Peripheral Port Renesis dyno's
12-27-2007, 10:58 PM
#127
Administrator
one of the previous discussions https://www.rx8club.com/series-i-engine-tuning-forum-63/na-emu-tuning-108455/
i was actually speaking about timing more than AFR the charts in this link i previously posted are helpful (albeit from apiston view point
)
http://www.daytona-sensors.com/tech_tuning.html
on the af side i believe this might have been bandied about earlier by BDC bu ti offer it now only because i found it while google researching
Jeff Hartmans book http://books.google.com/books?id=ze_...QQb93Ar6eLD67o
i was actually speaking about timing more than AFR the charts in this link i previously posted are helpful (albeit from apiston view point
)http://www.daytona-sensors.com/tech_tuning.html
on the af side i believe this might have been bandied about earlier by BDC bu ti offer it now only because i found it while google researching
Jeff Hartmans book http://books.google.com/books?id=ze_...QQb93Ar6eLD67o
12-27-2007, 11:03 PM
#128
Often proven wrong in the real world.
Just the belief that knock and peak torque goes together. Some motors are knock happy way before or after peak torque. I call it the knock zone and the only way to find that out is through trial and error. The rotary motor happens to be one of those that will always knock in a certain area of the curve even if the torque peak occurs much higher or lower. Also by moving the torque peak away form that area knock threshold increases.
Where would you say this motor would be most knock prone?
Just the belief that knock and peak torque goes together. Some motors are knock happy way before or after peak torque. I call it the knock zone and the only way to find that out is through trial and error. The rotary motor happens to be one of those that will always knock in a certain area of the curve even if the torque peak occurs much higher or lower. Also by moving the torque peak away form that area knock threshold increases.
Where would you say this motor would be most knock prone?
12-28-2007, 12:55 AM
#133
BDC Motorsports
The "cooling" effect of fuel is negligible - especially as RPMs rise.
You haven't actually done a lot of this before, have you?
B
12-28-2007, 01:03 AM
#134
BDC Motorsports
Yes you did sort of Charlie, but with all due respect, I asked a pointed question that was attempting to assert (at least in that video-linked example) the difference in burn rate and why, if I were to fire a plug later to somehow stave off knock (pre-ignition I believe is what you called it), and if burn rate had nothing to do with, why then have I and others who've done this countless times been able to change fuels to run more advance and produce considerable more power and torque, all things else remaining equal?
I know that I didn't charactise my thoughts well between the relationship on octane vs. burn rate and I appreciate Fred correcting me on it, but in my experience, atleast with the fuels I've messed with, it seems to me that the higher octane stuff I go and purchase at the speed shop (like VP Racing C16 117L race fuel or methyl alcohol) do also have slower burn rates by way of comparison between when I can fire plugs on those vs garden-variety pump gas. Perhaps it's true that in the strictest sense the term "octane" isn't inclusive of this factor but it strikes me that the two seem to coincide with one another atleast in some cases.
B
I know that I didn't charactise my thoughts well between the relationship on octane vs. burn rate and I appreciate Fred correcting me on it, but in my experience, atleast with the fuels I've messed with, it seems to me that the higher octane stuff I go and purchase at the speed shop (like VP Racing C16 117L race fuel or methyl alcohol) do also have slower burn rates by way of comparison between when I can fire plugs on those vs garden-variety pump gas. Perhaps it's true that in the strictest sense the term "octane" isn't inclusive of this factor but it strikes me that the two seem to coincide with one another atleast in some cases.
B
12-28-2007, 01:06 AM
#135
BDC Motorsports
Often proven wrong in the real world.
Just the belief that knock and peak torque goes together. Some motors are knock happy way before or after peak torque. I call it the knock zone and the only way to find that out is through trial and error. The rotary motor happens to be one of those that will always knock in a certain area of the curve even if the torque peak occurs much higher or lower. Also by moving the torque peak away form that area knock threshold increases.
Where would you say this motor would be most knock prone?
Just the belief that knock and peak torque goes together. Some motors are knock happy way before or after peak torque. I call it the knock zone and the only way to find that out is through trial and error. The rotary motor happens to be one of those that will always knock in a certain area of the curve even if the torque peak occurs much higher or lower. Also by moving the torque peak away form that area knock threshold increases.
Where would you say this motor would be most knock prone?
My guess is between 6000 and 7500rpm.
B
12-28-2007, 01:47 AM
#136
Good Lord! Have you ever done this stuff before or are you just regurgitating junk you've read (some of which you're gleefully willing to call your own)?? Of course firing spark at different points has a significant effect! If you've ever parked your rear-end in a car for a few hours on a dyno while changing spark advance tables you'd know this in a heart beat!
Oh, boy. Stare at an EGT and look at the differences between running 11:1 and 12.5:1 at the same load, same RPM when running the car hard. You'll see just how "negligible" this difference is.
Oh, boy. Stare at an EGT and look at the differences between running 11:1 and 12.5:1 at the same load, same RPM when running the car hard. You'll see just how "negligible" this difference is.
I'm not even going to address the first "paragraph" because I think you just missed the point.
I stare at EGT all day long. In fact, I just upgraded to a dual display with fast probes (so I can monitor the two ports instead of the throat), so its kind of apropos that you asked.
Changing the A/F does more than just "cool" the charge. It changes the flame front speed, so its point in the combustion cycle will be different by the time it reaches the exhaust port, which changes the temp as well.
The difference in EGTs between those A/Fs can be anywhere from "none" to 500°F or more. Its not relevant until you've established what you believe the proper EGT should be at the torque peak at MBT.
Plus, you just got done going on about how much difference ignition timing changes EGTs and now you want to talk about A/Fs without including the effective A/F shift from changes in ignition timing.
I'm not sure what your problem is (you might be a great guy and a capable tuner), but you might get a more interesting conversation going if you tried being a bit less hysterical.
I've got hours and hours of datalogs of this stuff if you are interested. Maybe you could get that under your belt and reintroduce yourself around here because as it stands now, you are just generating some really entertaining arrivals in my inbox.
12-28-2007, 08:32 AM
#137
Registered
Join Date: Dec 2007
Location: UK
Posts: 863
Likes: 0
Received 0 Likes
on
0 Posts
But you should be able to compensate for the change in flame front speed with more ignition advance while still keeping your safety margin on the ignition side the same.
And while I'm here I'll put my guess in at around the 5500rpm area.
And while I'm here I'll put my guess in at around the 5500rpm area.
Last edited by PhillipM; 12-28-2007 at 08:48 AM.
12-28-2007, 12:12 PM
#138
Administrator
Yes you did sort of Charlie, but with all due respect, I asked a pointed question that was attempting to assert (at least in that video-linked example) the difference in burn rate and why, if I were to fire a plug later to somehow stave off knock (pre-ignition I believe is what you called it), and if burn rate had nothing to do with, why then have I and others who've done this countless times been able to change fuels to run more advance and produce considerable more power and torque, all things else remaining equal?
Ignition at the wrong time can cause detontation. if you fire the plug and the fuel burns so fast that the pressure rises too quickly and cause the end gases to detonate then what was the cause? was it the octane of the gas or the flame speed? no it was the timing. the timing was innapropriate for the fuel. not the other way around. add an anit knock agent and you CAN run that timing.
as to why you can do what you did? its because of the alcohol which is the reason you chose it in the first place. the alcohol has a high resistance to knock but a fast burn rate. its resistance to knock is of its cooling attributes not in its effect on flame speed/burn rate. but its anti-knock ability is why it is used and why you can get so aggresive with the timing- but you already know that, it s why you choose to use it
page 3
http://www.epa.gov/otaq/presentation...-isaf-no55.pdf
Light load stability, meanwhile, is improved by the high compression ratio, which raises the temperature of compression and enhances the already comparatively high flame propagation velocities of alcohol fuels.
http://books.google.com/books?id=ze_...F_VBLNYbkhd0Wk
starting in the left column where he writes "Turbulence and swirl are extremely important factors in flame speed- more important,within limits, than mixture strength or exact composition" and continueing into the next column
01-13-2008, 12:53 AM
#139
I'm not sure what your problem is (you might be a great guy and a capable tuner), but you might get a more interesting conversation going if you tried being a bit less hysterical.
I've got hours and hours of datalogs of this stuff if you are interested. Maybe you could get that under your belt and reintroduce yourself around here because as it stands now, you are just generating some really entertaining arrivals in my inbox.
I've got hours and hours of datalogs of this stuff if you are interested. Maybe you could get that under your belt and reintroduce yourself around here because as it stands now, you are just generating some really entertaining arrivals in my inbox.
I hope you understand that there is a HUGE difference in ones datalogging experience vs someone who has numerious years of hands on experience with completely different applications?
01-13-2008, 01:03 AM
#140
BDC be careful! This place isn't like the rx7 forum. People have a funny way of completely DELETING threads when someone (who is supposed to be hi ranking) gets called out for not really knowing their stuff. I know this from experience as a thread I was involved in complete vanished because I proved a mod wrong. I think it's funny as hell as what some of these guys think they know. Crispeed and RG excluded.
Peace!
01-13-2008, 01:08 AM
#141
Administrator
not people and not mods. the plural is not necessary . that an individual did such a thing i can believe. but dont paint us all with that same brush. id like to know who it was though . privately
01-13-2008, 01:21 AM
#142
^ There's no need for a private discussion as I don't know who it actually was. I will say this, you were heavily involved in that thread and should know who it was....I'll leave it at that!
Last edited by T-von; 01-13-2008 at 01:23 AM.
01-13-2008, 01:24 AM
#143
I did notice one thing that was not included in this discussion that might help clear up the confusion; IMO- I relate Octane Rating to Flash point primarily.
The mixture of the fuel (Ethanol, Additives, Gasoline, etc) is actually used to determine the flame front speed (both Laminar and Turbulent) which in themselves are related. By doing the flame speed calculation based on Moles; you can see how the small molecular weight changes impact the Brisance.
As for determining knock; the math exists to forecast knock - the biggest problem is that we lack the sensor values required by the model.
An example (from my explosives work) we measure TNT in two areas; Stability and Sensitivity. Civilian grade TNT and military both have the same Brisance rating (or an RE of 1); but military grade is less sensitive and more stable due to additives - so it can take some heat, being dropped etc... what it requires is a higher INITIAL energy input to begin the chemical transformation.
The mixture of the fuel (Ethanol, Additives, Gasoline, etc) is actually used to determine the flame front speed (both Laminar and Turbulent) which in themselves are related. By doing the flame speed calculation based on Moles; you can see how the small molecular weight changes impact the Brisance.
As for determining knock; the math exists to forecast knock - the biggest problem is that we lack the sensor values required by the model.
An example (from my explosives work) we measure TNT in two areas; Stability and Sensitivity. Civilian grade TNT and military both have the same Brisance rating (or an RE of 1); but military grade is less sensitive and more stable due to additives - so it can take some heat, being dropped etc... what it requires is a higher INITIAL energy input to begin the chemical transformation.
Last edited by Kane; 01-13-2008 at 01:39 AM.
01-13-2008, 02:15 AM
#144
I just figured he might want to look at the numbers since actually being at a past tuning session is not possible.
Amen to that. Its like a bunch of teenagers with a bottle of Thunderbird over there.
I'm quite sure that your idea of "proved" might need some tweaking.
Last edited by MazdaManiac; 01-13-2008 at 02:21 AM.
01-13-2008, 03:44 PM
#147
Well the load is off my back! Here is a thread that goes off topic more then mine. I'm happy to join as a spectator only, I will not get involved. Just happy it is here.
Mods do not remove it, please.
But I might add that the only avitar that is showing up today belongs to Zoom44.
Veeerrrryyy interesting.
Mods do not remove it, please.
But I might add that the only avitar that is showing up today belongs to Zoom44.
Veeerrrryyy interesting.
