Beak or De-Beak
Turbo Mini Forums

Modern heads rely on "tumble" and not "swirl".

Also they sometimes happen to have several valves more than Minis.

Flow is not everything, combustion is also important.

Beak is good!

On 4th Oct, 2008 Paul R said:
i think my brian is bleeding!

In the 13's at last!.. Just

I fell off the chair laughing

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

indeed,

in A graham bells 4 stroke book there is an interesting bit about 5 valve heads, the 3rd inlet valve cocks up the tumble effect.

Simple.

As Pristic said and proved via pics.

Shrouded exhaust runs hotter than unshrouded.

Inlet charge cools exhaust valve.

Hot exhaust valve can cause det at close to det conditions.

So, having the beak increases the effective octane rating of the engine.

You lose the beak in turbo engines to get a bigger chamber.

How does the beak affect a compressed charge?

I would expect to see the beak still having an influence of the effective octane number....

vs the amount of boost that you can use from the lower compression ratio.

It's all much of a muchness and unless someone restricts 5 port head racing to a specific boost and compression ratio, it doesn't matter a shit.

Bigger chambers beat the tiny edge that the beak gives.

But in the days of shit fuel postwar, it enabled the A to be a lot more efficient than it would have been......

Weslake knew.... he was one of the greatest engine designers of all time....

(Not really the A series though, more like the old F1 stuff)....still.

Bugger off, I'm getting there.

well i changed from a 7.9:1 comp beak removed head that had 33mm wasted stem vlaves, was ported allegedly by vmax and was once fitted to JF's car. to a 8.5:1 comp head with MG metro valves, ported and beak in place. was running upto 18psi of boost on the old head and now run 13psi

i'd say 18 was the max i could run before but 13psi now is quite safe. maybe the lower compression and thus lower boost is more suitable to the turbo. or maybe the traditional one vale bigger than the other is better, or maybe its the beak, but i did a better 1/4 mile with the new head.

On 6th Oct, 2008 theoneeyedlizard said:

On 4th Oct, 2008 Paul R said:
i think my brian is bleeding!

Shit! Is Brian alright???

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

Own the day

I might attack another head.

i only have 600 miles left in my engine really, then ill be pusing it.

ill drop the compression to 12 or as close as posible this time.

my starter motor kicked the bucket this morning.

visard said de-beaking is an easy way to reduce C/R in forced induction engines.
i guess for the home-head modifyer de-beaking with a carbide bit is a fairly easy way to do it??
the beak would only add to squish if the pistons were flat-tops though no?

The beak is only 1-2cc I'd rather find these elsewhere.

So,

Im cutting my next head tomorrow night.
after reading through this and other threads i think i can gain the extra CC, by just enlarging the current shape(std turbo head),and leaving as much beak as i can.

ive only got about 3.5CC to find, i reakon! (std21.5,yet to confirm on my head, though)
Target c/r is 8.5 on my 1293, with 10CC omega dish. which seems to suggest, a chamber vol of about 25?
im thinking of 2.5cc of gasket ish, and 1.5 of ringland and tubbytelly land!

jump in quick if im wrong!!!

Id like to take as muchas i can from any area shrouding the exaust valve first, as priority numero uno.

Then...........


Is there anything to gain (burn wise) by opening up around the plug and leaving the beak as much as std as possible??

i usually cut the gospel according to N/A Viz!!

regards
Col