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, 01:26 AM
  #1  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 195
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 01:29 AM.
-CON- is offline  
Reply With Quote
Old 07-13-18, 10:34 AM
  #2  
Lives on the Forum
iTrader: (8)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 6,737
Thanked 83 Times in 73 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, 01:09 PM
  #3  
Full Member
Thread Starter
 
-CON-'s Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 195
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 02:13 PM.
-CON- is offline  
Reply With Quote
Old 07-14-18, 02:26 AM
  #4  
Lives on the Forum
iTrader: (8)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 6,737
Thanked 83 Times in 73 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
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
TURBODREAMS04
Race Car Tech
12
05-25-14 12:59 AM
TURBODREAMS04
20B Forum
8
10-20-13 02:48 AM
TURBODREAMS04
Race Car Tech
2
10-17-13 08:27 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.