V-8 Int. man. design

[Evert Rosseel]

> > > > If you have a LOT of money, you can also :
> > > > 4 - install a different crankshaft, so that it fires like two 4 in
> > > > lines connected in V Although this seems strange, it is done on some engines (Ferrari does for example) because the same effects of 
> (unevenly) timed flow also come into play in the exhaust. An equal firing 
> interval for each banks gives best performance because it allows the use 
> of tuned exhausts. The disadvantage is that the engine balance is badly 
> influenced (4 cylinder like instead of V8).
> > BTW, if you use a single plane crankshaft, you also have to change
> > the exhaust manifolds, as they should be optimised for the uneven firing interval.

> 	I was under the impression that with the single plane crank that 
> the firing pulses are even on each now and therfore make most current 
> headers perfect for this?

Basically, when connecting the exhaust pipes of cylinders with 
evenly spaced firing intervals, the lenght of each of the pipes 
should be equal (length between exhaust port and the point where they 
are connected) for optimal results. This way the same conditions 
apply to all cylinders, especially with respect to the amount of 
residual gasses trapped in the cylinder after the exhaust valve 
closes.

For a standard V8, the uneven firing interval will make a different 
geometry optimal, and it is probable that this has been taken into 
account already. Therefore these manifolds are likely to be 
suboptimal if a flat crankshaft is used.

Evert
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*    Dr. ir. Evert Rosseel                                             *
*    Laboratory for Machines                                   *
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