OST-030: a case in point

[oldeskewltoy]

Got this via FedEx yesterday....



I've gotten heads in all kinds of containers/packaging. But this one is unique, and lead to the title.....

It has very interesting latches....





I wish all clients would be able to do this.......




Safe and secure with plenty of protection around it




the head is clean, and it comes with all the hardware....



..... along with a set of Pon cams!!!!



More to come.......

[mad.matt]

That's a flight case, often used by musicians and such.
The latches are very similar to those used in Military cases (non Peli type) as they have a high latch strength and low profile

[oldeskewltoy]

(04-09-2015 02:32 PM)mad.matt Wrote:  That's a flight case, often used by musicians and such.
The latches are very similar to those used in Military cases (non Peli type) as they have a high latch strength and low profile

from another forum Wrote:hmmm...military owner by any chance?...we use those cases for equipment/parts

Now I (we all) know about this kind of case/latch :thumbup


While OST-031 is being cleaned and pressure checked, it gives me a few days to work on OST-030...


Besides the Poncams, my client is using a piston with a 3.2cc dome. He has to check, but believes he has .005" of positive deck - piston slightly ABOVE the blocks surface. He wants to run a squish of .040".

What chamber volume does he need for a 11.3 to 1 compression ratio?


My clients said his head had been already run through the mill once... .008"




Seems pretty close to me....

btw... look at the "round" exhaust port...


All the cam journals look pretty much the same as this...


Since MR2tailbreaker noticed a "small" problem in his cam and journal clearances using the Poncams, I'll be checking these journals for similar issues.....


Work begins on the bowls and seats of chamber #1




More to come....

[oldeskewltoy]

from another forum Wrote:What do you do about bad cam journals and caps?

not ignoring you... not quite ready yet to show that part of the process

from another forum Wrote:Is this a CA customer? 11.3 on 91 octane, better have clean chambers, and management dialed in nicely, my recommendation from experience... I would even worry that improved breathing/VE would skew things even more toward a little less CR. If this is 93 octane, probably it's fine, but potentially close to incipient detonation.

Other side of the country..... Part of the issue is opening the chamber to accommodate the piston. With the clients deck, and the piston volume, the chambers may need to be "opened".


Most pistons can be milled a few ten thousandths, which could drop the piston volume under 3cc

example of piston milling


The piston I designed could be milled .030" and drop the dome volume from 2.5cc to about 1.8cc.

[oldeskewltoy]

#1 is almost finished...




Here is #1 exhaust bowls/port in transition




And a closer view of the short radius, and the port in the background





More to come.......

[oldeskewltoy]

2 down.... 2 to go.....

Chambers.....




exhaust ports.....




More to come.......

[oldeskewltoy]

further progress... 3 down 1 to go....


this time the intake view - first short radii...


followed by the view down the ports



The exhaust...




And the chambers... 3 panel this time so you can see the progression





More to come.....

[oldeskewltoy]

4 down......








Next stop valve job and resurface... and then we set chamber volume....




More to come.......

[oldeskewltoy]

oldeskewltoy Wrote:Besides the Poncams, my client is using a piston with a 3.2cc dome. He has to check, but believes he has .005" of positive deck - piston slightly ABOVE the blocks surface. He wants to run a squish of .040".

What chamber volume does he need for a 11.3 to 1 compression ratio?


My clients said his head had been already run through the mill once... .008"

Here is what is now known....

82mm bore or 3.229"
77mm stroke or 3.031
.012" piston sticks out of the bore
.052" Cometic gasket
3.2cc piston dome

So I ask again what chamber volume does this build need to have a static CR of 11.3 to 1???

Now how do I achieve that target volume on a head already cut .008", and will be cut an additional .002"????

[oldeskewltoy]

from another forum Wrote:If all else remains the same and assuming the bore of the head gasket is 1mm larger than the cylinder bore then you need a volume of 37cc.

I should have had you answer these other responses

from another forum Wrote:Without checking it..

stroke volume is 3.14x41x41x77=369.5
piston sticks up 3.14x41.41.0.3=1.6
gasket is 3.14x41x41x1.3=6.86

Let X be the head volume.

So the BDC volume is
369.5+6.86+X-1.6-3.2 which is 371.56 + X

The TDC volume is
X +6.86 -1.6-3.2 which is X + 2.06

For an 11.3 to one CR
BDC volume = 11.3(TDC volume)
371.56 + X = 11.3(X + 2.06)
371.56 + X = 11.3X + 23.28
371.56-23.28 = 11.3X - X
348.28 = 10.3X
so X = 34.83


..and can I have 25minutes of my life back please!

from another forum Wrote:oh, and account for the gasket too. so chamber volume will need to be

so swept volume is 406638.3mm^3

so your desired theoretical chamber volume will be 35985.7mm^3, just add or subtract the various volumes from this, no? is the "dome" of the piston convex or concave?

As to the chamber volume I'll need... I find to save time, and poor calculating skills on my part - I use one of the online compression calculators..... https://www.rbracing-rsr.com/compstaticcalc.html or http://www.csgnetwork.com/compcalc.html

either of these work.....


in both cases we come up with about 37cc (37.3 in the RB racing calculator)