Small port A15

[_smp_]

I have an early A15 engine that I am planning to rebuild.
It has a small port H81 head, that seems to be a rarity amongst A15s.

according to the bible 1200 wiki, the H81 head was the 'swedish emissions head'...wtf?
not sure how it ended up in little ole NZ!

question is, I was considering giving the engine the 1608cc treatment, and am wondering if the head will constrain flows to an extent that I should look for an oval port and start from there?

I am not looking to build a 7500rpm screamer..more a higher displacement led torquey (for a 1600!), motor. so, in some ways, I'm wondering if the smaller ports could help (valve size essentially the same).

wots the general view on the small ports?
cheers

[Bartman]

The higher air flow requirements of a bigger engine, mean you're going to want all the flow you can get. I'd say the small port ones were for forklifts, or some other application where not much real power had to be made.
You'd be lots better off with an H89 head.
I have a mate with a bulldozer running an A15. A small port head might be right up his alley if you don't use it.
Small ports mean higher air speed, and better low end torque.

[Bartman]

Put up some pictures of it if you would be so kind.

[tlssunny]

i have a couple h89 heads available

[_smp_]

here 'tis.

it's had some porting done already and previously was in an off roader...hence, there would have been a need for torque.
although why the dude was using a little a15 for dirt buggying I have no idea...lightweight chassis, but big wheels/ mud

[Bartman]

What size are the valves? They look tiny......

[mint16]

This is interesting, keen to know valve sizes also.
I have several A14 heads like this, small port 4 bolt manifold type but with a14/a15 valves. Ill check what coding they have.