Yamaha TRX850 Enthusiasts Forum

Well, another day, and i made time to do some work.
Dont know how many of you know this, but i actually own a flowbench.

Its a homemade job, could be painted / finished better, but its 100% solid, works great, and its (as i always do) complete overkill.
It has 4 huge ass motors, each able to pull a genuine 125cfm @ 28" H2O. When all 4 run, you get a loss, but its good for around 420ish CFM, i dont have a orifice plate to test higher. But for an idea of how much air that is, a stock 5litre V8 would pull around 450cfm thru the manifold. So if you are testing individual cylinders, i could go up to basically anything you can buy "commercially". Ive made accomodations for 8 motors total if i ever need it.. Which i highly suspect i wont.


Now the fun stuff. Throttle bodies. Ive made up some trumpets (long time ago) and finally got my ass into gear to do some testing on them very briefly. now please remember that my throttle bodies are from a TDM900, which are 38mm diameter, the same as the stock Mikuni that the TRX runs, except ive bored mine out to 41.2mm. Ive not finished them off as i have much blending work to do, which is where the flowbench comes into it. Note that this is for a EFI total conversion. I already have 100% control over the spark tables, i can increase / retard spark at my hearts desire. Its good for a few hp actually.

You can clearly see ive left a bunch of meat to be ground out. Anyway.. here are some flow pics.



You can see that the trumpet was good for around 5cfm increase in flow. Im hoping at the end ill be upwards of around 220cfm. I dont have velocity readings, but i want to keep that above the 340FPS range, id prefer more if i can get it, but i need some cfm too.

Ive also made a "flowbox" which is an exact mould of something, to play with. In my case, ive cast my ports (inlet, exhaust, cylinder chamber) in a soft silicone, and then put those pieces into a box. Cast it all in hard resin (think "bowling ball" plastic) and squared it up on a mill so it sits flat. I also made a valve opening jig, and for 3 valves, it was a bastard. but i did it.






This way, i can grind away on the flowbox, and if i screw up, find out im loosing velo / cfm, whatever, i can mix a bit of resin, paste it on with a paddle pop stick (popsicle stick ?), wait for it to set, and go in another direction.
Doing this takes quite a while to figure out what is best. There are some rules that people come up with, but everyone is different. There is no "right or wrong" method, its the end result. And fingers crossed, ill get some more time to play.

Anyway, enjoy, and hopefully by the weekend ill post a full cfm / velo plotted graph of the cylinder head. Might help someone one day for some tech data / cam design / exhaust design, etc..

Questions / comments, please dont hesitate to whinge at me.

Wow...
So you do this for living or ..?
Looks very dedicated.
Almost forgot to mention: Interesting stuff of course!

Quan-time translates to 'too much time'

Your ongoing search is impressive. I may some questions for you down the track once the supercharger is purchased. (a while off yet, unfortunately)

That's simply awesome.

I actually got the name Quan-Time partly due to my strange perception of time. Long story.. weird.

Im a tradesman, toolmaker by trade, but do most everything. Welder, hydraulic / pneumatic tech, some PLC stuff, fitter, etc.. Ive played with almost anything you can imagine. Food processing plants, brewery (coopers for us aussies, screw that west end crap), coke-a-cola, aircraft loading trucks (those things that have 5 "UN-drop crates" that act like giant scissor lifts), huge ass trucks (catapillar), submarines, and im currently at a power station doing an overhaul of a 160MW turbine. Since power is needed 24hrs a day, you can see why my work schedule is a bit crazy.

Some one once joked to me about "in order to make an apple pie from scratch, you must first invent the universe". And that has always stuck with me. I have a sickness of wanting to know how things work. Instead of handing over a credit card / cheque book, I usually research how something is done, and do it myself. Even if it takes longer and costs more.
I built all my own EFI module from scratch, and have been tying in with the devs (its a megasquirt if anyone knows what that is) and poking around on the next generation ECU. Should come out soon, and ive already worked out some hardware / software hacks. Weather or not they work, wait and see when i actually get my hands on it. Ive also been doing some beta testing with someone for the linux port, which is unofficial, but we have it working quite well. The 3d tuning tables are a pig, but that was sorted. (i didnt do the software part, im lazy like that)
The new megasquirt ECU is WAY more powerful, and ive had to start "officially" learning assembler, ive always been able to "read" it, and limited program skill in it, but yer.. started doing it properly now just so i can hack the new code much easier / redo all the hardware properly.
A nice side effect is being able to rewrite firmware for different things. More on that later, but ive been workin on somethin cool which should work well on bikes if i can sort it out properly.

Wanted to know about EFI, so i built a crazy ECU, injector flow bench, full data logging stuff, etc.. Im currently working on a full traction control, anti wheelie system. Full lean angle sensors and other awesome trick stuff. Wanted to know about cylinder heads and how to make power. Spent the past 2 or so years studying fluid dynamics (air in a cylinder head) and ended up building a flow bench and messed around with a few spare heads. Got some good results.

Ive never been, nor will be, in this for the money. Im more than happy to share results / information with others, so everything can be reproduced for free, or at minimal cost. The biggest factor is, you need to spend time to do it all yourself.

Anyway, see how i go in the next few days. Im gonna try to sort out my balance problem on the counter shafts / crank setup. Gonna have to dust off the old thinking cap and get some maths working, but should be fairly easy.

Before I read the thread I saw the title and thought - oops best move that to The Roadhouse Bar

That's bloody beautiful! As always interesting to see/read about your efforts. Keep it up!

How the hell does your thinking cap get dusty.
Amazing, talk about thinking outside the square

OK, i have some prelim results. Ive only done inlet at this stage, exhaust is to follow. Im not going to post what i have as yet, mainly because ive found a small air leak and want to double check everything and verify what i have to make sure its consistant. Here goes. (no pics, but be prepared to read if you want, else ignore this and wait a few days for pics and other stuff)

Throttle body.
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Im getting around 280fps (feet per sec) air velocity at the main part of the body. Where the butterfly pivots / rotates from. Further down im getting upwards of 303fps. Ive already found 2 problems with my trumpet design and can dramatically increase cfm and velo. But for its fairly close to stock 38mm mikuni carbies. I should be able to get it over the flow rate of FCR41s fairly comfortably and get velo upwards of 340fps.

Inlet port
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Im getting a touch over 220cfm @ 8mm lift (stock cam) and 250fps velo. Im taking these readings with a pinch of salt. "Kent" cams have 8.4mm and the custom pistons ive designed can accomodate 9.5mm lift and 1mm bigger valves. At a guess (without calculator on hand) im guessing 245cfm @ 345fps. That equates to a (mental calc) of 122hp. My target has been 120hp+ so i suspect its quite possible with some good fuel and a bit of tweaking. Point is im quite confident now that the 120 barrier can be broken.
The biggest limiting factor that i can find so far is exhaust. I strongly believe there is much to be had in this area, and i have a REALLY weird plan for this. The one thing i dont want to do is change the TRX sound, but soon as you touch the exhaust port and pipes, its a subsequent by product.
Getting the exhaust out faster means your engine can get to the power stroke faster. You may note that many high reving IL4s have a "whine" to them. Its part of the inherent nature of "air". Tends to do some weird things like that. Either way, im still working on things, just dont want to put any "proof" up yet until i can be asured of the numbers.
But as i said, take these numbers with a bit of "generosity" until i can confirm everything. Im over estimating but time will tell.
Anyway, things to do... watch this space.

WOW the flow bench!

Nice reading stuff (understatement )

Greetz
Gerben

Wicked stuff.

Why is the air speed indentical with and without the trumpet (see first post in this topic) as cfm increases? Edit: ah never mind, you weren't measuring the speed at that time.

ok.. air flow time.. this is all theory stuff.. Please glaze over it if you dont care, else enjoy the ride.
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Air speed.. ok.. Get a garden hose (if your a chick.. *cough* jak *cough*) or get your wang if your a BLOKEY BLOKE.. next time you pee / use the hose, LIGHTLY pinch the end while the flow is constant.. When you choke the flow off you dont actually slow it down, you increase it. What you are doing is increasing the "velocity".

Velocity.. best way to explain it. Run a 100m sprint. Now try to do it with a straw in your mouth. You cant. You cant "pump" enough air thru the straw. The air speed of the straw is its "velocity". Try opening your mouth as WIDE as possible and inhaling as much as you can quickly. Go on, try it.. DO IT !!!.. ok. now very slightly close your mouth and repeat. Do it again until you notice you cant breathe in as easily. You will notice your mouth is approx 1/4 the size of wide open. You notice your lips might "suck in" a touch. Thats normal. Its due to "venturi effect"
You have now increase the velocity of air in your mouth. Watch an olympic sprinter and his mouth is never fully open, its naturally partially close for "efficiency".

Look at a storm water drain.. HUGE.. Now you have to pass 2 liters of water per minute. It would be trickling out. How big (or small) does it have to be to pass 2 litres per minute ? think of a 2 litre soft drink bottle.. Can you empty it in 1min ? yes ? well it can obviously go smaller then. Now you get the concept.

FPS is "feet per second". Imagine you have a piece of paper, or confetti, or rice, whatever. How many feet per sec could you shoot it thru a tube, at a given CFM (cubic feet per minute). Bigger tube = more CFM, and obviously smaller = less CFM. bigger has no more velocity, They sohuld be *idealy* same FPS
A huge storm drain has LOW velocity. the FPS rate would be like... 0.5fps. But a 1/4" or 6mm hole would be close to 300fps, or 100metres in one second. Thats hugely fast.
For regular "petrol / gasoline" you want a utopia of 350fps. Please remember that this is 238mph or 384km/h. Enough to whistle, shear, do some funky stuff.. More on that later.
This for for 2 fold reasoning. 1: fill the cyl fast, 2: fill the cyl fast
Faster you can fill the cylinder, guess what.. The faster you can ignite that shit. Faster filling = faster power. This is only HALF the equation. You need to get that spend gas out, and FAST.. Get it out the exhaust port means the cyl can get to its intake stroke faster, which inturn means faster power deliv..

If you go over 425fps air starts to do some REALLY crazy things. From now on, NEVER EVER think of of "air" that we breathe as a "gas". Think of it as a "fluid". Much like water. Lets go a bit deeper.

You have a water slide.. You are now "air".. or more precisely, you are made of the same stuff flowing down it. You go down a big drop.. What happens ? can i guess taht 90% of you said "you go flying off and crash to your demise".. Well,, you are wrong. "air" is hugely sticky.
As the big dip / drop occurs, there is a vacuum on the floor. It "sucks" you down. If the air speed is high, and the drop is too sudden, you create "turbulance". IE: you start to spin circles and probably throw up. If the drop is natural (11deg grad VS dia % drop over grad) you INCREASE speed and stick to the slide like glue. You get a huge rush.
"Air" isnt effected by gravity.. (it actually is, but examples here people).
Walk down stairs. If the stairs are too steep, you stumble and fall depending on how fast you were walking. If the stairs "match" your current speed, you very slightly increase as you go down.. Understand. ? The old "angle of the dangle" rule.

Velocity VS CFM is a HUGE deal in cylinder dead dynamics. Many pros will say "oh its more art than science".. PIGS ASS... its pure science. Lack of understanding doesnt make it some black art.. If you dont understand physics, yes, its art.. but dont expect what "looks" nice to actually work.. "Air" does weird shit.. even more so with fuel suspended in it.

A flowbench is a tool.. Much the same way a grinder, lathe or welder is. If you know how to use them, its art. If you DONT know how to, you make a mess of things. You must learn how to use it else you go backwards.
If anyone is interested, ive got a few interviews of some HUGELY influential people people in the cylinder head / manifold / exhaust market.

And now the class concludes. Im not a professional, but i do know what works for me. Im not in this for the publicity / fame, but im happy to help learn with others about what is possible and further my knowledge base if someone can please point out where i went wrong.

The usual "questions comments hate-posts" rule applies.

Bahh... It's more fun to read something where the writer doesn't know anything...

Great stuff!

How do one use a flowbench in practical life. I take it you measure flow with the valves in place. But how do one do, in order to simulate a running engine? I mean, there are more to it than measuring at 1/4, 1/2 and full lift, right? Standing waves, air stopping and starting all over again, and so on...

Hi quan-time, great thread, really digging the tech stuff, even if I don't understand more than half of it!

What are the odds of testing a few air filter/box combinations? The reason I ask is because I've made a foam replacement filter for my TRX, but I am unsure if it flows any better than the standard, & if it is on par with the K&N's etc.

Cheers!

Stick them on the vaccumm cleaner. The higher pitched one is working harder.