> On Oct 18, 2018, at 9:00 AM, krnet-requ...@list.krnet.org wrote:
> Message: 1
> Date: Wed, 17 Oct 2018 16:47:43 +0000
> From: Great Western Airsports <f...@greatwesternairsports.com 
> <mailto:f...@greatwesternairsports.com>>
> To: "krnet@list.krnet.org <mailto:krnet@list.krnet.org>" 
> <krnet@list.krnet.org <mailto:krnet@list.krnet.org>>
> Subject: KR> HAPI 1835 Questions
> Message-ID:
>       <894D2EEDDB99FD48A33353F6FB0162BBD07E15F9@exch3-mbx05.email3.local 
> <mailto:894D2EEDDB99FD48A33353F6FB0162BBD07E15F9@exch3-mbx05.email3.local>>
> Content-Type: text/plain; charset="us-ascii"
> Hi all,
> I'm pretty new to the group and hope there will be someone who can answer my 
> questions.  I've a KR2 with 1835 HAPI which I've not opened up yet hence some 
> of the questions I'm asking.
> 1. Engine is low hours and quite tight - what max static RPM should I be 
> expecting with a 52 x 48 prop?

The engine should make ~50hp max (HAPI spec says 60hp max at 3200rpm).   To get 
it you want something close to 2900- 3000rpm static. On take off you’ll get 
~200-400 rpm more.  You match prop to the engine - not the other way around.  
If you get only 2700 rpm static (and there is nothing wrong - common problem in 
with your 52 x 48, you need a different or re-pitched prop. 

> 2. Was this engine built with hydraulic lifters?

Actually - maybe.   HAPI did go for hydraulic lifters to counter the need to 
adjust every 5 hours (only a bit of an exaggeration). I think their Magnum 
engines had hydraulic lifters. Turned out that was a problematic approach and 
best practice (like Revmaster) is back to solid lifters - and sufficient head 
cooling to reduce thermal deformation (that may have been the root cause of 
frequent valve adjustment requirement and a bevy of other problems).

> 3. Was this engine built with a standard cam and standard 1:1 ratio rockers?
> 4. What is the max EGT figure?
> 5. Any recommendations for mild tune upgrades that'll maintain reliability 
> for the 1835 HAPI?

Perhaps the most important mod is the removal of the 4th bearing flow 

Some say the Hoover Mods are key to reliability:

I don’t know, but this manual is very informative:

You can also find a lot if information in the Yahoo KR group’s VW files:

And you can check out these two VW Yahoo groups for interesting threads and 

This site used to have a tonne of information, but seems to be under 
construction now:
http://vwengineconversion.com <http://vwengineconversion.com/>

Interestingly, the Sonex builders probably have the most recent experience with 
VW’s and their forum reflects that and their problematic experiences with the 

The take home is something like this:  Get rid of the 4th bearing flow 
restrictor and then keep the engine cool (pay a lot of attention to baffling 
and maybe make the revmaster oil cooler mod). You could consider the 30mm oil 
pump mod too.   

However, if you start mod’ing the engine to make more power, you’ll have to 
start making some major changes.  Higher power will probably necessitate moving 
to Revmaster or ForceOne 4th bearing and crank.  


> Many thanks in advance. 
> Brad Wagenhauser 

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