shinjuku

inertial ramming and pressure wave tuning with turbo?

does it still work the same as a n/a engine?

or does the turbo change the rules?

what about the intake?
cheers

RICE RACING

series 5 turbo intake manifold has one of the best examples of this philosophy.

It does work realy well.

RICE RACING

I use this theory on my exhaust manifold, I went to great length to make a proper tunned length divided exhaust manifold to take full advantage of this principle.

My manifold runner length is 12 to 13 inches from block to turbine entry.

shinjuku

Interesting RICE RACING.

does the ser4 intake not do this?

any chance you will divulge formulas/working priciples etc.....or even suggest some further reading?

cheers

RICE RACING

series 4 and series 6 do it.

Best book although very old is called "Scientific design of intake and exhaust systems"

I am sorry that I do not have more details, I do not have this text anymore as I leant it to some mother ****** and they did not return it !

Though I learnt what I needed I suppose, lucky I got a good memory

shinjuku

Ok do ya know who the author was?

with the exhaust would you just tune for inertial ramming or for the pressure waves as well? or does the turbo prevent the waves from working?

RICE RACING

waves, for scavenging.

shinjuku

can you give a rough guestimate as to the extra power and responsiveness to expect when done right?

crispeed

Port configuration and desired rpm use are also affected greatly by intake manifold ram tuning!
I've personaly found the stock turbo intake manifold designs to be affective with stock and midly ported motors. Power bands are normally in the 4.5K to 7.5K rpm range. When you start getting into heavily ported motors both intake and manifold tuning play an important role. I've seen BP motors actually make less peak power than SP motors with the same combination!
I had a SP TII motor that made aroud 450RWHP with the stock intake manifold on it. The power peaked right around 7.5K rpm and dropped off after 8K rpm!
Just by adjusting intake manifold length and plenum design the same motor now had a flat power band between 7K rpm and 9.2k rpm and power never varied more than 10RWHP plus or minus in that region too.
There's no written design(except stock) proven to work best!
Everyone got a different setup. It takes alot of R&D to figure out the right combination for a particular setup!

crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed

87GTR

iTrader: (61)

this is why the 4 rotor na has veriable intake runners so it could provide the lenght for the right rpm to give max power and torqe

crispeed

So do the RX-8!

crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed

Anthony Rodrigues

Maintaining the same lengths, but altering the diameters and reduction points I have found it possible to maintain the same peak power levels with varied ranges at up to 4psi less boost. Other factors we found were porting, injector location and plenum volumes/designs on determining ramming and pressure wave tuning. The RX4 that is currently shown on full boost has a std ser4 inlet and we hope to use it for some testing of inlet designs.
Regards-Anthony

shinjuku

what do you mean by reduction points Anthony?

cheers
Andrew

Anthony Rodrigues

Creating a continuous reduction has helped increase air speeds and as bends in the intake cause restrictions, stepping of runner diameters have helped me overcome these restrictions. I have been able to achieve a pressure difference of less than 1lb from throttle body to intake runner. As my manifolds are for personal R&D and I cant weld for **** I use mandrel sections and funnels, you can alter the point at which you reduce the runner size by the pipe lengths you use.
The principle behind what I was hoping to achieve on a turbo engine was to reduce the load requirements on the turbosystem to reduce both heat and backpressure. I am still developing a few things before I have them cast and make them commercially available. I need to be sure that the hp and torque bands created will still be suited to non race type applications. So far, So good.
Regards-Anthony

Anthony Rodrigues

We must always remember that there are more functions of Air MASS than pressure alone. If we work on other areas that dont have mechanical sideeffects we can then more appropriately improve efficiency. I hope you get where I'm coming from. There is so many things connected to the one part of the combination that it could take forever to fully understand. I dont otherwise I would already be finished.
Regards-Anthony......Sorry about answer length Andrew!

shinjuku

Very interesting Anthony.
Ur second post lost me though

cheers

relvinnian

Very Anthony.

We are in dire need of an aftermarket intake. I'm sick of seeing domestic V8s get all the cool stuff

setzep

What about the 90-95 cosmo intake manifold? It has a volume chamber right after the TB while the FD manifold doesn't. Whats the advantages/ disadvantages of the two?

waynespeed

"The intake system on a four-stroke car engine has one main goal, to get as much air-fuel mixture into the cylinder as possible. One way to help the intake is by tuning the lengths of the pipes.
When the intake valve is open on the engine, air is being sucked into the engine, so the air in the intake runner is moving rapidly toward the cylinder. When the intake valve closes suddenly, this air slams to a stop and stacks up on itself, forming an area of high pressure. This high-pressure wave makes its way up the intake runner away from the cylinder. When it reaches the end of the intake runner, where the runner connects to the intake manifold, the pressure wave bounces back down the intake runner.

If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.

The problem with this technique is that it only provides a benefit in a fairly narrow speed range. The pressure wave travels at the speed of sound (which depends on the density of the air) down the intake runner. The speed will vary a little bit depending on the temperature of the air and the speed it is moving, but a good guess for the speed of sound would be 1,300 feet per second (fps). Let's try to get an idea how long the intake runner would have to be to take advantage of this effect.

Let's say the engine is running at 5,000 rpm. The intake valve opens once every two revolutions (720 degrees), but let's say they stay open for 250 degrees. That means that there are 470 degrees between when the intake valve closes and when it opens again. At 5,000 rpm it will take the engine 0.012 seconds to turn one revolution, and 470 degrees is about 1.31 revolutions, so it takes 0.0156 seconds between when the valve closes and when it opens again. At 1,300 fps multiplied by 0.0156 seconds, the pressure wave would travel about 20 feet. But, since must go up the intake runner and then come back, the intake runner would only have to be half this length or about 10 feet.

Two things become apparent after doing this calculation:

The tuning of the intake runner will only have an effect in a fairly narrow RPM range. If we redo the calculation at 3,000 rpm, the length calculated would be completely different.
Ten feet is too long. You can't fit pipes that long under the hood of a car very easily.
There is not too much that can be done about the first problem. A tuned intake has its main benefit in a very narrow speed range. But there is a way to shorten the intake runners and still get some benefit from the pressure wave. If we shorten the intake runner length by a factor of four, making it 2.5 feet, the pressure wave will travel up and down the pipe four times before the intake valve opens again. But it still arrives at the valve at the right time.

There are a lot of intricacies and tricks to intake systems. For instance, it is beneficial to have the intake air moving as fast as possible into the cylinders. This increases the turbulence and mixes the fuel with the air better. One way to increase the air velocity is to use a smaller diameter intake runner. Since roughly the same volume of air enters the cylinder each cycle, if you pump that air through a smaller diameter pipe it will have to go faster.

The downside to using smaller diameter intake runners is that at high engine speeds when lots of air is going through the pipes, the restriction from the smaller diameter may inhibit airflow. So for the large airflows at higher speeds it is better to have large diameter pipes. Some carmakers attempt to get the best of both worlds by using dual intake runners for each cylinder -- one with a small diameter and one with a large diameter. They use a butterfly valve to close off the large diameter runner at lower engine speeds where the narrow runner can help performance. Then the valve opens up at higher engine speeds to reduce the intake restriction, increasing the top end power output. "


http://www.howstuffworks.com/question517.htm

Anthony Rodrigues

Shinjuku,
It was getting late, I think I confused myself. In basic terms what I meant was that you can make more power by winding up the boost. However there are other ways of getting more air and fuel into an engine without more pressure(boost). Most of the time these are alot safer methods but can be very hard to properly understand. While some members here truly understand the maths behind these, I try to use my limited knowledge of physics to the planning and then base my conclusions on the results that I find. This method might not be technically correct, but it is the only one that I know. I think Waynespeed is better at these explainations than me. Hope I havent made it worse!
Anthony

cach22

Anthony - So basically you are running a larger diameter pipe for the bend to increase airflow (remove restriction), and you rely on the funnel to reduce the diameter back down, which speeds up the velocity that was lost through the bend due to the bends larger diameter? It makes sence, have you had a chance to play around with it on a flow bench? If not i reckon it could be of benefit

Also whats your opinion on the 13b JC cosmo manifold, do you think it can be improved apon?

cheers

RETed

You guys are asking a question that takes MILLIONS of dollars to research & development for most automotive engineers.&nbsp I'm surprised people have tried to answer this question. If I knew the answer, I wouldn't tell anyone.


-Ted

Bigus Dickus

Being mostly ignorant on the finer points of tuned port and turbomachinery principals (oh, I understand the basic physics, equations, and applications, but you know what I mean), my guess would be that tuned port is not as important on a turbo motor.

Why do I think that? Well, tuned port helps to increase VE, albeit in a narrow rpm band. Since a turbo's job is to increase VE, then it would seem all you have to do is turn the boost up a few percent to make up for a less than ideal intake runner.

In other words, why bother tuning the intake to get a little more air in the chamber, when you can simply dial up boost slightly to achieve the same result but over a wider rpm range?

In fact, it would seem like on a turbo motor, you can overcome bad heads as well, to a point. So what if they don't flow that well... that's at atmospheric pressure. Just give a bit more boost, increase air density, and you can get the desired mass of air with a poor flowing head. Probably not the most elegant way to skin the cat though.

Just my ignorant rambling...

Bigus Dickus

Oops, didn't mean to say bad heads. I'm sure you all knew I meant porting...

Anthony Rodrigues

cach22,
I used a flow bench to design the runners and test that they will be equal in flow. That was a nightmare! Once I had them reasonablly equal I then designed the plenum and TB to maintain this. Unfortunately, the more I learn the more I realise how much more there is to know.
Bigus Dickus,
When you get to the point that more boost is not appealing, because of heat, turbo sizing, back pressures, etc you need to look in other areas. That is why I bothered. We do an Rx4 that at the same boost, with the same turbo, we picked up nearly 100rwhp. It all had to do with more efficient airflow.
Anthonyv