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Sun Jun 07, 2009 10:40 pm

Roadcow wrote: Maxton Update
Bruce Cook DSS new Record on first pass 99.8 mph on a 1493cc engine

Tom Bruch SSS new Record 90 mph and change on a 1415cc engine using stock carb and intake manifold.

Pictures

Also a question; Can you run a dry sump in the DSS class? Planning the 36 type 2 land speed DSS engine and the question was brought up

Mon Jun 08, 2009 6:15 am

A dry sump oil system would pass the "guidelines" if the components utilized were availalble prior to 1965 since it could improve performance. A "full flow" oil system is acceptable since it only contributes to reliability, not performance.

Burly

Thu Jun 11, 2009 7:36 pm

Ronnie you must be the "Cybil" of the bus world! You have one lowered, one raised , one stock, one racer, one original paint, one restored, yep you truly are a multi personality bus owner :twisted:

Thu Jul 30, 2009 1:57 pm

Tom have you got some comparison numbers for the exhaust flow ?

bvilletom wrote: After about a year and a half of work, ... I have worked out a whole system from combustion chamber to carburetor entrance that out flows the Okrasa set.

Thu Aug 06, 2009 4:05 pm

Yes, Uncle Ian. I will post a bunch of 36hp exhaust flow numbers soon.
Also I will describe some interesting facts & observations between the Okrasa heads, stock heads, and modified heads. At first I didn’t work much with the exhaust flow on the 36 head because the stock exhaust valve flows are very close to the same as the intake. This bothered me so I concentrated on the intake only. Now the intake side of things are going pretty well with the Cook, Blackline, and Brukrasa modified single port heads. The exhaust flow numbers are very similar to late 1600 heads.

BvilleTom

Thu Aug 06, 2009 6:52 pm

Yes, modern race heads are typically ported so the exhaust flows
60-80% of intake. Depends on the application, and builder.

bvilletom wrote:
Also I will describe some interesting facts & observations between the Okrasa heads, stock heads, and modified heads.

Looking forward to it.

Thu Aug 06, 2009 6:54 pm

bvilletom wrote: Now the intake side of things are going pretty well with the Cook, Blackline, and Brukrasa modified single port heads.

What class are you guys running this year ?
Going to take another run at NA36 ?

Tue Aug 11, 2009 4:58 pm

Posted are air flow summary sheets for two different 36 HP engines both with stock size valves and stock intake flanges. These both would be much better with big ports and bigger valves but this is just baseline information. The left side shows the average flow of 8 stock 36 heads. The far right side shows stock Okrasa flows, which has been my goal to equal or exceed. The center section shows a port by port intake and exhaust flow of a pair of heads identified to each port by the castings number and the date code. You will notice that all of the heads vary a little inflow from port to port because of valve head shape. Some are tulip shaped, some are flat, etc. The seat and throat shape, as well as the slight differences in port shapes and where the porting tool may have slipped a bit. On the modified intake sheet (4-27-09) the intake flows look better since I cut the guides off slightly to get more lift because of the use of high lift rockers and cam. The sheet from 04-27-09 is of the heads I ran at Maxton, NC in May, 2009 in the SSS (super stock single) class at 90.2 MPH.

Back to the exhaust, the Okrasa head slants the intake seat side of the exhaust port toward the exhaust flange quickly and the long side (top) of the port is raised toward the valve cover 1-2 mm. The best part of the exhaust port is that the short side port radius is about 5 mm higher into the port, causing less flow separation. Also the port just out from the valve guide boss widens out to about 35-36 mm and then blends into the long side radius. It is just about a “D” shaped port in the middle.

I measure all the ports with an inside caliper on the X & Y axis to plot out these diameters and shapes. I now flow all the ports without valves and actually get a before, during and after flow to get the port shape right. The whole key to getting flow is the right internal shape of the port. Bigger is not always better! Velocity works wonders. After that I get the valve shape, back cuts or whatever to make it work. With every set of heads that I’m doing now, I’m learning and improving the flow.

I could write a thread, if there is enough interest, of step by step instruction on how to port 36 heads, where to grind and where not to touch it.
Sheet #2 is coming soon.

Bville Tom

Tue Aug 11, 2009 5:12 pm

bvilletom wrote:

I could write a thread, if there is enough interest, of step by step instruction on how to port 36 heads, where to grind and where not to touch it.

Sheet #2 is coming soon.

Bville Tom

Tom,

Better yet would be to find an interested shop that would follow your directions, map and document your heads so that I can send my set of NOS heads for Brukrasa setup preferably with bigger valves. The shop should cut you a check, small or otherwise, for each Brukrasa head made. Heck tell me where to send them and I'll cut you the check. I sincerely appreciate all your research and more importantly you willingness to freely share it.

I have given up on finding one more Denzel head so am ready to start working on my NOS 36hp heads. I also need to get the chambers/piston tops (pre-a supers) matched. One thing at a time. Heads!

Please

Tue Aug 11, 2009 5:59 pm

Tom: Are you flow testing with a straight pipe on the exhaust,
and a radius on the intake port ?

Tue Aug 11, 2009 6:00 pm

Shorrock wrote:
I have given up on finding one more Denzel head so am ready to start working on my NOS 36hp heads.

Maybe Tom would be interested in flow testing the Denzel head.
Some people think they are superior to the Okrasa.

Tue Aug 11, 2009 6:45 pm

U Ian

I am flowing the exhaust right out of the flange, you can make the numbers better with a pipe i know. On the intake I Just break the sharp edge with some sandpaper. I am interested in the basic numbers without all the B S fluff.

Bvilletom

Tue Aug 11, 2009 7:43 pm

Unkl Ian wrote: Shorrock wrote:
I have given up on finding one more Denzel head so am ready to start working on my NOS 36hp heads.

Maybe Tom would be interested in flow testing the Denzel head.
Some people think they are superior to the Okrasa.

Tom,

I would be more than happy to send you the Denzel head for flow testing, if you want to take the time to do it.

Just let me know and it is on the way.

Maybe all the hype about the Denzel head is just that!

Howard

Tue Aug 11, 2009 9:55 pm

[quote="Shorrock"][quote="Unkl Ian"] Shorrock wrote:

Maybe all the hype about the Denzel head is just that!

Howard

I have looked at many drag race heads over the years, have two sets myself of type 1 heads that support 300hp on a 2.5 liter naturally aspirated... I had a chance to look at 36hp single, Okrasa 36hp DP, and Denzel 36hp DP... my educated eye would bet big money that if all things are equal, the stock Denzel head and manifold will outflow stock Judson by 20-30%.
Having made a bold statement, which I am not in the habit of doing, the flowbench will tell you for sure... dynoing an engine with those heads will tell the tail.

Wed Aug 12, 2009 1:42 am

bvilletom wrote:
I could write a thread, if there is enough interest, of step by step instruction on how to port 36 heads, where to grind and where not to touch it.
Sheet #2 is coming soon.

there is big interest tom,...your work and your instruction will make you the mr. okrasa of single port for me.

you and the work from oval56 here in germany inspired me to build my singleports that will tested soon.

you have PM

Sat Aug 15, 2009 6:29 am

Blackline 57 Engines lower end, Look at cam clearence, or lack of

Look at the installed 1500cc barrels, clearenced for pushrod tubes

Sat Aug 15, 2009 7:19 am

Hey Art, looking at the picture of the rod cap to cam lobe...
if a 36hp engine uses the same cam gear as a 1600, why the clearence issue with only a 74 stroke? You and I have both built big stroker T1 engines

Sat Aug 15, 2009 9:30 am

Because the engine is smaller, but the cam/crank spred is the same.. But this is just how it worked out.. Close!

Sat Aug 15, 2009 9:39 am

because the cam's from the camshaft sit on different places than typ1.
hold a typ1 cam next to a 36hp cam than you can see why (crankshafts also have other dimensions)

Sun Aug 16, 2009 8:43 am

Yes the lobes are closer together.. closer to the rods, not so much between them.