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#16
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Chike, I think its necessary to consider perspective when looking at what works with the V-8 people. With the exception of the newest V-8's, most factory V-8 exhaust manifolds do not flow particularly well, and there is significant exhaust flow overlap between cylinders on the same side of a V-8 engine, so even a shorty header can provide smoother flow and some improved isolation between cylinders. OTOH, our factory SVX exhaust manifolds have a nice smooth flow pattern, and there is no exhaust flow overlap between cylinders on the same side of the engine. I think that the only thing that an aftermarket header can provide for the SVX is tuned scavenging which requires primaries that are at least 36" long to provide any scavenging in the useful part of the powerband.
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
#17
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Tom,
I don't feel any of the bends in the Outback Motorsports mandrel bent headers are that sharp (the bends in those 5.7L Edelbrock shorties are sharper). Also, our stock exhaust manifold has a few that are quite sharp. I would agree that the rest of the exhaust will need to be altered, but I'm not ready to give up on this idea just yet. Mychailo, I agree that the stock V-8 headers aren't the most efficient. How efficient are the factory SVX headers at stock power levels (I think someone mentioned they were around 95%+)??? I'm just thinking with my cams and other upgrades, these primaries could flow better than stock and produce some +ve gains. I'm also wondering if those claims by Stebro were in fact true. -Chike P.S. However, it seems from the discussion taking place in the n/a upgrade thread more gains can probably be made from a better intake system.
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) Last edited by Chiketkd; 11-21-2005 at 10:38 AM. |
#18
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Okay, I spoke with the owner John at Outback Motorsports and those primary tubes are designed for a dune buggy - the flanges match up with the EG33 and will be a direct fit to our engines, but he thinks it'll butt into a motor mount or something (never tried to test fit it to an EG33 that was still in the SVX).
He was really nice and said that the pair of EG33 headers are sold for $250.00. However, he thinks that for a street application, it would be better to have custom ones made. He's willing to sell the flanges that fit up against the motor and even the pair of 3-into-1 collectors seperately. Here are the specs for his dune-buggy primary tubes: 1 5/8" ID primary tubes leading to the 3-into-1 collector that exits as a 2 1/4" ID pipe. On a stock EG33 dune buggy he normally sees 270-280hp with his primaries. -Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#19
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Chike,
Nice stock manifold pics I see you found Outback. The guy who blueprinted my injectors and rails told me about them - he does all their injector work. Outback also offers a braided steel line to connect our fuel rails, it you're interested. -Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#20
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Quote:
Looking at the exhaust layout behind the exhaust manifold: I really doubt those headers will butt into a lower subframe. I may just go your route Bill and get a spare set of stock manifolds, have them sand blasted and then send them out for an extrusion and temp coating. However, those Outback Motorsports 'shorty' headers look sweet! -Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#21
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Quote:
On the other hand, did you get the chance to ask him about the price of the flanges and 3 to 1 collectors as they are Chike? or same price?
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Danny 1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon) 1967 Mercedes-Benz 250SL Euro Specs, Hard/Softtop, White/Red. Under Complete Restoration 2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection. |
#22
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Quote:
-Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#23
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Gentlemen,
A few header basics;
Out exhaust ports in the heads are 1.5". They ( the exhaust ports at the head surface) are about 4" from the back of the exhaust valve head. From my reasearch, we need 1,5/8" Inside Diameter primary tubes. For a NA, turbocharged, or Supercharged engine, WITH THE STOCK CAMS, 1,5/8" about 30" long for the primary tubes/pipes is/was the correct length from about six different sources. The longer the primary tube, the better the power at lower engine speeds. The shorter the tubes the higher rpm maxium torque is reached. Collectors should be about 2,1/4" ID and the length is argueable. For an expantion chamber effect it should be ten times the volume of ONE cylinder displacement. Equal length primaries, and MANDREL bending is very important, and hard to do. Keeping the heat inside the headers and exhaust system raises the speed of sound, and helps speed the flow of exhaust out of the cylinders! This is why ceramic coatings, OR stainless steel headers/exhaust systems are better than conventional mild steel systems. And not just pretty. I have made two sets of headers, and am happy with the performance of the second, equal length set, but ground clearance is lost, and unless it is coated, heat is lost at the expence of power. Pictures are in my extensive locker. More later, Tom
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www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#24
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Quote:
-Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
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