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#539969 - 04/26/14 11:51 am A65 porting and throttle response video.  
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Mark Parker Offline
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This video may show a bit how port configuration can effect throttle response. I'm experimenting on a theory, Bigger carbs ports and valves flow more air therefor make more HP, how ever there are side effects and other factors. What happens if one finds and fills the big port where the airflow is pretty dead? Will it flow more or less? The carb and valve are the same the port is only filled where air is very slow moving, all that can do is speed up the flow of air through the port giving it more energy and more volume past the valve at a given RPM,(I'm guessing that is what is happening) the effects of which are pretty cool. Interestingly the thing effected is throttle response, turn the throttle it goes, turn it more it goes more.
https://www.youtube.com/watch?v=1Bb4XfUkyVU&list=UUUP_VDGHuTLC5wUtLg-Y8dA


mark
#585820 - 02/15/15 8:14 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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saefifty Offline
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Port Perry
Im thinking what IMO you need to figure out first is the flow numbers you need on the intake side that will make the horsepower in the RPM range you need. It helps if you have probed the port velocity before hand and after porting. The loss in velocity if there is any can be regained along with throttle response by filling and reprobing the port to win back some velocity. IMO This high velocity also helps creates better intake pulses to take advantage of as well.

#585828 - 02/15/15 9:02 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Allan Gill Offline
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Mark, in answer to part of your post.

By only filling the dead area, I was able to keep the same main jet but increase max RPM ( to a point where I didn't want to see if it would go higher) esp in the lower gears.

Increase in torque was noticeable, where as normally you would down gear the bike to improve acceleration, you can now upgear the bike and improve acceleration - sounds daft but the rpm's climb at the same rate regardless if the load, the taller gearing just turns the back wheel more for the same rpm

Mixture at lower throttle openings was effected however ( now too rich) and it would be interesting to see how high you can lift the floor until it drops off.

The way I see it on a flow bench, the higher the velocity the higher the CFM on the flow bench.

Last edited by Allan Gill; 02/15/15 9:07 pm.

beerchug
#585837 - 02/15/15 9:40 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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konon Online content
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Saw a big block Chevy that used dimples like a golf ball in the intake ports, creating lift. Would this slow velocity or help flow? Any opinions.


1968 BSA Firebird
1200 HD
XS 1100
1971 Rickman 125
#585979 - 02/16/15 5:36 pm Re: A65 porting and throttle response video. [Re: konon]  
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OZ
This is interesting. Just recently a friend, who has an aircraft background, was telling me how this had an advantageous effect on laminar airflow. Look at pictures of Lindy's Ryan monoplane, for example, the area behind the engine and in front of the cockpit.
Unfortunately, the gist of the conversation was a bit beyond me, but the dimples are important. Thats why they are on golf balls. I guess when applied to an inlet port,a flowbench would have the answers.

#585987 - 02/16/15 6:20 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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The problem with all these things is that without a flow bench to test every mod, you can be taking 2 steps forward and one back every time. I know a couple of guys who swear that inlet port downdraft is the most important thing as this removes any dead area but to get that on these old heaps requires massive modification to the head and fitting practicality is a problem. I still maintain that several approaches may all produce good results and the final differences may only be small. IE. Inlet side mods can be massively affected by changes in exhaust system. Noise regs messed up a lot of our tuning and took a long while to sort out.



#585988 - 02/16/15 6:20 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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DMadigan Offline
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The dimples creates turbulence which changes the pressure distribution. A smooth sphere has separation shortly after the maximum diameter due to the adverse pressure gradient. The dimples create turbulence which energizes the boundary layer, keeping the flow attached and decreasing drag. "Laminar flow airfoils" have their maximum thickness far aft along the chord keeping the favorable pressure gradient compared to the older style airfoils. Near the natural separation point the flow has to transition to turbulent in order to keep the flow attached. Otherwise it would have the aerodynamics of an "sport" utility vehicle.
On a spinning ball the dimples move the low pressure point from directly opposite the velocity vector to a point around in the direction of spin also increasing the pressure on the surface moving against the velocity. So a ball moving to the right with a counterclockwise spin will generate a pressure which is pointing upward and rearward rather than directly opposite the veocity.
This has nothing to do with flow in an intake tract. Some builders now do not polish the intake tract to add turbulence which helps keep fuel droplets from falling out of the air stream and collecting on the walls.
On these old bikes the ports were more shaped for manufacturing than flow. The corner of the floor at the valve is way too sharp. You could fill in about 1/3 of the port floor without affecting the total flow. Racers have done this with JB Weld.

#585991 - 02/16/15 6:35 pm Re: A65 porting and throttle response video. [Re: DMadigan]  
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Yes, that was the stuff my friend was talking about. I remember years ago worrying about completely understanding all this sort of thing and a bloke gave me the best advice ever. He said," Look, all that stuff has been worked out by clever people, dumb bastards like you should just concentrate on screwing all together properly".

#585993 - 02/16/15 6:47 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Bigger ports, carbs and valves flow more air and therefore make more horsepower only if the ports, carbs and valves you have are too small.











http://www.oxforddictionaries.com/words/affect-or-effect


Amateur Loctite enthusiast.
#586061 - 02/17/15 8:06 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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I think it is admirable to take on such a serious mod, without any of the specialized tooling, but there are HUGE key elements that have been completely left out of this equation that are essential for peak performance head flow. Have you taken in any consideration of what your squish band should be? Have you done the math to learn where the "50's" are? Have you done any modifying to the valve train to optimize the flow of the port design? Do you even have enough valve lift to get anything out of the new port design? Did you take the time to do a baseline dyno before and after the mods to determine WHERE in the rpm there were any effects that took place?

Without a dyno or flow bench, you really have no way of knowing the effects of what you did other than "it feels faster". All of the things I mentioned coincide with each other, any changes must be considered as to how it will effect other elements of the motor. With all that said, it does sound like it is running good, but you really don't have any solid evidence that indicates that the mods were an improvement, or even a hindrance.


Scottie J ~ 1958 Enfield/Indian Trailblazer ~ Drinks Corn
#586077 - 02/17/15 11:43 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Port Perry
I like what Triton Thrasher said.

#586813 - 02/22/15 6:34 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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RPM graphs before and after Bulldog: Red trace is latest spec with extra fill on the port floor, slightly retarded cam timing and 12.3-1 compression. All traces are roll ons from 3,000rpm. The main difference occurs between 3,000 and 4,300rpm and gives a massive improvement in that range and below, and does not diminish top end, so it is a definite win especially useful in 3rd or 4th where throttle response in that range is so much better.


Gear change out of second on red trace is at 100.
I've since lowered the comp to 11-1 though the higher comp gave no problem other than distorting the head gasket around the centre head bolt where I have now fitted a spigot that is tight in the gasket and should prevent distortion.


mark
#586819 - 02/22/15 8:00 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Hillbilly bike Online content
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Running from demons in WNY
A long thread about intake port " Burr" finish.

Intake port finish


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
#586832 - 02/22/15 9:20 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Scottie J Offline
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There you go! And here I thought you hadn't logged any info. LOL So, yeah it looks like you did get, if not more power, better throttle response overall throughout the revs. Was this info obtained from data logging?


Scottie J ~ 1958 Enfield/Indian Trailblazer ~ Drinks Corn
#586881 - 02/22/15 1:21 pm Re: A65 porting and throttle response video. [Re: Hillbilly bike]  
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Originally Posted By Hillbilly bike
A long thread about intake port " Burr" finish.

Intake port finish


as usual, hb, you point out that there is more to know about everything there is than i will ever have time to even look at, much less understand.

one lesson that is common to all of this is that all the various parameters that go into changing airflow interact in different ways, and various combinations of them can all achieve similar results without being similar.

one thing i noticed in the speedtalk thread was that one advocate of rough port surfaces went on to do the same to the surface of the combustion chamber:



that to me seems counter-intuitive, because the combustion chamber itself is a place where flow is disrupted into turbulence by the charge slowing down against the moving piston, cylinder head surfaces, and the valve heads, and turning back on itself as it gets squished. i don't see any advantages to trying to maintain a boundary layer in a place where laminar flow doesn't even exist. it seems like the rough surface would make carbon stick that much better, which would change the size and shape of the chamber very quickly.


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#586886 - 02/22/15 1:52 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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triton thrasher Online content
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It appears to be commonly accepted that boundary layers play a role in the combustion chamber.

As for carbon build-up- how long does a drag race last?


Amateur Loctite enthusiast.
#586893 - 02/22/15 2:28 pm Re: A65 porting and throttle response video. [Re: triton thrasher]  
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i don't know enough about airflow to have an opinion that's worth anything.

but you're right-- if it does work in the combustion chamber, then cleaning it up after each race meet would be a just another routine operation.


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#586908 - 02/22/15 3:43 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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konon Online content
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Sure seems everyone has there own opinion on what performance tricks work and what doesn't.
Just have to try it like Mark and test with data logger or dyno.


1968 BSA Firebird
1200 HD
XS 1100
1971 Rickman 125
#586939 - 02/22/15 6:28 pm Re: A65 porting and throttle response video. [Re: kevin roberts]  
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Hillbilly bike Online content
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Running from demons in WNY
Originally Posted By kevin
Originally Posted By Hillbilly bike
A long thread about intake port " Burr" finish.

Intake port finish


as usual, hb, you point out that there is more to know about everything there is than i will ever have time to even look at, much less understand.


I don't understand it all but find it fascinating. Speed Talk is primarily a car drag race/circle track engine builder's forum but there are several vintage bike engine builders.
Years ago drag racing cars there was always one guy who was faster than everyone else in the class. We all said he had a trick cam or some special some mega ported heads... Reality was his engine's intake,heads,cam and exhaust worked together and along with attention to every detail made him a winner. And money...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
#587069 - 02/23/15 3:55 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Allan Gill Offline
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Money is always a good start, although the Hero's out there like Burt Munro proved otherwise. I'd love a close up of that Indian.


beerchug
#587422 - 02/26/15 6:26 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Mark Parker Offline
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Bulldog, that's using a veypor data logger. The rpm graphs are very dependable, sometimes the speed messes up which puts the dyno HP measurement out, But rpm against time is good for comparisons.
Still summertime here so it's a nice time of year for riding.

Last edited by Mark Parker; 02/26/15 6:27 am.

mark
#587424 - 02/26/15 6:35 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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OZ
That "Spiteful" is absolutely brilliant work!

#587428 - 02/26/15 7:13 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Scottie J Offline
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Cool bike! So is that a vintage BSA power plant stuffed inside a newer sport bike chassis? I'd like some more details of what you have going on there, because it just lit a bunch of light bulbs in my head. smile

Also, interesting design on the exhaust cross-over.....

Last edited by Bulldog Kustoms; 02/26/15 7:14 am.

Scottie J ~ 1958 Enfield/Indian Trailblazer ~ Drinks Corn
#589689 - 03/11/15 8:02 am Re: A65 porting and throttle response video. [Re: Mark Parker]  
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Mark Parker Offline
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Similar motor to my 90degree 883 only 744cc with 80x74 bore and stroke, just put some EDV forged B44 pistons in plus a head with 'D' ports. This is it's first run.

https://www.youtube.com/watch?v=y_qCYXktwPo&feature=youtu.be


mark
#589764 - 03/11/15 6:36 pm Re: A65 porting and throttle response video. [Re: Mark Parker]  
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konon Online content
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Nice bike Mark, did you recently build it? Sounds good.


1968 BSA Firebird
1200 HD
XS 1100
1971 Rickman 125
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