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Want boost but really?


2002newb

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What crankshaft are you running?  Looks like you have 2 liter pistons but a 1.8 crank. The difference is 9mm of stroke. That will leave the piston 4.5mm deep in the block at TDC, and that is about what that looks like. 

1970 1602 (purchased 12/1974)

1974 2002 Turbo

1988 M5

1986 Euro 325iC

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That's odd- E21 pistons?

 

That's not ideal for quench- there'll be a big ring around the perimeter that

will ignite late in the combustion cycle...

 

t

<edit, simultaneous typing>

I think Byron nailed it- that's too low for E21 pistons.

Edited by TobyB

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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  • 2 weeks later...

Wondering if using 144mm connecting rods would solve my problem? 9mm difference than the stock ones correct?

 

Oh and these aren't stock pistons but unsure if they will work with the longer con rod

Edited by 2002newb
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To me it looks from the picture that the piston is approximately 2,5...3mm below the block. By fitting 9mm taller rod it would be about 6mm proud. 

Also if my estimation is correct it doesn't quite match to 1.8 vs. 2.0l crank difference. I could be wrong though especially since the block is already shaved unknown amount.  

Basically what I'm saying is that I don't know what pistons you have... and you don't know what pistons you have. You should measure how they actually are positioned, measure the stroke just to be sure, take the pistons out and measure the compression height. Then you should specify what CR you want for your application. Actually you should have done all this before machining anything but well - live and learn. Then you do the math to see whether the pistons can be used or not. My guess is not. I would not recommend shaving the block (and even less the head) unless it's about some tenths of fine tuning. Millimeters will run you to problems with timing chain. Taller rods would be a solution...but they would need to be custom unless you can find some about 138mm tall ones (don't know about them existing).   

Racing is Life - everything before and after is just waiting!

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After losing my original block to a less than honest machine shop I bought a bunch of engine components - block 4 sets of pistons, head, gaskets etc etc - that had all been machined and was ready to be assembled. These pistons were the brand new ones and so they were the first ones that got placed in the block. Going to have to measure things up and see if one of the other sets will work better

 

Thanks for reading and all the input folks - keep em coming

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