Motor has comps biggest blower cam but there's a good chance the car will be getting a single this month. Can anyone give some actual facts on how well this cam and lets say a big 76mm will work? Don't be afraid to give me an in depth explanation lol
Single Turbo question
- Thread starter biltnsprayed5.0
- Start date
The blower cams have more exhaust duration then i would like to see on a turbo.
The deal with cams on blowers vs turbos is very different.
with a blower you are trying to get as much exhaust out as possible. Hence all that extra duration.
with a Turbo you have to limit the duration do to the fact the exhaust is pressurized. SO if you hold the valve open too long it will let exhaust back in the chamber.
I have a feeling you will see slower spool times and not as much power as you could with a turbo specific cam or just go back to stock cams.
What Springs are you running and is your setup limited or locked out or stock VCT?
CPRsm
Active Member
Eric beat me to my long winded post. Posting while watching cartoons with kids makes simple things take too long lol
Idk the cam specs on those. But as a generalization you're going to give up low and midrange for top end. If the cams are small enough to maintain a good intake closing event, you could gain top end without losing it down low. The duration is a big reason for losing power down low. The longer the duration the earlier the valves open, and later they close.
An intake valve actually closes after bottom dead center and is heading to TDC. Closing the intake earlys give the piston more time to make compression. It also can cause detonation.
Exhaust valve can cause a power lose as well. Long duration makes the valve open early. Holding the exh valve longer give the combustion process a longer amount of time to push on the piston to create torque. After a certain point, holding it closed has diminished returns. On a turbo especially(because of back pressure), opening it earlier helps higher rpm cylinder fill. Opening early gives the piston more time to evacuate the cylinder for a fresh charge. The important part of a turbo kit lies here. Pushing the EVO(exh valve opening) forward can raise back pressure. Opening earlier puts the opening point of the valve closer to the combustion event. So EGTs are higher. So when it opens earlier, that same comustion has more volume to it. Your exh and more importantly turbine, needs to be able to process more volume.
A valve opening sooner or later is assuming the lobe center line is the same. Like mentioned, because of variable cam timing, it may be possible to keep valve events close enough to stock if the cams are small enough.
Idk the cam specs on those. But as a generalization you're going to give up low and midrange for top end. If the cams are small enough to maintain a good intake closing event, you could gain top end without losing it down low. The duration is a big reason for losing power down low. The longer the duration the earlier the valves open, and later they close.
An intake valve actually closes after bottom dead center and is heading to TDC. Closing the intake earlys give the piston more time to make compression. It also can cause detonation.
Exhaust valve can cause a power lose as well. Long duration makes the valve open early. Holding the exh valve longer give the combustion process a longer amount of time to push on the piston to create torque. After a certain point, holding it closed has diminished returns. On a turbo especially(because of back pressure), opening it earlier helps higher rpm cylinder fill. Opening early gives the piston more time to evacuate the cylinder for a fresh charge. The important part of a turbo kit lies here. Pushing the EVO(exh valve opening) forward can raise back pressure. Opening earlier puts the opening point of the valve closer to the combustion event. So EGTs are higher. So when it opens earlier, that same comustion has more volume to it. Your exh and more importantly turbine, needs to be able to process more volume.
A valve opening sooner or later is assuming the lobe center line is the same. Like mentioned, because of variable cam timing, it may be possible to keep valve events close enough to stock if the cams are small enough.
I have the +20 limiters... So probably no way to test all this until I actually put the turbo on and see how the cam and turbo work together?
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