Welcome to the North American Subaru Impreza Owners Club Friday August 29, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC General > Proven Power Bragging

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 11-25-2008, 08:26 PM   #1
bigboyzben
Scooby Newbie
 
Member#: 91583
Join Date: Jul 2005
Location: CA 91786
Vehicle:
2005 STI
Aspen White

Default EQ Tuned ATP GT35R 91 octane and a little meth 390WHP/368WTQ

First and foremost I'd like to thank Steve at Aerosim Research for working on my car over the past year doing a bunch of crazy custom stuff and putting up with my whacky ideas And also to Ed for taking the time to tune even while sick and especially for re-tuning my setup after my SZ60 bent the shaft and blew a seal during our last tune. That's another story, but let's just say straightening a bent shaft to "fix" it isn't the best thing to do when performing a "free" rebuild.

Ed from EQ Tuning worked his magic on my car last night. I've taken my car to 5 tuners in California and Ed is by far the best for a blow through MAF setup. Other tuners couldn't even get the car to idle properly, but Ed got my STi to idle and drive around like stock. Until you get into boost I previously had a FP Green IWG setup tuned by Mike at GST which I ran for 27,000 miles with no problems. But over the past 16 months I decided to go with a bigger setup.

Anyway, onto the details:
2005 STi, Cobb AP V2
ATP GT35R stock location turbo with integrated wastegate flange
Tial 44MM wastegate routed into DP
PDE catted DP, full 3"
Borla XR-1 catback, full 3"
Perrin EL headers, Swaintech coated
DW 850CC injectors
Hallman Pro RX MBC
ACPT CF Driveshaft
TurboXS FMIC core with custom piping
APS dual port BOV, recirculated
3" ID blow through MAF setup
Coolingmist Stage 2 injection kit with Aquamist DDS3v8, spec C 12L tank(49/51 VP M1/water mix)
Fluidyne radiator
Exedy Twin-Plate ceramic clutch
NGK 1 step colder plugs
Perrin pulley
STOCK BLOCK with 33k miles

Also have some custom CF parts molded and made by Steve Ramm of Aerosim Research. Amazing engineer and fabricator, one of the best! We're getting another STi to do a twin scroll GT35 on with a semi-built block. Then people can see what a well designed manifold looks like and not one where you just keep thickening the pipe until the manifolds don't crack anymore
Custom CF Turbo inlet pipe
Custom CF airbox with air feed from CF NACA ducts on hood
Custom CF duct for oil cooler
These CF pieces were basically prototypes that will be going into production.

Some pictures of my setup. Unfortunately we didn't get back from Ed's until 1AM this morning and we're getting some scattered showers in Socal today so these are the only pictures I have for now.








Now, the results. Keep in mind this is NOT another typical "conservative" NASIOC tune. More details on that in a bit. I DD my STi, but requested Ed to push it a little.

As you can see the turbo just wants to rev to 8000 RPM on some race gas! The torque is lower than I had hoped, but the HP is way higher than we expected. This is on 22-23PSI of boost to redline. We didn't experience any boost loss due to "turbulence" with the wastegate casted into the turbine housing. The turbo had no problem holding 26 PSI of boost to redline on a couple of runs before we dialed it down. The spool up is great even for around town driving. I believe we were hitting 20 PSI of boost by around 4000 RPMs, I'd need Ed to confirm that, but it's right around there.

However, when spraying the meth we noticed the AFR would barely change and the flow meter would only register 2 bars max even with the scale on the DDS3 turned to the maximum. After 3 hours of tuning we used MAYBE 1/3-1/2 gallon of meth mix so it definitely isn't spraying right, even with a small 6 GPH nozzle. We're quite sure it's the nozzle since that's the only thing we didn't check, but once we switch to a bigger nozzle we'll get it retuned and see what it can really do. Due to the severely limited meth spray Ed suggested we just keep it at around 22-23PSI.

With that in mind, I'd say this is more of a 91 octane tune, the minute amount of meth we used makes it hard for me to call this a 91+meth tune. On our previous tune attempt on the SZ60 the flow meter was easily maxing out the 8 bars and on the 4 pulls we did before the turbo blew we used 3 times the amount of meth we used this time over the course of 20+ pulls. It was drinking the meth last time! But regardless, 390 WHP on Ed's software is no joke. It'll easily break 400 WHP once the injection kit is fixed and then the fun begins! Hopefully the next time I'm up at EQ Tuning Adam and Ed will be having another BBQ, the chicken was amazing! Free food FTW!
* Registered users of the site do not see these ads.
bigboyzben is offline   Reply With Quote
Old 11-25-2008, 09:09 PM   #2
subenerd
Scooby Specialist
 
Member#: 72630
Join Date: Oct 2004
Location: CA
Vehicle:
2004 STi

Default

Damn, 390whp on the road dyno software - impressive. Must haul ass.

Interesting custom parts...
subenerd is offline   Reply With Quote
Old 11-26-2008, 01:19 AM   #3
benw
Scooby Specialist
 
Member#: 103320
Join Date: Dec 2005
Location: Oklahoma City
Vehicle:
2005 wingless
aspen white

Default

which nozzle are you using? 0.6? I tuned a 8cm Green the other day, and I ended up using a 0.9 and 0.4 in conjunction to get the proper amount of flow (20% injection to gasoline ratio). Spray more!
benw is offline   Reply With Quote
Old 11-26-2008, 01:47 AM   #4
jigga
Scooby Guru
 
Member#: 9960
Join Date: Sep 2001
Location: in bed...
Vehicle:
2002 Impreza WRX
WRBlue Perl

Default

interesting ducting work... Can we see some shots of the bonnet itself? Just want to see what it looks like underneath where the ducts come in..
jigga is offline   Reply With Quote
Old 11-26-2008, 02:05 AM   #5
bigboyzben
Scooby Newbie
 
Member#: 91583
Join Date: Jul 2005
Location: CA 91786
Vehicle:
2005 STI
Aspen White

Default

Quote:
Originally Posted by subenerd View Post
Damn, 390whp on the road dyno software - impressive. Must haul ass.

Interesting custom parts...
Thanks, I agree. Definitely stout numbers on Ed's software considering someone who put down 395 WHP on the Agile Auto dyno claims they only did 325 on Ed's. Hopefully Auto Club Dragway will be open on 6th and we can see some traps.

Quote:
Originally Posted by benw View Post
which nozzle are you using? 0.6? I tuned a 8cm Green the other day, and I ended up using a 0.9 and 0.4 in conjunction to get the proper amount of flow (20% injection to gasoline ratio). Spray more!
What measurement are you referring to? We were using the 6 gallon/hour nozzle, but it definitely wasn't flowing much, if anything, due to a clog in the nozzle most likely. On our previous tune it was drinking meth at full boost! We will definitely be switching to a 12 GPH nozzle regardless.


Quote:
Originally Posted by jigga View Post
interesting ducting work... Can we see some shots of the bonnet itself? Just want to see what it looks like underneath where the ducts come in..
Sure, I'll try to get some pictures tomorrow of the bottom side of the hood, however it's raining in Socal right now so no guarantees
bigboyzben is offline   Reply With Quote
Old 11-26-2008, 02:06 AM   #6
NSFW
Scooby Guru
 
Member#: 140444
Join Date: Feb 2007
Chapter/Region: NWIC
Location: Near Seattle, WA
Vehicle:
05 Stage Free LGT
ATP 3076, 6MT, AVO FMIC

Default

You get bonus points for creativity. That's pretty sweet.

Also, what jigga said.
NSFW is offline   Reply With Quote
Old 11-26-2008, 03:10 AM   #7
verc
Scooby Specialist
 
Member#: 41754
Join Date: Aug 2003
Location: san ramon
Vehicle:
03 wrx
gt35r, 2.5L, meth

Default

wow, were you able to hit peak boost around 4000-4100? That sounds amazing for this turbo - dyno'd in 5th right?
verc is offline   Reply With Quote
Old 11-26-2008, 04:02 AM   #8
socalLGT
Scooby Specialist
 
Member#: 89752
Join Date: Jun 2005
Chapter/Region: SCIC
Location: On the dyno at Yimi Sport
Vehicle:
08 STI
SWP

Default

Very stout results on Ed low reading road dyno software. The ATP GT35R is a really nice turbo. Any particular reason you chose to go blowthrough MAF? On a stock location turbo I really don't see that point and it just makes tuning the car more finicky... and this is coming from a guy who is running blowthrough MAF on his own car. I'll echo the comments of others by saying that the custom CF ducts/boxes/parts are interesting. Honestly they are probably more trouble/time/money than they are worth, but it definitely sets your car apart from others.
socalLGT is offline   Reply With Quote
Old 11-26-2008, 05:06 AM   #9
bigboyzben
Scooby Newbie
 
Member#: 91583
Join Date: Jul 2005
Location: CA 91786
Vehicle:
2005 STI
Aspen White

Default

Quote:
Originally Posted by verc View Post
wow, were you able to hit peak boost around 4000-4100? That sounds amazing for this turbo - dyno'd in 5th right?
The pulls were all done in 4th. 5th on the STi gearing would take us well into the 130s I believe the CF turbo inlet pipe helps with the spoolup since it was designed to maximize the minimal area under the intake manifold. Peak boost of 22-23 PSI was around 4200 RPMs I believe. Ed was very impressed with the turbo response as well.


Quote:
Originally Posted by socalLGT View Post
Very stout results on Ed low reading road dyno software. The ATP GT35R is a really nice turbo. Any particular reason you chose to go blowthrough MAF? On a stock location turbo I really don't see that point and it just makes tuning the car more finicky... and this is coming from a guy who is running blowthrough MAF on his own car. I'll echo the comments of others by saying that the custom CF ducts/boxes/parts are interesting. Honestly they are probably more trouble/time/money than they are worth, but it definitely sets your car apart from others.
I definitely agree, it's an extremely well made turbo. I had my doubts at first, but the results speak for themselves. Your results on the Yimisport 08 STi actually got me interested in the ATP GT35R! I was actually hoping to do a few runs on the Yimisport dyno after I get my meth issue sorted and get retuned to see how Dynojets compare to Ed's software. The CF parts are prototypes that will be going into production, so I was just being the guinea pig which isn't too bad.

I decided to go with the blow through mainly because I wanted the MAF as close to the throttle body as possible and Ed also recommended it. I was told by quite a few tuners that blow throughs can be finicky and some tuners wouldn't even touch it. After a local tuner couldn't even get my car to idle or accelerate properly I was worried. But after Ed dialed in the idle my car has never run smoother, and that's not an exaggeration. Under 4000 RPMs the car is just as quiet and smooth as when I was stage 2, if not smoother. The key for me was to clean my MAF sensor, it was unbelievably dirty! With Ed tuning I wouldn't hesitate to recommend a blow through MAF to anyone, he really put all my fears to rest that you can have a well running big turbo setup.
bigboyzben is offline   Reply With Quote
Old 11-26-2008, 05:34 AM   #10
Phatron
Scooby Guru
 
Member#: 36033
Join Date: Apr 2003
Chapter/Region: SCIC
Location: Tuning Lab
Vehicle:
CEO PhatBottiTuning
2006 STi GTX3582 + Meth

Default

do you think its the smartest idea to put the MAF (which is a temperature delta based sensor) right above the turbine and downpipe?

wait a minute....kinda looks like you figured that out and moved it...and plugged the maf sensor hole right by the throttle body...

is that what happened?
Phatron is offline   Reply With Quote
Old 11-26-2008, 05:38 AM   #11
kennyvb
Scooby Guru
 
Member#: 70234
Join Date: Sep 2004
Chapter/Region: Tri-State
Location: NYC
Vehicle:
MY86 BMW E30 325
SCIC/NWIC tranplant (-_-)

Default

Hey Ben, how's it going? Nice power. Car looks good! I like what Steve did with the CF. Ducts look legit.
kennyvb is offline   Reply With Quote
Old 11-26-2008, 03:16 PM   #12
Equilibrium Tuning
NASIOC Vendor
 
Member#: 26933
Join Date: Oct 2002
Chapter/Region: BAIC
Location: Fairfield, CA
Vehicle:
2006 STI
CGM

Default

Thanks for the kind words Ben. Your car has some very interesting pieces that I would be interested in carrying if you ever put them into production. To answer a few questions,

We were seeing 20psi by about 4k RPM and 22-23psi by 4200. The great part about this turbo is that partial boost is very easily attained even at low RPM's making it very drivable around town. Considering the very little amount of meth we were running, the power this thing made was awesome on all accounts and the response is very impressive for a 35R in general. Also don't forget this is all going through a fairly quiet exhaust with a cat!

As far as the blow-through MAF. In general I would always go with a well set up blow-through for any FMIC setup. The benefits outweigh any negatives and as long as the piping is set up properly and the tune is right, BTM's always run smoother and drive better in the end.

Thanks
-- Ed
Equilibrium Tuning is offline   Reply With Quote
Old 11-26-2008, 03:17 PM   #13
bigboyzben
Scooby Newbie
 
Member#: 91583
Join Date: Jul 2005
Location: CA 91786
Vehicle:
2005 STI
Aspen White

Default

Some additional pictures of the NACA ducts and underside of the hood. The carbon on the underside of the hood on the passenger side is to seal the airbox better against the hood.




Quote:
Originally Posted by Phatron View Post
do you think its the smartest idea to put the MAF (which is a temperature delta based sensor) right above the turbine and downpipe?

wait a minute....kinda looks like you figured that out and moved it...and plugged the maf sensor hole right by the throttle body...

is that what happened?
That was one of the reasons why we moved it, but definitely not the main reason. The main reason was to get the MAF on a longer section of straight pipe to give it a more consistent reading. Ideally we wanted a diffuser inside the pipe to stabilize the air flow, but putting the MAF on a 10-11" section of straight pipe was the easier way of doing it.

Quote:
Originally Posted by kennyvb View Post
Hey Ben, how's it going? Nice power. Car looks good! I like what Steve did with the CF. Ducts look legit.
Hi Kenny, haven't heard from you in awhile! Things are going well, finally got the STi up and running. Yeah, Steve definitely does some amazing stuff, you should see the M5 headers he's working on
bigboyzben is offline   Reply With Quote
Old 11-26-2008, 04:03 PM   #14
Equilibrium Tuning
NASIOC Vendor
 
Member#: 26933
Join Date: Oct 2002
Chapter/Region: BAIC
Location: Fairfield, CA
Vehicle:
2006 STI
CGM

Default

Quote:
Originally Posted by bigboyzben View Post
That was one of the reasons why we moved it, but definitely not the main reason. The main reason was to get the MAF on a longer section of straight pipe to give it a more consistent reading. Ideally we wanted a diffuser inside the pipe to stabilize the air flow, but putting the MAF on a 10-11" section of straight pipe was the easier way of doing it.
Its also important to isolate the MAF from the throttle body to avoid turbulence on throttle transitions. There are a couple straight forward guidelines I use to properly locate the blow-through MAF and they always seem to run great.

-- Ed
Equilibrium Tuning is offline   Reply With Quote
Old 11-26-2008, 04:14 PM   #15
paikman
Scooby Specialist
 
Member#: 43002
Join Date: Sep 2003
Chapter/Region: MAIC
Location: VA
Vehicle:
GRB & FD3S
SUSPENSION GEOMETRY O NOE

Default

Functioning naca ducts are so cool
paikman is offline   Reply With Quote
Old 11-26-2008, 07:11 PM   #16
Iflysti06
Scooby Newbie
 
Member#: 156955
Join Date: Aug 2007
Chapter/Region: SWIC
Location: Peoria, AZ
Vehicle:
2006 STI
UR GT35R w/ mad bolt ons

Default

those ducts are straight gangsta, good work!
Iflysti06 is offline   Reply With Quote
Old 11-26-2008, 08:21 PM   #17
SaabTuner
Scooby Specialist
 
Member#: 67608
Join Date: Aug 2004
Location: SoCal
Default

Quote:
Originally Posted by paikman View Post
Functioning naca ducts are so cool
Except that those ones look like they missed the part of the NACA design which makes that type of duct so special: the bottom of the duct is supposed to widen faster than the top so that there is a lip about halfway down the duct- that lip helps create rotation in the airflow which brings in more air, as well as pulling the boundary layer in more quickly.

Still, it's just nice to see functional ducts at all, even if they aren't quite perfect NACA ducts.
SaabTuner is offline   Reply With Quote
Old 11-27-2008, 08:07 AM   #18
Aerosim Research Ltd
Former Vendor
 
Member#: 45648
Join Date: Oct 2003
Chapter/Region: SCIC
Location: Costa Mesa, CA.
Vehicle:
GC8 CF 22B widebody
Lancia Stratos Replica

Default

Quote:
Originally Posted by SaabTuner View Post
Except that those ones look like they missed the part of the NACA design which makes that type of duct so special: the bottom of the duct is supposed to widen faster than the top so that there is a lip about halfway down the duct- that lip helps create rotation in the airflow which brings in more air, as well as pulling the boundary layer in more quickly.

Still, it's just nice to see functional ducts at all, even if they aren't quite perfect NACA ducts.
Bzzzzzzz ... sorry, wrong answer. NACA ducts have straight walls. Unfortunately it's impossible to make a straight wall and still pull it from a mold ... you need at least a few degrees of draft. The vortex that you speak of is created by the shape of the sharp edge at the surface and the inclination to the airflow. That's why NACA ducts work best in an area with a positive pressure gradient.

Anyway, these are NACA ducts. If you want to know more, the original NACA paper is here. Ironically at the school where I went for my masters in CFD.

-Steve
Aerosim Research Ltd is offline   Reply With Quote
Old 11-27-2008, 03:28 PM   #19
Phatron
Scooby Guru
 
Member#: 36033
Join Date: Apr 2003
Chapter/Region: SCIC
Location: Tuning Lab
Vehicle:
CEO PhatBottiTuning
2006 STi GTX3582 + Meth

Default

this is a very cool idea...but (and please dont take this as hating/bashing/etc in any way)

couldnt the same effect have been had by simply extending the intake into the fender well like all the other CAI's out there?

i mean with all the CF parts, hood cutting, labor etc thats gotta be like a $2000 intake...

basically my questions is....is there really any benefit to it over a traditional CAI?

Steve,

have you done any CFD of the underhood aero? i've always been very curious about what it looked like with the normal scoop and with the reverse scoop.
Phatron is offline   Reply With Quote
Old 11-27-2008, 03:53 PM   #20
Angry Toaster
I'm not angry
Moderator
 
Member#: 62555
Join Date: May 2004
Chapter/Region: SCIC
Location: socal
Vehicle:
2001 SF5 / 2001 GC8
08 E92 / 08 CBR600RR

Default

Quote:
Originally Posted by Aerosim Research Ltd View Post
Bzzzzzzz ... sorry, wrong answer. NACA ducts have straight walls. Unfortunately it's impossible to make a straight wall and still pull it from a mold ... you need at least a few degrees of draft. The vortex that you speak of is created by the shape of the sharp edge at the surface and the inclination to the airflow. That's why NACA ducts work best in an area with a positive pressure gradient.

Anyway, these are NACA ducts. If you want to know more, the original NACA paper is here. Ironically at the school where I went for my masters in CFD.

-Steve
Zing!
Angry Toaster is offline   Reply With Quote
Old 11-27-2008, 04:33 PM   #21
SaabTuner
Scooby Specialist
 
Member#: 67608
Join Date: Aug 2004
Location: SoCal
Default

Quote:
Originally Posted by Aerosim Research Ltd View Post
Bzzzzzzz ... sorry, wrong answer. NACA ducts have straight walls. Unfortunately it's impossible to make a straight wall and still pull it from a mold ... you need at least a few degrees of draft. The vortex that you speak of is created by the shape of the sharp edge at the surface and the inclination to the airflow. That's why NACA ducts work best in an area with a positive pressure gradient.

Anyway, these are NACA ducts. If you want to know more, the original NACA paper is here. Ironically at the school where I went for my masters in CFD.

-Steve
Bzzzz yourself: NACA submerged ducts do not all have straight walls, and that's just the article Wikipedia references, and certainly not the only design iteration: http://en.wikipedia.org/wiki/NACA_duct

Here's one where the walls slant outward from the bottom up: http://naca.central.cranfield.ac.uk/...rm-a51l03a.pdf

Another paper: http://naca.central.cranfield.ac.uk/...a-rm-a8a20.pdf

NACA refined the duct design after doing much more extensive testing with deflectors. Here's a later report with a 1/5th scale fighter plane test using deflectors: http://naca.central.cranfield.ac.uk/...a-rm-a7i06.pdf

Another test using deflectors: http://naca.central.cranfield.ac.uk/...a-rm-a7a31.pdf

A revised lip and deflector: http://naca.central.cranfield.ac.uk/...a-rm-a7d14.pdf

At this point, you should notice that deflectors increased the efficiency of the original design, this article explains why, and why you can imagine what I described earlier being a logical final design to help keep the vortices inside the duct (page 26): http://naca.central.cranfield.ac.uk/...ca-tn-2323.pdf

By widening the bottom, the vortices can move outwards to the side and continue to suck fresh air down into the duct without blocking any, or rolling out the top.

It's ironic that most people just copy the old NACA designs exactly. NACA didn't stop coming up with new versions because they'd perfected the old ones: they simply moved on to supersonic jet aircraft research, where submerged ducts aren't very useful.

I tried to find the old paper I had on walls which were wider towards the bottom, but I didn't see it on their technical report site, or the UK mirror. They used to have a different website and I noticed a few other papers missing. But I might have just skimmed over it by accident, since there are soooo many papers. (I love the Tungsten-Carbide + Cobalt cermet that they did work on so long ago ... and is only fiiinally becoming popular again. )

-Adrian
SaabTuner is offline   Reply With Quote
Old 11-27-2008, 04:40 PM   #22
SaabTuner
Scooby Specialist
 
Member#: 67608
Join Date: Aug 2004
Location: SoCal
Default

Quote:
Originally Posted by Angry Toaster View Post
Zing!
Not really. Here's a picture from this NACA technical report showing the most recent NACA Duct design posted on that particular server, and it does not have vertical sides. This paper: http://naca.central.cranfield.ac.uk/...a-rm-a8a20.pdf



Dun dun dunnnnnn ...
SaabTuner is offline   Reply With Quote
Old 11-27-2008, 04:45 PM   #23
bigboyzben
Scooby Newbie
 
Member#: 91583
Join Date: Jul 2005
Location: CA 91786
Vehicle:
2005 STI
Aspen White

Default

Quote:
Originally Posted by Iflysti06 View Post
those ducts are straight gangsta, good work!
Quote:
Originally Posted by paikman View Post
Functioning naca ducts are so cool
Thanks, I like them! Functioning and I love how they look.

Quote:
Originally Posted by Phatron View Post
this is a very cool idea...but (and please dont take this as hating/bashing/etc in any way)

couldnt the same effect have been had by simply extending the intake into the fender well like all the other CAI's out there?

i mean with all the CF parts, hood cutting, labor etc thats gotta be like a $2000 intake...

basically my questions is....is there really any benefit to it over a traditional CAI?

Steve,

have you done any CFD of the underhood aero? i've always been very curious about what it looked like with the normal scoop and with the reverse scoop.
I know the look/cost isn't for everyone, but with the prototypes done additional units wouldn't be nearly as costly. I never liked the fender CAIs to be honest, and unfortunately there was a F40 sitting at the dealership right around the corner of Steve's shop so Steve got some ideas If you've never seen a F40 in person there's seriously around 30 NACA ducts all over I was hesitant at cutting the hood at first, but this really was the best way for a CAI and I absolutely love how the front looks now. I've asked Steve about the reverse scoop a few times, but I'll let him properly explain it


Quote:
Originally Posted by Aerosim Research Ltd View Post
Bzzzzzzz ... sorry, wrong answer.

-Steve
Thanks Steve, was hoping you'd chime in

Happy Thanksgiving!
bigboyzben is offline   Reply With Quote
Old 11-27-2008, 09:01 PM   #24
Aerosim Research Ltd
Former Vendor
 
Member#: 45648
Join Date: Oct 2003
Chapter/Region: SCIC
Location: Costa Mesa, CA.
Vehicle:
GC8 CF 22B widebody
Lancia Stratos Replica

Default

Quote:
Originally Posted by SaabTuner View Post
Bzzzz yourself: NACA submerged ducts do not all have straight walls, and that's just the article Wikipedia references, and certainly not the only design iteration: http://en.wikipedia.org/wiki/NACA_duct

Here's one where the walls slant outward from the bottom up: http://naca.central.cranfield.ac.uk/...rm-a51l03a.pdf

Another paper: http://naca.central.cranfield.ac.uk/...a-rm-a8a20.pdf

NACA refined the duct design after doing much more extensive testing with deflectors. Here's a later report with a 1/5th scale fighter plane test using deflectors: http://naca.central.cranfield.ac.uk/...a-rm-a7i06.pdf

Another test using deflectors: http://naca.central.cranfield.ac.uk/...a-rm-a7a31.pdf

A revised lip and deflector: http://naca.central.cranfield.ac.uk/...a-rm-a7d14.pdf

At this point, you should notice that deflectors increased the efficiency of the original design, this article explains why, and why you can imagine what I described earlier being a logical final design to help keep the vortices inside the duct (page 26): http://naca.central.cranfield.ac.uk/...ca-tn-2323.pdf

By widening the bottom, the vortices can move outwards to the side and continue to suck fresh air down into the duct without blocking any, or rolling out the top.

It's ironic that most people just copy the old NACA designs exactly. NACA didn't stop coming up with new versions because they'd perfected the old ones: they simply moved on to supersonic jet aircraft research, where submerged ducts aren't very useful.

I tried to find the old paper I had on walls which were wider towards the bottom, but I didn't see it on their technical report site, or the UK mirror. They used to have a different website and I noticed a few other papers missing. But I might have just skimmed over it by accident, since there are soooo many papers. (I love the Tungsten-Carbide + Cobalt cermet that they did work on so long ago ... and is only fiiinally becoming popular again. )

-Adrian
NACA research moved from subsonic to transonic and then supersonic. I think you'll find that the ducts you are illustrating were designed for higher (transonic) speeds. In fact that's in the title ... "some effects of side-wall modifications on the drag and pressure recovery of an NACA submerged inlet at TRANSONIC speeds".

At the speeds we're dealing with the vortex development isn't as strong with the walls slanted outwards. I agree that the protruding lips would help, but I'll give up a few % in efficiency for aesthetics ... the lips look horrible. On that front, you'll probably pick up that the ducts aren't aligned with the local flow. Aesthetics again ... sometimes form doesn't follow function.

As far as the function part of it ... I'm sure you'll agree that there's little to be gained from ram air so this is purely a cold-air intake. The size of the duct is more than adequate for the air intake and honestly, a 10% reduction in drag is going to do nothing in terms of overall drag on the car. As to the reason why everyone else chooses to use the parallel wall NACA design ... I'd guess it's feasibility. Making a one piece molded NACA duct with the walls flared out towards the bottom is near impossible. You'd need a multi-piece mold and even then it would be a PITA.

I know what you mean about the high tech metal matrix and ceramic composites. I tried to push to use some in Champ Cars but nobody wanted to pay for them. Funny thing is that the biggest users of those materials are golf club manufacturers. Go figure.

-Steve
Aerosim Research Ltd is offline   Reply With Quote
Old 11-27-2008, 09:46 PM   #25
SaabTuner
Scooby Specialist
 
Member#: 67608
Join Date: Aug 2004
Location: SoCal
Default

Quote:
Originally Posted by Aerosim Research Ltd View Post
NACA research moved from subsonic to transonic and then supersonic. I think you'll find that the ducts you are illustrating were designed for higher (transonic) speeds. In fact that's in the title ... "some effects of side-wall modifications on the drag and pressure recovery of an NACA submerged inlet at TRANSONIC speeds".

At the speeds we're dealing with the vortex development isn't as strong with the walls slanted outwards. I agree that the protruding lips would help, but I'll give up a few % in efficiency for aesthetics ... the lips look horrible. On that front, you'll probably pick up that the ducts aren't aligned with the local flow. Aesthetics again ... sometimes form doesn't follow function.

As far as the function part of it ... I'm sure you'll agree that there's little to be gained from ram air so this is purely a cold-air intake. The size of the duct is more than adequate for the air intake and honestly, a 10% reduction in drag is going to do nothing in terms of overall drag on the car. As to the reason why everyone else chooses to use the parallel wall NACA design ... I'd guess it's feasibility. Making a one piece molded NACA duct with the walls flared out towards the bottom is near impossible. You'd need a multi-piece mold and even then it would be a PITA.

I know what you mean about the high tech metal matrix and ceramic composites. I tried to push to use some in Champ Cars but nobody wanted to pay for them. Funny thing is that the biggest users of those materials are golf club manufacturers. Go figure.

-Steve
Right-o. The "shallow" walls work better at higher speeds, but having the larger base should help generate more inward flow at lower speeds. When you look at side-intakes on cars newer than the F40, the Koenigsegg for example, part of the duct work goes up above an outer lip for largely that reason.

I also gave some thought into making a mold! If you made the mold so that, instead of the mold going into the top of the piece, it went into the back of the piece, the ratio of area from upper to lower shouldn't matter. You just wouldn't be able to make the duct constrict down to a circle or anything. From what I can see with what was done in this hood, that might have been a possibility.

But still, yeah these are more just nice cold air intakes. They're a bit steep for functional NACA ducts, but they should get just enough flow to ensure cold air, even if not much "head", or dynamic pressure, into where they lead. They'll certainly create a lot less drag than just some random "scoop" at any rate.

I'd like to see a well-designed (perhaps with the "flush" lips, like I described?) NACA duct used for a Subaru TMIC! That way you can still see over the hood well, and get good airflow without complicated Air/Water, or laggy FMIC.

-Adrian

p.s. I studied fluid mechanics for a while too, and did a little CFD for fun with a friend. I have to admit that I find the calculations sometimes boring, but I'm really good at finding flaws in models so that they match up with measured results. I'm just glad the computer does the iterating.
SaabTuner is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
EQ Tuning: 04 WRX, EQ Built Engine, ATP3076, 91 Octane - 352whp! Equilibrium Tuning Proven Power Bragging 4 03-17-2010 02:24 PM
EQ Tuned ATP GT35R 91 octane and a little meth 390WHP/368WTQ bigboyzben Proven Power Bragging 0 11-25-2008 08:28 PM
JDM Ver7 ECU Ecutek for GT35R 91 octane VF34GRL Engine/Power/Exhaust 0 01-02-2007 07:32 AM
04 STi, GT35R, 91 octane + H20/Meth Scuba Steve Proven Power Bragging 45 12-09-2006 10:22 AM
Tuning UTEC for 91 Octane? muddywaters Engine Management & Tuning 6 01-15-2003 10:44 PM


All times are GMT -4. The time now is 10:12 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.