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Performance NA Cams on a Turbo? 

 

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 Post subject: Performance NA Cams on a Turbo?
Posted: Tue Oct 31, 2006 12:06 am 
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hey guys, i've currently got a stg1 RPD cam (very happy :D) and i'm working on a turbo setup for my car. just wondering if having a performance NA cam on a turbo engine (stock compression) will increase/decrease performance or lag, etc??

Also, what are the differences between a turbo cam and a NA cam? shorter duration and more lift because of higher pressures and you don't want valve overlap because you'll loose boost out the exhaust valves?

cheers guys
Slabz

 

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Posted: Tue Oct 31, 2006 2:39 am 
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It more a case of reversion back from exhaust which is why overlap is not good ..
The main part is plenty lift and aroud 114 lobe centre .. Cam timing around 224 / 220 @50 and 530 or so valve lift n 110 centerline..Good springs are a MUST as in doubles....

 

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Posted: Tue Oct 31, 2006 10:10 am 
Getting Side Ways
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EBXR8380 wrote:
It more a case of reversion back from exhaust which is why overlap is not good ..
The main part is plenty lift and aroud 114 lobe centre .. Cam timing around 224 / 220 @50 and 530 or so valve lift n 110 centerline..Good springs are a MUST as in doubles....


cheers EBXR8380, found this too on reversion:

http://www.hotrod.com/tipstricks/34219/index20.html wrote:
Exhaust reversion is the unwanted reversal of the exhaust gas flow backward into the cylinder during the exhaust stroke. There are several theories with regard to what causes exhaust reversion, and one held by Reher-Morrison goes like this: The exhaust gases burst into the header tube and then create a region of very high pressure. Similar to a compressed spring, the gases uncoil in both directions. Some of the exhaust gases travel backward into the port, and ultimately back into the cylinder. What’s the point? You can control exhaust reversion with a header-tube diameter that’s larger than the port (don’t port match the exhaust exactly to the header size). Additionally, quality valve springs are a must since they help to control the valves (valve bounce) which is also a contributor to reversion.


and i supposed that having a turbine in the exhaust (extra restriction) would add to the tendency for the gases to try and get back into the ports.

 

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EBII 4.0L GLi | T5 | 3.27 Spool | POD | KKK K27 Turbo | 600x300x76 FMIC | 40mm Wastegate (dead) | RPD Stg1 Cam | B&M Launch Control | Thermos | 3" Dump | Twin 2.25" Zorst | 197kw@3500rpm, 7psi LEAN!

To Come: Hydraulic Handbrake | Coilover Springs | Fuel Pump | Microtech MT8 | 455cc Injectors

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Posted: Tue Oct 31, 2006 11:52 am 
Getting Side Ways
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Yea don't get too into therory though...Mild N/A cams are o/k.. When you go over the imaginary line power / drivability drops.... Big cams on turbo engine in street cars is just not good company....A nice XR 6 cam would work fine. Use the turbo to make power....

 

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As in ZOOM 126 edition
331 Dart block,3.25/ 4340 steel crank, Oliver rods,TFS ported track heat heads, TFS track heat inlet Twin SC61 turbo's
Project 1UZ-EF has started.. S475 Turbo 4.0 V8 Mustang Celica.....

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Posted: Tue Oct 31, 2006 2:56 pm 
Getting Side Ways
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righto, one of the reasons i'm askin is because i've got someone who wants to buy my cam so i was thinking i could sell it to fund the turbo project if i could justify (to myself) that i wouldn't be sacrificing any power :P

 

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EBII 4.0L GLi | T5 | 3.27 Spool | POD | KKK K27 Turbo | 600x300x76 FMIC | 40mm Wastegate (dead) | RPD Stg1 Cam | B&M Launch Control | Thermos | 3" Dump | Twin 2.25" Zorst | 197kw@3500rpm, 7psi LEAN!

To Come: Hydraulic Handbrake | Coilover Springs | Fuel Pump | Microtech MT8 | 455cc Injectors

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