
Just out of interest are any of the heads you are testing offset valve ones ?
Yes. Both Swiftune heads use 1.48" inlet valves combined with 1.22" exhaust valves. As this combination will not fit the standard valve spacing dimension, I suspect the exhaust valve has been offset by the usual .050".
Midget's Longman head uses a 1.48" x 1.15" valve combo. I'm pretty sure it is at the standard spacing.
The other Longman head uses a1.48" x 1.22" valve combo. Would have to suspect that it also has an offset on exhaust.
When I get some time this week, I'll measure the valve spacing centerlines for several of the heads I've been flow testing and post up the results.
What is interesting to note however, is that:
A/ The Swiftune heads DO NOT flow as well on exhaust, as the Longman heads, offset or not. (See the previous graphs.) My previous experience is that this would
require a "slightly" different cam grind for best output . . . . . .
2/ The "optimum" cam grind for a particular cylinder head is going to vary. Based on engine displacement, rpm range desired, component strength, shape of the torque
and bhp curves desired, etc, etc, etc. (
It's Complicated.)
d/ EVERY HEAD SO FAR TESTED, has responded positively to the substitution of 'RimFlow' exhaust valves. Now having said this, I will also state that I have not tested
every head with the 'Rimflow' exhaust valves. So at this point I would classify this as a "trend", as opposed to a "certainty". Additionally, there MAY be other
considerations concerning a specific engine build, which MAY find the 'RimFlow' valves unsuitable. The 'RimFlows' are heavier and give less valve to piston clearance,
etc.
z/ In the results driven world I live in, there is no such thing as "too much low lift flow". What I have seen consistently between flow testing and dyno testing is that:
The engine with the best "area under the output curve" is the winner. PERIOD. Very seldom, if ever, have I seen an "airflow dog" become a "dyno winner". AND, if
that is the case, some engineer or technician did not do their job . . . . . .
But again, it is significant for me to note here that: Except for the testing results, which are facts, most of this is my opinion. And in the world of "professional motorsport" (un-caged verbal wrestling, as it is . . . . .

) there is some "professional disagreement" as to what is, and what is not, important. Smart pros let their results talk for themselves.
Does the Swiftune price you quoted include VAT? I would be interested to know their current quote for a full race spec (8500/9000 peak rpm on a 1310cc Mini) complete head assembly for export. I have a client who just trashed a head and needs a replacement as soon as possible. What is your experience with MED head assemblies?

Fordboy