Heads

[keeny]

Good evening all has anyone had there heads(on the stag)gas flowed and port matched and what was the performance gains like

Thanks keeny

[keeny]

Come on am i lead to believe that no one on this forum has had there heads modified whilst off the block?

[Bob Heritage]

Come on am i lead to believe that no one on this forum has had there heads modified whilst off the block?

There's a few had them modified on the block

[keeny]

Thanks bob.Im trying to find out if any gains can be had by this approach as it will probaly not come cheap

Many thanks

Keeny

[Andy Rundell]

i'd imagine you could talk to Tony H about this, i'd expect him to have gone down this path and know whether it is worth investing your time/money

............ Andy

[Westfaling]

I've had my heads gas flowed on a flow bench. The graphs showed an approx 15% increase in air flow. I'll try to dig out the graphs and post them. They could have got a greater increase but the heads weren't in great shape so they did not want to push the grinding too far.
Regards
Nick

[flying farmer]

I have modified the heads on 3 stag engines but I don't have any back to back dyno figures to provide any definative answers about performance gains. What is certain is that the basic port design is pretty good, but is let down on the inlet side in particular by a large sharp ridge on the short side. This can be easily removed with the side of a drill bit as a cutting tool, then the surface smoothed off a bit with a drill mounted grinding stone. The edges of the ports don't always align with the inlet manifold, but these can be flared out a bit to match in the same way. I reckon a couple of hours per head gets most of the job done and costs only time.
The closest I have to a standard engine is fitted to the Estate. This has county pistons fitted to mk2 heads giving a compression ratio of only 8.5 : 1. The engine is fitted with stag tubular manifolds and a straight through exhaust system, otherwise it is completely standard with strombergs, original air filter, and unmodified inlet manifold.
On its one and only dyno run it made 162.4bhp at only 5000rpm. It should have done much better but the mixture was badly out over 3000rpm. Ideally best power air/fuel ratio should be in the region of 13.2:1, but this was down to only 10.5:1 by 5500rpm.
I have since replaced the float chamber needle valves which I knew were knackered, and also the needles and jets (standard parts). The lumenition air/fuel ratio meter I have fitted, that reads off a lambda sensor in the exhaust balance pipe, now shows the mixture is steady right up to the red line, but as I say, I have not had another chance to get it on a dyno.
I want to get both the Stag and the Stag engined TR on the dyno at Malvern next year to compare them, as now the only difference between those two engines is the size of the exhaust manifold primary pipes.
If the rolling road is there for both days, I might nip home and fetch the Estate and give that a run as well
Neil

[keeny]

Thanks for all the advice chaps

Keeny

[V Mad]

If you want to get the best increase for your money then according to David Vizar porting is relatively low on the scale. Have a look at his lectures on Youboob (I mean youtube). He reckons biggest increase to be had is to work in the area around the valves. Very interesting.