I wish I had not lost my dyno sheet. My ported #'s look similar to yours, except my high point in HP peaked at 8.2k rpm.
Your porting looks real good btw.

 

It seems to me that if we were to begin comparing mass airflow numbers across the RPM range from one ported engine to the next, we would not need to speculate so much on what the FWHP or RWHP figures are from.

 

Even more so, you wouldn't need to pay for or take the time to go to a dyno. as you could flow bench every change, between the AEM intake, and the "heavy intake mods" and the cat replacement pipe and the "heavy exhaust mods" so on and so forth... and from a mild port job to an aggressive port job to, Bridgeporting. my First rx-8 ships to me in 3 days time. it will be my 12th rotary. can't wait. i'll be sure to post up my findings on the same subjects.

Nice work so far brian, now weres those AIR FLOW NUMBERS??

 

For those without an airflow bench, we have the Cobb AccessPort and the MAF sensor readings, which are already temperature and baro-corrected.

 

Please explain to me how having just air flow numbers accurately equates to measured power output (chassis or engine). I didn't know that was possible and love to learn new stuff

Eric

 

I want to answer, but I feel like I might get slapped because I only know the theory behind it, and can't explain it to the tip.

The theory, I believe, is simply more air = more power, and given the environment of WOT, you know how much power you are making by how much air you are flowing at any 1 point in time / RPM.

With a calculation to get from one to the other of course.

And I imagine that the calculation would differ from engine type to engine type due to thermal and mechanical efficiency differences, but it should be the same calculation for each engine/drivetrain setup.


Edit: It also assumes that the MAF sensor is calibrated the same. A calibration difference of the MAF would be no different than a dyno calibration difference in terms of skewing the power calculation

 

Who has made that inference, here? The primary effect of porting is supposed to enhance the quality of airflow, is it not? Whether that results in preferred torque development is dependent on many other factors. To make a direct corollary between porting and power increases ignores many other potential variables.

 

Unless the potential variables are not actually variables---correct?

 

you know all those kids with honda's that put a cone airfilter right before the intake and think they're making more power.. variables.

More hot Air is not better then less cool air. but the Hotwire MAF negate the need for such calulations. as they're reading the density of the air also.
Varibles.

Now when it comes to porting.....

you'll have to understand TDC, BDC , and all the befores and afters of them.

If you're intake opens before the exhaust closes you have overlap. bad for low rpms. if it closes to far late you loose the amount of time"duration" air has a chance to flow into your engine.

If you're intake closes to soon, you suffer in the amount of time"duration" air has a chance to flow into your engine also. IF your intake closes to late .. the rotors will actually begin to compress the air and send some of it back into the intake. that results in lower RPM Hp and TQ, but at higher rpm's the Air Velocity forces the air in against the compression of the rotor. Still with me? Variables.

For exhaust ports, opening too early results in some of the power "stroke" being lost into the exhaust. too late and it doesnt all have a chance to get out.

Closing to soon of the exhaust has the same effect opening late.
And closing too late can cause the same overlap that opening the intake.

porting is a fine balance between maximizing Duration of flow, and not having overlap/loosing your power stroke or getting.. "intake charge reverstion"

Soo did i miss something? or is any part of this incorrect?

 

What kind of differences were there in the intake and exhaust...that will give us a better idea of what the porting has potentially done for power

Would have been great to see the same intake/exhaust on the stock motor to compare

 

I can make my MAF read almost anything that I want....so nothing ideally

I have seen a supercharged RX-8 on here dyno high 200's and flow close to 500g/s....that kinda blows this theory all to hell ( even though there seems that that supercharger had huge boost leak issues at the time

 

LastPhase:

I don't think that was the reference here. I'm pretty sure Eric is familiar with those variables and factors of porting.

I think the variables vs non-variables is when you take a dyno of the engine at the wheels. A short list of variables that can come into play are:
- Environmental
- Engine variances
- Sensor variances
- Intake modifications
- Exhaust modifications
- Powertrain losses
etc...

Just within the engine itself, there is seal tolerances, porting, ignition strength, ignition stability, rotor balance, rotor weight, and probably several others that I am unfamiliar with.

I think those are the variables Ray was referring to.

But, in the case of Eric, having a race car with a race team and development time, those variables can actually be made to be non-variables due to consistent pre-dyno setup and minimizing or eliminating changes to the car between dyno runs, narrowing the possible reasons for the change in output to what has actually changed.

For example, taking the car, putting a new engine in it with measured seal tolderances, dynoing it, pulling the engine, verifying seal tolerances, porting that same engine, re-measuring tolerances to be sure they are the same, re-installing the engine in the same car, an re-dynoing.

Any variance should, repeat should, be a result of the porting work. A tall order, but removing those variables is possible.

And I think that is what Eric was referring to.

Dannobre:
I don't think that it eliminates the theory any more than a malfunctioning dyno would support proof of Jedi's car putting out 1,000hp. Vacuum leaks cause all sorts of havok with the readings. If all of that is under control, then the theory holds. For X fuel and x*13.1 air you will get Y energy. Since we know the thermal and mechanical efficiency of the engine, we should be able to get VERY close to the actual power being produced.

 

This is getting too technical for me. I am going to grab a hammer, hit something and make grunting sounds. I think I should grab a beer too.

 

This situation can be handled by using the same MAF for both setups. Even if it displayed some serious out of range value you could easily observe the difference between the two and obtain your data.

This is the same reason why it's important to perform all your accurate dyno measurements from the same dyno as the variances between the devices could be enough to show gains where none actually exist.

I was just hoping some MAF figures had been grabbed because I have yet to see any ported RENESIS motor display this data.

 

You and me both... minus the beer...

 

Ditto... I just want to see more data, as its quite an acomplishment.

 

If you are talking about the same car same engine/intake/maf calibration/intake air temp/engine temp/humidity/air pressure etc then yes , any differences you see in mass airflow should translate into a relative difference in hp .

In reality , although there are many variables as you say , most of them make such minor differences that (so long as you are aware of and control the variables to some extent) you can actually get a rough idea of your gains just from g\s comparisons.

Although if we are only talking a couple of hp then .......................................no

 

I did not really think my point was all that complicated. Once a MAF sensor is properly calibrated to the housing in which it is used it need not be recalibrated when a given engine's airflow is changed. The range in which the Mitsubishi MAF ranges out is well out of reach for any N/A Renesis. Control point #1, N/A only.

How about this proposal; anyone who wishes to proclaim their particular porting to be beneficial, superior, or even preferred versus other offerings should build an engine to whatever internal specs they wish. Then measure the total engine airflow at WOT from 1K-redline. Control point #2.

Disassemble the engine and keep all the seals in the same order for reassembly after whatever porting work is done. Reassemble the engine with ALL the same components that are able to be reused while using whatever new gaskets, o-rings, etc., are needed. Control point #3.

Compare the airflow data across the same RPM range at WOT and see what the results are, devoid of power concerns.

This same person could even measure the airflow and torque, simultaneously, and glean some pretty decent information for themselves and might create some nice conversation fodder.

Better yet, this requires no fancy equipment nor complicated process.

Just sayin'.

 

's how we built our car

 

How many variables have you been able to successfully eliminate during your research and development? Mother Nature changes hers every moment. Human frailty makes matters even worse.

 

This would be a purposeful skewing of the process and data gathered.

 

Brian is this on any type of tune or just the latest flash from mazda?

Also do you have an afr readout and of course the requested g/s readings?

Oh last question I am assuming you cut your own side seals versus using the pre-cut ones.

It would be awesome to see these figures, this thread seems to be getting out of control and I think these 3 answers would help quiet the masses.

Thanks man!

 

There is nothing out of control, at all, in this thread. Brian asked for the input and he is getting it. At the very least, we are discussing the idea of setting standards for the next round of Renesis inspection and the process for obtaining data that matters.

Isn't that what we rotary geeks are most interested in? I don't have a foregone conclusion here. I am just wondering who sees things as I do when it comes to airflow and I am waiting for MM to chime in and tell me I don't know WTF I am talking about.

 

the way I understand it, increased flow allows for the potential for more power. Nothing more , nothing less. Aiflow in itself cannot predict what power will be made.
But, the dyno plot he has provided as shown that some of that potential has already been taken advantage off.
This is cool stuff and if this engine can get to the point that 250hp to the wheels can be obtained on pump gas with a street driveable car--it will be a significant milestone.
Perhaps this could even make a low boost FI application more attractive to some.
5 psi of boost with these ports could put out 300 rwhp?
Now that is very liveable.

 

Possibly. Depends on what the blower/turbo compressor is producing the pressure in the first place.