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Dw12 Crankshaft


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37 replies to this topic

#1
B1ack_Mi16

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A picture and some details.

 

Big end diameter 50mm.

 

It is forged, but differs from the earlier forged XU cranks though as it still has 24mm wide rods, whereas the older forged ones XU10J4TE and XUD11 + some XUD9's used 26mm wide rods.

 

20170321_204445_zpstkeanxeg.jpg

 

I'm still considering to offset-grind it, but as my life situation is changing I'm also considering a budget build instead.

 

I have found that if one uses Honda pistons with 29mm pin height (87 or 87.5mm bore), it is possible to use 158mm rods and have 10.8:1 compression, which would be quite nice for a strong  daily driver engine.

Attached File  2017-03-22 09_56_28-AcuraHonda.pdf.png   141.68KB   0 downloads

 

These cheap china rods (I know, but for a daily driver engine non-turbo I can't see them beeing poorer than a standard rod), can possibly be modified.

They are a perfect match apart from pin diameter, so would have to be re-bushed from 22 to 23mm as that's what the pistons are.

 

http://www.ebay.com/itm/251696468825

 

If not one can possibly also use XU10J4RS GTi6 rods, but I'm not sure if they have enough meat in the small end to take a 23mm bush insert?

 

 


Btw. The 87.5mm bore pistons will make it a 2309cc engine.



#2
welshpug

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I'd rather mod an oem rod or use a robson rod, it's in n-a applications that the shortcomings of the chinese rods are shown, not under compression.

#3
B1ack_Mi16

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Sure I still was thinking rev limit 7000ish and not a very high power application.

 

Most aftermarked XU10J4RS rods probably have 20mm pins as that the orginal size, that chinese thing was the only one I could find with 22mm which is close enough to 23...



#4
welshpug

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or just order a rod in exact spec and rev to whatever you want :D

its very little extra cost especially if you have to mod them as well.

#5
petert

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Why not use a K20 piston? Then you get a 22mm pin but you'll need to take 0.9mm off the top of the piston. That seems easier to me.

#6
B1ack_Mi16

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That's a good point. If one is to use a 88mm HG maybe one just can order a thicker gasket and leave piston untouched?

Or is it not good practice to let it protrude above deck?



#7
allye

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Garage View Garage

I'd very much like there to be a couple of spec lists/shopping lists/list of parts needed to make a 2.1,2.2 or even as here a 2.3!

 

My rotrex set up on a 2.3 with some proper management would be nice.



#8
welshpug

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rods and pistons and a longer stroke crank, 88 92 or 96mm.

insert into xu10 block taken to 87mm

#9
welshpug

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or ew12 block of course, with ew12 crank.

#10
drmo

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That's a good point. If one is to use a 88mm HG maybe one just can order a thicker gasket and leave piston untouched?

Or is it not good practice to let it protrude above deck?

Depends how much it protrudes above deck. If it not much (less than a few tenths of a mm) I wouldn't bother, as long as the squish is good.

 

I would advise you not to use those cheap rods. First thing, they come without bolts, second, they most likely are badly machined and would need quite some work to make them better, and third, questionable material quality.

Just go with Robson. I work with them on all the builds with Peugeot engines. They make them exactly like you want them to and the finish is superb. The price is also not that bad (150gbp per rod). You get what you pay for.



#11
B1ack_Mi16

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Indeed, but it does make it not so much of a budget build anymore. I got the crank for 80 euros, so if pistons can be bought for ~450 euros and rods for ~250 it'll be a quite affordable setup.

Of course it is possible to check what re-bushing of a standard XU10J4RS rod costs, maybe it ends up cheaper.

 

At that price level +25% VAT and shipping it starts to add up.



#12
Type-R

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Cheap thrills are the best kind.

Have you looked at Duratec pistons?

87.5x28.65 with a 21mm pin



#13
dcc

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Biggest issue with the crank is the oil pump drive

#14
B1ack_Mi16

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Ok, is it different from a regular XU10 one? I haven't checked any details like that yet.



#15
petert

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It's costs AUS$25 per eye to re-bush here.

 

It's easy to get copper gaskets in various thicknesses, but you'll need to o-ring the block which is another expense, approx. AUS$200.

 

The K20 pistons have a 9cc dish. Thus there isn't a lot of metal to be removed in order to achieve a flush deck with a 0.9mm skim.



#16
B1ack_Mi16

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Agree, those K20 pistons looks quite promising.

 

However (depening on valve pockets of course) I have also found the Wiseco K669M87AP for Mitsu 4G63 / 4G64 engine.

They are 28.875mm CH and 22mm pin, 87mm bore. Giving 0.125mm deck clearance.

 

However 12.5cc dish so compression is down to 10.2:1 with 1.3mm HG.

 

The Honda pistons are probably a safer bet regarding valve pockets, even though it looks like the Mitsu ones probably will be OK too.

Attached File  img_20161219_122114_4315bad5c604aabe9f43f90eb934708e522092d0.jpg   127.02KB   0 downloads



#17
B1ack_Mi16

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The Duratec also seem to have quite large valves as the Mi16, so they may indeed also fit good regarding pockets, but hard to know without really testing it.

 

The Duratec pistons seem to give the best compression ratio of 10.8:1, whereas the K20 ones gives approx 11.6:1 and the mitsu ones 10.2:1.

 

For an engine with modest camshafts I guess 10.8:1 is quite perfect.



#18
drmo

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Kristian, trust me, don't use the cheap rods. In the end they will cost almost the same as anything else and a lot of hassle. I had to re-bush these cheap rods a few times now. And even Manley rods. Once the pin didn't even fit in, other times the clearance was to big.

The other thing with these cheap rods is the big end ovality when torqued properly (stretch method). If you measure them assembled as they come out of the box, they are almost round (0.005mm oval). I've tested how much the rod bolts come stretched from the factory and in some cases the results were horrifying. It got me thinking whether to re-use the same bolts that rods came with...that much...some overstretched, some under stretched... And then, when I torqued them properly, the "almost perfect" roundness came to more than 0,01mm, which is in most cases max accepted ovality.

 

And remember, the ones that you linked come without bolts.

 

Since you're on a budget and looks like you're not building a race engine, I would stick with OE rods that can be modified to fit.

 

The Wiseco pistons for 4G63 I have in stock so I can measure if you need some other info.



#19
B1ack_Mi16

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Thanks for your input. If you have 4G63 pistons in addition to a Mi16 head you could possibly check if the valve pockets are fine, if not I think it'll be too much hassle figuring that out by measurements alone though.

 

Regarding rods, bummer I sold one of my XU10J4RS piston/rod asselblies, so just have 3.. but it's also a job to separate that orginal press-fit from the orginal RS rod though.



#20
drmo

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I think Mandic has some Mi16 heads and I'll lent him a piston to check. ;)