sniperstevedave

I ran across the tech section of the yawpower website. They describe, and show, how tiny changes in port shape can increase or decrease flow and the only way to tell is flowtesting. It is a wake up call for those of us considering doing our own porting or those who think flowtesting is a waste of time. I was considering doing some porting, but I think I will wait until I have had some CFD classes.

Check it out at http://www.yawpower.com/Flow%20Testing.html

sniperstevedave

They also have an article explaining, in great detail, how and why engine torque is completely irrelevant to acceleration.

Now I can provide a link to all those poor fools doing a V8 swap who say "but it has more torque" without having to go to the trouble of explaining why they are complete morons.

http://www.yawpower.com/tqvshp.html

jgrewe

iTrader: (1)

Its all good info on Paul's site. Some think its a bunch of crap about flow testing. In general if you gather all the info you can before you start grinding and use known good port templates, like Racing Beat, you will have good results. You may not win a championship with the engine but you will get more power.
I'm with Paul on the flow testing, but I have a Superflow 110 at my shop from piston engine days. There is a lot that you can check with a flow bench but there is a lot that goes on in a rotary that is hard to recreate in test situations.
The engine gets pumped by air just like any other engine so knowing the flow has to help.

Kyrasis6

Havn't read the flowbench article yet but his article on hp and torque is so rediculously over detailed and exampled that most people forget the point he is trying to make and loose interest in the article before they get half way through it.

sniperstevedave

I wonder if they could use a ME intern/co-op at some point?

I get tired of seeing people post about how doing such and such will make more power but they don't have any reliable test data, or worse they try to do testing but have multiple variables unconstrained at once. I am glad somebody rigged a flowbench for a rotary. Some of the trial and error process could be sped up with computer modeling I bet.

And the article on torque vs horsepower may be long, but you can't argue they did a thorough job. Fortunately the math is really simple, so anybody can follow it.

Kyrasis6

I think the flowbench article was pretty good for the most part there are some important things I think he is missing though.

He did not specify at how many inches of water the flow was, for instance 260 cfm at 14" of water is totally different from 260 cfm @ 28" of water. If anybody wanted to build off of the information he gave they would have to know that or there would be one of those unconstrained variables.

The only mention to velocity made was on port matching the 12A intake manifold, he gave no supportive information on his claims nore did he make any comments on how opening the exhaust port could potentially kill the velocity of gas flowing through it and negate any benefits from added flow.

Considering the much more complex shapes and angles of the intake ports I believe he could have made his article much more convincing but incluidng some intake flow data.

Sideways7

iTrader: (7)

I think you give some people way too much credit. I know people that see anything related to math (even a + sign) and have a panic attack.
The torque/hp article is very good. Its all stuff I already knew but just never quite thought of in that manner.
That said, a V-8 will definately feel (and be) faster in regular street driving since it will have more hp at the lower rpms used in normal driving. The principles applied in that article mainly apply to a race car where it is running at its peak operating speed for a majority of the time. For a car with low end power it is much closer to its peak power under normal operating conditions than a car with high-end power like a rotary.
But after all that, it still means that a rotary will be every bit as fast on the track as a v-8 powered car of the same power.

jgrewe

iTrader: (1)

As much info as he gives on his sight he should be allowed to keep some info for people to pay him for it. I would say the support for his statements would be the success of his products and services. If I was trying to make a living doing this stuff and I found a cool little trick that worked wonders you can bet you aregoing to pay me to learn that trick.

I can look at his pictures and tell why he chose a certain angle for the shot in some cases, this web site is to build a business not to give info away.

sniperstevedave

Kyrasis6: He wasn't trying to provide hard data here, just show that seemingly insignificant changes can have big effects, and not necessarily in the way you would expect. Which he accomplished. Since he wasn't trying to provide hard data, he didn't need to specify the number of moles of gas, which means the atmospheric pressure is irrelevant.

Sideways 7: Everything you said about v8s is true, but I guess I am missing the point. Anyway I find it hard to compare piston engines and rotaries. The thermodynamics are the same, but all the mechanics are different.

RotaryEvolution

iTrader: (30)

yep, he's trying to build a business by stabbing other builders.

"Do you want your engine builder to be measuring, or guessing?"

i will elaborate:


yes he did gain 16% airflow, if that is really in relation to HP figures after tuning i seriously doubt it is directly related, maybe only a portion of that percentage will be in actual power numbers. the other point i want to mention is it is very time consuming bench flow testing every time, he would have to be charging out the *** for that increase in flow so if $1000+ for a 16% increase in air flow is worth it to you, well then more power to those people, for most people that is a pipe dream. this is more of a pure performance mod and most people won't have access to tools such as this.

simply copying the shape of the port he has will not yield the same results unless everything is proportionally exact so beware to the plaguerists out there.

sniperstevedave

I still would want my builder to measure, because its what I would do. Well, I would do modeling first, then make several checks as I progressed to make sure the model is valid.

And flowrate is not the same as HP. But it is directly related (porportional). And for a racing team, 16% flow increase for $1000 is a steal. And they only work on race motors.

RETed

It's a fricken waste of time.
Rob Golden of Pineapple Racing basically summarizes this on his website.


-Ted

jgrewe

iTrader: (1)

Every business needs a 'Hook'! There might be guys that get more power, or power over a wide range or whatever. I've been around rotary cars road racing that were built by a couple guys scratching their heads in a barn that pulled $10,000 engined cars down the straights at Mid Ohio. Total engine cost less than $1000.
You can get power guessing or from experimenting for a long time. Does that 16% increase in flow result in power someone else hasn't found? Who knows. Does Paul provide good service and strong engines? From what I hear, yes.

I know guys that will sell their souls for 5 hp in racing classes that are tightly controlled. On the street you won't miss it, in racing you don't care what it costs.

RETed

Reference link:
http://www.pineappleracing.com/TechLinks.html


-Ted

J-Rat

iTrader: (2)

I dunno.. My motor was flow tested at Paul's shop and I am pretty happy....

RotaryEvolution

iTrader: (30)

i was going to basically say the same but then people who take bench numbers for a set in stone performance figure would disregard it anyways.

jgrewe

iTrader: (1)

One of these days I'm going to build a special apperatus with a rotor and a housing to simulate operational characteristics just because I'm curious. Of course the ports feed AT each other so I'll need both plates.... Damn, I'll do it after I finish my perpetual motion machine.. Or when I can't improve my driving anymore!

sniperstevedave

Yeah, I've seen that before, RETed. It's pretty obvious you didn't bother to read the article, because they explain they have a custom built setup, with different adaptors for different applications. Again, for a racing team $100 per HP is a steal, and yawpower only works on racing engines.

I've read enough of RETed's posts to know that one should ignore him if he is talking about anything related to engineering.

RETed

Ah, interesting, that explains your derogatory tone...

Just to satisfy anyone who gives a crap...

The dynamics of the (2 rotor) rotary engine has a lot more than to do with the intake ports on the side / middle irons.
There's a reason why Mazda design the intake manifolds (on the non-turbo engines) with the Dynamic Effect in mind.
The pulsing between the rotors has a big effect on the intake system.
There is reversion in the intake system that most people don't think of (do you flowbench the ports in reverse too?).

Also, a big difference between rotary and piston engines is the dynamics of the combustion chamber.
The piston engine combustion chamber is pretty much static.
Compared to the rotary engine combustion chamber, the rotary engine is dynamic and constantly moving and changing (in dimensions).

Sure, flow matching the intake ports has gains, but *I* think it's a waste of time and money.
With a turbo motor, run more boost will make more power, period.
Unless we're talking about spec racing, where you cannot touch anything else in the engine, most people are wasting their money...IMNSHO.

So get the facts right - I didn't say it didn't work; I said it's a waste of time...IMNSHO.

But don't worry, I'm just talking **** out my ***.


-Ted

sniperstevedave

For everybody else, I would recommend reading the article, then reading RETed's post. I am not sure what he means by 'flow matching the intake ports has gains', but yawpower claims
"1. Port matching the intermediate runners on a stock 12A intake manifold. This absolutely ruins the flow. Additionally, the velocity is reduced, and so both high, and low rpm power is reduced
"

My appologies to RETed, I could have phrased things more politely. I read his posts on the archived thread about pulsation dampener remover and got disgusted. I guess some of that carried over.

rotarygod

iTrader: (1)

Nevermind.