Pistonheads engine.

[ihatesissycars]

http://www.pistonheads.com/sales/162037.htm

How come some people can get over 400hp out of a 4.5 with rover head castings yet we normal(ish) folk struggle to get over 300hp?

[Lewis]

Depends if those dyno figures are a) proven or b) rolling road or actual engine dyno readings.

Many rolling roads can give you 'more than' optimistic readings for engine BHP.

I guess full race engines also make compromises in terms of streetability and lifespan that can generate the extra BHP, as after all, they only cover a fraction of the miles between rebuilds so you could run high C/Rs, on full race fuel and so on.....

Have to say though, would love that engine in my car. Would prefer fuel injection though!

[chodjinn]

That power figure is a bit questionable IMO The heads and dry dump will help a bit, but 411bhp would be an extremely impressive figre from that set up.

[kiwicar]

If there is any truth in the rumours and legends about "group A heads" then there is your answer, the bottom end would support it, I think the cam would be enough timing for 90 odd break per litre, the induction is good enough, all you ever need with the rover is a decent head casting to base your porting work on. Though I suspect it is also dodgy bhp numbers.
Mike

[HairbearTE]

I have seen a JE engine of around that capacity make over 400bhp but I can tell you it was at more like 7500+ rpm. Only at high rpm can you make 400+ from a rover of that size. 411bhp @ 5750 is either a) a typo, or b) bullshit.