The V8 Owners Forum -

southernd wrote:Thanks for the head info, that makes sense. The Vitesse do seem to have bigger valves etc, would they be classed as performance?

Valves are not bigger just a waisted stem as are most later heads - flow is still strangled by the throat - you can put all the valve you like, big as you can but without the throat / port being worked nothing gets in that cylinder

Good news is that the work to move the restriction is not very difficult but makes a huge difference.

Going to a big valve and making those work is a bit more involved and where it all starts getting costly. 225 can be had reasonably cheaply - 250+ start getting pricey and 300+ very ££££

Thank you so much for your help, I really couldn't work out why the figures were so low for a sub 10k full rebuild.

It's been around 20 years since I was under the bonnet so I'm a bit rusty. Getting the heads ported is what I need to do?

I'm only looking for around 190bhp, I've owned much more powerful cars and been left wheel spinning at 90mph, I prefer usable power.

Just found an article for a 350i wedge, seems to hit the nail on the head:


I've just ported a set of heads to stage 1, which involved opening the throat diameter by about 1.5mm, cutting a 3 angle seat ,enlarging the bowl area and a back-cut on the inlet valves. This gave around about a 15% increase in flow on my flowbench, which in theory is good for an additional 40bhp*.

http://www.pistonheads.com/gassing/topic.asp?t=1274951

A search on here will also bank a fair a mount of info.
A ported RV8 is like night and day compared to stock the heads are just that bad for flow.

southernd wrote:Just found an article for a 350i wedge, seems to hit the nail on the head:


I've just ported a set of heads to stage 1, which involved opening the throat diameter by about 1.5mm, cutting a 3 angle seat ,enlarging the bowl area and a back-cut on the inlet valves. This gave around about a 15% increase in flow on my flowbench, which in theory is good for an additional 40bhp*.

http://www.pistonheads.com/gassing/topic.asp?t=1274951

I'm really grateful for your help. I'll get the work done and report back