On a side note ... I'm just curious .. how would one know if their rods are on its way out ...

 

Steel rods can be x rayed to find internal imperfections. Titanium cannot be x rayed. You must visually inspect titanium rods. Just be sure not to scratch them! Titanium is very “notch sensitive.” Small surface imperfections caused by rough handling must be polished immediately, or they can grow quickly. For that matter any weakness or imperfections can grow quickly.

 

With the engine in the car a compression test would show big variances between cylinders.

 

Titanium can be X-rayed as anything but the use of the film on Titanium without extensive work and knowledge will still produce a likely useless result in our application. UT would be better but still not even close to a cost effective form of inspection.

I love Ti and my alcohol drag quad frame is complete Ti but it has its own issues, compared to Steel Alloys.

 

From what I am reading I would say gt3 crank carrillo rods with CARR bolts. gt3 crank is about 2 lbs lighter then turbo crank. weight saved and at the same price as ruff TI rods. I would never use TI rods on a boosted engine, as others have said they give no warning they do not bend like steel they shatter. Use updated lifters and you can run 7500-8

 

No one is saying titanium isn't strong. The question is bearing the costs of more frequent inspection tear downs. As with things associated with these motors. The hp/torque becomes more expensive as you add more and more power.

 

A compression test isn't going to tell you anything about the rods. Valve/ring seal yes.

 

I agree with you.

 

any issue revving the stock TT crank to ~7500-8000rpm?(where is the 'safe' limit?) Or just suggesting the GT3 crank for mass reduction?(where is the power limit on the GT3 crank?)
Cheers,

 

Sweet. Keep the input coming guys. I think we're getting somewhere. So the concensus is steel rods, GT3 crank and updated lifters (had those done last year). Anything else to rev reliably to 7500? Better valve springs??? What about the Mahle 3.8 pistons? Much benefit to those? Are they lighter or heavier than the stockers? Pauter or Carillo rods better? What is this clearing the oil pump business? Wouldn't it be better to go with rods that dont require modding the oil pump?

 

3.8 pistons cant be done without changing liners. and thats a 5500$ cost.
you get more low end grunt, and torque and more power, faster spool etc.

Clearancing the oil pump means Machine/grind the oil pump case so the larger rods dont hit the oil pump casing. (they are extremely close together)

 

Ummm yeah sure right, so as the rods bend and shorten where does it make itself known.... Even if they bend or twist in a straight pattern the wee bit does show up in a compression test. If they bend in a parallel fashion not perpendicular ring seal may still be good; but no matter if you do a compression test and leak down can usually tell you if your rods are not quite Honky Dory.

See this for more input.
https://www.6speedonline.com/forums/...knowledge.html

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I agree you could pickup the change in compression number and that tell you that you have a problem. But you dont know exactly the problem you could have a valve seal leaking just a touch, or a bit more blow by in that cylinder or...

But you can use the Compression test to monitor the condition of each cylinder to see if a problem is there/becoming worse etc.

 

As a guy that builds a fair number of engines I will say from my fairly vast experience that when con rods start to bend it usually show up as major red flag during a compression test and leak down, yes a failed compression test could be telling you something else is wrong and the rods are fine; but no matter what you are going looking for a problem.

 

agreed,

in your experience what kind of deviation on a running driving motor have you seen first hand (doesn't have to be a porsche)? where the rods bent and a compression test was performed?

personally ive not seen it but have found many other issues with a compression test.