velocity porting verse old school port and polish

[slamdak8782]

Hello all, Im unsure of the whole velocity porting issue. Does anyone have actual pictures of this done to a 400ex head. Nobody seems to know what there talking about on this issue so im trying a tounleash few things with this thread.
1. Does it work well
2. is top end destroyed
3. pics of velocity port jobs and regular ones
4. get motoman to give better pics
5. dynos of each with 440ex and 400ex
6. end the whole discussion with which is better for different riding styles
RULES
1. no comparisons with 350 v8 heads with 2 valves
2. no my buddy did it and it was real fast BS
3. Hard facts dynos pics and good info.
4. dynos have to reflect the torque curve or at least give some numbers. to see which is best overall
Cool lets see who shows up on here sparks,tc,Motoman,CT lets dig deep here

[dork]

450 head (http://www.trx450r.org/forum/index.php?showtopic=4468&hl=) and .yfz (http://www.trx450r.org/forum/index.php?showtopic=5541&hl=)

one guy emailed motoman, i think it was rage atv (http://www.rageatv.com/) and said he tried it on a 400ex head that his rider then went on to win his class on, so...

nobody seems to have any direct comparison before and after dyno runs though. if you search around on sportbike websites, its somewhat proven, some riders have done it and had good results. on yfztech.com, there's some talk about it too, do a search under reduction porting.

[slamdak8782]

somebuddy has to have some info
:ermm:

[chad502ex]

yes there is a few .org members that has tried this porting, but i think they havn't testing the mod on the dyno before and after the expoxy fill.

I believe their call-signs are:
lukester
Boone
kgbg

Once again, I pretty sure they have tried the mod but havn't dyno tested. maybe, they have dyno tested, but have discovered that it didn't work. I'm thinking the later.

[Aallron]

Velocity porting is exactly as it sounds. The theory is something like this... To get the same amount of air into a given space (your cylinder) you either flow and port it which essentially lets the air travel into the cylinder easier or as motoman says you increase the velocity by reducing the hole it goes through. Air being elastic will be drawn into the cylinder by the air in front of it... kinda like a poor mans ram air injection.

[MMS]

I have been playing around with the HV port design for 2 years now..And have had good results on certain set ups..It builds more power in the mid to top RPM Range on a stock motor but will take some of your bottom away. This can be compensated for by a Cam change and or a higher Comp piston...I picked up 6 Hp and 4 Lbs Of torque on the 686 We flat track Just by Redoing the head to A HV design and not changing any other parts not even a Fresh Piston But jetting Jumped up a Couple jet sizes and required a new Needle for more flow....My 770 is in the middle of a Rebuild and going to get The HV ports and then we will see what kind of # it pulls I was at 76 Hp and 48 Lbs on the last Dyno run on Pump gas Just before the Tear down..I have a stock 2005 that is going to get them later in the season... I am just porting and Jetting it and leave every thing else alone just to see what affect it has on a stock motor..THese are the first Quad Motors I have done With the HV port design..I have several Customers that I have done their street Bikes and Have seen some decent Hp gains over stock and the old school port design (Bigger is Better)....So take it for what its worth They do work...

[slamdak8782]

[URL=http://www.mototuneusa.com/the_2007_superbike.htm] You guys wondering about this have to check this out. This is hands down the best site for velocity porting on the net. I really think hes on to something with this. I never saw this the first time i went on the site. The idea of dead space never occured to me but it makes sense, think of water hitting a bump it leaves an air pocket behind it that the dead space. GOOD STUFF :eek2:

[slamdak8782]

hey mms do you have any pics of the porting or your bike. Sounds awesome

[PHIL_B54]

Badhabit is a member here...pretty good guy, i went riding with him at little sahara.

maybe he will stop by and enlighten us here when he gets done

[MMS]

Yes I do But My Computer system is Down , Im on a non net work computer right now just to check some mail...I should be able to post some pics by Tues...

[dork]

MMS, did you follow mototunes pictures and leave the floor completely flat? and did you use 65%?

[slamdak8782]

Hey check this out mototune guys. I talked to an old school guy to day he said that yes bigger is not btter:confused: I did not think of that but his school of thought was changing the angles at which the air comes in according to him getting a striaght shot to the valve is the important part. This is getting more complicating depending on the type of riding the bike is getting built for determines the angles and also whether its a low end bike or top end bike you take matieral from either the top or bottom of the intake passage. Looks like im going to have to get more jb weld gosh:grr: Its starting to sound like two strokke porting now. My port job is very similar to this [EMAIL=http://www.off-road.com/atv/projects/raptor2001/porting/] not so bad 42 on stock raptor but not the greatest around either

[Bad Habit]

If you click on the "450 head" link posted by dork, you will see the pics of the intake side of the head that I did. The choke height is right at 70% and uses stock valves. I don't have any pics of the ports from the combustion chamber side, it's really hard to see the added material from that angle anyway.

I've only made one run on a dyno with it to test the A/Fr. Eventually I want to get a traditionally ported head and do some comparison runs on the same dyno (the one I've been talking with is indoors and the environment is mostly controlled which will lessen the changes due to atmospheric conditions). The one thing that was very interesting from the only dyno run was the torque and hp curves. The TQ curve is extremely flat and the HP curve falls off less than 1hp from peak to rev limit. Pretty much every graph I've seen with stock valves and HRC cam shows the HP falling off around 3hp or so from peak to rev limit.

Having said all that, I believe that I am going to open up the choke height slightly to try and increase the bottom end response some.

[chad502ex]

what were to happen if the epoxy from the heat cycles in the head were to seperate and break off the port walls into the engine? I mean, what gaurentee that the epoxy permantly adhears without flaking?

just wondering what your thoughs are on this,...


chad

[kgbg]

I was referenced as trying inporting on my cylinder head on an earlier post.
My head is ported in the traditional way, however, most proficient engine guys I talk to are in favor of in porting.

[slamdak8782]

as to the jb weld falling off I suppose its a risk but moto man has done it im going to try it in the near future. I have a friend who tried it on a Harley he never had a problem my cuurent setup has it on the 400ex. But i only used it to cleanup some trouble spots in the intake. JB weld is some very tough stuff. I ve used it to to sucessfully repair a 230 quadsport case and its held up for over a year and also on a 350x case ive even used it to fix worn threads that dont take to much abuse. the epoxy is added to the intake side only so the operating temps are within range on that side of the head more than likely if pieces did fall off they would blow out. but i really cant see them coming of its hard to evan sand the stuff when it gets hard so i usually do it before it sets up the whole way. Oh i also patched a gas tank once with it never had a problem there either :eek2:

[Juggalo]

why cant you use regular weld instead of JB weld?

[slamdak8782]

you can but its harder to do and the heads are cast aluminum which adds even more complexity but if a pro welded it up you could do it. There is a post on motomans website that a guy did that for his exhaust side. you cant put jb weld in the exhaust side it is much hotter that is why this guy welded it. he said the velocity porting on the exhaust side sped the air up to a supersonic speed. I dont know sounds like bs to me though.

[slamdak8782]

looks like the sparks pipe is edgeing out the hmf pipe on my poll might have to get one but the hmf is pretty cool too. Are both those pipes stainless at the header?

[lukester720]

Originally posted by chad502ex
yes there is a few .org members that has tried this porting, but i think they havn't testing the mod on the dyno before and after the expoxy fill.

I believe their call-signs are:
lukester
Boone
kgbg

Once again, I pretty sure they have tried the mod but havn't dyno tested. maybe, they have dyno tested, but have discovered that it didn't work. I'm thinking the later.

My head is ported by Boone, it is a traditional port job not in-porting.

[450ar]

Originally posted by Bad Habit
Pretty much every graph I've seen with stock valves and HRC cam shows the HP falling off around 3hp or so from peak to rev limit.



I also hvped my head. I have no "Facts" just how it felt. Before the hvp when you got to the limiter is was hard to feel cuase the power was droping off so quik anyways. Now it pulls to the limiter, and then when i hit the limiter it feels like someone hit the brakes.

[chad502ex]

thanks for the input fellas!

[slamdak8782]

ttt any more info on this dynos or pictures

[tater_kamik]

Originally posted by MMS
I have been playing around with the HV port design for 2 years now..And have had good results on certain set ups..It builds more power in the mid to top RPM Range on a stock motor but will take some of your bottom away. This can be compensated for by a Cam change and or a higher Comp piston...I picked up 6 Hp and 4 Lbs Of torque on the 686 We flat track Just by Redoing the head to A HV design and not changing any other parts not even a Fresh Piston But jetting Jumped up a Couple jet sizes and required a new Needle for more flow....My 770 is in the middle of a Rebuild and going to get The HV ports and then we will see what kind of # it pulls I was at 76 Hp and 48 Lbs on the last Dyno run on Pump gas Just before the Tear down..I have a stock 2005 that is going to get them later in the season... I am just porting and Jetting it and leave every thing else alone just to see what affect it has on a stock motor..THese are the first Quad Motors I have done With the HV port design..I have several Customers that I have done their street Bikes and Have seen some decent Hp gains over stock and the old school port design (Bigger is Better)....So take it for what its worth They do work...

how much power were you putting down on the dyno before and afterwards and exactly what all was done to the motor? i am extremely interested in hvp now since i have a 686 and wouldnt mind gaining some more power and torque, do you have any pics?

[slamdak8782]

tater look at motomans site he has lots of pics of it and Alot of people are trying it basically you measure you intake valves then the smallest point in your intake runner. Make it 70 to 75% of the diameter of the valve it looks like a lot of work but there are people who will do it for you if you got the bucks. Probably wouldnt cost any more than a traditional port job but I dont know bout it. If it works for your raptor my 440 is going to get it soon after you. Even macdizzy uses this on his port jobs. But he doesnt call it velocity porting. if you read his threads for 250rs only he does it on the boost ports instead of the intake runners. I think that is why he radiuses the boost ports rather than knife dgeing them as well. He has a stock bore 250r on the dyno making 53 hp. Which is more than enough for the average joe. Almost too much really.

[slamdak8782]

here is a picture of what it would look like

[slamdak8782]

read this shortened version I found in some chat mototune was in

Another View on Intake porting.....again think outside the box... LONG y0! « » 5:19 PM 1/27/2004 Reply Edit

756,220 to 1 !!

If you type the words "Intake Porting" into the Alta Vista search engine,
you'll find an incredible 756,220 pages on the topic !!

Every one of those pages will tell you the exact opposite of what
I'm going to teach you today.

The Magical Myth of Flowbench - Porting

Once upon a time...

The flowbench is a machine that measures the airflow through the ports by sucking air thru like a vacuum cleaner. The vacuum gauges on the bench actually measure the resistance to the flow thru the ports, and the result is converted into CFM. That means "how many Cubic Feet of air will flow through the port per Minute."

Anyone who buys a flowbench and a dremel tool is "qualified" to flowbench - port heads. The Superflow flowbench owner's manual says that:

" For every 1 CFM of increase in intake flow,
you'll gain .43 horsepower. "


If you want more water to flow through a pipe, just make the pipe bigger.
There's something wrong with this though.

It's easy to understand why so many people automatically think Flowbench - Porting, or "more is better" is a way to improve power.

Without closer examination,
it seems quite logical.


Okay, Let's examine it a little closer !!

We were all taught to think of a 4 stroke engine by the traditional textbook explanation of Intake, Compression, Power & Exhaust.
Textbooks and magazines achieve a sort of instant credibility that comes from the association with $$.
Because of this association, the vast majority of people never question the things they learn in school, or read in mainstream publications.

First off:

There are 3 distinctly different ways the intake charge enters the engine.

Intake Overlap:
The intake phase actually begins during the end of the exhaust return phase. About 15 degrees before the top of the piston stroke, the intake valves open. This is also called the camshaft overlap period because the intake and exhaust valves are both open a small amount at the same time. (the exhaust valves are closing and the intake valves are opening.)

The low pressure from the exiting exhaust creates a flow pattern across the top of the cylinder that draws fresh intake mixture into the cylinder to displace the last remaining spent gases. The truly ingenious part of this design, is that the flow of intake mixture into the cylinder has been started while the piston is still going up... against the direction of the flow it's pumping !!!

Intake Suction:
Now the piston has passed the top and now accelerating down it's stroke. At the same time, the valves are opening rapidly to allow the intake charge to enter the cylinder with minimal resistance. Since the fuel/air mixture has a certain amount of mass, it tends to lag behind the piston, and this lag time becomes more pronounced as the RPM's increase. As a result, the piston first creates a low pressure condition in the cylinder, and the mixture rushes in to fill it.

Intake Charging:
This is the time when the piston has passed the bottom of it's stroke, and begun to move up. Because of the charge momentum created by the intake suction phase, lots of fuel and air mixture is still rushing down the intake tract to fill the cylinder. This phenomenon increases with the engine speed, to the point that a progressively higher percentage of the cylinder filling occurs after the piston is no longer physically "sucking" the charge in. Because of this, it's necessary to extend the intake phase way past the physical 180 degree intake stroke. On average, the valves don’t completely close until the piston has moved up about 55 degrees past the bottom of it's 180 degree stroke !!

The tuning tradeoff: As you can see, the length of these phases has to do with the speed of the engine ! This is another compromise, because while the delayed valve closing improves high RPM cylinder filling, the charge velocity isn't high enough at lower RPM, and the piston will push some of the fuel/air mixture back into the port. This is one of the most important things to understand about the intake process !!

It turns out that a flowbench measures the least
important aspect of intake cycle efficiency !!

It's true !!
When you stop to think about it, a
flowbench only measures the efficiency
of the "suction phase".

That's not the right
thing to measure.

Why ??
Because, it doesn't matter how well
the cylinder is filled at that point in
the intake cycle !

What ... that sounds crazy !!!

It's 100% true ... it's simply a matter of the sequence of events ! The success of the last event, the charging phase, determines the success of the entire intake process.

What happens when a low velocity port fills the cylinder really well, but too early ?? The result is a slower intake charge that stops flowing into the cylinder. Then some of the charge gets pushed back out of the cylinder and into the port as the piston returns up the bore during the intake charging phase. The gain in flow doesn't offset the loss in port velocity.

Here's an analogy:

It's just like a roadrace; you can lead for 3 laps, then run out of steam and end up in 7th place.

In racing, only the last lap counts, because the one who leads at the checkered flag wins.

In the intake cycle "race" the last lap is the charging phase,
and the checkered flag is the intake valves closing.

So in the final result, the first 2 phases don't matter if the 3rd phase is unsuccessful !! The total intake volume that will be burned is determined by the amount that remains in the cylinders after the intake valves close. That means that an early gain during the suction phase can be easily lost during the charging phase. And, if the intake charge returns back into the port during the piston's upstroke, the result is going to be a net loss !!

What's The Secret ??
Using the race analogy, if you increase the Port Velocity, by making the port smaller, the intake cycle "race" starts out slower, gains momentum and makes a tremendous charge on the "last lap" to overtake the high flow port and win the "race". The interesting thing is, this type of port will always lose in a flowbench contest.


why hasn't anyone else
thought of this before ?!?!

In real world situations, many people forget to apply the simple principle that all productive science is based on: The Scientific Method.
When someone builds an engine, they usually port their cylinder heads and make other modifications like higher compression, valve job, different cams and big bore kits.
The combination of all these modifications usually results in a net gain in power. The problem with attributing a gain to the porting in this scenario, is that it goes against the scientific method, because there are 4 other variables coming into play.

Know the difference between association and causation !

Could More Flow = Less Power ??
Flowbench Porting has always been associated with more power... Superflow even says more flow equals more power in their official owner's handbook !!

Yet, in most cases, Flowbench Porting motorcycle heads actually results in less power.

(Actually, a few creative thinking tuners in Europe do already know about this. They're not anxious to reveal this info, because their success on the racetrack is somewhat dependent on it remaining a secret.)

What happens when we apply the scientific method to intake porting ??
To find out, let's test 2 progressively smaller porting specs against a stock head,
without changing any other variables ...

[2muchquad]

very interesting reading,im impressed,and here i thought this forum had all teenagers on it.:D i still think there is no free lunch when it comes to porting.you can build a motor for strong mid to top performance but it wont be a torque monster like a utility quad.that why when you look at camshafts they say "all around" of high speed applications.the longer duration is a dead giveaway that its top end oriented.there will always be the endless pursuit of the perfect powerband.:)

[hawaiiansupaman]

slamdak8782

very good info, alot a good info i never thought about.

[slamdak8782]

thats one thing that is kind of hard in this site. Trying to learn and not having a lot of really good advice, but hey its the best site you can find around.

[prepracing]

I've seen performance gains on a dyno with this type of porting done to crotch rockets in mid to high rpm's, they had good HP gains. But I ride with a few people that have this done to both yfz450 and 450r and swear by it. But they have not been on a dyno, and I know from riding them I wouldn't have it. Their bottom end power sucks and does not seem to come alive till you hit the high rpm's. I just don't think quad motors rev high enough or fast enough to see the advantages of this.

[d kelley]

Most of this velocity porting was begun in nascar engine shops after their engineers began finding more power on restrictor plate engines by lowering the cubic inch of the engine to actually use the smaller amount of air that the engine able to flow with the resrictor plates. The theory is that with the reduced air flow the engine needed to be brought back to maximun volumetric effiency by reducing the engine size. When those smaller motors (by about 3or4 c.i.) made more power with the plate installed, almost every engine shop began to Velocity Port the cylinder heads. Most shops realized that since there was now less amount air able to come though the head, their only choice was to increase the speed at which the air could come though. There is a lot more of an engineering school of thought with these engine builders and they have an unlimited amount of resource to test these theorys. The most important point is to remember that engines are a combination of parts that work together and no one part or modifcation will be optimal by itself. These engines are built to actually use less air at higher speeds (RPM).

[JOEX]

Originally posted by d kelley
........... The most important point is to remember that engines are a combination of parts that work together and no one part or modifcation will be optimal by itself......
:) :macho

[chronicsmoke]

Grave robbing large with this, but now that HVP porting is a proven thing, I'm wondering if there's any info of adding epoxy on the floor of the 400ex intake ports to invrease velocity?