High Compression Pistons for Haflinger

HafWit · Post by **HafWit** » Thu Oct 19, 2006 9:46 pm

I am curious if anybody here has switched out their stock pistons for high compression pistons, and if so how that influenced their vehicle's performance. There are a few different upgrade paths that I am aware of, and before I seriously consider an upgrade, I'd like to learn from other people's experiences.

Thank you in advance for any information you provide.

Profpinz · Post by **Profpinz** » Fri Oct 20, 2006 12:06 am

I fitted factory high compression pistons many years ago (back in the late 70's) but it wasn't very successful.
I remember I kept getting pre-detonation no matter what I did....I got it down to a minimium but I could never get rid of it totally.... Back in those days I used the Haflinger as my everyday car.

Years later when I pulled that motor down, I found the crankcasing had broken around the base of one of the central crankcase bolts ...... something I can only attribute to the pinging!

I wouldn't say the increase in performance from fitting the HC pistons was dramatical but it was an improvement, and when you've only got 28hp, any extra power is "an improvement".

HafWit · Post by **HafWit** » Fri Oct 20, 2006 8:58 am

Peter,
That being the case, without swapping the motor altogether, what other "upgrades" have you done or are you aware of to improve the stock motor. My Swiss Haffy has had the exhaust system replaced with a stainless one that was made locally--this added some slight improvement. My NA Haffy will be undergoing a tune up shortly and I'm planning on doing the exhaust on it as well--since I plan for the NA Haffy to be more of an "on-road" vehicle than the other, it would be nice to give it a little more umpf so that I can use it on roads with posted limits of 40-45 mph.

Profpinz · Post by **Profpinz** » Sat Oct 21, 2006 1:20 am

Well to be honest I haven't done a lot on Haflingers lately.....but I do intend to start restoring my LWB in the next year or so.
Back in the 70's - 80's when I used the Haflinger a lot and was a member of the Haflinger Club of Australia, I reckon you would have been hard pressed to find a totally stock Haflinger motor anywhere..... most owners "tinkered" to try and extract a little more hp.

The first mod most people did was to block off the exhaust heater tubes (the ones connected to the inlet manifold)....the most basic one I saw was an owner who had just loosened the bolts and slid in part of an aluminium Coke can. (Cold intake air = more hp)
The next mod was to remove the fuel pump, block off the hole and fit an electric unit......(less hp lost driving the mechanical pump)
Blokes also used to also fiddle with the carby jets with limited and varied success.

The next generation of modifications required removal of the motor and included work such as blueprinting and balancing, machining a groove in the cam gear to minimise oil pickup and power loss, fit VW pistons, port and polish the heads etc.

The most radical mod was to change the motor to a VW, BMW motorbike or Subaru Sherpa motor.

The other people to talk to are those that used to race Steyr / Fiat 500's.....some of the mods and power outputs were incredible.