A simple electronic RPM based actuator? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 05-02-2010, 08:54 PM   #21
Hittin' Boost & Cones
iTrader: (2)
 
240_to_miata's Avatar
 
Join Date: May 2007
Location: Cromwell, Connecticut
Posts: 2,572
Total Cats: 11
Default

Quote:
Originally Posted by fooger03 View Post
I've got 2 designs floating around in my head with the idea of maximizing helmholtz resonance across the entire RPM range by adjusting the length of the runners as engine speed varies.

I wish I had an ME degree

I wish I had a machine shop

I wish I had welding experience
I worked a bit with helmholtz resonance at my summer ME internship. cool stuff.
240_to_miata is offline   Reply With Quote
Old 05-02-2010, 11:37 PM   #22
Elite Member
Thread Starter
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187
Default

Looks like BMW has already invented/proven the theory with something called "DIVA"
fooger03 is offline   Reply With Quote
Old 05-03-2010, 12:57 AM   #23
Elite Member
iTrader: (12)
 
Join Date: Jan 2007
Location: Hermosa Beach, CA
Posts: 2,575
Total Cats: 11
Default

I feel like I should design some sorta system like this for our fsae car... keep us updated.
cardriverx is offline   Reply With Quote
Old 05-03-2010, 10:32 AM   #24
Elite Member
Thread Starter
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187
Default

Anyone have any technical information regarding best dimensions for the intake runners before I do the math and "over engineer" (i use the term lightly, because the end result will likely be crude at best ) the range of runner lengths?
fooger03 is offline   Reply With Quote
Old 05-07-2010, 01:25 AM   #25
Junior Member
 
Join Date: Aug 2006
Location: Cedar City, UT
Posts: 228
Total Cats: 4
Default

If I remember correctly, the Mazda 787B had adjustiable length velocity stacks too, and they used the headlight motors from the same year RX-7 to move them. Aparently they were tough enough to survive 24 hrs and win
Le Mans in 1991 on an engine that redlined a bit higher then ours

Im sure they were tired into RPM somehow, not sure exactly how they worked though, if different pulsewidths would cause them to extend only so far or what ever, and im sure that they were geared so they would go from max to min position quickly... the headlights on mine move really quick, so i can see them extending and retracting the intake stacks faster then you reving it from idle to readline in nuetral

Theirs seems to be made of a FRP or some other composite material... probobly good so it does not heat soak i guess

Could probobly get more info from rx7club about the specifics

Dlaitini is offline   Reply With Quote
Old 05-07-2010, 11:18 AM   #26
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

Quote:
Originally Posted by Dlaitini View Post
That is very cool!
ZX-Tex is offline   Reply With Quote
Old 05-07-2010, 11:51 AM   #27
Junior Member
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default

Just saw a neat article about this.

Porsche is using some form of variable length intake on one of their turbo cars. The intent is a little different though. Typically, like on the 787B, the intent is to use the resonance to compress the air into the cylinder.

Well, this creates excess heat.

So what Porsche is doing, is while not in boost (or in low boost, not sure), their manifold acts like normal and helps compress the air into the cylinders. Then as boost pressure builds, the harmonic tuning changes such that the manifold causes the air to expand. They're making up for the lost charge pressure with additional boost and allowing the intercooler to do its job. Just avoiding the addition heat generated by harmonic resonance compression.

Neat stuff....
--Alex
AlexO35 is offline   Reply With Quote
Old 05-07-2010, 02:26 PM   #28
Elite Member
Thread Starter
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187
Default

Dlaitini, thats fantastic! I just dont know how well it would fit into our engine bays :P

They are compensating for heat caused by harmonic tuning? It sounds like these guys are running on the ragged edge! I'm not sure it would be a good idea for porsche to put this into production cars, but good on them for engineering to such an exacting requirement!
fooger03 is offline   Reply With Quote
Old 05-07-2010, 02:28 PM   #29
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

Quote:
Originally Posted by fooger03 View Post
They are compensating for heat caused by harmonic tuning? It sounds like these guys are running on the ragged edge!
Yeah that is what I was thinking. That has to be well into diminishing returns territory and not that important on a street car. That is the kind of design detail that makes high-end racing engines so interesting.
ZX-Tex is offline   Reply With Quote
Old 05-11-2010, 01:42 AM   #30
Junior Member
 
Join Date: Aug 2006
Location: Cedar City, UT
Posts: 228
Total Cats: 4
Default

for some reason, the only way packing wise on a miata, i see an intake shaped like a trombone.

The runners will increase and decrease their lenght, and if also tied into an Plenum, can also use forced induction if the tolerances are close enough on the sliding part... or if enough air is pushed in to overpower what leaks, lol
Dlaitini is offline   Reply With Quote
Old 05-11-2010, 09:51 AM   #31
Elite Member
Thread Starter
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187
Default

I'm currently considering an idea which involves a rotating cylinder to increase/decrease runner length. An rotating inner cylinder would be completely encased in a non-moving outer cylinder with the exception of a seal where the servo connects to the inner cylinder assembly. The seal would look similar to the current VICS actuator seal.

I just need a better way to prototype it than what I'm currently doing.
fooger03 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
In need of base map for stock 1997 brandonbkd MEGAsquirt 0 09-29-2015 12:52 AM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 09:38 AM.