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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 1014447 times)

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Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1035 on: January 26, 2013, 01:55:34 PM »
These next three posts are for the second motor.  The problem child.  Changes were a set of performance cams, a pair of flat slide carbs, bigger 865cc bores, higher 10.5 to 1 compression pistons, and a stage 3 spark advance curve.  I got smart and ran a pair of big oiled foam filters.  Everything else was the same.  It ran great on regular pump gas which was good.  This is a street motor that runs on the salt.

This engine was a fast little bugger.  It lasted about 10,000 miles.  The bores and pistons were very worn out.  The initial barrel to skirt clearances were 0.004 inches.  This might be .001 loose, at the most.  The pistons were 2000 series alloy, not 6000 series.  This might have been a factor.  The flat slides are like old style Amals.  There is no starting enrichener.  Lame design.  The engine was flooded when cold.  This might have been a significant problem.  The engine ran rich or very rich at low street running rpm.  It seemed that reversion was a major cause of this and any sort of muffler that quieted down the exhaust made the problem a lot worse.  This probably was a big problem, too.  Second opinions are welcome.

The first PipeMax sheet with engine info.         

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1036 on: January 26, 2013, 02:00:12 PM »
The cam grinder does not want the specs shown.  They are crossed out.  The cams had enough lift to prevent choke.  The intake valve curtain area and diameter seem reasonable.  The cam lobe rpms are way high.  I do not understand how this might affect the engine, how this is calculated, if there are benefits to reducing t, and how to lower it.  Any help is wanted.

The valve and cam sheet is attached. 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1037 on: January 26, 2013, 02:07:02 PM »
The intake port minimum area is 1.55 square inches.  This is near the "Recommended Port CSA."  The exhaust port minimum area is 1.53 square inches.  This is in the "Largest Exhaust Port Exit CSA" range.  This last sheet has the port area info.  The ports are a better match for this larger engine than the smaller first one.

Offline fordboy628

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1038 on: January 26, 2013, 05:54:30 PM »
W/Walrus,

Sorry to hack up your post, but I'm a slow & crappy typist.
These next three posts are for the second motor.  The problem child.  Changes were a set of performance cams, a pair of flat slide carbs, bigger 865cc bores, higher 10.5 to 1 compression pistons, and a stage 3 spark advance curve.  I got smart and ran a pair of big oiled foam filters.  Everything else was the same.  It ran great on regular pump gas which was good.  This is a street motor that runs on the salt.

This engine was a fast little bugger.  It lasted about 10,000 miles.  The bores and pistons were very worn out.  The initial barrel to skirt clearances were 0.004 inches.  This might be .001 loose, at the most.  The pistons were 2000 series alloy, not 6000 series.  Forged 2618 is a high expansion alloy (requires more initial clearance) & forged 4032 is a "low"(er) expansion alloy which can be fitted more tightly.   I'm unsure of which 6000 series alloys might be used.  This might have been a factor. Yes, larger than optimal clearance to begin with causes more wear.   The flat slides are like old style Amals.  There is no starting enrichener.  Lame design.  The engine was flooded when cold.  This might have been a significant problem.  Yes, overly rich low speed mixtures are a HUGE cause of piston/bore wear.  The engine ran rich or very rich at low street running rpm.  It seemed that reversion was a major cause of this and any sort of muffler that quieted down the exhaust made the problem a lot worse.  This probably was a big problem, too.  Yes, definately.  Second opinions are welcome.   It would appear the carb's idle & low speed circuits are quite rich.  You will need to correct this.

The first PipeMax sheet with engine info.

The first thing that jumps out to me is that with bigger displacement, bigger (? probably) cams, AND 10.5 C/R, your V/E only goes up 1%!!!   Can you post up the Bmep #'s for file 865IN12.PMD?   I want to see if they went up or down.   If they went down for a higher bhp output, you are going in the wrong direction with your combination.

The cam grinder does not want the specs shown.  They are crossed out.  The cams had enough lift to prevent choke.  The intake valve curtain area and diameter seem reasonable.  The cam lobe rpms are way high.  I do not understand how this might affect the engine, how this is calculated, if there are benefits to reducing t, and how to lower it.  Any help is wanted.

The valve and cam sheet is attached.

It is hard to make any intelligent deductions without the cam numbers being shown, but if your Bmep #'s (see above) are down or flat, AND, the cam lobe rpm's are higher than you are using, sounds like too much cam for the engine spec/rev range being used.   Enough lift to prevent choke at what rpm??   Excess lift/duration/cam timing @ overlap can be the cause of reversion problems.

In general, and this is a very rough guideline, for 4 valve engines with standard size ports:
Seat to seat duration                      Rpm range
270 degrees                                  1500/7000
280 degrees                                  2500/8000
290 degrees                                  3500/9000
300 degrees                                  4500/10000
Engines with enlarged port to valve area will have a higher (1500/2000rpm higher) rpm range.......    4 valve engines breath so well at low rpm, long duration/slow acceleration cam grinds designed for 2 valve engines can be a problem.   Fast acting cams more suitable for 4 valve engines MAY have high rates of jerk, depending on the design.   It is difficult to correctly generalize about cam specs.   The shape of the displacement curve, velocity rate, acceleration rate and jerk values are more precise.   2 cams with the same lift @ say .020" or even .050" valve lift, can be vastly different because of the overall valve displacement curve shape.

If the cam specs on the 790cc @ 7400rpm engine are correct, your cam specs (valve displacement area) for the 865cc @ 8000rpm engine need to be only 10/18% more to adequately feed the flow demand @ that displacement & rpm.   This does not consider port sizing or flow numbers because I don't have that info yet.   Ie: if the port(s) flow MORE at the new valve lift(s), LESS duration (and LESS displacement area) would be needed to sustain the flow demand for a target bhp.   Etc, etc.


The intake port minimum area is 1.55 square inches.  This is near the "Recommended Port CSA."  The exhaust port minimum area is 1.53 square inches.  This is in the "Largest Exhaust Port Exit CSA" range.  This last sheet has the port area info.  The ports are a better match for this larger engine than the smaller first one.

Intake port CSA appears to be a good match.   Exhaust port CSA appears too large, the problem is the reduced flow velocity.  How is the exhaust system size & length compared to what is recommended?   How do the ports flow compared to a flow demand chart for the engine @ target Hp?  What % of intake flow is the exhaust flow?   Port size and flow MUST be carefully matched to engine flow requirements if you want a flexible, well running, dual purpose engine.   Your build is more difficult than a pure race engine where low end throttle response might be ignored in favor of top end Hp.....     This is always the case with "street/race" engines.

Hope this helps some.   Need more info to be more precise.

All facets of all components need to be properly matched and compromises need to be made in every build spec.  Mismatched components/sizes/etc contribute to poor performance in some rpm range.   The trick is to choose wisely on the compromises........     This is much easier to say than to accomplish.    
 :cheers:
Fordboy
« Last Edit: January 26, 2013, 06:06:31 PM by fordboy628 »
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Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1039 on: January 27, 2013, 11:06:36 AM »
The 790 pistons were original Triumph.  The word escapes me right now, but I think they were eutectic cast.  The forged racing pistons are 2618.
The 865 engine was on the dyno annually when we developed different things over three years.  The peak torque in 2012, represented by the PipeMax runs, was a few pounds feet lower than it was the year before.  The pistons were rocking and had poor ring sealing at high rpm.  Also, it needed valves and guides.

The BMEP for the 790 engine was 183.8.  The BMEP for the worn 865 engine was 194.5.

I do not have seat to seat duration numbers.  I do have maximum lift and duration at .05 inches.  A reasonable sine type curve was drawn through the three data points and it was extrapolated zero lift.  It looks like  am in the 290 to 300 degree range.  The standard cams had 12 degrees overlap, and the racing cams have 32, at .05 lift.

The intake port areas on the PipeMax notes are wrong.  I took some measurements.  The bore area in the 39 mm carb is 1.85 square inches, the carb has some tapered spigots that neck down where they connect to the inlet manifolds and the area at this connection is 1.64 square inches.  The port area where the inlet manifold connects to the cylinder head is 2.38 square inches.  I matched the exhaust port outlet to the standard header area of 1.53 square inches.   

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1040 on: January 27, 2013, 08:06:29 PM »
The big motor was modeled in PipeMax months ago.  The cam and valve performance data is attached.  The intake lift to prevent choke is 0.396 inches.  This is higher than the maximum cam lift.  Also, the Intake Valve Diameter Operating Range, at 5248 to 7248 rpm is less than the 7400 rpm target for maximum power.  Some 2mm larger intake valves will do what I need.  I ordered them and they are being made.  The old valve seats were removed and new 2mm larger ones were installed.  The first attached sheet is the PipeMax printout that told me I needed larger valves.

The second sheet is the data for the bigger motor.  The 2mm larger inlet valves are represented on this sheet.

         

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1041 on: January 27, 2013, 08:34:25 PM »
The other two data sheets for the big motor are attached.  One shows the valve and cam data.  The seat to seat duration data was on the cam card.  It is less than the 270 degrees for a lower rpm cam in FordBoy's recent post.  The duration is just right for an engine with a 7,400 peak horsepower rpm, considering the cylinder head has a performance port job.  The lift is OK, too, and so are the valve diameters.  I changed the lobe center angles in PipeMax to lower the operating rpm's down to just over 8,000 rpm on both cams.  There was over 50 degrees overlap.

This 50+ degrees is too much for a street bike with four valve heads.  I will set the cams up according to the cam card with overlap is between 30 to 35 degrees.  Vizard, in his book "How to Build Horsepower" lists overlap between 10 and 35 degrees for "engines requiring best low-speed output and mileage."  He also says "This puts multi valve engines at the lower end of each range..."  The cams have plenty of overlap, but not too much, according to Vizard's guidance.

The 1.64 square inch minimum intake port cross-section area is between "Recommended Smallest Port CSA" and "Recommended Port CSA."  This is OK for this street/race engine.  The 1.53 square inch exhaust port area is in the "Largest Recommended Port Exit CSA" range.  I hope, the faster port velocities in the larger displacement big motor will cure the low rpm reversion problems.

I think I am good to go.  Second opinions are welcome on this.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1042 on: January 28, 2013, 08:34:17 PM »
It took awhile to digest the information provided by FordBoy.  It makes sense.  The engine was run with the racing port job in the 790cc engine for years and it made the motor run much better.  The port size was big, but not too much.  The reversion problems started with the 813 cams. Probably the cams, in combination with the port job, were too much.  The low port velocities in conjunction with the overlap made the reversion.

A PipeMax model was made with the old 790 cams in the 865 cc motor.  The specs are on the first page.  The cam and valve data is on the second.  The cams lift the valves far enough and there is sufficient curtain area.  This is the way I should have built that engine.             

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1043 on: January 29, 2013, 08:46:26 PM »
A piece of billet was laying around here with a brass rod.  All was made into a little box for the lambda meter connections and fuse.  The drill press and Shop Fox vise were used.  There are some mistakes with the depth of the cut.  That is hard to get this exact with a drill press.

Offline Peter Jack

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1044 on: January 29, 2013, 09:39:17 PM »
Considering the tools Bo that's a rather nice piece of work.  :cheers: :cheers:

Pete

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1045 on: January 31, 2013, 12:24:37 AM »
Thanks, Pete.  Sometimes I turn the feed screws the wrong way.  That is the source of most of my problems.

Offline Peter Jack

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1046 on: January 31, 2013, 12:42:44 AM »
You can do that with a mill too. Guess how I know.  :roll: :roll: :|

Pete

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1047 on: February 01, 2013, 12:17:17 AM »
The Triumph has 12mm x 1.25 mm tapped holes just above the exhaust ports and downstream from the exhaust valves.  Some sort of smog device tubes plugged in there at one time.  Now the device is removed and they are blocked off with bolts.  I was thinking of putting exhaust gas temperature sensors there.  Has any one done that?   

Offline Grandpa Jones

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1048 on: February 01, 2013, 08:33:32 PM »
Hi Wobs, I have an '01 Bonney, are these the ports next to the spark plugs? I think
that is  a small diameter passage to the exhaust port for the air injection system.

Likely not enough room for an egt probe in there. I've done a little reading, seems
the probe should be centered in the exhaust stream, and mounted a certain distance
from the exhaust valve, according to what the probe manufacturer recommends.

Aircraft Spruce has a bunch listed under "Instruments". Good reference material there,
they show several of the clamp-on type. Drill a hole in the exhaust pipe, clamp on,
and you're done. Or the weld-on bung type, which you could remove and plug when
you convert over to street-bike mode.

Cheers, Dave

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1049 on: February 01, 2013, 09:45:57 PM »
The sensor needs to be in the typical location if my readings are going to mean anything when I compare them to reference data.  Also, the hole in the head is for the air injection system and it is much too close to the exhaust valve.  My brilliant idea won't work.

The lambda meter I use is made by Innovation Motorsports and I noticed they also have a setup for monitoring exhaust gas temp and cylinder head temp with a gauge and/or data logging.  This is the way I will go.  The standard Triumph headers are stainless steel and I am making up some stainless bungs to be welded on for the lambda meter.  I will also make a set for the EGT probe.

A few questions.  Does the inside of the exhaust pipe need to be clean before the bungs can be welded on?  Is there a good exhaust pipe welder in the Salem/Portland area?  Innovation Motorsports recommends TIG.