GT186 Question

[Donnie]

Not disimilar to mine

gt186-1 by Donnie Canning, on Flickr

gt186-2 by Donnie Canning, on Flickr

gt186-4 by Donnie Canning, on Flickr

[Dimitrios_231]

[Dimitrios_231]

Almost done,
ground control to major Tom

[Warkton Tornado No.1]

Post by Dimitrios_231 » Wed Nov 09, 2016 2:01 pm

Almost done,
ground control to major Tom

It can be seen that there’s some matching to do yet of the crankcase transfers port entries to the barrel.

I wondered if you are going to modify the top of the boost port which is controlled by the crown of the piston.

Is there a current ‘school of thought’ for that angle? As it is, the theory remains that the boost acts as a ‘purge’ rather than a ‘fill’ which might still be best practice....for all I know

[Dimitrios_231]

The transfer port entries are already done and matched,
what you see in the pic is the spigot base cut,this is larger than the duct width,no problem,
the end of the cranckcase and the entry of the cylinder is well matched and flowed,
I should had taken a picture from the other entry (base cylinder via crankcase).

I need to match and flow the middle port,it needs a little extra work.

If you are talking about this angle,it is 27 degrees (or 63),
I won't change it.

[Warkton Tornado No.1]

When I said:

“It can be seen that there’s some matching to do yet of the crankcase transfers port entries to the barrel.”

I was referring to the RH side in that view, but if you say it’s matched, then so be it!

As for:

“I wondered if you are going to modify the top of the boost port which is controlled by the crown of the piston. Is there a current ‘school of thought’ for that angle? As it is, the theory remains that the boost acts as a ‘purge’ rather than a ‘fill’ which might still be best practice....for all I know!”

& your response:

“I need to match and flow the middle port,it needs a little extra work.
If you are talking about this angle,it is 27 degrees (or 63),
I won't change it.”

You’ve kind of answered my question as the nominal angle suggested in the old Robinson tuning guide is 70°which he suggests is a purge.

I'm only picking your brains out of interest, not 'point scoring' as to see this work applied to existing barrels does show that development can still progress further

[Dimitrios_231]

Ι feel you,don't worry

I had posted this image,
on the RH side port you can see the scribe mark of the spigot cut window,
I matched the entry of the cylinder,no need to match all the area,I just gave an angle there to help flow.

Modern engines use 50 to 65 boost port angles
Check out this engine,37.7 or (52.3)

[johnnyXS]

Thank you,
I won't use base and head gaskets,(threebond only),standard 58/107 crank with 1.15 squish and 22.5ml compressed volume.
(I just felt like I went for confession )

]

three Hail Marys and 6x Our fathers

I shall follow this thread with interest as I am hoping to fit a 186 to my S3 special this Winter
I never cease to be incredibly impressed with the high level of experience and knowledge of members

[Dimitrios_231]

I'm not experienced or full of knowledge,
I just like to experiment

Update:
I'll use a 0.5mm base gasket (the one in the last pics) because i skimmed the head 0.5mm off.

[Dimitrios_231]

Crankcase done,did some extra work

I'll start cylinder port work...

[Toddy]

[quote="Dimitrios_231"]I'm not experienced or full of knowledge,
I just like to experiment

agree and Dont we all

Great work BTW