TU8 or TU9?

[Arthur 12]

hi guys. All talks about 1.5, 1.4 short stroke alu tu engines and such now got me thinking. The EC8 engines from China seems to be the same iron block as TU5 but with 92.5 stroke and 79 bore. 

 

Now I'm wondering how big one could go with the iron tu. With 84mm cylinder spacing, what would be the max bore for non turbo? Would one dare to go 81mm? 81 x 92.5 would make a TU9JP4 of 1906,5 cc 

 

New crankshaft with 92.5 stroke are available dead cheap.

Edited October 22 by Arthur

[welshpug 1,657]

Why not start with a readily available XU ?

[Arthur 12]

5 minutes ago, welshpug said:

Why not start with a readily available XU ?

Sure that would be possible. but I'm just wondering. And I just happen to like the TU setup. Maybe not logical, but oké. 

 

[SRDT 175]

The crank may be cheap but importing the whole engine could save you a lot of time and effort.

Maybe the crank can fit inside a TU5 block, maybe you need special rods and a bit of work on the block or maybe you will grind your way to the outside of the block before it fits.

[Arthur 12]

Yeah. Looking at pics of stoker builds there’s room left with 89 stoke. Whole EC8 was quite expensive but block and head looks the same.  So either they use shorter rods or lower ch pistons. Well, took the gamble and ordered the crankshaft. Guess I’m going to find out.

[SRDT 175]

Piston pin is very close to the rings, the head has "EC8" on it :

https://club.autohome.com.cn/bbs/thread/83a86e267aa9bb0f/80933612-1.html

https://kknews.cc/car/9oy242j.html

Edited October 24 by SRDT

[Arthur 12]

Hi all. I found a piston that is quite low CH and 80 mm from standard design. (and available forged).  I do not dare to go 81mm. Should fit with 137,75 conrods so the rod/stoke ratio will not decrease a lot. It would result in 1860 cc