2.1 8v engine build

Discussion in '8-valve' started by stytrhe, Jun 10, 2020.

  1. stytrhe Forum Member

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    Hi, Im currently getting some parts together to make a 2.1 8v engine. Ive got a PB 1.8 block coming, I've bought a 1Y diesel crank, and I've all ready got a tsr pack C head on the current engine. Ive got a few questions if anyone is able to help.

    1. What sort of machining has to be done to the engine block, I assume some work to the crank so it does hit anything. Also a rebore to 83.5 I believe ?
    2. Is there any point in getting forged pistons & rods as its going to be an NA engine.
    3. I guessing I'm going to have to increase the fueling, so bigger injectors, higher pressure fuel pump, and new engine management. See what have people used on theirs.
    4. Also I'm assuming I need a bigger/heavy duty clutch, the car all ready has a diesel gearbox in, which I'm going to have rebuilt.

    Thanks for any advise people can give.
    Ross
     
  2. stytrhe Forum Member

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  3. Jon Olds Forum Junkie

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    2L bore std is 82.5, 1.8 is 81mm , do you want to bore the 81mm block out?
    Big rebores cost big bucks
    I would start with a 2L bottom end,
    Forged?, depends what budget you have. I have a lot of trust in the quality/strength of VW rods.
    7K revs should be ok standard, but its all your choice.
    Don't underestimate what the whole job will cost....
    Jon
     
  4. Tristan Forum Junkie

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    Jon has done more than most with these engines, so I'd heed his advice.
    And I'd agree, unless there's some specific reason for keeping the original block, I'd start with a 2.0
    In fact, I myself actually did. AGG bottom end with a TSR "pb" head.
    Rods and pistons are fine unless you're chasing high compression and/or high rpms.
    If you're using it in a mk2, running Digifant equipment, standard injectors will probably be adequate unless you push big power, G60 ones are a simple upgrade after that. Standard fuel pumps are both quite reliable and have good reserve capacity.
    Otherwise, for REAL power, you'll be ditching the oe manifold and fitting ITBs or carbs.
    Management wise, both Digifant and kJet are very old technology. There is a CGTI member working on a mappable version of Digi, I myself fitted an Omex ecu I had in stock, but haven't gotten it mapped yet (dealing with rust!). DTA is very popular also, as is Megasquirt.
    Any stand alone management is going to need some extra work, realistically a Throttle position sensor, Lambda sensor, Crankshaft position sensor and coolant temp.
    Original ecu (blue) CTS will work, I fitted a trigger wheel to the front crank pulley, and modified a Ford TPS to work.
    I also decided to upgrade to a wasted spark setup.
    There's a reasonably large amount of wiring to be done too, so be aware of that.

    I'm a 2nd generation mechanic, with my own workshop, access to lathes/mills etc and I was still quite surprised how much was involved.
     
  5. stytrhe Forum Member

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    Hi, thank you for the replies. I wanted to keep the pb short block, rather than go to a 2e tall block. I'm fine with the cost involved, I've been thinking about engine upgrades for about 5 years, so it's finally time to do something. Any idea where to get the larger pistons from ? I've seen larger ABA pistons but they have a 21mm wrist pin as opposed to the standard pistons are 20mm. Also I'm guessing I used standard rods ? With increasing the stroke, is there any problems with pistons to valve/head contact ?

    Cheers Ross
     
  6. Tristan Forum Junkie

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    Why so keen to keep the short block?

    As regards pistons, you'd probably buy a set of SRP or Wiseco or similar as cheap or cheaper than OE style cast ones.
    Standard rods are strong, rifle drilled and cheap/free.
    I can't comment on interference.
     
  7. Jon Olds Forum Junkie

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    Got to measure everything and work out what needs doing when buying pistons. Don't rely on t'internet advise.
    If you know someone who has built 'custom' (bitsas…) engines follow their advise.
    Look at all the main forged pistons suppliers and study sizes/shapes (ie where the gudgeon pin is)
    Jon
     
  8. Tristan Forum Junkie

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  9. stytrhe Forum Member

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    Thank for the advise Jon and Tristan, its much appreciated, I'll research the pistons and get some ordered.
     
  10. mr hillclimber Club GTI Supporter and Sponsor

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    There's a reasonable amount of work to get the longer stroke cranks to work in the std height 1800 blocks.

    I'm in the middle of a 2ltr using a DX block. The crank isn't a problem but the bottom of the bores needed clearance slots for rod beams. That's with a slightly thicker H beam steel rod but there's a strong chance you'll need the same with the longer stroke diesel crank and std rods.

    You'll also need some clearance near the oil pump platform to clear the rod cap swinging by.

    Rods: std will be more than fine as it won't be a revvy engine and they're pretty decent anyway. Rod bolts must be changed as they're a one shot stretch item. Your next issue will be rod bolts. The last time I checked O.E wernt available and ARP re usable bolts are the same price so cost for cost they make sense, but must be fitted by a competent machine shop. Direct replacement O.E or O.E spec bolts can be fitted at home but precautions and common sense must be applied.

    I managed to round up a couple of sets of Febi bolts and nuts recently for a few std and fast road builds but it was a real struggle. Febi keep saying there's a new batch coming but don't hold your breath....you'll need 02126 & 02127 for the bolt & nut...or go the ARP route.

    Other rod options are Manley that come with ARP bolts and are a decent budget race rod, or ZRP. I've no personal experience with ZRP but have used a few sets of Manley rods to 8k so you won't over work them in a road application.

    Pistons: std spec cast pistons are fine to 7k so would be more than fine for your needs. However, you'll need an oversize of the short block 2ltr piston for the Audi 3A engine. The std bore is 82.5mm and 0.5 and 1.0mm oversize use to be available, but I don't think you'll find them now. I can have a hunt as I have part numbers but the last time I looked a few years ago they were no longer available in the various O.E spec KS/Mahle/Nural versions.

    Bore size: The STD 1800 block as you no doubt know is 81mm. A bore to 83mm is ok but going to 83.5mm is getting thin for no real world power gain over the 83mm size apart from capacity bragging rights. At an 83mm bore with your 95.5 diesel crank you'll have 2067cc rather than 2092 with an 83.5mm bore...so technically still 2.1. The other advantage in using an 83mm bore is you can use an O.E 2ltr head gasket in fibre or MLS (different thickness) which have 83.5mm bores, so an 83mm piston fits easy with clearance for you to juggle deck heights and squish. An O.E type piston will need some machining to work but it can be done.

    The other option is a custom forged piston. Overkill for your application but a sure way to get exactly what you want to suit your long stroke in terms of crown and deck height, bowl size, ring placement and bore size...even odd sizes to get you closer to your 2.1 goal to fit with the O.E type gasket and keep the bore thicker.

    You'll also need to feed the bigger capacity with a high flow big inlet valve head ideally or you'll find you'll have good grunt but poor top end breathing...bigger lungs need air capacity to fill them or you'll just compress the powerband....unless that's part of the goal going for the bigger capacity of course.
     
    Last edited: Jun 25, 2020
  11. stytrhe Forum Member

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  12. Jon Olds Forum Junkie

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    Compression height will be wrong for a 2L crank, as they are listed as 1.8L
    Jon
     
  13. mr.brown

    mr.brown Paid Member Paid Member

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    Jason - any reason for using the DX instead of a 3A?
    Also, part numbers for the o/size 3A pistons would be great.
     
  14. stytrhe Forum Member

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  15. mr hillclimber Club GTI Supporter and Sponsor

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    More than welcome Ross.

    As Jon said above, they're no good I'm affraid due the crown height being wrong, likewise with the ABA pistons you mention as I "think" that's a tall block 2ltr...same stroke as the short height 2ltr block but 16mm shorter, so basically the piston needs to fit within 16mm less height. That's done in simple terms by raising the pin location in the piston.

    I'd say custom is maybe your only option to get the right combination you need in terms of bore, compression height and bowl size. I can ask my piston supplier to look at juggling the sizes on the ones we did for the 2ltr and factor in the extra stroke and look at bore options.
     
  16. mr hillclimber Club GTI Supporter and Sponsor

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    Hi Sean

    Yep, race regs.
     
  17. stytrhe Forum Member

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    That would be great if you could Mr Hillclimber, there's a lot to know and I'm getting quite confused by it all.
     
  18. mr hillclimber Club GTI Supporter and Sponsor

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    No problem at all. It's easy enough when you know how.
     
  19. drunkenalan Paid Member Paid Member

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    Most of its has been already covered, I built a 2042, which is a diesel crank but using a Standard AGG bore as the engine I had was very low miles. It ran Megasquirt using a 2E distributor. And made about 150bhp with similar torque. the options are much simpler using a tall block.

    however, why a 2.1? It’s not the simplest engine to build into a short block? I have a 1900 in a PB block, that makes as more BHP (157), but a little less torque. Running Kjet. Depends on what you are after.

    I quite fancy putting the current head, on proper 2.1 based on my 2042, but that’s not going to happen soon.

    my next step is a set of 45’s and improving the ignition side of things, currently it uses a vacuum advance dizzy, with the vacuum blanked off.
     
  20. mr.brown

    mr.brown Paid Member Paid Member

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    What cam is that running Alan?
     

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