So after reading these articles Im very skeptical of everything I thought I knew about porting... to the point that I have an idea to redesign a flowbench to actually mimic a cylinder, instead of vacuum cleaner.
Start with article 18, or 17 so you have a grasp on his way of thinking of engine phases. He definitely lacks enough volume of proof to make this a complete game changer but I think he has something here, and its not at all new.
http://mototuneusa.com/thanx.htm
can someone summarize for me.. my ADD just kicked in and i left the page after 'in january of 1992..' LOL
Interesting. Very interesting. I wonder how much of this transfers to a fuel injected car engine as opposed to a small motorcycle engine. I'd love to see some dyno results for part 19, where he puts grooves in the intake ports.
whoa.. no no no no no.. NOOOOOO.. grooving is BAD.. it's been tested by micro engine builders (on CBR600RR, ZX636, GSXR600 and R6 motors) and it made performance WORST than stock.. it was also tested by a builder that goes by the name of maveric on 2 strokes.. i had 2 of those experimental cylinders and they were GARBAGE.. it was also tested on a couple YZ450F's with piss-poor results.. i just skimmed through some of article 19 and i'm horrified by what i read..
ask anyone here who has run their heads stock, then removed them for portwork.. they will all agree, performance was increased.. making ports smaller? really? way to kill the flow rate.. motorcycle manufactures use large ports and restrict them by using smaller TB's/carbs and headers.. removing the stock, junk header for a performance unit is a VAST improvement.. i had a 98 honda F3 on the only 600cc micro i ever ran.. it was mildly built with a stock cam trick (a factory intake cam in place of the exhaust cam), an S&S 4-2-1 header/ler combo, 36mm keihin flatslides (over the factory 33's), some sort of aftermarket ignition (dyna2000 i think?) and massive portwork.. the motor dyno'd 149 @11500 (rev limiter set to 12500).. guess what it dyno'd with a stock head? 122 @10200.. this guy is a crackpot, hands down.. i dislike streetbikes, but i'm willing to bet i could build 1 that smokes his, if he's really performing the work he posted on his site..
well the latest details of his work end around 2007, at which point we've already discovered every trick we have in the book to this date. And shadow, you totally fell into the trap he mentions over and over and over. Like i said, he lacks the extensive proof to make me a believer, but I see very good physics in his theory. especially when he's comparing the gsxr 1000 to the fzr400. Also note he doenst think this will work as well on a 2v as it does on a 4v.
Break it down like this too, how many people have you ever known that had port work done, and NO OTHER MODS at the same time? its pretty rare. And so often in port work, you're removing obvious restrictions along with hogging out the port so most likely you're gonna come out positive anyway. The dynamic events happening during a cycle do hurt us in many ways as we increase flow. Plus im 100% convinced he's right about the complete failure of a flow bench to mark the performance of a port as the motion of a cylinder not only varies in suction but also in direction while the port is still open.
Is he right? maybe, is he wrong? maybe. He'res where it gets me tho, look of the shape he puts into that port... isnt it a lil familiar, havent you read "dont take material off the bottom wall!" havent you seen the extreme effects that venturi tuning can have on performance? Or maybe he's just a crackpot and no other person on this forum should bother reading the articles.
i vote crackpot lol what trap? i can't read the whole article, my mind won't allow me to sit still that long.. as for 'only portwork,' it's rare occurrence.. i've only done it twice for 1 customer (2 different cars), without messing with anything else (except VGS lol)
Easy fix. Get boost and port till ya can't port no more. He has an interesting point, but so did the guy who invented the flowbe. :clown:
It was an interesting read, I personally have no idea if he knows what he is talking about though.
Thanks for sharing! :D
I wonder what he would do to my 5 valve headed 998 Yamaha?
close the ports completely by the logic i get out of it LOL
No just to 65% of your valve.
LOL i'm going to attempt to read it all today.. then i can really pick it apart :p
Unless you FULLY understand how a process works, you'll never fully optimize it by throwing broad general theory at it and playing trial and error. I've wondered this as well about "flow testing". How is a flow bench set up? What moves the air through it? A "bladed" fan like you would expect to see in front of a car radiator or in your house? Compressed air from a tank? A squirrel-cage fan? As you stated, air flow out of an engine is PULSED. Could is be "better flow is better flow is better flow"? Sure. Could it not be? Sure. You won't know until you put your input parameters into the "black box" and see what comes out. That's testing. The scientific method. :)
At some point I want to learn how and port things on my own. Kind of along the lines of my freakish exact-factory-appearance with non-factory performance fetish :giggle: But I need to read through that article, I'm very curious to see what he has to say as well. It is a busy-looking page, probably keeps you interested with the jumping around and colors and everything lol.
google 'how to port cylinder heads' and you'll find some step by step how-to pages.. it won't make you a pro, but it'll get your foot in the door
Biggest thing is slowly accumulating some junk/cheap heads which I am doing from time to time so I can practice practice practice and if I ruin 'em...oh well :hick:
craigslist lol i come across E6/7's all the time for $50 or less
I workbench ported my 2.02/1.60's on my 355 and noticed a decent gain in power. It wasnt enough to get all giddy about. the 70 belair is a 4500 pound tank after all.. But I did notice a that I freed up some low end that the car was lacking. It felt qucker off the line went from snail to turtle in my book. I hogged out the valve bowls, made the exhaust ports a humanly large as I possibly could without taking away to much and made them as smooth as I could using what I had. I hogged out the intake ports quite a bit also. I didnt go crazy on the intake side though. I deepened the port so it was almost straight down to the valve seat with maybe less than 1/4 inch lip and left the ports semi-rough.
I noticed a big difference in how it ran ,of course tuned to my liking and timed where I wanted it. So if I can do it. Just about anyone can do it. the sad part is I didnt realize how hard to find FACTORY 2.02/1.60s are for a SBC Im really glad I didnt fudge em up. Porting is easy and its a very easy power gain if you have the air power and the know-how to do it.
I only skimmed through the article. From what I read, he is right and wrong. Too large of ports will kill low end torque. Too small of ports will kill HP. 4V Cleavland heads are not so good for quarter mile due to the huge ports. SB Chevys seem to out perform SB Ford due to larger ports. One must keep a happy medium. From what I have been told on porting, you are not supposed to remove much. Only enough to straiten the air flow. What I have been taught in school was be leary of port and polish on intake side because it will take away much needed turbulance.
Velocity is what you want. It kills me when someone suggests you need backpressure for low end trq on the exhaust side! Backpressure is very bad, the correct term would be velocity needed, which smaller ports/exhaust gives, not backpressure.Kinda unrelated,Large overlap on cams is what causes the engine to run rough at idle and low rpms because there is not enough velocity to make it flow like it should, you get reversion in the intake tract etc.As the rpms increase, velocity increases and the engine starts making power. I get into exhaust technology and stuff like this. Sorry for the sidetrack.
yes, too large of ports will kill the low end.. as for 4V heads, i wouldn't recommend them on a stock bore/compression motor.. on a 10.5:1+ motor with at least .030 taken off the cylinder walls and a considerably high lift/long duration cam, the 4V's will kick a$$ on the track.. that being said, i wouldn't want to drive said motor on the street everyday lol
I was referring to the intake side.
I agree completely. If you build the out of the bottom end and cam the sh#t out of it, you will have something totally awesome. Not recommended for daily driver.
no one wants to run race gas on the street everyday LOL.. well, price wise anyway lol i'd love to run race fuel and high boost daily, if the price wasn't through the roof :hick:
I knew that Chrome, but the same theory works on the intake side, velocity is what you want to try and create at low rpm's. I kinda get all over the place, just yakking. LOL
with cams, timing and other things of the sort, you adjust accordingly to build stronger low-end torque, while reaping the benefits of the larger ports above 2krpms
I think the loss of bottom end torque is due to loss of velocity. A port job will straiten the airflow and increase velocity. Funny thing is, this guy is basing all this on motor cycle motors. Although a motor is a motor, with such a small motor, little changes will cause a big effect. His theorys should be looked into, however, we must remember car motors and motorcycle motors have totally different behavior due to size.
Most modern sport bikes have 13-1 compression and run on pump gas. My Yamaha has almost 13/1 comp, while my MV Agusta does. If they could design car engines like that. My 5 valve Yamaha is lacking on low end, but screams mid to upper rpm.
The new Coyote 5.0 has 11.1 compression, but also has variable cam timing and runs on pump gas.
i read SOME of it while laying here, waiting for my pills to kick in.. i can kind of see where his 'adding material' would help, if put in the right place.. IF there was a way to gain the volume somewhere else.. now let me elaborate..
in most windsor heads, when the top of the intake port comes to the valve guide, it bubbles a little more than half way around the guide, then shoots (almost) straight down, probably at a 75-80* angle with little to no 'gradual transition.' it's almost like the flowing air/fuel mix ishiznitting a wall, before being pulled down past the valve.. i'm willing to bet, if there was a smooth, gradual transition there, it would improve flow.. BUT, only if you can make up for the loss of the runner volume on the bottom/side walls of the port
glad to see some nice discussion got rolling. Upon a lot of thought I think a few key points make his ideas possibly work in my head. (keep in mind he says this is all of 4v heads and he doesnt even know if it'll work on 2v heads that we base almost all our opinions and experience on)
The up and down action of the piston leaves room for gases to enter AND exit the cylinder. He refers to his porting's ability to stop this as back pressure but I call it anti-reversion, a principle proven to work on the exhaust side. How much flow is required to fill a cylinder? Ive never read a tech article or seen a formula that can accurately tell me. But the very foundation of making more power is increasing flow and this is realized at high RPM's where the piston is moving its fastest and giving the shorted time span for the cylinder to fill. Its also a point where the engine creates the least amount of vacuum on the intake. The more we raise top end power, the more vacuum we loose on the bottom as well. Right around here is starts getting kind of confusing what we're trying to accomplish exactly. Is FLOW the only thing that matters? Obviously not because top flow sacrifices almost every other bit of efficiency and efficiency translates to power.
Truthfully I figured something out a long time ago that I really hate about engine design. The way to best tune an engine for ultimate performance, is to engineer it to run at one specific RPM. You can tune the intake cross-section, length, 180 degree pulse tuning the exhaust. But it only works best at one specific rpm and fairly well in the near by range. Racing is completely dependent on trying to keep the vehicle in the right gear to utilize that specific range as much as possible. Maybe in all that rush for power, we're forgetting a few things that might be just as important. We know a huge flat torque curve is best. But its a side thought for some reason, maybe we should forget flow and concentrate on producing that perfect torque curve and design our ports to create the curve and our engine internals to raise it as a whole.
Dont get me wrong, I love a strong pull at 3k rpm, or 8k in my yamaha's case. But I'm thinking I've been chasing the wrong dragon. Trust me I've spent ENDLESS hours on a really nice engine simulator i stole online tweaking numbers and producing absolutely sick power out of nothing. I knew almost every dynamic of the 4.6 engine and could have built a far better intake manifold than any manufacturer out there because the number's dont lie. When ford redesigned the 5.0 I was astonished to find they had near cloned my parameter's for 4.6 streetable engine and came out with nearly identical power... So this is getting long, but now that i've seen the ins and outs of tuning the known, I want some CAD-type software I can do variable vacuum airflow with.
On an engine where getting air in and out quickly increases performance, I think you have to be an idiot to think restricting air will help and engine.
its not a matter of restricting, its a matter of optimization. We all know bigger is not always better. If it was we would all have 6" dual smoke stacks on our cars. Its tuning (no not like imports like to use the word) but "fine tuning" engine components. HP2G has proved to the world that improving the efficiency of EVERY part of the engine not only improves mileage dramatically but it also does wonderful things for power. Its just a shame they dont want to share their research with the rest of us.
bite your tongue! i would rather run stock exhaust.. stacks are ridiculous and stupid, i wish they were illegal.. especially with the morons with cummins diesels put a 10" stack in the center of the bed :barf: