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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 773630 times)
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fordboy628
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« Reply #2100 on: August 29, 2015, 05:20:22 AM »

The cylinder head flow test results are plotted.  The exhaust cam that has been in the engine for a few years has 0.388 lift and the exhaust valves are standard size.  The flow curve shows the valves and ports certainly are not oversized for the in the bike now.  It will be a good idea to enlarge them before installing the higher lift cam.

The intake cam also has 0.388 lift and the intake valves are 2mm larger than standard.  The flow curve flattens out at lifts above 0.300.  A higher lift knocker will not do any good until the valves and ports are enlarged to handle the flow.

Horsepower is directly proportional to intake flow at 28 inches according to some commonly used equations.  The flow limitation in the cyl head limits horsepower.

Wobbly,

If you are willing to share, PM me the raw flow data so I can enter it into my flow program for analysis.   Engine is a 2 valve hemi, right?

Send me also:

A)   Cam duration @ .050"
2)   Valve angle from vertical, referenced from cylinder C/L, both valves.
d)   Distance from valve edge to valve edge, valves seated.
z)   Refresh my memory on desired peak bhp rpm & peak torque rpm.

 cheers
Fordboy
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« Reply #2101 on: August 29, 2015, 10:15:50 PM »

Hi Mark.  Right now I am waiting for the cams to be ground and the bike to be cleared from US Customs in Portland.  I will measure everything up when I get something to work with.  That is real nice of you to offer to do this.  The combustion chamber is a Cosworth design with four valves, a pent roof, and a sorta flat piston.  The goal is 100 rear wheel horsepower at 8,400 rpm on gasoline.

A question about fuels for all of you experts.  Straight non-oxygenated leaded gasoline was compared to two different brands of oxygenated gasoline using dyno tests during a two year period.  The oxygenated fuels used ethanol to supply the oxygen at around 8% and 2% added O2.  No power increase was noted with these oxygenated fuels.

Straight leaded race gas was used during the first day at Pendine.  The bike did just over 110 mph in the standing start kilo and it felt like it was topped out at 110 and not much more speed could be had if the track was longer.

During the second day I raised the needles one notch and increased the main jets four sizes.

The third day straight leaded race gas was used with 1.6 percent nitropropane, 0.8 percent toluene, and 0.8 percent other ingredients added.  Percentages are by volume.  It was like adding another cylinder to the engine.  The bike did over 130 in the standing start mile.

The nitropropane could have not added enough O2 at that low percentage to achieve such dramatic results.  Something else is happening.  This is I think it is.  The ethanol oxygenated gasolines and to some extent, the straight race gas is vaporizing before it gets past the intake valves.  The expansion associated with this change from liquid to gaseous form is lowering the charge density.  That is a big deal on this engine 'cause the flow restriction of the smallish intake valves.

Something in the nitropropane/toluene/other ingredient mix is inhibiting the vaporization of both the gasoline and the nitropropane until both are past the intake valves.  This unvaporized charge is more dense.  This is important 'cause the intake valves are small and not much gets past them.  This mix vaporizes after it gets into the chamber and voila, lots more power.

I do not know much about this and this is my theory.  Am I full of carp or might I me on to something?     

 

   



   
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« Reply #2102 on: August 30, 2015, 08:54:34 AM »

Based on the results, you have to conclude that extra output is being developed.    What, exactly, is going on, is more difficult to determine without a cylinder pressure measurement and records to compare.

Something to keep in mind is that air cooled engines (is this air cooled?) typically run hotter chamber temps, and this assists in fuel vaporization.   BUT, some engines (and some fuels) do NOT like vaporized fuel.    Yeah, I know that in theory, complete vaporization SHOULD produce more bhp, BUT, some engines (and fuels) simply produce more bhp when the fuel "rains in" in larger "droplets".    How do you know what works better for you?    Testing and documentation is the only way.    Race tracks can substitute for dynamometers if you can data log . . . . . .  although the changing conditions of the track or the weather can drive a person batty.

Most "Cosworth" designs function very well with .41"/.44" gross cam lift, and you are not very far from that.    The Cosworth cam designs, do however, run "lots" of duration, usually not a fitment problem with 4 valve engines.   BUT, yours may be "unique" depending on the Build Geometry.    A "high" rod length/stroke ratio may hamper flow demand and room for valve clearance @ overlap.    At least you should be rid of the 2 valve hemi valve to valve clearance problem.

The compression ratios can be "modest" with "flat-top" style pistons, depending on displacement per cylinder.    You might want to do a very accurate measurement and calculation of your actual C/R, you might be surprised.    If you do the measurements, I'll run it through my copy of Compression Ratio Calculator Pro.   Be prepared to measure a few things not normally checked.    Modest "intruder" style pistons can gain some output via higher C/R, at the cost of increased component stress . . . . . .

Keep in mind that there are ALWAYS compromises for fitment, or to utilize existing bits, etc, etc, etc.

The "trick" is to make the best choices out of the options available.    Informed decision making ALWAYS works out better in the long run.     There is never a short run, because measurement and analysis takes time, adding to the length of the build.     AND, analysis can make you regretful of parts choices that were guesses.

 cheers
Fordboy
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« Reply #2103 on: August 30, 2015, 10:14:49 AM »

The Pendine engine was a mongrel with a mixture of standard Triumph and racing parts.  Fortunately I have lots of data on the motor.  Today it is raining and I am stuck at home.  This is a great time to look up the info and I will post it.
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« Reply #2104 on: August 30, 2015, 11:15:24 AM »

The cam timing is considered to be proprietary and it will be sent by PM.  The flow data printouts will be scanned and posted.  Pendine engine data is, displacement = 865cc, bore = 90mm, stroke = 68mm, rod/stroke ratio = 1.787, measured static compression ratio = 8.9 to 1, intake valve head dia = 33mm, exhaust valve head dia = 26mm, intakes and exhausts inclines 15 degrees from vertical, distance between intakes = 0.166 inches, distance between exhausts = 0.490 inches, distance between intakes and exhausts = 0.362 inches, rear wheel horsepower =81 at 7,800 rpm, torque = 60 foot pounds at 6,200 rpm, based on curves from three pulls using Sunoco Supreme and Dynojet "std" correction.
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« Reply #2105 on: August 30, 2015, 12:20:51 PM »

Flow data in tabular form.


* intake at 28 inches.jpg (96.32 KB, 1015x768 - viewed 157 times.)

* exhaust at 28 inches.jpg (71.07 KB, 1024x688 - viewed 128 times.)
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« Reply #2106 on: August 31, 2015, 11:24:25 PM »

Today I worked on my theory during lunch at work.  Dyno comparisons a couple of years ago between Sunoco Standard non oxygenated leaded and a highly oxygenated Australian blend showed no power increase.  The year before last another dyno comparison was made between leaded Sunoco Supreme and leaded Sunoco MO2X.  The supreme is non oxygenated.  The MO2X has 6.8 percent ethanol by volume.  The distillation data for Supreme are 10% evap at 169 degrees, 50% evap at 217 degrees, and 90 % evap at 231 degrees.  The same data for MO2X are 10% evap at 124 degrees, 50% evap at 207 degrees, and 90% evap at 226 degrees.  The ethanol gas tends to vaporize at lower temps.  I saw this trend with ethanol mixes from other brands.

Next, I looked at toluene.  It is an oxygen bearing molecule.  I like the stuff 'cause of its relatively non-toxic combustion by products - in comparison to other additives.  The stuff is a bit hard to ignite and is the opposite of ethanol in that respect.  I ran out of lunch time and did not look at nitropropane.

The engine on the Triumph is big and complex and the inlet tract is long by bike standards.  Also, it is air cooled.  My feelings are premature vaporization might be a problem.  It will not hurt to put thermal coatings on the inlet tract and inlet valves, as well as the piston tops.  This will help to keep the incoming charge cooler.  Vizard says, in his port and flow test book "If you have to pick one single element of the induction/exhaust of the head, coat the valves...The biggest power influence is the face of the intake valve because it cuts heat going into the intake charge."

Comments sure are welcome on this.     
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« Reply #2107 on: September 01, 2015, 10:58:00 AM »

Bo..............I appreciate the gas/fuel tech. The only thing I know is experience........fumes explode.........liquid burns. I was an A-student in HIGH SCHOOL physics. No classes since.  Question: If the heat causes evaporation, and the air-density is low, would this not make for improved 'explosion' characteristics in the sealed chamber?
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2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2018 AMA Record - 750cc M-CG HONDA CB750 sohc - 136.6 mph
2018 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 143.005 mph
2018 AMA Record - 750cc M-CF HONDA CB750 sohc - 139.85 mph
2018 AMA Record - 750cc MPS-CF HONDA CB750 sohc - 144.2025 mph

Chassis Builder / Tuner: Dave Murre
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« Reply #2108 on: September 01, 2015, 11:56:00 PM »

My thoughts are there is a volume increase when the fuel goes from droplets and gases to mostly gases and this is best if it happens after the mix gets past the intake valve.  This engine seems to mix up the charge pretty good before ignition so I am not worried about that.
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« Reply #2109 on: September 02, 2015, 01:40:20 AM »

Shrouding, or the blockage of flow out of the valve curtain, is discussed at length in Vizard's 2012 book on porting and flow testing.  Interruption of flow by the edge of the valve pocket in the piston crown is a topic he addresses.  These new high compression pistons have deep valve pockets and the potential to shroud.

Washers are placed in the pockets to get their dimensions.  The intake pocket is 38mm dia and the exhaust 32mm.  Also note that 38mm dia washers touch each other when placed in the pockets.

Intake valve dia is 31mm on a standard OEM bike.  Mine has 33 mm dia valves and they are too small.  35 mm dia intakes are a commonly used oversize.  The clearance between the valve margin and piston pocket wall is approximately (38 - 35) / 2 = 1.5 mm.  This is sort of marginal from a shrouding viewpoint.  Big 36 mm dia intakes are also used by a successful builder on a bored and stroked Bonneville that displaces over well over 1000cc.  These will give only 1mm of clearance.  This is a tight fit.  There is a shrouding issue with this size.  Vizard gives some advice about radiusing the pocket edge to reduce shrouding.  The downside of this is a consequent drop in compression ratio.

It looks like there are two choices, one is to use the 35mm valves with no pocket relieving or the 36mm ones with relieved pockets.  This is a topic I will discuss with the fellow who does my valve work.

Exhaust valves are 26mm dia on a production bike and mine has the same size.  A common modification is to install 28mm, 30mm, or 31mm oversize valves.  Valve pocket shrouding can be an issue here, too.  The 28mm valves have 2mm clearance which is enough.  The 30mm ones have 1mm clearance which is not enough, and the 31mm valves have only 0.5mm clearance, which is way too tight.  This is another topic to discuss with the machinist. 


* 2016 Build 020.JPG (123.36 KB, 800x600 - viewed 140 times.)

* 2016 Build 021.JPG (127.14 KB, 600x616 - viewed 128 times.)
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« Reply #2110 on: September 02, 2015, 11:45:35 PM »

Calculate the ex flow as a % of intake flow.    If you are normally aspirated, AND, at 85% or better, you probably do not need bigger ex valves.

 cheers
Fordboy
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« Reply #2111 on: September 02, 2015, 11:52:19 PM »


The engine on the Triumph is big and complex and the inlet tract is long by bike standards.  Also, it is air cooled.  My feelings are premature vaporization might be a problem.  It will not hurt to put thermal coatings on the inlet tract and inlet valves, as well as the piston tops.  This will help to keep the incoming charge cooler.  Vizard says, in his port and flow test book "If you have to pick one single element of the induction/exhaust of the head, coat the valves...The biggest power influence is the face of the intake valve because it cuts heat going into the intake charge."

Comments sure are welcome on this.    

Yes.    Do it.    Keep in mind though, that this will gain low single digit % improvement, like 1 or 2% typically.    You still have all the latent heat of an air cooled cylinder head to get rid of.    And, as you speculated, the latent heat of the head does not help charge density.

 cheers
Fordboy
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« Reply #2112 on: September 03, 2015, 12:18:33 AM »

Shrouding, or the blockage of flow out of the valve curtain, is discussed at length in Vizard's 2012 book on porting and flow testing.  Interruption of flow by the edge of the valve pocket in the piston crown is a topic he addresses.  These new high compression pistons have deep valve pockets and the potential to shroud.

Washers are placed in the pockets to get their dimensions.  The intake pocket is 38mm dia and the exhaust 32mm.  Also note that 38mm dia washers touch each other when placed in the pockets.

Intake valve dia is 31mm on a standard OEM bike.  Mine has 33 mm dia valves and they are too small.  35 mm dia intakes are a commonly used oversize.  The clearance between the valve margin and piston pocket wall is approximately (38 - 35) / 2 = 1.5 mm.  This is sort of marginal from a shrouding viewpoint.  Big 36 mm dia intakes are also used by a successful builder on a bored and stroked Bonneville that displaces over well over 1000cc.  These will give only 1mm of clearance.  This is a tight fit.  There is a shrouding issue with this size.  Vizard gives some advice about radiusing the pocket edge to reduce shrouding.  The downside of this is a consequent drop in compression ratio.

It looks like there are two choices, one is to use the 35mm valves with no pocket relieving or the 36mm ones with relieved pockets.  This is a topic I will discuss with the fellow who does my valve work.

Exhaust valves are 26mm dia on a production bike and mine has the same size.  A common modification is to install 28mm, 30mm, or 31mm oversize valves.  Valve pocket shrouding can be an issue here, too.  The 28mm valves have 2mm clearance which is enough.  The 30mm ones have 1mm clearance which is not enough, and the 31mm valves have only 0.5mm clearance, which is way too tight.  This is another topic to discuss with the machinist. 

.75mm (.030") is enough, IF, that is at the closest point, (probably TDC, but check if your pins are offset) with "tight" piston clearances.   "Loose" piston clearances, like most air cooled guys need to run, require more radial clearance, because there is more "piston rocking" at TDC.    Pick your poison by checking how much "rock" you have cold and add that to the suggested clr.    There will be less "rock" at operating temperature, giving you a margin of error in your favor.

Yes, shrouding is always bad, BUT, if you are going to push the compression ratio, what other choice do you have?

The gain in expansion ratio from increased static C/R, outweighs the slight shrouding during the overlap period.    The shrouding occurs only from about 18/15 degrees BTDC to 15/18 ATDC, and maybe less, depending on your build geometry.   This is a point in the cycle where the int flow demand is LOW, and the exhaust blow down is dropping.

I want to get all the "gravy" from my plate, so to speak.   I concentrate on the big puddles and I don't worry about the molecules I miss . . . . . . . . .    I would push the compression ratio hard, and remember that the engine will be very sensitive to state of "tune".    You will need to keep track of A/F and ignition, or risk melting parts.    Sorry, that's just the way it is when you punch up the power.

 cheers
Fordboy
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« Reply #2113 on: September 04, 2015, 12:50:34 AM »

The pistons are wide in relation to their height and they have 0.004 skirt clearance to start and the wear wider from there.  The gudgeon pins are offset 1mm.  The pistons do rock.  It is not unusual to see wear marks from the side of the cylinder on the piston above the top ring. 

Bigger seats are needed for larger valves.  The distance between the outer edges of the intake valve seats is only 3 mm on a stock head with standard OEM 31 mm dia valves.

Does this add up to it being a good idea to use 4 mm oversize intake valves, rather than the 5 or 6 mm oversize ones? Again, comments are welcome.


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« Reply #2114 on: September 04, 2015, 08:19:47 AM »

The pistons are wide in relation to their height and they have 0.004 skirt clearance   Where?  At the pin C/L?  Or at the bottom of the skirt?   How much taper is ground in to the skirt from the pin C/L to the bottom of the skirt?   How much clearance does the piston mfg. recommend?   to start and the wear wider from there.

The gudgeon pins are offset 1mm.  The pistons do rock.  Is offset necessary to prevent the piston from "leaning" on one side of the cylinder?   Or is it just to prevent the noise from "slap"?

It is not unusual to see wear marks from the side of the cylinder on the piston above the top ring.  You don't want this to be happening, as it can wear/distort the bore.   This can be an indication of too much clearance, OR, top land dia too large.   Top land should be about .030"/.035" less than the bore dia max.   The top ring land can also be tapered toward the top to prevent this. 

Bigger seats are needed for larger valves.  The distance between the outer edges of the intake valve seats is only 3 mm on a stock head with standard OEM 31 mm dia valves.   Does the benefit in potential increased airflow, justify the cost to enlarge the valve size?   See my comment below.

Does this add up to it being a good idea to use 4 mm oversize intake valves, rather than the 5 or 6 mm oversize ones?   What is the port cross sectional area going to be?   What % of valve area for the various valve sizes being considered?    Increases in valve area alone typically favor low/mid lift flow.    It takes an increase in min CSA to gain flow on top end.    No increase in flow is "bad", you just might not see much power increase if it is all low lift.      Again, comments are welcome.

Bo,

See my comments in your text.

Off for a few days.   Will check in when I get back.

 cheers
Fordboy
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