Engine rebuild

Engine rebuild

Author
Discussion

rossyl

453 posts

113 months

Wednesday 9th October
quotequote all
Amazing thread

A questions if you don't mind

- Do de-catted cars pass MOT requirements, or, are you refitting the CATs before an MOT?

- Also, is there any way at all to tell if your pre-LP Gallardo's CATs are disintegrating?

Thanks very much

4321go

Original Poster:

486 posts

133 months

Wednesday 9th October
quotequote all
I’ve sent you a PM Ross.......

GregorFuk

514 posts

146 months

Thursday 10th October
quotequote all
4321go said:
And talking of sound........

It’s often noted that the 5.0 litre Gallardo engine is one of the best sounding out there. It’s generally agreed that it’s much better sounding than the replacement 5.2 litre LP-series engines. And that’s down to the crank. On any V engine, two con rods sit together on a journal between a pair of crank webs. On the later engine, that journal is a straight one; the pairs of con rods sit side-by-side. But on the earlier engines, the journals are staggered. Which subtly alters the firing angle and hence the sound of the engine. As ever, much easier to illustrate with photos:

My crank, with the staggered journals between the webs (and note crystalline face of one of those fractured rods going into place):



And a later 5.2 engine, with straight journals:

So the 5.2 is a flat plane V10.

4321go

Original Poster:

486 posts

133 months

Thursday 10th October
quotequote all
Neither engine has a flat-plane crank. A flat-plane crank has the crank throws at 180°, like this, from the Shelby GT350



The split crankpins of the 5.0 results in an even firing order, one cylinder firing every 72° of crank rotation.



The shared crankpins of the 5.2 apparently results in an uneven firing order, every 54° or 90°.

Apparently.