The '2 ton bugswatter' - back for a gentle stroke

[Acidburn]

very nice and now I see what you meant earlier when I saw you. Have to let me know how you get on with regards to tyre ware, I need to find something for my daily to help out and don't like 034's solutions.

[Jonnybravo]

Nice update and nice top mounts, I'd make a cover to go over them as if there anything like the ones I had made you will get all sorts of crap off the wheel spray up into the engine bay.

[JP]

Cheers and re the UrS6 mounts there is a solid plate mounted to the chassis with a small hole through it for the strut which the top mount secures to and fully covers the main hole other than some minor bits. Then you also have the original plastic cover that locates over it of the 3 nuts that secure the mount so I should be OK on that front

[Jonnybravo]

Ah cool, these Audis were slightly better thought out than mk2 escort lol

[G60Rallye]

Engine build looks amazing JP! Whats the thoughts behind the liners?

[JP]

Engine build looks amazing JP! Whats the thoughts behind the liners?

Cheers,

Stock cast grey blocks average around 30-35,000 tensile strength. As you throw more boost pressure and ultimately more hp at the block the pressures involved on the thrust side of the block at times can exceed this.
As you exceed the elasticity threshold of the cast grey when you release the pressure it doesn't return to its original form. Over time the result is ovalled bores which don't seal aswell and ultimately equals less power.

Ductile liners are 110,000 tensile and therefore have a much higher elasticity capability preventing long term ovalling. For example most of the shelf piston rings are ductile iron due to their elastic capability. Only recently with improved manufacturing techniques have the top rings been upgraded to gas nitrided steel rings with even greater tensile capability in performance ring sets.

As my car covers on average 15,000miles a year I'm making sure she lasts for as many miles as is physically possible

[G60Rallye]

As usual a very interesting reply! It had slipped my mind that you use the thing so much, I am always thinking about weekend cars, which is what most high hp builds are. Its going to be insane with the stroker in it, it was fast enough last time I was in it and it wasn't even running spot on then I seem to remember?

The liners are obviously better than a normal cast block, just not something I have seen much of in the 5 cylinders. It seems to be a must for the cosworth lot when they are going much over 600bhp.

[JP]

Think it was only in its running in stage of around 410-420 back then. Been a while so can't remember exactly as had so many power variations over the last couple of years.

As a general rule of thumb VAG castings are some of the stronger production ones so less prone to out and out failure like the cossie lumps but more a gradual decline through time. if I could've gotten closer to a 1.75:1 rod ratio instead of the stock 1.67:1 I might not have bothered with the liners. Saying that the stroker RS4 lumps suffer from heavy bore wear despite their good rod ratios but that's more to do with the big end journal configuration IMO.

[andy10v]

So the liners combat deformation rather than actual wear?

Is the oval bore in a normal engine (say a 200k 7a) due to "stretching" the bore or wear, being physical abrasion?

[JP]

I've fitted them specifically for counter acting ovalling as although the liners are now harder and less prone to wear through abrasion (honing them was very long!). The rings themselves will wear quicker now, on average I'd be expecting to swap the rings every 50,000miles or so especially due to the lateral gas ports I've had put on the pistons.
Although when swapping rings I'm hoping to do 3-5 passes with a flexhone for a fresh surface finish with the crank in and fit a fresh set of rings and of I go rather than a full blown rebuild as the bores shouldn't be worn or out of round. Although time will tell on that one.

As for wear and tear on a normal cast engine this is 99% down to physical abrasion which can be seen from the lack of honing marks and the ridge around the top of the bores.

Hth JP

[Jeffer]

What a great idea on the maincaps spacers. That looks very rigid! As always great updates from your hand.
Did you line bore the mainbearings after you torqued them down? Or did you measure them for warpage?

[JP]

Just finished gapping the rings and balancing the rods andd pistons last night so another pictoral update following soon.

The block is being dropped of for line honing/boring tomorrow when everyone is back to work after the bank holiday. I've let it sit on purpose for as long as possible including a retorque over two weeks ago before I left just to see how everything would settle and its still out by 2.5thou on the height although the width is spot on on all 6 caps.

[QuattroFever]

truely amazing build!

wish my block came back that clean after acid dipping. The guy who gave mine back did so with it looking like it had just been dug up!

you'll have to start charging for those quick blats in the local dip in the road with this monster!

[prj]

The turbo will still be a GT3076R 0.64A/R?
Now that you have more displacement, have you considered using the 0.82A/R hotside again? Or do you feel that this will counteract what you tried to achieve by enlarging the displacement?

[JP]

Currently running the .82 housing on the 76, the .63 is definitely too small for the application.

Initially I'll run the car with that turbo but on the long run looking to go bigger and tubular mani with improved intercooler setup. I've got a desired rpm for spool up in mind and a desired hp target in order to maintain daily hack status. But intend to only buy once so awaiting to see on some other motors and their results with the same/similar head design before commiting.