and valve collets. Only problem is...
    Why would the difference of the early and late 16v heads be down to a chassis number on a 1994 "P" Corrado "50"?. The the first public ABF engine code was in 1992 and was in a "1L" Seat Toleado. This would have had a 053 *** 351B head casting. The valves on headcasting 053***351B/C have the same part nos and are different to the valves found on early 051/053***351 headcastings found in the KR,PL,9A and 6A cars.
    As far I can see the 16v Corrado came with a 9A motor and the head used would be casting 053103351. But when you look at the part nos for the complete head which is denoted by 027/051/053 103 373 this is where you can have changes to head components like what you mentioned by placing a letter after the number. If VAG did carry out a modification to an engine component and not change the engine code those cars will be updated in the parts list from the chasiss number and year the revised engines started to be installed.
    I am interested in that infomation on those spring retainers for the 9A and will look into that a bit more. It might well be they used a 053******B head with the 97.5mm length exhaust valves on the 9A from that year and chassis number. I will search and see
     
    Last edited: Oct 24, 2006
  12. MARTINH Forum Member

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    Hi,
    With regard to the KR heads that have 28mm exhaust valves but a 27mm seat, could a 28mm seat be fitted for extra flow? I know the space in the 16v is limited for fitting larger valves but just wondered if increasing the seat size would help flow?

    I'm going to be stripping a PL coded 16v in the coming week or so and I'll post what head number I find. :thumbup:

    Regards
    Mart
     
  13. allan1816v New Member

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    hi
    this may be a bit on the late side but a good way to help flow on the 16v head is to remove the ridges and edges left by the manufacturer in the chambers the ridges are quite deep and defined by the time they have been removed the valve heads are in effect raised within the chamber this unshrouds the valves and allows the valves to breathe instantaneously a good mod and will improve torque.
    allan.
     
  14. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Wheels are VW Estorils look great when polished. Took me a year to find a good set for my Monza Blue. I see from the head rest shadow on the N/S he also has Recaro seats.
    Those numbers on the head casting (*** 103 373) are for a complete head and not a bare head casting which ends *** 103 351. The 027 is the early 1.8 16v unit with better intake ports. The later 051 heads were a bit more restrictive on the intake ports but had better exhaust ports where also on the 6A and 9A motors but with tamer mid range intake cams. If both came off a KR motor then they would carry the better intake cam as the exhaust cam was the same on KR,PL,9A and early 6A codes. See the list above to get the cam part number for the KR intake camshaft. I also state that VW still mangaged 139BHP from both head castings so the performance may be down to the intake cam.
     
    Last edited: Nov 12, 2006
  15. Mike_H Forum Addict

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    I've discussed this with The Man In The Shed and his view is you could fit larger seats, but it's expensive, and doesn't yield a lot of extra power. He knows of N/A engines running standard size seats at 240 bhp (ITB's and hairy cams). So if you want to spend the 200 for bigger seats and the inserting, don't expect a huge increase in the engine's potential... not really worth doing for road use.
     
  16. TrackCab16v Forum Member

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    ive actually gas flowed and ported three types of heads, and then fitted and rollin roaded them on tsr old rollers , they were 027, 051 late kr and abf , all on a 9a and 6a block, end results were all pretty much the same , but when driving on the road ther was a big difference in whitch they all delivered the power , this is my personal opinion, the worst head was the abf , in the middle was the 051 kr , but best of all was the 027 , ther are lots of different views on this subject by different tuners , it also takes more skill to port the later heads , ... cheers paul
     
  17. vw_singh Events Team Paid Member

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    I have an array of 16v heads and have stripped a couple down and thought I would do some investigation while I was there.

    After some calculations I have found the following:

    Late KR head casting has a 49.47cc combustion chamber volume including the head gasket squish area.

    ABF head casting has a 52.22cc combustion chamber volume including the head gasket area.

    TrackCab16v, this is probably the reason for your loss in torque with the ABF head as it would reduce your compression ratio in comparison to the KR/9A heads.

    Spring retainers/caps. The ABF caps have a different part number because they are not as thick. This results in far greater valve lift before cap to seal collision. I measured the following:

    Exhaust valves varied between 13-14mm of lift upon collision.

    Inlet valves varied between 14.8-15mm of lift upon collision.

    This is a factory standard ABF head and has not been reconditioned as far as I know.

    I have to double check the following but I also measured the following figures for the valve springs going coilbound on the ABF head:

    The larger valve springs have 13.26 mm of travel before going coilbound.

    The smaller valve spring has 12.26 mm of travel before going coilbound.

    This limits the total valve lift to the travel of the smaller spring. Just out of interest, I also have a quick look at the KR springs on ABF retainers. Large spring is the same but the smaller inner spring had 13.16 mm of travel before going coilbound! So by the looks of things, its possible to use cams with 13 mm of lift on an ABF with KR inner springs! :o

    Open to critisim.

    Gurds
     
  18. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Gurds you may need to check piston protrudsion above block deck on KR, early 9A and ABF/ACE as all the 2.0 16v engines have the same quoted compression. Did you use a burette?
    But that is some good hard evidence.
     
  19. vw_singh Events Team Paid Member

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    I know the valve to piston clearance will have to be checked and piston pocketing might be in order. I have measured block protrusion and found that the KR had more block protrusion than the ABF which will make a difference if you swap the heads and blocks over. I did not use a burette but the figures were calculated based upon compression ratios and factory engine cc's. 10:1 for the KR and 10.5:1 for the ABF. A burette measurement would be good though just to double check the calculations. The chamber design in the ABF head is different though, seems to had small ramps between the exhaust and inlet sides of the chamber.

    Gurds
     
    Last edited: Nov 3, 2007
  20. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    I understand how you did it. But it would be best to get a burette and do this as the 10:1 ADL Seat 1.8 16v uses the same head as the ABF, ACE and late post 94 9A. The quoted figure for 16v heads = 45cc
     
    Last edited: Nov 3, 2007

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