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#1
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Dohc...
For Automobile's "Tech Talk" in a special issue:
<<DOHC: Camshafts are responsible for opening an engine's valves. Engineeers have stuck them all over the place, but the current concensus is that using two for each bank of cylinders and mounting the camshafts atop the cylinder heads is the best arrangement, hense the term "DUAL OVERHEAD CAMSHAFTS".>> Our SVXs have quad overhead cams, right? It says "4 cam" on the engine cover. So, doen't that mean that there's two for each cylinder bank, like most cars, and like most cars also, there's two cylinder banks, so...shouldn't this term be called QOHC for quad overhead cams? <<VARIABLE VALVE TIMING: To make engines cleaner and more efficient than walking, car companies have turned every stone seeking performance gains. A recent method is to alter how and when the valves open versus engine speed and load. Variable valve timing is a very effictive method of increasing top end power while maintaining low end smoothness and response>> Our SVXs have IRIS (Intake Resonance Induction System) that is supposed to do the same thing as VVT, right? I'm pretty sure this is true, because with my BlitZe intake, when i'm accelerating and I hit past 4k RPM, the engine rips open, pulls harder, and you can hear the wooshing of the air going through the cone filter. So, is IRIS basically the same as VVT and VTEC? Thanks for the info |
#2
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well a v6, v8, v10, v12 or v16 with two sets of camshafts per cylinder bank is still called a twin cam engine.. i don't exactly think "quad cam" is a necessary term when talking about our engines..
and as far as the IRIS goes, i'm really not sure -adam |
#3
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We are really only dohc - just 2 cams for each cylinder but 4 total due to the boxer layout
The iris varies the air intake into the runners before it hits the valves. (open/ closed to both sets of runners) vvt/vtec (or whatever) varies the actual opening of the valves (lift/ duration) I think it might be a stretch to call ours variable valve timing - since it is not varying the actual valve timing one bit. But it does do something and you can definitely feel it when it comes on.
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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. |
#4
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As above on the Quad-Cam thing, we still only have double-overhead-cam on each bank. Concider how many cams control all the valves in one cylinder.
Variable Valve timing requires some really slick technologies attached to the valves and/or the cam drive. The SVX does not have this technology.
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Chris G 92 Pearlie, sold @ ~209k miles. Now owned by Tim. Current Ride, 1985 Honda Aero 80, stock 3024 klms |
#5
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really depends who you are taling with...MRT rally calls them quad cams...some Muscle car guys say they have quad cams....but generally only count the number of cams per cylinder...not total number of cams.
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I like my EJ205 swap...it's fast |
#6
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Thanks for the input
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#7
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Ya know that DOHC question seemed a little....... duh didn't it??? I mean when you call an engine a "Quad cam engine" you are saying that it has 4 camshafts total... Not Four on each bank of cylinders... Just think about it...
And there is no such thing as "QOHC"... When you say Dual Overhead Camshaft, that means that there are only 2 camshafts "Overhead" ..... I'm done with that...
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2020 Subaru Outback Touring - Wife's first Subaru 2005 Volvo V70R - 5-cylinder love! :Heart: ** SOLD **1998 Subaru Legacy 2.5GT Wagon - MOST RELIABLE car I've ever owned ** SOLD **2006Subaru WRXSTi (Former "Boxer4Racing.com / Continential Tire" STi) - Built EJ22t block / EJ207 JDM STi "big port heads" - 9,000rpm MONEY PIT!!! ** SOLD ** 1995 "Tree-Hugger Green" SVX L AWD(5 MT) --- "Gumby" 130K miles #399 in MY95, my original love... |
#8
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well I seen a TOHC (triple overhead cam) in real life...it was designed for some crazy piston powered Airplane....go figure...sort of like having the 5 valves per cylinder....why?...really?
And I believe there is actually a QOHC engine out...I think it is bugatti....not sure though
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I like my EJ205 swap...it's fast Last edited by homemade wrx; 01-17-2004 at 10:29 PM. |
#9
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Triple over head cam???? If you can show me a picture of that then it will be the first time I've ever seen that...
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2020 Subaru Outback Touring - Wife's first Subaru 2005 Volvo V70R - 5-cylinder love! :Heart: ** SOLD **1998 Subaru Legacy 2.5GT Wagon - MOST RELIABLE car I've ever owned ** SOLD **2006Subaru WRXSTi (Former "Boxer4Racing.com / Continential Tire" STi) - Built EJ22t block / EJ207 JDM STi "big port heads" - 9,000rpm MONEY PIT!!! ** SOLD ** 1995 "Tree-Hugger Green" SVX L AWD(5 MT) --- "Gumby" 130K miles #399 in MY95, my original love... |
#10
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My Honda XR500R had triple overhead cam, with an override for a compression release, let me see if I can find a blowup of it, its very cool.
double with an extra gear driven cam for valve #5.
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Chris G 92 Pearlie, sold @ ~209k miles. Now owned by Tim. Current Ride, 1985 Honda Aero 80, stock 3024 klms |
#11
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That's crazy... I've never heard of TOHC before..... I guess there's a first time for everything and hey, you're suppose to learn something new every day right, or that day is wasted...
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2020 Subaru Outback Touring - Wife's first Subaru 2005 Volvo V70R - 5-cylinder love! :Heart: ** SOLD **1998 Subaru Legacy 2.5GT Wagon - MOST RELIABLE car I've ever owned ** SOLD **2006Subaru WRXSTi (Former "Boxer4Racing.com / Continential Tire" STi) - Built EJ22t block / EJ207 JDM STi "big port heads" - 9,000rpm MONEY PIT!!! ** SOLD ** 1995 "Tree-Hugger Green" SVX L AWD(5 MT) --- "Gumby" 130K miles #399 in MY95, my original love... |
#12
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Does anyone know the cam configuration on VW's "W" engines?
Ron (I know what a Camry is).
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Good s**t happened. 69 was worth the wait. '92 stock semi-pristine ebony - 160K '96 Grand Caravan - 240K '01 Miata SE - 79K '07 Chrysler Pacifica - 60k - future money pit. |
#13
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Hey Ron.
I bet someone does just not me OOO Quick quiz: Name 2 engines with no camshafts.
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Chris G 92 Pearlie, sold @ ~209k miles. Now owned by Tim. Current Ride, 1985 Honda Aero 80, stock 3024 klms |
#14
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Quote:
Mazda & NSU's rotarys. Name an engine without valves (as we know them). Ron.
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Good s**t happened. 69 was worth the wait. '92 stock semi-pristine ebony - 160K '96 Grand Caravan - 240K '01 Miata SE - 79K '07 Chrysler Pacifica - 60k - future money pit. |
#15
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Very good, a Rotary engine has no camshafts. and no valves, persay.
One more type of engine. ???
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Chris G 92 Pearlie, sold @ ~209k miles. Now owned by Tim. Current Ride, 1985 Honda Aero 80, stock 3024 klms |
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