Grob 109B engine

[Charles Longley]

I am doing an Annual on one that sat for over a year. It needs one new head. After a little research it appears the engine is based on the VW T3/T25 Transporter engine. This head appears to be the correct one- https://www.autohausaz.com/pn/071101351AC
Can anyone with experience confirm it?

Thanks!

[Kristin Nowell]

Just eyeballing it...
The intake manifold is a different configuration.
The exhaust ports are differently located.
The combustion chamber is smaller and differently shaped.
The rocker box is differently shaped.

[Charles Longley]

On Thursday, April 2, 2020 at 8:15:56 AM UTC-7, Kristin Nowell wrote:
> Just eyeballing it...
> The intake manifold is a different configuration.
> The exhaust ports are differently located.
> The combustion chamber is smaller and differently shaped.
> The rocker box is differently shaped.

What are you comparing it to? I did a little more research and borescoped the head. I am reasonably sure that it's a Porsche 914 head. They're very similar to the VW Vanagon head except with bigger valves and combustion chamber. Also the one I need has 3 intake studs instead of 4. All of the Vanagon and some of the 914 had 4.
http://www.autoatlanta.com/Porsche-914-Cylinder-Head-srch.html
http://mp.motoplaneur.free.fr/images/A_CIMG1936.jpg

[Kristin Nowell]

Sorry Charles,
My bad... I assumed that you had a Limbach up front, i.e. L2000EB1AA.
I can see from your photo that I was wrong. Straighten me out... What am I looking at?

[Charles Longley]

Grob 2500 engine. I am pretty sure it’s a modified Vanagon engine with Porsche 914 heads. Single magneto but hey you’re in a glider right? ;)

[Kristin Nowell]

Sweeeet! I haven't seen one in the flesh before.
Obviously, I also don't know jack about grobs, although I did try to visit their factory once back in the olden days (2001?) but they wouldn't let me in. I have always been fond of the egret.
Sorry again for my mistake, I will shut up now.
Tom

[[email protected]]

I believe you are looking for a head from a 1972 Porsche 914 with a possible code or part number of 039101371A. There are some postings on a motor glider web site that discussed the correct heads for the Grob 109B that you should be able to locate if you Google this part number. The .pdf of the Grob 2500 engine IPC that I have doesn’t really state the number but there is a hand written part number and arrow to the head on the diagram in the IPC. From what I have read, there are also certain specifications for the correct valve seats as well. Hope this helps

[Charles Longley]

OK thanks. I saw that hand written note in the IPC but didn’t quite figure it out.

[[email protected]]

On Thursday, April 2, 2020 at 11:50:13 PM UTC-5, Charles Longley wrote:
> OK thanks. I saw that hand written note in the IPC but didn’t quite figure it out.

Sure would be nice to see an STC for Grob 109bs to use the Rotax 912is3. The price has come down a good bit since they were introduced and there's a charity in the UK that looks like they may well already have EASA's blessing on the resulting product. This would certainly breath new life into them and the extra power would be pleasant when the temps bump DA up.

[Dave Nadler]

On 4/5/2021 1:04 AM, wrote:
> On Thursday, April 2, 2020 at 11:50:13 PM UTC-5, Charles Longley wrote:
>> OK thanks. I saw that hand written note in the IPC but didn’t quite figure it out.
>
> Sure would be nice to see an STC for Grob 109bs to use the Rotax 912is3. The price has come down a good bit since they were introduced and there's a charity in the UK that looks like they may well already have EASA's blessing on the resulting product. This would certainly breath new life into them and the extra power would be pleasant when the temps bump DA up.

No idea about the later Rotax, but IIRC there were some 109B converted
to original 912 (one I know in Germany), and I think they eventually got
proper EASA papers. Contact me if you'd like to get further info...