Small Intake Ports

[LE05BUSA]

With two ports with identical port length from the 45° to the intake or exhaust interface and one has a larger runner volume than the other (and the smaller volume runner flows more air from .050"-max" lift, steady state, at the same depression), the smaller runner will make more HP and LB-FT 99% of the time ACROSS THE BOARD on a gasoline fueled ICE. Why? Increased port velocity.

Small cross sectional area ports are highly sensitive to surface finish...I.E. - you may see as much as a 15% increase in flow by producing an intake port with a Ra of 15 (microinches) v.s. one with an Ra of 75 as a result of the low Reynolds number and the corresponding laminar flow. I have found this to be even more likely in ports that have a cross sectional area at the short turn window of less than 1.375 sq. in. and have high swirl.

This is hard to prove with a large inch motor............if its a small inch, i agree...I have proved that increased port volume over velocity will make more power and run faster...........Now, we need to know the balance of volume and velocity for the displacement...........

Is 403 cubic inches big enough?

[crazybill]

How do ya like that Flowcom ? I was looking at buying one for my bench...
ever messed with an FP1 first-hand ?

[LE05BUSA]

How do ya like that Flowcom ? I was looking at buying one for my bench...
ever messed with an FP1 first-hand ?

Flowcom is nice. It's easy to use. Outputs are convenient. Sure beats trying to adjust depression, wait, change valve opening, adjust depression, wait, etc...

The integration factor has a lot going for it, as well as the time savings and consistency. I recommend it, wholeheartedly for anyone that owns a SF bench.

FP1 is targeted for kit bench builders. It needs a laptop or pc to operate it which is another drawback. If you already have a SF600, call Harold and order a Flowcom.

[whtrthanu]

403 ci really isnt big for a car motor...........you know what im trying to explain here...if you put the head you are running from the 1397 on a 1660 it would be a turd........But if you put one of my heads on your 1397 it wouldnt run right either........

[LE05BUSA]

403 ci really isnt big for a car motor...........you know what im trying to explain here...if you put the head you are running from the 1397 on a 1660 it would be a turd........But if you put one of my heads on your 1397 it wouldnt run right either........

I'll agree with you that a larger displacement motor is less sensitive to superfluous runner volume...especially one that has some compression and camshaft in it. I.E. - on a 572 with say, 14:1 compression and a camshaft in the mid 270's @ .050" and .750"-ish lift you could get away with anything from 350cc intake runner to a 390cc intake runner with similar flow numbers and still make 900+HP with similar power curves. Ya' know what I'm sayin'?

[enginetuna]

403 ci really isnt big for a car motor...........you know what im trying to explain here...if you put the head you are running from the 1397 on a 1660 it would be a turd........But if you put one of my heads on your 1397 it wouldnt run right either........

Not necessarily, it all depends on what size the head we made for the 1397 is.  I can guarantee that even if you are up to 1660 with your busa that with some epoxy i could gain you power over what you have now if you have none in there at all.  Obviously a tiny tiny port will most likely hurt top end when you up capacity 20%, but if your port is already 30% too large for the sotck engine then you could still make more power with a 10% smaller than stock port on the 20% larger engine.  As i said before, its knowing where and how that is the key, but hey that's just my opinion.  This is why putting on a big bore kit often makes such good gains (providing the port isn't hogged!!), because you are effectively making a smaller higher velocity port in relation to the original port to cylinder size.

And yes, flowcom is worth its weight in gold.  Time saved = money saved.  Shops that don't use it and sit their with pen and paper are burning $$$$

[enginetuna]

Here is a small port gsxr1000k6.
Its also had 20 thou skimmed off head and cams dialled in.
But ports are pretty small.
Draw your own conclusions.

[whtrthanu]

When i get back to the shop I will post a 1000 i did with a larger than stock port, we can see the differences.......i am always up for trying new things, but in the case of a 1600, I bet you $1 that you are wrong with the epoxy in the port as far as power......Ive tried alot of different things on my bench and then the dyno........What is working for me might not be what works for you

[enginetuna]

I guess we all do it differently though, so no worries.  Please post up, its always ncie to see what each other does and hopefully pick up a new trick.
Most of my engines are not built for outright bhp numbers as i never do drag race stuff.  Its all about fast recovery and drive, the datalogging often proves the dyno wrong .  If you do a lot of sweep testing on the dyno and look at it from a time based point of view, you will never want to do 4th gear roll-ons again
Have you tried epoxy in busa port?  I wouldn't rule out yours as being the best job you can do until you have.
Most of my greatest breakthroughs have come from trying weird things.
What would you all say about things like either side of a single inlet port being totally different sizes and angles, how about offset lobes for the same cylinder on the cams or how about a 4-valve chamber with 4 different valve sizes in it?  I'm not saying these are the next great thing (or maybe i am ) but its all been tried and the results can be quite surprising to say the least
Right, time to do some work.  Its still only 4pm and i've been pissing around with a motec loom all day, time to do some useful work   Half a dozen supersport R6 motors calling to me and i'm really not interested.  Shitty black crap.

[enginetuna]

Forgot to say, k6 1000 graph above is stock cams on both curves, just wanted to make that clear

[whtrthanu]

Sorry this is the only way I can post the graph, dyno is not hooked up to the internet....

but this was an 05 with the head milled completely stock bottom, I couldnt really put the cams where I wanted to because of room, and this is on reg race gas NOT oxy fuel, with mrxo1 it made 191hp...........they look close, your looks alittle earlier on the power which would make sense, the torque curve is close too......

[whtrthanu]

Oh ya, check out the date!!!!!!! I think I can do alittle better now......
Beacause Im older

[enginetuna]

Cool thanks for that.
You sure can see the belly through the mid, its down around 10bhp up until just after 9k rpm.  Filling nearly always gives a straight curve on this size motor.
What cams are you running?
Do you have a base run on the bike to compare the head against, because if you started 20bhp down then you are way up on mine.
Mine is pump gas and as said before stock road cams.
The base run on mine in red is completely stock motor with full system and pc3, i'm not comparing conventional ported versus filler there.  Again, just to be clear.  Also ex port is cleaned up on blue curve and not on red.
Good work

[gazza414]

I guess we all do it differently though, so no worries.  Please post up, its always ncie to see what each other does and hopefully pick up a new trick.
Most of my engines are not built for outright bhp numbers as i never do drag race stuff.  Its all about fast recovery and drive, the datalogging often proves the dyno wrong .  If you do a lot of sweep testing on the dyno and look at it from a time based point of view, you will never want to do 4th gear roll-ons again
Have you tried epoxy in busa port?  I wouldn't rule out yours as being the best job you can do until you have.
Most of my greatest breakthroughs have come from trying weird things.
What would you all say about things like either side of a single inlet port being totally different sizes and angles, how about offset lobes for the same cylinder on the cams or how about a 4-valve chamber with 4 different valve sizes in it?  I'm not saying these are the next great thing (or maybe i am ) but its all been tried and the results can be quite surprising to say the least
Right, time to do some work.  Its still only 4pm and i've been pissing around with a motec loom all day, time to do some useful work   Half a dozen supersport R6 motors calling to me and i'm really not interested.  Shitty black crap.

ET, that I do find of interest ( valve sizes that is ). I havent considered 4 different sizes , however I was going to play with 2 different sizes on the INLET to begin with and not sure how to configure  ie all LHS of chamber or symetrically about centre going out ( make sense )?

any suggestions ?

[enginetuna]

I a current supercar maker is doing this on at least one of their models and I guess the theory is that mismatching the valve sizes causes more swirl.
As for offsetting the valve centres from where they are now, you may find that hard as the guide is bored through the head already so if you want to reposition the valve you are into a problem straight away putting a new guide in.
Lets say you went 1mm up on one valve and 1mm down on the other than you are still running the same valve area but you are creating a different throat area per side of port.  Then if you match the port csa per side to this you could effectively run a higher speed on one side than the other.  So going back to these discussions on port volume and velocity, you could have high velocity and small volume one side and low and large the other.  So now you are not loosing volume over stock port which i know some guys are concerned will rob peak cfm, but you are still retaining some of the value of speeding up a port.  And again you may be picking up some advantageous swirl of tumble in the port.
Ok, so now after this, lets say you open one of the valves a degree or 2 before the other and also close it earlier.  Maybe then there is the chance to take extra advantage of super high speed on valve open and close as only one side of the port can pull from the valve for a few degrees.  You are also changing the cam duration and getting benefits of both a shorter and longer duration without actually running either.
Or maybe you run same size valves and epoxy one side as an arrow straight run at the valve and the other to drop down like an old style port with big bowl and big turn ssr.
Or maybe all this is just bullshit.  But i bet it makes you think twice

[whtrthanu]

Here are two more runs from the motor with a pipe on my dyno.....

[enginetuna]

What cams?

[Oz Booster]

.  So going back to these discussions on port volume and velocity, you could have high velocity and small volume one side and low and large the other.  So now you are not loosing volume over stock port which i know some guys are concerned will rob peak cfm, but you are still retaining some of the value of speeding up a port.  And again you may be picking up some advantageous swirl of tumble in the port.
Ok, so now after this, lets say you open one of the valves a degree or 2 before the other and also close it earlier.  Maybe then there is the chance to take extra advantage of super high speed on valve open and close as only one side of the port can pull from the valve for a few degrees.  You are also changing the cam duration and getting benefits of both a shorter and longer duration without actually running either.
Or maybe you run same size valves and epoxy one side as an arrow straight run at the valve and the other to drop down like an old style port with big bowl and big turn ssr.
Or maybe all this is just bullshit.  But i bet it makes you think twice

Wouldn't doing something like this require a nearly full divided port

[whtrthanu]

This is the same motor with the stock cams and stock bottom end..........

[enginetuna]

Well 22bhp from just port work with no epoxy is real damn impressive.  I've worked on a lot of superbike engines and not seen that much of a gain without changing a lot of other stuff.  If you are not already doing national or international race engines then i would try to get your foot in the door with some major teams, there is a lot of money to be made

[whtrthanu]

Yep,  my name is byron!!!!! 
Listen im not going to bullshit like some of the OTHER people do.......the two runs are comparable but the one with 180+
is a much better day............You can see from the other graph it was more comparable and there is still a decent gain, 12 or 13 hp.......still good....what ever we can pick up in power on these motors is good.....In my book if you are making 2.8 hp per cube or better on the tire your doing your job.... period........
i said it before, there is a million ways to skin a cat!!!!!!!!!!!!!!
The way i am going, i will stay on that path and keep going forward, you will do the same with your r/d.....eventually we will both cross  somewhere in the end...........

[whtrthanu]

I also dont port intakes the way that most shops do....... I speed my air up in another point......

[enginetuna]

I see now, the one graph on your last run post went offline for a while.  The upper is obviously uncorrected looking at the dates and times on the 2 of them.
Same peak gain as my motor then which is cool.
But if you do get the chance i would really recommend trying some epoxy.  See my 1000 loses nowhere and makes same peak gains.  Please don't feel i'm pushing, i was really reluctant for ages thinking it was bs, but if you have chance i recommend having a play.

Here is the data from the yoshimura tuning manual for the k6 1000.  I can email you the manual if interested.

[enginetuna]

I speed my air up in another point......

Using a turbo is just not fair

[whtrthanu]

i see that your engine does not loose any power, but where mine dips alittle is below the power band on this drag motor.....so i really dont know what the difference would be at the track........If you stretch out your graph alittle more it might reveal a bit more of the curve...

I enjoy comparing work, no matter what is the outcome, it is always a learning lesson.....I am starting another 1397 this week, I will try to do some epoxy work....What i will do is, post flow data, than dyno results.........I want to see what the difference will be from the previous one i just finished......They both will be the same combo, 2 intakes and 13.2 compression.....only difference will be the head.....