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Andy

Yet another XU9/10 engine build

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Kane

You can tig weld magnesium, I believe it's quite common in the aerospace industry (repairs to gearbox casings etc.). Problem is filler rod is super expensive and pretty hazardous to weld as well. Would it not be easier to drill and install a fitting with appropriate washers? Problem I see is there isn't a great deal of flat surface on the top xu9j4 lid. How big is the fitting you have already? 

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Andy

Thanks for that link. Chemical metal it is 

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mmt

Just wondering if that 4 kg lighter crank is a “mass production” unit or a “race unit” you use in your race engines? If it is from a street Car which one? 

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Andy

Evening Kane. 2” I.d tube with external thread for the cap. Underneath on the inside there is not much room. JB weld I think for this one. Worth a try anyway.

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petert

The crank came straight out of a 405 turbo diesel. I didn't even regrind it or balance it. Just through it straight in, as it was a rush job. From memory the numbers were 31 vrs 27. Perhaps the 31Kg was an 86mm crank? You'd think an 88mm cast iron crank was heavier anyway. I don't think there's anything wrong with the 88mm Mi16 cranks at all. When you've got the choice however, you're always going to use the forged one for a race engine.

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Kane

Threaded fitting through the casting doesn't seem like an option then. Just one point to note. I've read that magnesium can become quite porous when subjected to heat cycles similar to that found in engines. It may not be a problem with the cam cover as it isn't submerged when in use but may be worth heating up to see if any residue is expelled prior to cleaning for applying chemical metal. 

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Andy

Good idea on the heating front. Oven I think ( when my wife is out) As for the cranks Peter, I got , in round figures, 16kg for the mi crank and 15kg for the diesel one . I must admit that I was surprised that the diesel one was lighter . And you did not balance it ? Wow. They must be better than I think . Just had another thought about these diesel cranks. Having re read what Welshpug wrote above, perhaps I/ we  are not talking about the same diesel crank. The one I tried in an xu9  and was not going to be a plug and play swap  was from the Xu9D . However, if the crank from the xu9dte ( the turbo version ) is not the same as the n/a diesel crank, that might explain the apparent discrepancies . From the sound of things, it is the 88mm (or92mm) turbo diesel cranks that are the ones to have. Bit academic really for the moment. I will settle for an mi crank that  is useable. 

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Tom Fenton

You can weld the cam cover. I don't think there is all that much magnesium in it. Easiest way is bore through and weld round on the inside rather than trying to do a fillet. However the Mi head we know is slow to return oil to the sump anyway so not sure how good it will be as a fill point.

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welshpug

There are a few different 88mm diesel cranks, depends if they come from the XUD7 or 9, or DW10, and which version of the 10.

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petert

I assumed as it was made by Stihl and weighs approx half that of an XU10J4 cam cover, that it was mostly magnesium.

 

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Andy
1 hour ago, petert said:

I assumed as it was made by Stihl and weighs approx half that of an XU10J4 cam cover, that it was mostly magnesium.

 

It is and it is. If I had Tom’s ability with a tig welder, I might give it a whirl, but I do not, hence chemical metal . I take the point about being potentially a slow fill. The current arrangement is not exactly rapid , and is not the neatest arrangement in the world. 

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xy8

Have you considered  S16   head , xu10 block    with dw12 96mm crankshaft.

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Andy

Yep. Start of the thread. Got the s16 head. Got both xu9 and xu10 blocks and both have pro’s and con’s . The dw12 crank in the xu10 block is an option, but I am pretty sure it would be a no no for the xu9  block, as the deck height is only 225mm- 48mm for the dwcrank and  that leaves 177mm for both rod and piston . If one used an off the shelf Wossner , with 38mm compression height, the rod would have to be 139mm ( bespoke ) . Even worse, rod/ stroke ratio is 1.45 which is uncomfortably low . The very best that could be achieved is to use a compression height of 29mm ( right on the limit ) and a bespoke rod at 148mm with rod/ stroke ratio of 1.54

Using the iron block makes life easier, as there is 10mm more deck height to play  with. However, that brings me back to my opening dilemma .

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welshpug

I'm not sure the DW12 will fit in the alloy block, 96 may be a bit too far!

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xy8
2 hours ago, Andy said:

Yep. Start of the thread. Got the s16 head. Got both xu9 and xu10 blocks and both have pro’s and con’s . The dw12 crank in the xu10 block is an option, but I am pretty sure it would be a no no for the xu9  block, as the deck height is only 225mm- 48mm for the dwcrank and  that leaves 177mm for both rod and piston . If one used an off the shelf Wossner , with 38mm compression height, the rod would have to be 139mm ( bespoke ) . Even worse, rod/ stroke ratio is 1.45 which is uncomfortably low . The very best that could be achieved is to use a compression height of 29mm ( right on the limit ) and a bespoke rod at 148mm with rod/ stroke ratio of 1.54

Using the iron block makes life easier, as there is 10mm more deck height to play  with. However, that brings me back to my opening dilemma .

Sorry I didn´t realize you already decided to use alloy block, then of course dw12 crank is useless.

Iron block height is not  a problem , it´s not too difficult to lower engine by 10-15 mm.

 

 

 

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Andy

Well. Not quite. The alloy block has the advantage the all the effort I have gone to getting the whole installation exactly how I want it, based on the xu9 block is a motive for staying with it. Yes, accommodating  the taller block is not a huge issue. Cutting and re welding exhaust manifold is more of a pain given that it is a high cost, SS Miles Horne manifold . For the moment, my internal debate is whether to stick with hydraulic lifters or go to solid ones , with better ( and lighter) valves , as the head is going to fit on which ever block I use . Thanks for your interest. It is helpful to get the views and ideas of others .

 

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Andy

 Next decision taken. Solid lifters and associated cams will be the way forward. Kent, Catcams, Piper and Arrows all do solid lifters. However,It is not entirely clear whether the internal pillar is parallel  in any of all of them and therefore can take the adjustment shim , as otherwise the shim fits over the top of the valve stem. Potential snag there is that the collets can be very close to the top of the stem, making it difficult to put the top hat shim on the stem. Anyone  who has knowledge or experience here, comments most welcome . As for valves, the Supertech ones look extremely good.Cams are decided. Petert .  When he gets back from his Cycling jolly in the lovely warm sunshine .Me. Envious . Nah

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JeffR

Andy I had the same issue when changing to mech lifters. There was'nt enough valve stem above the spring retainer to safely sit the lash cap shim on.

The Arrow buckets I'm using had a parallel sided nose inside, so we inverted the shims. Only problem was to ensure they didn't slowly fill with oil and prevent the valve from closing (or worse).

I decided to grind a small section on the side of the nose as an escape for any oil in the shim. (crap pic).

 

DSCF0711.jpg

Edited by JeffR

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petert

Haha, Adelaide will be hot, 41 later in the week. Anyway, Corkscrew today, pleasant 23. The solid decision is significant as it effects other things. Eg there's no point having smooth idle cams, hydraulic would have sufficed. You want to be able to exploit the extra RPM range available, 7500-8000. This means bigger cams, higher CR and lower gearing. To get the best grinds you also need to have a billet on the inlet, thus more expense. I have some proven combinations however, which we can discuss later.

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Andy

Thanks for the picture and the tip about the shims. I have checked with both Piper and Kent, both of whom confirmed that the shim fits in the stem of the lifter . Arrows are likewise, so I know what is involved.As for cams Peter, enjoy the Cycling . We can chat about those in a couple of weeks 

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Andy

Oh. Gearbox. Got the 1.6gti final drive , 1.9 1st, 1.6 2-4 and a taller 5th . Even then, 70mph is 3700rpm 

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allanallen
5 hours ago, Andy said:

Oh. Gearbox. Got the 1.6gti final drive , 1.9 1st, 1.6 2-4 and a taller 5th . Even then, 70mph is 3700rpm 

A standard 1.6 gti does 71mph at 3700rpm so it looks like you’ve got a standard 1600/1900 5th gear. 

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Andy

The 5th gear is the 6th speed from a gti6 box, so slightly higher than the 1.9  5th, but not by much

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petert

Thus 0.790, which is 9% longer than the 0.865 GTi 5th. I'd be seriously considering a 4:43:1 cwp. Consider this. A 1.9L Mi16 (4.43:1) has an 0.76 :1 5th and the Mi16x4 (4.43:1) has a 0.81:1 5th.

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Andy

Hi Peter .I thought you were Cycling all week and therefore much too occupied to spend time on the Internet.! However, grateful for your input. When I rebuilt the box with the 1.6ginal drive, my thinking was to have a reasonably high fifth , just for motorways, and a closer and relatively lower 1-4( hence the 1.9 1st) . I agree that an Mi16 set of ratios would be ideal and engine swap time is an ideal time to change the box or rebuild mine with the 4.43 final drive. More bits to go looking for . I have some other questions for you, but will save them until your return . Got a free day to ride today. Absolutely chucking it down and the wind has got up, so turbo again.

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