240 B230 rebuild questions

As some will know Im in the process of determining the issue with the engine in the 240+t. The plan is to have it rebuilt if possible/necessary.

Ive got a hold of a 940s incase the fx motor is cactus.

The 940s is too good to wreck at this point so I and want to explore the options of a rebuild of the FX motor if its not stuffed. I think ive got a soft spot for them developing...

The idea is to run a 16t at 10-15psi and use the car as a daily. It already has an alloy intercooler and boost will be controlled electronically. Otherwise its standard LH2.4. Just want a sweet motor, not wanting to reinvent the wheel.

What head work or tidying can be done with the 531 head while its apart to sweeten it up? Im only familiar with 16v peugeot heads. We usually clean up the throat area, cut 3 angle seats and take of any poor casting marks as a minimum.

How much is safe to shave off the head assuming its never been done before? 1. To clean it up. 2. To raise the conpression lightly. Im not after crazy compression just asking to see if there are common issues or not in doing this.

Concerning pistons. Apparently there is a slight difference between the NA and Turbo b230 pistons. Is it worth tracking a turbo set down or just run the NA ones with new bits? (If there fine)

Having the rotating parts balanced would be nice. New bearings and rings and everything cleaned if need be And then pop it all back together.

Ive got lots of spare time coming up in April and want to hit the ground running with it.

Budget is $2500 Tops


  • Well this escalated quickly!

    I will try to answer everything in order.

    1. I dont think the 531 head will be providing much of a restriction to a 16t at 15psi. The 531 is favourable to the other castings due to the shape of its combustion chamber and the location of the spark plug. If you were going to the trouble of cutting the seats then it may be beneficial to have a look into installing larger valves while you are at it. @AshDVS can sell you the larger valve kits which will definitely increase exhaust flow and help the 16t get onto boost quicker. That being said, the 16t is a small turbo and will boost easily without much encouragement. For a daily im not convinced it would be a worthwhile spend.
    2. Shaving the head too much can sometimes result in the cam timing being put off or the belt being loose because the head now sits too low. The solution ive seen to this is to run a thicker gasket. I have no personal experience with this so take it for a grain of salt. In all honesty, I wouldnt be keeping that 531. It appears to have some serious corrosion going on and a healthy 530 would perform just as well when being controlled by LH2.4
    3. Yes there is a difference in the NA and Turbo pistons. The NA pistons have a shallower dish in them and less material where the top ring seats. This isnt usually a problem until you experience detonation or excess heat and the piston cant get the heat away from the ring. If you were to swap in turbo pistons then i would consider not running a 531. Your compression ratio would be lower than that of a stock B230FT which from memory is 8.7:1. If you swapped in the turbo pistons then it would be a good idea to install a 530 to retain the compression ratio. If the NA pistons are fine then I would keep those. If you can manage the heat and detonation then they will live.
    4. I dont think you will need to have it balanced as I think each part is individually balanced and not as a set. That being said, it could help find any causes for vibrations in the assembly that could get into the cabin. The B230 isnt a refined engine by any stretch of the imagination.

    Hope this helps!

  • Good advice.

    Not keen on the expense of the the valves at this point.

    Ill have the head looked at by the machine shop to be certain. If its not great Ill look for another or the fate of the 940 will be a little certain.

    That said if the bottom end is ok I could find a good 531 head and just pop it back together. That would be ideal.

  • For your goals, the original NA pistons are more than good enough. And would work better in your application due to the shallower dish for more CR

  • Thanks rr. I was hoping that would be the case.

  • Having the head checked by a shop is a good idea. They will be able to sonic test it for any weaknesses that the eye cant see. @jamesinc recommended my 405 head to go to Thornleigh Cylinder Heads and it ended up coming back good as new after sitting under a tree for a few years.

  • Ok great. Is there a known Redblock specialist to give ma a yes or no on the head? Ive used Rams before with great results.

  • You don't need a Volvo specialist to inspect the head, the machine shop will say

  • Just checking if there was someone who knew them better for the other work if required.

  • Adding a few things to what @Slowbrick said - definitely not worth doing O/S valves with a 16t. That money could be spent elsewhere for better return. And another way to combat the timing change with decking the head and block is to run an adjustable cam gear. Agree regarding NA pistons being fine especially with the lower comp 531. I have a spare 531 here in good nick if you need a new one and can't find it locally.

  • Thanks for the ‘heads’ up on the ‘head’ sam. Sorry, couldnt resist.

    Will be in touch.

    Picking up the hoist this morning so will know a little more today!

  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress

    Thornleigh Cylinder Heads do all my machining work and have always been good. Nas is a top bloke. They're not Volvo specialists but have done plenty of OHV and OHC redblock work.

    If you want a painless experience, best to go to them with new valve stem seals and valve guides in hand, and always ask for a hot tank, the casting will come back looking like it's brand new.

  • Thanks James. Ill keep that in mind. If you look over at the other thread I have theres some progress.

    Its not all that bad but certainly not pretty.

    Ill probably DM you soonish to harass you for suppliers and part numbers.

  • I would rebuild what you got. That way you know it’s going to be good for life

  • Too true. Thats what Im trying to tell myself!

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