Semi pp throttle body. - RX7Club.com - Mazda RX7 Forum

Race Techniques Talk about your Road Race, Time Trial, Autocross, Rally and Drag techniques in here

Semi pp throttle body.

Reply

 
 
 
Old 07-13-18, 02:26 AM
  #1  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
Semi pp throttle body.




So I have been having this problem with vacuum drop. With Webers ida it was at least bearable, but now I switched to ecu and it's just "pain in the ***" wouldn't idle between 1500 -2000. It's like a race car, I mean it is but on street. So I had this vision for a while, and decided to get at it and got that far.

Last edited by -CON-; 07-13-18 at 02:29 AM.
-CON- is offline  
Reply With Quote
Old 07-13-18, 11:34 AM
  #2  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 6,896
Thanked 113 Times in 101 Posts
Unfortunately, that is the exact wrong way to address the problem.

The peripheral port overlap draw in exhaust gas while the throttle plates are closed as the increasing intake chamber volume creates vacuum and sucks the exhaust around the apex seal as it crosses the peripheral intake port because there is less restriction to the vacuum there than the closed throttle plate.

By closing off the intake of the peripheral port with the throttle plate you increase the restriction on the intake side at the most critical area and so will increase the amount of exhaust pulled across the apex seal as it crosses the peripheral intake port.

The correct way to minimize the affects of peripheral intake port is to run the peripheral intake port as the primary port. This maximizes the amount of airflow through the peripheral intake port so there is less restriction to the engine vacuum and it sucks in more air than exhaust.

OEM manufacturers that used peripheral intake ports had some tricks to do this.
They used a tiny primary peripheral intake port and dedicated carburetor idle circuit at the top of the main big peripheral intake port to maximize intake velocity at low rpm.
They shut down ignition on 1 rotor of the 2 rotor engine so that the other rotor would have more drag and the throttle could be opened more to maximize intake velocity at low rpm without the idle rpm climbing out of control.
BLUE TII is offline  
Reply With Quote
Old 07-13-18, 02:09 PM
  #3  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
theoretically sounds right. but prior to this what I did was, I made thin aluminum gasket that went in between the engine and manifold with other ports open and the p-port closed and I drove it like that for a bit. It did start easier, idle lower, and it had a bit more torque on the lower end. So I dunno. In diesel engines they have an egr valve that recycles the exhaust gas on under no load or I don't know what other criteria. So exhaust gas in the charge is not a bad thing where you don't strive for power. Anyway the fact seeming to be that there is vacuum increase with p-port closed. Also I want to mention this that the exhaust design influence the engine with a p-port by a lot. When I was experimenting with the exhaust, the high flowing exhaust actually draws the intake mixture trough the p-port and out into the exhaust and burns inside or doesn't and stinks, my design was actually blowing flames at idle. I will try to post video of it. But that was of coarse with a Weber.

Please excuses me moderator, I think I posted this thread in the wrong section, i meant in the tech section. )) if would be possible please move it. Thanks.

Last edited by -CON-; 07-13-18 at 03:13 PM.
-CON- is offline  
Reply With Quote
Old 07-14-18, 03:26 AM
  #4  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 6,896
Thanked 113 Times in 101 Posts
Ah, you are right.
There will be the improvements you noted from blocking off any of the intake ports as the reduction in port volume will increase intake velocity through the remaining ports.

This is why the Mazda blocks off the 2ndary ports stock so all the intake goes through the primary ports at low rpm.

It is harder to test, but I propose the motor would run smoothest with the most torque having all the side ports blocked off and just the peripheral port open at low rpm.
BLUE TII is offline  
Reply With Quote
Old 07-29-18, 01:21 AM
  #5  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
Ok, I had some chance to play around with this. So here are the difference between the two. According to the boost and vacuum gauge at idle it was showing around 10 in Hg. and idle speed was around at 1500-2000rpm, rough and hot.

​​​​​​With p-port closed idle speed was around at 1000-1150rpm smoother, the gauge was showing around 15 in Hg. In vacuum.

I had a vacuum actuator that was controlling the p-ports. Basically if the vacuum is on it would shut the p-port close and if the vacuum dropped at WOT it would open them up. Worked nice until I twisted the pin of the actuator and ripped the actuator inside. Now it ****. But interesting thing with this that I discovered was that at slight opening of p-port would change the whole thing. The p port effect the engine at all rpm, the flow of the p port thats what I am talking about. Even though you have other ports open if you play around with that throttle body that I made on the p-port it would effect the speed of the engine, pretty much at any positions. I bet that me placing the throttle body like I did, it have restricted some of the flow and probably dropped some horse power. Anyway just wanted to share what I found out by playing with it. Because you never really know unless you put it to the test.






​​​​​​
-CON- is offline  
Reply With Quote
Old 07-29-18, 02:08 AM
  #6  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 6,896
Thanked 113 Times in 101 Posts
Nice.
Are you getting a new actuator for the set-up?

If you feel there is too much restriction from the butterfly valve you may be able to switch to a ball type valve for the semi p-ports. You would probably have to bore the entry bigger so the hole in the ball can be as large as the semi p-ports.



BLUE TII is offline  
Reply With Quote
Old 07-29-18, 11:29 AM
  #7  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,048
Thanks: 0
Thanked 72 Times in 64 Posts
Originally Posted by -CON- View Post
Because you never really know unless you put it to the test.​​​​​
this is true. i've tuned a couple of P ports and i've tried a bunch of stuff.

mine: i found mine idled, and drove best with less intake vacuum. i have holes in the throttle plates. it actually does not even want to brap at idle much anymore. the carb, also a Weber, is the limit, and warned up i can idle it down to 700rpm or so, but if i set it to about 1000, it'll idle cold. distributor is locked, so i'm running 18BTDC all the time, trailing has a split, but i'm not sure what it is (my MSD died, i used to have the MSD fire both coils at once)

FM's: this one is a milder port, and its running a stock distributor (both cars are running Rx8 leading plugs, they are better), i did not drill the throttle plates. this one braps more, but it will idle down to 500rpm if you want. i forget what i set the idle to, i think about 900 warm. i didn't verify with the wideband, but i think the timing curve is letting me run it a little leaner in the low rpm area.

i think the next iteration with mine will be to put a distributor in it with a timing curve, with the timing all in by about 2500 (it does ping a little under that), possibly this will let me run it leaner at idle/under 2500

j9fd3s is offline  
Reply With Quote
Old 07-30-18, 01:14 AM
  #8  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts




The ball is an awesome idea. I already thought about it a lot long before I did this, but it is a bit to it. Sliders would actually be more simple and easier to do and just as effective I would think.
i gotta say this think. I am a little bit scared because there is some pulsation going on when that p-port closed, if you put your finger on the lever of that butterfly, it's like somebody knocking with a little hammer from the inside when the engine is running. This makes me worry that it won't fly apart. After some tests I took the manifold off to see, it was ok but I don't know. I think being so close to the chamber making it pulse so hard.
yeah, I am thinking I am not going to go with actuator, I think I will go with throttle position. I am not sure yet because I didn't see how I can hook it up yet. I think it is better that way because you only need p-port when you floor it so..

Ok regarding the spark timing I think it was working on 20.5+ on leading and my traling on tdc. But I also have 3 plugs per rotor like on 787b car)

Actually I wanted to say something about spark plugs. I am experimenting with completely not rotary spark plugs.
One time I used rotary spark plug on the small two stroke engine. And I cooked few of them. Actually it was funny because when it is cold I wasnt able to start so easy, then hardly runner to warm up. I figured the rotary spark plugs was so cold that it had problem starting it and running when cold. But when I got it warmed up I went for a ride and cooked it, so it stopped working. I did cooked few as I said. Was very disappointed at rotary plugs. I couldn't believe that two stroke plugs were better for the two stroke engine than the rotary ones.)))) So I stopped using rotary plugs on the rotary engine. Plus they like so expensive))

Last edited by -CON-; 07-30-18 at 01:50 AM.
-CON- is offline  
Reply With Quote
Old 07-30-18, 01:39 AM
  #9  
Automotive Designer
 
RGHTBrainDesign's Avatar
 
Join Date: Aug 2012
Location: San Jose, CA
Posts: 1,364
Thanked 31 Times in 30 Posts
Originally Posted by -CON- View Post

Actually I wanted to say something about spark plugs. I am experimenting with completely not rotary spark plugs.
One time I used rotary spark plug on the small two stroke engine. And I cooked few of them. Actually it was funny because when it is cold I wasnt able to start so easy, then hardly runner to warm up. I figured the rotary spark plugs was so cold that it had problem starting it and running when cold. But when I got it warmed up I went for a ride and cooked it, so it stopped working. I did cooked few as I said. Was very disappointed at rotary plugs. I couldn't believe that two stroke plugs were better for the two stroke than the rotary ones.)))) So I stopped using rotary plugs on the rotary engine. Plus they like so expensive))
Have an NGK Part # for us on the spark plugs?
RGHTBrainDesign is offline  
Reply With Quote
Old 07-30-18, 02:44 PM
  #10  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
No, not yet. Not until I am convinced that they are good plugs. I don't want anyone to bash me and curse me if they receive some bad results.
once I feel good about the plugs I will post the number, as I said I still experimenting. Besides applications may vary the results of the plugs.
Anyway It is NGK though.
-CON- is offline  
Reply With Quote
Old 10-07-18, 09:43 AM
  #11  
malignant narcissist
iTrader: (2)
 
diabolical1's Avatar
 
Join Date: Feb 2002
Location: FL
Posts: 9,265
Thanked 28 Times in 26 Posts
What's going on with this?
diabolical1 is offline  
Reply With Quote
Old 10-18-18, 03:43 AM
  #12  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
here is the video that i was talking about where the intake volume was sucked out trough semi p-port by the exhaust "vacuum".

-CON- is offline  
Reply With Quote
Old 10-18-18, 05:51 PM
  #13  
malignant narcissist
iTrader: (2)
 
diabolical1's Avatar
 
Join Date: Feb 2002
Location: FL
Posts: 9,265
Thanked 28 Times in 26 Posts
Pretty cool-looking.

So that's with the ports closed, you said? I find your experimentation fascinating.
diabolical1 is offline  
Reply With Quote
Old 10-18-18, 07:16 PM
  #14  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 6,896
Thanked 113 Times in 101 Posts
Event I go to sometimes has a formula car with a carbed bridge port rotary (so short exhaust because in back of car).

Once it has been out on track and exhaust is hot is literally constantly ***** fire out the tailipipe non-stop even at idle because carbs pull fuel through with the air even with throttle plates closed.
BLUE TII is offline  
Reply With Quote
Old 10-19-18, 02:21 AM
  #15  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
No, this is with the semi p-port open. The reason I have made throttle body on the p-ports is because I discovered that it draws fresh intake charge into the exhaust. I had very bad fuel mileage, well and vacuum drop.. and so I made this throttle bodies.


Last edited by -CON-; 10-19-18 at 03:29 AM.
-CON- is offline  
Reply With Quote
Old 10-27-18, 03:45 PM
  #16  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 211
Thanks: 0
Thanked 0 Times in 0 Posts
Well, I posted 6 times the pics but they just not here..site doesn't work, forget it... Sorry.

Last edited by -CON-; 10-27-18 at 04:08 PM.
-CON- is offline  
Reply With Quote
Old 10-27-18, 10:33 PM
  #17  
My job is to blow **** up
iTrader: (8)
 
lastphaseofthis's Avatar
 
Join Date: Jan 2005
Location: palmyra Indiana
Posts: 2,877
Thanked 0 Times in 0 Posts
well. i told you so. then everybody told me naw u wanna keep the p port open and use it as primary.

there are post of old, probably 2 years or more, where i suggested shutting the port off at the manifold, i bought most of the stuff todo it, but still havent managed to tackle tuning my ms3-pro, and getting the issues resolved on my stock port well enough to continue... glad to see i was in the right direction and my parts will still be of use.

good job con! do da man. all you need now is to put the pp ort thorttles hooked to the last 20 perent of pedal throw. then you will have 80 pedal of streetable side ports, and the last 20 bit is all p port powah!
lastphaseofthis is offline  
Reply With Quote
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
TURBODREAMS04
Race Car Tech
12
05-25-14 01:59 AM
TURBODREAMS04
20B Forum
8
10-20-13 03:48 AM
TURBODREAMS04
Race Car Tech
2
10-17-13 09:27 PM


Thread Tools
Search this Thread
Quick Reply: Semi pp throttle body.


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.