TU44J2 - is it possible?

[205rallye_slo 0]

On 2/9/2025 at 3:34 PM, AndreasN said:

Okay, I got it at last 

 

Any progres on tu4 engine? 

[Arthur 20]

Hi, any updates? In the meantime my 1860 cc EC8/TU5 engine,inspired by this treat, is running. 

[205rallye_slo 0]

No from my side. 

Still run standard tu3s.

Working on manifold for 2xdhla.

 

Your ec8/tu5? Where we can see more about?

[Arthur 20]

I have a threat about it on here

[AndreasN 0]

Apologies for the lack of updates, but there haven't really been anything to write. Due to various circumstances I have not been able to do much work on the car, but I've resumed again now

 

I decided to change the plan a bit by using the pistons and rods from a TU3JP. This is both due to parts availability (with the previous plan I'd basically have to buy a set of TU24 pistons and cylinder liners, just to throw out the liners, whereas I can use a complete set of TU3JP pistons+liners "as is"), and partly to get the advantage of the more modern pistons in the TU3JP. They have a much shorter compression height (27.75 mm), and a corresponding longer connecting rod (140,25).

 

Full of optimism I ordered a complete set of Mahle cylinder liners + pistons, and a bunch of connecting rods from a breaker's yard. I'm still waiting for the Mahle parts, but I've received the connecting rods...

 

But now I'm having second thoughts. I know that modern engines tend to have much slimmer rods than the old TU3A, but the TU3JP rods just seem so fragile that I don't know if I'll dare rev them to 7000+ RPM.

Sure, the pistons will be 10-15% lighter, but the rods are SO thin under the piston pin - which is 18mm on the 3JP, as opposed to 19.5mm on the 3A.

 

On the other hand, I suppose the JP rods may be made of stronger steel. The sides of the forging certainly look cleaner. I've attached some pictures of a TU3JP rod next to a TU3A rod. And if the failure mode of a TU bottom end is ovalization of the big-end bearing or stretch of the rod studs, rather than breaking of the rod itself, then I suppose the lighter TU3JP bottom end might actually be better...

 

What do you all think? Has anyone tried building a 120hp+ engine on a TU3JP bottom end?

Edited August 6 by AndreasN