Topic: visualizing valve flow

[turboguzzi]

well, I was drying some parts i washed with a blow torch, the Kxxxxxx 750's head was nearby, it gave me a swell idea....

[turboguzzi]

nothing really new here but i thought it quite nice how well you can see the flow pattern descrived in the books (and the sad fact that the bottom of the inlet doesnt flow much at all). Most of the flow seems to attach to the chamber roof, so any improvement in flow in the short side radius of the port should be cool.  Really tempted to try those bolt on ramps in the port like Howell's tuner did.

on the exhaust side, quite impressive how the floor of the port (white line) doesnt get any flow at all. no wonder so many tuners D-shape it.

not bad way to viusalize stuff for 0$

TG

[kos]

Yes, addressing the short turn issues, is where all the power is on all these old style motorbikes. Not so much on the newer, modern down draft racing engines and  modern street bikes which utilize almost straight intake parts. Look at the RS750 Honda from mid 1980's and the ex ports go almost straight up, so even Honda had the short turn issues addressed on the exhaust side. The ports on our SOHC Honda's especially the ex side, are also way TOO large to begin with. We made more power as we had more flow with material added to the inlet side of our M3 racers as we increase velocity of the incoming air/fuel mixture by adding epoxy to the port  floor and reshaping the port, then testing on flow bench.

The science of working with the short turn radius probably goes back to the 1950"s or earlier, there is not much new here. it's all in a "cook book" somewhere.

KOS

[turboguzzi]

Yes, addressing the short turn issues, is where all the power is on all these old style motorbikes. Not so much on the newer, modern down draft racing engines and  modern street bikes which utilize almost straight intake parts. Look at the RS750 Honda from mid 1980's and the ex ports go almost straight up, so even Honda had the short turn issues addressed on the exhaust side. The ports on our SOHC Honda's especially the ex side, are also way TOO large to begin with. We made more power as we had more flow with material added to the inlet side of our M3 racers as we increase velocity of the incoming air/fuel mixture by adding epoxy to the port  floor and reshaping the port, then testing on flow bench.

The science of working with the short turn radius probably goes back to the 1950"s or earlier, there is not much new here. it's all in a "cook book" somewhere.

KOS

So Kos, do you D-shape the floors of your inlet ports before they turn down towards the valve? Was looking at Gordon Jennings work together with jerry branch on a sr500 head and they ended up adding some 1/4" to the floor...

http://sr500forum.bravehost.com/sr500ehopup.html

[MRieck]

I'm very interested in what information comes from this thread. I'm all ears...or should that be eyes?

[kos]

I knew that Mike would get in this thread a some point I am all "ears" when he chimes in. Here is a pic of a port cut down the middle from a Suzuki 4 valve IDBA record holder. You can see the amount of epoxy that was layed down on the floor of the intake port. Measured at the thickest point it was 6 mm's.

NOTE: valve seat is missing, as it came out when I sliced the head in half.

KOS

[HedNut]

Very cool info here! Great pics...and interesting finds!.... got me thinking...

[srook]

Is their any chance of the epoxy breaking out of the port during use?  Is this just for race use where engines are frequently rebuilt or would the epoxy hold up for street use?
Scott

[turboguzzi]

i've posted about this in another forum and one experienced tuner added that actually he has measured higher velocities at the floor rather than the roof of the port. the head i am working on has a similar banana shape the one in Kos's pic. so its interesting that they actually added to floor still, maybe even higher floor velocity (smaller venturi) makes the flow stick to the floor more and hence "use" more of the valve perimeter.

high temperature JBweld is supposed to hold on intakes but i do like Howell's tuner's solution of bolting an ally piece (+ some devcon too)

http://forums.sohc4.net/index.php?topic=63228.msg702333#msg702333

it will all be like shoooting in the dark without some flow bench testing though, really got the itch to build one...

TG

[iomtt9]

Hi TG hope all is well, we have one of the heads done by  Howells tuner, but not on the bike yet. We are building 2 new bikes up. 500/4s and when we get them all up and running, we will send in the Dyno Results to see if any improvement on the ......BHP we are getting now.
Also as you may know our bike are on route to OZ for the Island Classic in January. I wont tell you the name of the boat because i think it stops off in Italy, and there are 3 nice Honda 500/4s on board !!!!!!!
Maybe the Phillip Island organisers should have a Europe team in. I know there was talk of the USA last year but i dont think that has happened.
Wouldnt that be good Australia, New Zealand, United Kingdom, Europe and the USA classic racing at Phillip Island !!!
Col

[kos]

I would not use epoxy on a street bike, only for race only. The head I showed as an example, was drag race only and at very high level, at that. Drag racers have for years, used a plate the extends into the floor of the exhaust port, that is an extention of the exhaust pipe where the headers attach's to the engine at exhaust port. This extension, in effect, raises the ports floor.

KOS

[kos]

Here is a picture showing how Honda went to the max to get max flow on exhaust side of RS750 AMA flattrack racer. note: how the ex pipe leaves top of cylinder head. Hard to do on street bike, but when going for max power and torque...anything can and must be done!

KOS

[MRieck]

Is their any chance of the epoxy breaking out of the port during use?  Is this just for race use where engines are frequently rebuilt or would the epoxy hold up for street use?
Scott

The epoxy will eventually break off a bit.....at least that is my experience. Filling the floor increases the surface area and "tricks" it (the short side) into thinking it is the long side. Velocity goes up along with flow. I have been thinking about doing this to the head for my 1000cc engine as the bike really doesn't get ridden much. Securing the epoxy to the floor really requires some type of "pin" be "planted' in the floor to really hold well. Heads like the GS1100, early GSXR, FJ's etc have long, exposed intake tracts....drilling and screwing in sheet metal screws works well to hold the epoxy. I guess I could mill some of the lower fins on the CB and use the same approach. I don't know....I've had very good luck with my current port design but my new flow bench is on the way from Superflow so I could screw around with some very different epoxy ports.
 I have had the exhaust floors welded up on 600cc road race bikes. It is difficult to tell if it made a noticeable difference. It does make a difference on big boost turbo heads as it keeps the velocity high. I have seen turbo exhaust ports so small you wouldn't believe it. That is for 50 to 60lbs of boost.