I was looking at some of the some of the test data on the site in your sig. I noticed a common dip around the 5K range for almost everyone. Is the a product of the intake runner lengths? I know from tuned ports on the early Chevies, runner lengtht was a compromize. Since I'm real particular about that range, has any one addressed it?

 

Motordyne Engineering.... the company is Motordyne Engineering.

 

Which plot are you referring to? There are many.

 

This one.

 

It's a characteristic of the stock engine.

It's there no matter what upper plenum mod you do (or don't) use, so its probably due to the stock ECU making changes to the cam map or spark timing map.

It could probably be pushed up a little with a tune.

 

@ the dumbass OP

ever hear of PM? that way you wouldn't have to look this dumb to everyone

 

OTOH, I don't mind admitting that I learned something from the reply to the OP's question. Not all of us can be as brilliant, informed, and humble as you are.

 

You seriously learned something? Lol

 

Yep, I've heard of a PM, but I'm not looking for a personal answer. See I've built and modified engines on cars and bike since I was 13, this week I turned 51, you do the math. Hydrazine seems to know what he talking about so I asked about the runner length.

Runner length can effect the performace curve in many ways and if you understood that you might have followed along. When the intake valve closes, what happens to the mass of air that was flowing in, does it just stop? NO, it hits the intake valve and bounces back and heads its way back up the runner. As it does this, it creates a low area of pressure behind it. So after it gets a certian distance back up the runner, it'll tend to turn itself around and go back towards the intake valve. We'll call these, harmonics for the sake of explaining.

Car manufactures realized this many, many years ago and started putting this to use. I want to say the third harmonic is the one they shoot for. So when the pulse is returning on the third bounce, if they can open the intake valve, they can capture the pressure and movement of the charge to increase the volume of the intake charge. So any mods to the intake length will effect the way these pulses act and the timing at which they return.

Before you try and wiggle out and say just another old man that doesn't know how to use the computer, it might help you to understand that I've been programming computers since the 70's, back when a 1K hard drive was as big as a trash can. I had a 286 12mhz machine controling dedicated functions of my house back in the 80's. Built the interface using the parallel port and talked to it using fortran.

I do process controls for a living, 35 years worth. Every thing from a small food processing plant to 500 Mega Watt utility boilers and everything inbetween. I'm currently in two plants, one which is the largest of it's type in the world. At last count, we had over 40 thousand tagnames and over 16 thousand wired devices in the field. I've been involved in every aspect of the design/commisioning and start-up of the both plants.

So that little ECU in your car, my work is tuning these, but the scale of my ECU takes up whole buildings and that doesn't even get near all the other interfaces we have to build to make the system work. Your one dash, we have thousands of windows, enough so that we have a dedicated building for operators to sit in and watch screens all day long.

So yeah, my question might have seemed dumb to you, but understand, my simple little mind can't comprehend as well as yours. Maybe, just maybe, some day I'll be as wise as you.

 

in for Fluids1 response...

 

I'm picking his brain. If you read my other post in this thread about harmonics, it would appear to me that the intake pulse is out of time with the intake runner. Notice that all the motors did the same thing at around 5700 rpm. The power took a dip and didn't return until around 5900. And if you look at the way the curves slope, the intake pulse didn't just snap back, it slowly came back in line. Draw a line from the first peak straight across and visualize the pulse being out of time.

Picture the pulse hitting the valve while its still closed. This is right after the peak. The timing gets a little worse as we go, that is the pulse arrives sooner and sooner before the intake valve opens, so it has actually bounced off the valve and moved further back up the runner. Then we hit this spot on the curve where the intake pulse is further down the runner and has begun to make it's turn around, but it's way up the runner so the natural charge we were using before is coming back to us, but it's not close enough to the valve to make good use of.

Engine speed and air speed are going to effect how this all works. The setup maybe for using the forth harmonic at lower engine speeds and then moving towards the third at higher speeds.

Valve timing can help to control some of this and since the introduction of variable valve timing, I'm scratching the dirt to see if any one is playing with the two together, valve timing and runner design.

 

LOL..........Fluid1, you just got pawned. OP, don't mind some of the *** hats on this forum. I applaud your intelligent response without any sort of personal insults.

 

HAHAHAHAH! Awesome.

 

 

lawl

 

This thread is evidence that we could have some extremely intelligent, and contributing members on this board if it weren't' for f@ckheads running them off at the first chance. I'm sure many have left in the past who did not have the patience to put up with such inconsiderate adolescence.

 

if thats the case im sure they are smart enough to know this is a forum and no hard feelings. If not then they need to leave

 

Your right, this is a forum, a car forum. Most places I've posted on try and keep the childish remarks down. For some reason the remarks flurish here. The way I look at it, if you have nothing to contribute to a post in an adult type manner, then why say anything other than to try and make your internet tough guy personality look good.

On this board, I see more insults than I do contributions. There's an opportunity to build a good forum, but the childish ways do run people off. Then you say fine for them and what you have left is a forum full of children spouting off back and forth at each other. Hardly what I would call a forum to exchange ideas and learn more about the car we all seem to have an interest in.

The way I look at it Abe Lincoln said it best. "Better to remain silent and be thought a fool than to speak out and remove all doubt."

 

@ the pwnage. Dryseals, sorry to ruin your fun, but he was banned last night prior to your response. It'll be a while until he can see your post.

 

dryseals, great response! It looks like you have done your homework on this. Fluid1 always seems to have great advice for everyone on here.....