V8 crank

[spice]

Call me stupid but is it cross or flat ? I thought cross from the exhaust burble ?

[V8LM]

I think the firing order shows it's cross and not flat.

Stand to be vilified though.


ETA: Although I don't think it has a centre cruciform so surprising if it is.

Edited by V8LM on Friday 20th January 23:14

[Murph7355]

Crossplane. You can tell by the sound if nothing else.

Compare to a Ferrari V8 (flatplane).

[Al 450]

It's both as the road cars have a cross plane crank and the race cars have a flat plane crank!

[Speedraser]

I think the racing V8V cranks are cross-plane like the road cars.

[With these feet]

Al 450 said:

It's both as the road cars have a cross plane crank and the race cars have a flat plane crank!

The racing engines (GT2) "had" flat plane cranks. I believe they reverted to original after a couple of issues at Spa.

[spice]

My F430 buzzed the Aston burbles if you know what I mean , so the flat plain fires two cylinders at a time like two fours on a common crank with no counter weights , so revs quicker and higher.Aston V8 has an uneven fire patern on each bank of four but even overall , however you can't disperse fire pattern in the way you can in a 10 or 12 , so two cylinders will always fight for exhaust hence the burble .So I have been told ? I have searched the web and seems about right , lots of technical stuff about degrees of pins etc but Aston V8 deffo cross plain

[spice]

Apparently if you look down the length of the crank you see a cross . Hence the name and the flat looks , well flat.

[V8LM]

I don't think flat plane crank fires 2 concurrently (flat boxer engine can) but allows alternating banks to fire. The cross needs at two pairs of cylinders on the same bank to fire consecutively, which causes the uneven increase in exhaust pressure, the characteristic American burble, and the problem of localized heating. In the case of the V8, it's cylinders 4 and 2, and 7 and 8 (*). The latter causes most of the problems in the original V8 cars as this region gets hotter than the rest.

The original V8 has a cruciform to even out the pressure difference but I don't think the V8V has for some reason.

• ETA: Using the old numbering convention: The current ISO standard labels cylinders alternating right/left between banks from front to back (so has firing order 1-2-7-3-4-5-6-8) as opposed to the older right bank 1-to-4/left bank 5-to-8 (1-5-4-2-6-3-7-8).

Edited by V8LM on Saturday 21st January 08:53