The Subaru SVX World Network   SVX Network Forums
Live Chat!
SVX or Subaru Links
Old Lockers
Photo Post
How-To Documents
Message Archive
SVX Shop Search
IRC users:
SVXBot

Go Back   The Subaru SVX World Network > SVX Main Forums > MOD Mania > Proven Engine Enhancements

Reply
 
Thread Tools Display Modes
  #1  
Old 10-27-2007, 09:43 AM
Evil One Evil One is offline
Pinto Boosting Freak
 
Join Date: Sep 2003
Location: Holyoke Ma, USA
Posts: 291
Send a message via AIM to Evil One Send a message via MSN to Evil One Send a message via Yahoo to Evil One
Custom air box

I have dealt with many different kinds of cars over the years.
One constant is that cars make more power with a larger charge of cooler, denser air.
My car came with a green cone filter sitting open in the engine compartment.
Great for sound but not so good for performance.
I had been looking at making a custom enclosure drawing air from where the stock airbox intake was and a couple of other places.
I am now on the list for the ToMyx intake, and plan to follow thru with the construction of my box.
It is not going to be a fully enclosed box, actually more of an elaborate shield forcing the engine to draw cooler air than what is available underhood.
I have dynoed cars with outside of the engine compartment filters and underhood filter enclosures, there have been 1-2 hp variance in the runs..
For me, this is chalked up to standard variance in dyno runs.
Many people worry about hydrolocking the engine with a remote mounted filter, using an enclosure pretty much quells that worry.

I was just wondering if anyone on SVXWN has built one of these and what their experience with it was.


Jim
__________________
1992 Dark Teal LS-L with 4.44 swap. NC Plate "EVIL I" *Dont Fear the GEAR*
1977 Ford Pinto baby blue with 79,000 miles
Reply With Quote
  #2  
Old 10-27-2007, 10:50 AM
ensteele's Avatar
ensteele ensteele is offline
Betcha can't buy just one!
Alcyone Gold Contributor
 
Join Date: Jan 2002
Location: Burlington, WA
Posts: 19,553
Send a message via ICQ to ensteele Send a message via Yahoo to ensteele Send a message via Skype™ to ensteele
Registered SVX Classic SVX
I have seen several. You might use the search and see if you can find the threads about them. Good luck.
__________________
.
Earl .... ... .... ><SVX(*>

Subaru Ambassador

[COLOR=”silver”]1992 Tri Color L[/COLOR] ~45K (06/91) #2430
1992 Dark Teal LS-L ~184K (05/91) #0739
1992 Claret LS-L ~196K (05/91) #0831
1992 Pearl LS-L ~103K (06/91) #1680
1992 Pearl LS-L ~151K (06/91) #2229
1992 Dark Teal LS ~150K (07/91) #3098 (parts car)
1992 White LS-L ~139K (08/92) #6913
1993 25th AE ~98K (02/93) #164
1993 25th AE ~58K (02/93) #176
1993 25th AE ~107K (02/93) #215
1993 25th AE ~162K (02/93) #223
1994 Laguna Blue Pearl LSi ~124K (1/94) #2408
1994 Laguna Blue Pearl LSi ~144K (10/93) #1484
1994 Laguna Blue Pearl LSi ~68K (10/93) #1525
1994 Barcelona Red LSi ~46K (02/94) #2624
1994 Pearl LSi ~41K (12/93) #1961
1995 Bordeaux Pearl LSi ~70K (02/95) #855
1996 Polo Green LSi ~95K (03/96) #872
1997 Bordeaux Pearl LSi ~55K (08/96) #097
2003 Brilliant Red LS1 Convertible ~29K (04/03) #8951
1999 Magnetic Red LS1 Coupe ~33K (04/99) #6420

My Email | Old Locker | New Locker | Picture of 15 of the 19
Reply With Quote
  #3  
Old 10-27-2007, 11:15 AM
nextse7en's Avatar
nextse7en nextse7en is offline
Graphic Artist
 
Join Date: Sep 2004
Location: Eugene, OR
Posts: 789
Subaru designed the intake to be provided with pressurized air from the "wake effect" essentially, air splits when it meets the radiator, and crams into the hollow where the intake resonator lives. I don't think you are going to find colder air, or a much more effective way to create pressure in the upper intake.

If you wanted - you may find it possible to chill the exterior of the stock airbox by scooping pressurized air into some sort of heat sheild surrounding the box.

That being said, I think you would be looking at miniscule power gains, if any. The airbox is already kept cooler than the amient temps in the engine bay, because it constantly has air flowing thru it from the outside.


I would instead focus on smoothing out the intake flow from a stock box to the throttle body. Or, barring that, design a ram air duct. Ram air has been shown to add a few ponies at high speeds.

In closing, I would say that a stock airbox, with a mild ram effect, a tomynx intake - properly shielded, and phenolic spacers from outlaw would provide an optimal intake for a stock engine.
-Patrick
__________________
Patrick

1995 Ebony Pearl. S.N. 0001 "Araby"

JDM Power Mode Switch, Integrated GPS/Video Player
6Xk Miles.

1992 Teal - Sold to Mysvxrocks
[SIGPIC][/SIGPIC]

Last edited by nextse7en; 10-27-2007 at 11:26 AM.
Reply With Quote
  #4  
Old 10-27-2007, 11:58 AM
Evil One Evil One is offline
Pinto Boosting Freak
 
Join Date: Sep 2003
Location: Holyoke Ma, USA
Posts: 291
Send a message via AIM to Evil One Send a message via MSN to Evil One Send a message via Yahoo to Evil One
I got my car without the stock airbox


Jim
__________________
1992 Dark Teal LS-L with 4.44 swap. NC Plate "EVIL I" *Dont Fear the GEAR*
1977 Ford Pinto baby blue with 79,000 miles
Reply With Quote
  #5  
Old 10-27-2007, 07:04 PM
Trevor's Avatar
Trevor Trevor is offline
Registered User
 
Join Date: Feb 2002
Location: Auckland, New Zealand
Posts: 5,195
Registered SVX
Thanks Patrick,

A breath of fresh air (pun intended!), after all the BS that has been on offer of late regarding intake systems.

Good on you, Trevor.
__________________
Trevor, New Zealand.

As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit!
Reply With Quote
  #6  
Old 10-27-2007, 08:15 PM
SVXRide's Avatar
SVXRide SVXRide is offline
Official AutoX Part Breaker
Subaru Gold Contributor
 
Join Date: Aug 2002
Location: Dunkirk, Maryland, zip code=20754
Posts: 8,137
Registered SVX
Quote:
Originally Posted by FOMOGO View Post
I got my car without the stock airbox


Jim
Jim,
Check my locker....I've been running a true ram air set up for over 2 years...calculations based on the pressure readings I took when I first installed it indicate ~5-10 hp improvement once you get over ~30mph.
-Bill
__________________
NASA future mission development - MAVEN (now orbiting Mars and making amazing discoveries) and OSIRIS-REx (asteroid sample return, launched in September 2016, returning with samples in September 2023)
Center Network Member #989
'92 Black LSL aka Shooting Star -- FP class in the works with multiple interesting one-of-a-kind "improvements"
'92 Pearlie LSL aka Mach 5 -- STX class now being pushed to the rule book limits
Official sponsor of OT's RaceCar - now with sticky Hoosier 295 A6s on Cobra rims!
My Locker
Reply With Quote
  #7  
Old 10-27-2007, 09:02 PM
Trevor's Avatar
Trevor Trevor is offline
Registered User
 
Join Date: Feb 2002
Location: Auckland, New Zealand
Posts: 5,195
Registered SVX
Something which appears to be missed in discussions regarding intakes, is that the OEM system incorporates a plenum immediately before the throttle bodies and this fixes the start of a carefully designed variable system. Eliminating this plenum is surely not desirable.
__________________
Trevor, New Zealand.

As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit!
Reply With Quote
  #8  
Old 10-27-2007, 09:24 PM
crazyhorse's Avatar
crazyhorse crazyhorse is offline
242,000 mi on oem trans
 
Join Date: Aug 2007
Location: Greeneville, TN
Posts: 1,111
Registered SVX
The variable part of the intake is primarily behind the throttle blades. The plenum actually slows down the incoming air @WOT. Though at part throttle it gives a reserve of air for the engine to draw from. It helps throttle response, but after tip in, it's a hinderance.
The Tomyx intake is designed to speed up airflow, and smooth out the transition going into the throttles. From the supplied data, it does just that, very well.
__________________
[SIGPIC]http://www.subaru-svx.net/forum/image.php?type=sigpic&userid=5569&dateline=1207440 507[/SIGPIC]
Naught but by the grace of God
"42"
Current Stable By Age:
'89 Subaru XT6 Silver "Audrey" as in Hepburn
'96 SVX LSi #767Brilliant Red "Lil Red" Now on the front burner. Looking for a totalled, but running parts car.
Reply With Quote
  #9  
Old 10-27-2007, 10:16 PM
Evil One Evil One is offline
Pinto Boosting Freak
 
Join Date: Sep 2003
Location: Holyoke Ma, USA
Posts: 291
Send a message via AIM to Evil One Send a message via MSN to Evil One Send a message via Yahoo to Evil One
Bill, many thanks.
This is very similar to ram air setups I have built and/or run on other cars.
The tube from the airbox down you are using... is that the snorkle from the stock airbox?
I now have to decide on making a box and keeping my cone filter, or sourcing a stock airbox to replace the cone with.
As to the plenum. at WOT I can see it as being a spot of turbulence. I can, as crazyhorse mentioned, see it holding extra volume for tip in.
One thing I have wondered since looking under the hood, and this is a WHOLE new topic/can of worms, has anyone tried increasing intake manifold plenum volume?


Jim
__________________
1992 Dark Teal LS-L with 4.44 swap. NC Plate "EVIL I" *Dont Fear the GEAR*
1977 Ford Pinto baby blue with 79,000 miles
Reply With Quote
  #10  
Old 10-27-2007, 10:29 PM
Myxalplyx's Avatar
Myxalplyx Myxalplyx is offline
XT6 is SVX's Daddy
 
Join Date: Apr 2002
Location: New Castle, DE
Posts: 1,113
Send a message via ICQ to Myxalplyx Send a message via AIM to Myxalplyx Send a message via Yahoo to Myxalplyx
Quote:
Originally Posted by FOMOGO View Post
One thing I have wondered since looking under the hood, and this is a WHOLE new topic/can of worms, has anyone tried increasing intake manifold plenum volume?


Jim
I thought of this but that was as far as I went with it. The thought was to increase the dual piping going to the the two throttle bodies to be slightly larger than the stock throttle body size. This would help in initial tip in with increase air available but would slightly slow down intake air velocity at wide open throttle. It is a compromise. I think this setup may be best with a larger Maf sensor. Perhaps the throttle bodies themselves would be the point of discussion after this point though (larger throttle bodies). Even still, a larger throttle body in and of itself will improve throttle response. That's for another discussion though. (Just for giggles, I am looking into this now. Haven't read anything around it here yet but I'll keep searching).
__________________
Kevin Thomas
1997 2.2ltr Subaru Impreza Outback Sport Wagon (AWD/Auto) 13.03@100mph
1989 2.7ltr Subaru XT6 (AWD/Auto) 15.912@85.93mph
1996 3.3ltr SVX (AWD/Auto) 15.070@91.38mph
***R.I.P***
2010 RAV4 AWD Sport (13.717 @ 99.19mph )
2015 Honda Fit LX CVT (15.2 @ 90mph)

Last edited by Myxalplyx; 10-27-2007 at 10:34 PM.
Reply With Quote
  #11  
Old 10-27-2007, 10:50 PM
crazyhorse's Avatar
crazyhorse crazyhorse is offline
242,000 mi on oem trans
 
Join Date: Aug 2007
Location: Greeneville, TN
Posts: 1,111
Registered SVX
Like this?

That's a BBK throttle body for an F-150 truck
__________________
[SIGPIC]http://www.subaru-svx.net/forum/image.php?type=sigpic&userid=5569&dateline=1207440 507[/SIGPIC]
Naught but by the grace of God
"42"
Current Stable By Age:
'89 Subaru XT6 Silver "Audrey" as in Hepburn
'96 SVX LSi #767Brilliant Red "Lil Red" Now on the front burner. Looking for a totalled, but running parts car.
Reply With Quote
  #12  
Old 10-27-2007, 11:00 PM
Evil One Evil One is offline
Pinto Boosting Freak
 
Join Date: Sep 2003
Location: Holyoke Ma, USA
Posts: 291
Send a message via AIM to Evil One Send a message via MSN to Evil One Send a message via Yahoo to Evil One
My thoughts, and you have to keep in mind I come from a turbocharging background, was to eliminate the divider in the intake... bubble the top... and go with a single blade TB such as the accufab unit used on the 03-04 cobras.


Jim
__________________
1992 Dark Teal LS-L with 4.44 swap. NC Plate "EVIL I" *Dont Fear the GEAR*
1977 Ford Pinto baby blue with 79,000 miles
Reply With Quote
  #13  
Old 10-27-2007, 11:48 PM
nextse7en's Avatar
nextse7en nextse7en is offline
Graphic Artist
 
Join Date: Sep 2004
Location: Eugene, OR
Posts: 789
To suggest that you could increase power levels by further modifying the intake beyond a slight smoothing of the intake to the plenum, and a ram air setup is dubious at best.

Please rember, these cars are not mid 60's american V8s, there is no identifiable restriction area that can yeild large gains when rectified. What you do to the intake, you must to to the injectors, what you do to the injectors, you must to with the ports, what you do with the ports, you must do with the valves, what you do with the valves, you must to with the cams, what you do with the cams, you must do with the exhaust, and when you are done with all of it, you must consider the MAF and ECU.

In the end, it must be said that Subaru made this particular engine to produce a particular amount of HP/Torque. To increase the amount of HP/Tourqe, you must do one of the following.

Update the entire engine with cams, intake, heads, exaust, maf and ecu. This will create more HP - albeit in the higher RPM band (then you'll want to get a 5 speed, or at the very least, 4.44s)

-OR-

Update the entire engine with cams, intake, heads, exaust, maf and ecu. pistons, bearings, etc.
and then supercharge, or turbo the damn thing.

-Patrick
__________________
Patrick

1995 Ebony Pearl. S.N. 0001 "Araby"

JDM Power Mode Switch, Integrated GPS/Video Player
6Xk Miles.

1992 Teal - Sold to Mysvxrocks
[SIGPIC][/SIGPIC]
Reply With Quote
  #14  
Old 10-28-2007, 07:01 AM
Evil One Evil One is offline
Pinto Boosting Freak
 
Join Date: Sep 2003
Location: Holyoke Ma, USA
Posts: 291
Send a message via AIM to Evil One Send a message via MSN to Evil One Send a message via Yahoo to Evil One
You are 100% correct.
Subaru made these engines to function as a perfect unit.
At stock power levels with no mods.

From looking at dyno charts and making comparisons, when you make 1 modification you run the gamut of related mods to get maximum power out of it.
Looking at the dyno chart Myxalplyx posted of his TMyx intake, even tho his car has cams it followed the stock power curve closely with the better flowing STi filter in the stock airbox.
It made more power than stock with the airbox... but still had the same power characteristics.
With the more free breathing allowed with the ToMyx intake it still followed the same power characteristics... but at the top end seriously pulled away.
This says, to me at least, that the stock airbox is perfect for a stock car... but with a few mods it starts being a bottleneck.

I am interested in maximizing the airflow of the engine.
The engine is designed to have good midrange tq and an acceptable top end.
In my opinion it lays down at least a thousand RPM too early.
I want to see what it does with optimized flow.
Subaru had to follow emissions and low sound requirements, in general this will slow down flow.
I want to dyno the car as stock as I can get it, then after my battery of mods. I fully believe that increasing plenum size will move the powerband up slightly... while sacrificing some midrange for an improved top end pull.
I know the MAF is going to be another power bottleneck.
So I will either be getting an eprom burned or purchasing a chip from LAN.

I know there have been many knowledgeable people do many things with these cars, but there shouldnt be any harm in trying some new things.
My ideas may work... they may be dismal failures.
But I will have fun trying things.


Jim
__________________
1992 Dark Teal LS-L with 4.44 swap. NC Plate "EVIL I" *Dont Fear the GEAR*
1977 Ford Pinto baby blue with 79,000 miles
Reply With Quote
  #15  
Old 10-28-2007, 08:25 AM
immortal_suby's Avatar
immortal_suby immortal_suby is offline
Thread Killah
Alcyone Gold Contributor
 
Join Date: Feb 2001
Location: Greenville, SC
Posts: 5,835
Registered SVX
This had to be the ugliest - but it worked
Underhood of the immortal suby (my little red wagon)




Good luck with your idea!
__________________
Matt
Locker Link
2015 BRZ Limited 6MT
92 Ebony LS-L ECUtune Stage2av1, Z32 MAF, 370cc injectors, TomsSVX intake, BontragerWorks 22mm RSB #003, HID Hi and Lo beams, OT endlink and bushing mods, PWR Aluminum radiator, Harvey's QC shift kit, 2.5" flowmaster 80 exhaust, 17" Michelin Pilot Sport A/S, Poly sway bar bushings, Slotted Bradi rotors, AFBeefcake powdercoated calipers, 97 grill, and a huge set of air horns. 300,000 miles and counting
92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles
19 Subaru Ascent Premium - -Hers !.
89 DL 4x4 little red wagon - a.k.a. The immortal suby. 275k R.I.P.
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


All times are GMT -6. The time now is 12:08 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
© 2001-2015 SVX World Network
(208)-906-1122